299 results on '"G. Guo"'
Search Results
2. Genetic analyses of blood β-hydroxybutyrate predicted from milk infrared spectra and its association with longevity and female reproductive traits in Holstein cattle
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W. Lou, H. Zhang, H. Luo, Z. Chen, R. Shi, X. Guo, Y. Zou, L. Liu, L.F. Brito, G. Guo, and Y. Wang
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β-hydroxybutyrate ,Chinese Holstein ,metabolic disease ,random regression model ,Dairy processing. Dairy products ,SF250.5-275 ,Dairying ,SF221-250 - Abstract
ABSTRACT: Ketosis is one of the most prevalent and complex metabolic disorders in high-producing dairy cows and usually detected through analyses of β-hydroxybutyrate (BHB) concentration in blood. Our main objectives were to evaluate genetic parameters for blood BHB predicted based on Fourier-transform mid-infrared spectra from 5 to 305 d in milk, and estimate the genetic relationships of blood BHB with 7 reproduction traits and 6 longevity traits in Holstein cattle. Predicted blood BHB records of 11,609 Holstein cows (after quality control) were collected from 2016 to 2019 and used to derive 4 traits based on parity number, including predicted blood BHB in all parities (BHBp), parity 1 (BHB1), parity 2 (BHB2), and parity 3+ (BHB3). Single- and multitrait repeatability models were used for estimating genetic parameters for the 4 BHB traits. Random regression test-day models implemented via Bayesian inference were used to evaluate the daily genetic feature of BHB variability. In addition, genetic correlations were calculated for the 4 BHB traits with reproduction and longevity traits. The heritability estimates of BHBp, BHB1, BHB2, and BHB3 ranged from 0.100 ± 0.026 (± standard error) to 0.131 ± 0.023. The BHB in parities 1 to 3+ were highly genetically correlated and ranged from 0.788 (BHB1 and BHB2) to 0.911 (BHB1 and BHB3). The daily heritability of BHBp ranged from 0.069 to 0.195, higher for the early and lower for the later lactation periods. A similar trend was observed for BHB1, BHB2, and BHB3. There are low direct genetic correlations between BHBp and selected reproductive performance and longevity traits, which ranged from −0.168 ± 0.019 (BHBp and production life) to 0.157 ± 0.019 (BHBp and age at first calving) for the early lactation stage (5 to 65 d). These direct genetic correlations indicate that cows with higher BHBp (greater likelihood of having ketosis) in blood usually have shorter production life (−0.168 ± 0.019). Cows with higher fertility and postpartum recovery, such as younger age at first calving (0.157 ± 0.019) and shorter interval from calving to first insemination in heifer (0.111 ± 0.006), usually have lower BHB concentration in the blood. Furthermore, the direct genetic correlations change across parity and lactation stage. In general, our results suggest that selection for lower predicted BHB in early lactation could be an efficient strategy for reducing the incidence of ketosis as well as indirectly improving reproductive and longevity performance in Holstein cattle.
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- 2022
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3. Branched-chain volatile fatty acids and folic acid accelerated the growth of Holstein dairy calves by stimulating nutrient digestion and rumen metabolism
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Y.R. Liu, H.S. Du, Z.Z. Wu, C. Wang, Q. Liu, G. Guo, W.J. Huo, Y.L. Zhang, C.X. Pei, and S.L. Zhang
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nutrient digestibility ,ruminal microflora ,cellulolytic rumen bacteria ,microbial enzyme activity ,microbial protein ,Animal culture ,SF1-1100 - Abstract
The combined addition of branched-chain volatile fatty acids (BCVFAs) and folic acid (FA) could improve growth performance and nutrient utilization by stimulating ruminal microbial growth and enzyme activity. This study was conducted to evaluate the effects of BCVFA and FA addition on growth performance, ruminal fermentation, nutrient digestibility, microbial enzyme activity, microflora and excretion of urinary purine derivatives (PDs) in calves. Thirty-six Chinese Holstein weaned calves (60 ± 5.4 days of age and 107 ± 4.7 kg of BW) were assigned to one of four groups in a randomized block design. Treatments were control (without additives), FA (with 10 mg FA/kg dietary DM), BCVFA (with 5 g BCVFA/kg dietary DM) and the combined addition of FA and BCVFA (10 mg/kg DM of FA and 5 g/kg DM of BCVFA). Supplements were hand-mixed into the top one-third of total mixed ration. Dietary concentrate to maize silage ratio was 50 : 50 on a DM basis. Dietary BCVFA or FA addition did not affect dry matter intake but increased average daily gain (ADG) and feed conversion efficiency. Ruminal pH and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition did not affect acetate proportion but decreased propionate proportion and increased acetate to propionate ratio. Total tract digestibility of DM, organic matter, CP and NDF was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition increased activity of carboxymethyl cellulase and cellobiase, population of total bacteria, fungi, Ruminococcus albus, R. flavefaciens, Fibrobacter succinogenes and Prevotella ruminicola as well as total PD excretion. Ruminal xylanase, pectinase and protease activity and Butyrivibrio fibrisolvens population were increased by BCVFA addition, whereas population of protozoa and methanogens was increased by FA addition. The BCVFA × FA interaction was significant for acetate to propionate ratio, cellobiase activity and total PD excretion, and these variables increased more with FA addition in diet without BCVFA than in diet with BCVFA. The data indicated that supplementation with BCVFA or FA increased ADG, nutrient digestibility, ruminal total VFA concentration and microbial protein synthesis by stimulating ruminal microbial growth and enzyme activity in calves.
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- 2020
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4. Effects of sodium selenite and coated sodium selenite on lactation performance, total tract nutrient digestion and rumen fermentation in Holstein dairy cows
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Z.D. Zhang, C. Wang, H.S. Du, Q. Liu, G. Guo, W.J. Huo, J. Zhang, Y.L. Zhang, C.X. Pei, and S.L. Zhang
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selenium ,milk performance ,nutrient digestibility ,ruminal microbiota ,microbial enzymatic activity ,Animal culture ,SF1-1100 - Abstract
Se can enhance lactation performance by improving nutrient utilization and antioxidant status. However, sodium selenite (SS) can be reduced to non-absorbable elemental Se in the rumen, thereby reducing the intestinal availability of Se. The study investigated the impacts of SS and coated SS (CSS) supplementation on lactation performance, nutrient digestibility, ruminal fermentation and microbiota in dairy cows. Sixty multiparous Holstein dairy cows were blocked by parity, daily milk yield and days in milk and randomly assigned to five treatments: control, SS addition (0.3 mg Se/kg DM as SS addition) or CSS addition (0.1, 0.2 and 0.3 mg Se/kg DM as CSS addition for low CSS (LCSS), medium CSS (MCSS) and high CSS (HCSS), respectively). Experiment period was 110 days with 20 days of adaptation and 90 days of sample collection. Dry matter intake was higher for MCSS and HCSS compared with control. Yields of milk, milk fat and milk protein and feed efficiency were higher for MCSS and HCSS than for control, SS and LCSS. Digestibility of DM and organic matter was highest for CSS addition, followed by SS addition and then control. Digestibility of CP was higher for MCSS and HCSS than for control, SS and LCSS. Higher digestibility of ether extract, NDF and ADF was observed for SS or CSS addition. Ruminal pH decreased with dietary Se addition. Acetate to propionate ratio and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was greater for SS, MCSS and HCSS than control. Ruminal H ion concentration was highest for MCSS and HCSS and lowest for control. Activities of cellobiase, carboxymethyl-cellulase, xylanase and protease and copies of total bacteria, fungi, Ruminococcus flavefaciens, Fibrobacter succinogenes and Ruminococcus amylophilus increased with SS or CSS addition. Activity of α-amylase, copies of protozoa, Ruminococcus albus and Butyrivibrio fibrisolvens and serum glucose, total protein, albumin and glutathione peroxidase were higher for SS, MCSS and HCSS than for control and LCSS. Dietary SS or CSS supplementation elevated blood Se concentration and total antioxidant capacity activity. The data implied that milk yield was elevated due to the increase in total tract nutrient digestibility, total VFA concentration and microorganism population with 0.2 or 0.3 mg Se/kg DM from CSS supplementation in dairy cows. Compared with SS, HCSS addition was more efficient in promoting lactation performance of dairy cows.
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- 2020
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5. Effects of guanidinoacetic acid supplementation on growth performance, nutrient digestion, rumen fermentation and blood metabolites in Angus bulls
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S.Y. Li, C. Wang, Z.Z. Wu, Q. Liu, G. Guo, W.J. Huo, J. Zhang, L. Chen, Y.L. Zhang, C.X. Pei, and S.L. Zhang
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guanidinoacetate ,weight gain ,nutrient digestibility ,rumen microflora ,blood indicators ,Animal culture ,SF1-1100 - Abstract
Guanidinoacetic acid (GAA) can improve the growth performance of bulls. This study investigated the influences of GAA addition on growth, nutrient digestion, ruminal fermentation and serum metabolites in bulls. Forty-eight Angus bulls were randomly allocated to experimental treatments, that is, control, low-GAA (LGAA), medium-GAA (MGAA) and high-GAA (HGAA), with GAA supplementation at 0, 0.3, 0.6 and 0.9 g/kg DM, respectively. Bulls were fed a basal diet containing 500 g/kg DM concentrate and 500 g/kg DM roughage. The experimental period was 104 days, with 14 days for adaptation and 90 days for data collection. Bulls in the MGAA and HGAA groups had higher DM intake and average daily gain than bulls in the LGAA and control groups. The feed conversion ratio was lowest in MGAA and highest in the control. Bulls receiving 0.9 g/kg DM GAA addition had higher digestibility of DM, organic matter, NDF and ADF than bulls in other groups. The digestibility of CP was higher for HGAA than for LGAA and control. The ruminal pH was lower for MGAA, and the total volatile fatty acid concentration was greater for MGAA and HGAA than for the control. The acetate proportion and acetate-to-propionate ratio were lower for MGAA than for LGAA and control. The propionate proportion was higher for MGAA than for control. Bulls receiving GAA addition showed decreased ruminal ammonia N. Bulls in MGAA and HGAA had higher cellobiase, pectinase and protease activities and Butyrivibrio fibrisolvens, Prevotella ruminicola and Ruminobacter amylophilus populations than bulls in LGAA and control. However, the total protozoan population was lower for MGAA and HGAA than for LGAA and control. The total bacterial and Ruminococcus flavefaciens populations increased with GAA addition. The blood level of creatine was higher for HGAA, and the activity of l-arginine glycine amidine transferase was lower for MGAA and HGAA, than for control. The blood activity of guanidine acetate N-methyltransferase and the level of folate decreased in the GAA addition groups. The results indicated that dietary addition of 0.6 or 0.9 g/kg DM GAA improved growth performance, nutrient digestion and ruminal fermentation in bulls.
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- 2020
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6. Effects of isovalerate supplements on morphology and functional gene expression of rumen mucosa in pre- and post-weaning dairy calves
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Q. Liu, C. Wang, G. Guo, W.J. Huo, Y.L. Zhang, C.X. Pei, S.L. Zhang, and H. Wang
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isovalerate ,rumen development ,morphology ,functional gene ,dairy calves ,Animal culture ,SF1-1100 - Abstract
Isovalerate supplements could stimulate rumen development by improving morphology and function of rumen mucosa, and then promote the growth of calves. This study was done to evaluate the effects of isovalerate supplements on morphology and functional gene expression of rumen mucosa in dairy calves. In total, 48 Chinese Holstein male calves with 15 days of age and 45.1±0.36 kg of BW were randomly assigned to four groups. The treatments were: control, low-isovalerate, moderate-isovalerate and high-isovalerate with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. Supplementary isovalerate was hand-mixed into milk in pre-weaning calves and into concentrate portion in post-weaning calves. The study consisted of a 15-day-adaptation period and a 60-day-sampling period. Calves were weaned at 60 days of age. Three calves were slaughtered from each of the four treatments at 30, 60 and 90 days of age. The weight of body and stomach were measured, samples of ruminal tissues and blood were analyzed. Total stomach weight, total stomach to BW ratio, rumen wall and keratinized layer thickness, serum growth hormone and IGF-1 for both pre- and post-weaning calves increased linearly with increasing isovalerate supplements. Rumen to total stomach weight ratio, the length and width of rumen papillae, and serum β-hydroxybutyrate increased linearly for post-weaning calves. However, abomasum weight to total stomach weight ratio decreased linearly for both pre- and post-weaning calves. The relative messenger RNA expression for growth hormone receptor, IGF-1 receptor and 3-hydroxy-3-methylglutaryl-CoA synthase 1 in rumen mucosa increased linearly for post-weaning calves. Our results suggested that isovalerate supplements promoted rumen development in a dose-dependent manner. The optimum dose was 6.0 g isovalerate per calf per day.
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- 2018
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7. Effects of branched-chain volatile fatty acids on lactation performance and mRNA expression of genes related to fatty acid synthesis in mammary gland of dairy cows
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Q. Liu, C. Wang, G. Guo, W.J. Huo, S.L. Zhang, C.X. Pei, Y.L. Zhang, and H. Wang
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branched-chain volatile fatty acids ,ruminal fermentation ,nutrient digestibility ,milk fat synthesis ,gene expression ,Animal culture ,SF1-1100 - Abstract
Branched-chain volatile fatty acids (BCVFA) supplements could promote lactation performance and milk quality by improving ruminal fermentation and milk fatty acid synthesis. This study was conducted to evaluate the effects of BCVFA supplementation on milk performance, ruminal fermentation, nutrient digestibility and mRNA expression of genes related to fatty acid synthesis in mammary gland of dairy cows. A total of 36 multiparous Chinese Holstein cows averaging 606±4.7 kg of BW, 65±5.2 day in milk (DIM) with daily milk production of 30.6±0.72 kg were assigned to one of four groups blocked by lactation number, milk yield and DIM. The treatments were control, low-BCVFA (LBCVFA), medium-BCVFA (MBCVFA) and high-BCVFA (HBCVFA) with 0, 30, 60 and 90 g BCVFA per cow per day, respectively. Experimental periods were 105 days with 15 days of adaptation and 90 days of data collection. Dry matter (DM) intake tended to increase, but BW changes were similar among treatments. Yields of actual milk, 4% fat corrected milk, milk fat and true protein linearly increased, but feed conversion ratio (FCR) linearly decreased with increasing BCVFA supplementation. Milk fat content linearly increased, but true protein content tended to increase. Contents of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0 and C15:0 fatty acids in milk fat linearly increased, whereas other fatty acids were not affected with increasing BCVFA supplementation. Ruminal pH, ammonia N concentration and propionate molar proportion linearly decreased, but total VFA production and molar proportions of acetate and butyrate linearly increased with increasing BCVFA supplementation. Consequently, acetate to propionate ratios linearly increased. Digestibilities of DM, organic matter, CP, NDF and ADF also linearly increased. In addition, mRNA expressions of peroxisome proliferator-activated receptor γ, sterol regulatory element-binding factor 1 and fatty acid-binding protein 3 linearly increased, mRNA expressions of acetyl-coenzyme A carboxylase-α, fatty acid synthase and stearoyl-CoA desaturase quadratically increased. However, lipoprotein lipase mRNA expression was not affected by treatments. The results indicated that lactation performance and milk fat synthesis increased with BCVFA supplementation by improving ruminal fermentation, nutrient digestibility and mRNA expressions of genes related to milk fat synthesis.
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- 2018
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8. Effects of isobutyrate supplementation in pre- and post-weaned dairy calves diet on growth performance, rumen development, blood metabolites and hormone secretion
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C. Wang, Q. Liu, Y.L. Zhang, C.X. Pei, S.L. Zhang, G. Guo, W.J. Huo, W.Z. Yang, and H. Wang
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isobutyrate ,growth performance ,rumen development ,blood parameter ,dairy calves ,Animal culture ,SF1-1100 - Abstract
Isobutyrate supplements could improve rumen development by increasing ruminal fermentation products, especially butyrate, and then promote the growth performance of calves. The objective of this study was to evaluate the effects of isobutyrate supplementation on growth performance, rumen development, blood metabolites and hormone secretion in pre- and post-weaned dairy calves. In total, 56 Chinese Holstein male calves with 30 days of age and 72.9±1.43 kg of BW, blocked by days of age and BW, were assigned to four groups in a randomized block design. The treatments were as follows: control, low-isobutyrate, moderate-isobutyrate and high-isobutyrate with 0, 0.03, 0.06 and 0.09 g isobutyrate/kg BW per calf per day, respectively. Supplemental isobutyrate was hand-mixed into milk of pre-weaned calves and the concentrate portion of post-weaned calves. The study consisted of 10 days of an adaptation period and a 50-day sampling period. Calves were weaned at 60 days of age. Seven calves were chosen from each treatment at random and slaughtered at 45 and 90 days of age. BW, dry matter (DM) intake and stomach weight were measured, samples of ruminal tissues and blood were determined. For pre- and post-weaned calves, DM intake and average daily gain increased linearly (P
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- 2017
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9. Effect of microwave drying technology on drying kinetics of Al₂O₃–ZrO₂ composite ceramic powder
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Zhou, J. (Ju), Cao, W. (Wei), Zhang, Y. (Yanqiong), Omran, M. (Mamdouh), Chen, G. (Guo), Gao, L. (Lei), Zhang, F. (Fan), Tang, J. (Ju), Zhou, J. (Ju), Cao, W. (Wei), Zhang, Y. (Yanqiong), Omran, M. (Mamdouh), Chen, G. (Guo), Gao, L. (Lei), Zhang, F. (Fan), and Tang, J. (Ju)
- Abstract
Al₂O₃–ZrO₂ composite ceramic is a significant structural material and functional material, and the preparation of high-quality Al₂O₃–ZrO₂ powder is a key step to meeting practical application requirements. The major factor affecting the quality of Al₂O₃–ZrO₂ powder is the drying effect. This paper uses modern microwave drying technology to dry Al₂O₃–ZrO₂ powder. The result was indicative that the average drying rate increases with initial moisture content, initial mass, and microwave heating power. Four dynamic models were applied to fit the empirical data of Al₂O₃–ZrO₂ powder under different pretreatment conditions, the Modified Page model can precisely delineate the Al₂O₃–ZrO₂ microwave drying procedure. To evaluate the changes in samples before and post-drying, the specimens were characterized by Fourier transform infrared spectroscopy. These results demonstrate that microwaves can accelerate the drying of Al₂O₃–ZrO₂ and improve its dispersion. Fick’s second law calculates the effective diffusion coefficient. When the initial moisture content of Al₂O₃–ZrO₂ was 5.6%, the microwave heating power is 560 W, and the initial quality is 15 g, the effective diffusion coefficient of Al₂O₃–ZrO₂ is 0.006361 m²/s. Based on the relevance of the microwave power and activating energy, the activating energy of microwave drying Al₂O₃–ZrO₂ was calculated, which is −34.80 g/W. This paper provides basic study data and theory instructions for microwave drying technology in drying Al₂O₃–ZrO₂ even the drying process in green metallurgy.
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- 2023
10. Microwave efficient extraction of manganese from low-grade pyrolusite by pyrite reduction acid leaching process
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Du, J. (Jinjia), Zhang, Y. (Yanqiong), Lu, J. (Jiajia), Gao, L. (Lei), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, J. (Jin), Chen, G. (Guo), Du, J. (Jinjia), Zhang, Y. (Yanqiong), Lu, J. (Jiajia), Gao, L. (Lei), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, J. (Jin), and Chen, G. (Guo)
- Abstract
With the continuous economic and social development of China, the demand for pyrolusite has increased tremendously, accompanied by a decrease in high-grade pyrolusite (HGP). Thus, it is urgent to find viable alternatives, such as low-grade pyrolusite (LGP). Currently, a relatively mature process technology is a one-step acid leaching of manganese (Mn) from pyrolusite using pyrite (PY) as a reducing agent. While the method can achieve a relatively high leaching efficiency of Mn at atmospheric pressure, it requires a significant amount of time. To pursue maximum effectiveness and efficiency, here we applied microwave leaching technology to the one-step acid leaching process to the extraction of Mn from LGP, and PY as a reducing agent. The results showed that the leaching efficiency of Mn reached 96.2% at time = 150 min, agitation speed = 400 rpm, temperature = 363 K, acid concentration = 1.5 M, liquid-solid ratio = 10: 1 (mL: g), and SLGP-SPY- mass ratio = 10: 2. Furthermore, the kinetic analysis showed that the chemical reaction control model (1-(1-X)1/3 = kt) can be used to explain the mechanism of the microwave leaching process. Finally, according to the Arrhenius equation, the apparent activation energy (Ea) for the microwave leaching process was calculated as 44.8 kJ/mol. This work provides the preliminary theoretical and technical basis for recovering Mn from LGP. In summary, these results imply that LGP could be effectively utilized and developed by microwave heating technology in the future.
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- 2023
11. Research on the drying kinetics for the microwave drying of Y₂O₃–ZrO₂ ceramic powder
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Cao, W. (Wei), Zhou, J. (Ju), Ren, C. (Chunxiao), Omran, M. (Mamdouh), Gao, L. (Lei), Tang, J. (Ju), Zhang, F. (Fan), Chen, G. (Guo), Cao, W. (Wei), Zhou, J. (Ju), Ren, C. (Chunxiao), Omran, M. (Mamdouh), Gao, L. (Lei), Tang, J. (Ju), Zhang, F. (Fan), and Chen, G. (Guo)
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Y₂O₃–ZrO₂ ceramic powder has emerged as a vital structural and functional material in ceramic applications owing to its remarkable performance including wear resistance, temperature resistance, and corrosion resistance. Agglomeration during the drying process is the other key issue that needs to be resolved, which improving the quality of zirconia powder becomes crucial in reducing industrial expenses. This study focuses on investigating the influence of modern microwave heating technology on the drying kinetics of Y₂O₃–ZrO₂ ceramic powder. The experimental results revealed that the average drying rate of Y₂O₃–ZrO₂ ceramic powder increased with sample water content, microwave heating power, and sample mass. Four kinetic fitting models, namely Page, Wang and Singh, Quadratic Model, and Modified Page, were employed to analyze the experimental data for Y₂O₃–ZrO₂ ceramic powder with a mass of 20 g, initial water content of 7.5%, and the microwave heating power is 480 W. Among these models, the Modified Page model demonstrated the best fit and effectively described the drying kinetics of Y₂O₃–ZrO₂ceramic powder. The Modified Page model successfully captured the kinetics across varying masses, microwave heating powers, and initial water content. FT-IR spectroscopy was employed to describe the material before and after microwave drying. The results exhibited a significant reduction in water molecule content in the Y₂O₃–ZrO₂ ceramic powder after microwave drying, thus confirming the high efficiency and rapidity of the microwave drying procedure. This research provides comprehensive experimental data and offers a theoretical foundation for the industrial application of microwave-enhanced drying of Y₂O₃–ZrO₂ ceramic powder.
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- 2023
12. Preparation of novel Ti–Y/ZrO₂ ceramic by two-step of mechanical alloying and microwave-assisted sintering process
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Zhang, Y. (Yanqiong), Zhou, J. (Ju), Ren, C. (Chunxiao), Omran, M. (Mamdouh), Tang, J. (Ju), Zhang, F. (Fan), Chen, G. (Guo), Zhang, Y. (Yanqiong), Zhou, J. (Ju), Ren, C. (Chunxiao), Omran, M. (Mamdouh), Tang, J. (Ju), Zhang, F. (Fan), and Chen, G. (Guo)
- Abstract
Zirconia composite ceramic materials are popular for their many excellent properties. In this study, nTi-3Y–ZrO₂ composite ceramics were produced by the mechanical alloying-microwave sintering method with different Ti-doping amounts and microwave sintering temperatures. The sample’s phase composition, stability rate, lattice parameters, micromorphology, relative density, and grain size are characterized. The results showed that when the sintering temperature is 1200 °C, the samples with different doping amounts are mainly mixed crystalline structures with tetragonal and cubic phases, and the stability rate remains above 90 %. As TiO₂ doping increases, the lattice parameters a(Å) and b(Å)first increase and then decrease, while the lattice parameter c (Å) shows an overall increasing trend. Raman data demonstrated that the increase in Ti content promoted the generation of tetragonal phase zirconia. The average grain size is 61.33 nm, 76.23 nm, 58.77 nm, 63.35 nm, and 68.99 nm, respectively. The increase in doping is also accompanied by a narrowing of the grain size distribution, which increases the sintering activity of the sample. In addition, the relative densities of the samples were 67.85 %, 73.94 %, 84.25 %, 84.87 %, and 77.54 %, respectively, showing a gradual increasing trend overall. When the microwave sintering temperature is 1200 °C, and the doping amount is 5Ti–3Y–92Zr, the performance of the sample is superior to other groups. The preparation of nTi-3Y–ZrO₂ composite ceramics can provide certain ideas for preparing ceramic materials with excellent performance in various aspects.
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- 2023
13. Research on the tetragonal phase content and microstructure of microwave-assisted sintering Y-PSZ system doped Bi₂O₃
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Huang, W. (Weiwei), Lu, J. (Jiajia), Zhang, Y. (Yanqiong), Omran, M. (Mamdouh), Gao, L. (Lei), Chen, J. (Jin), and Chen, G. (Guo)
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Doping amount ,Y-PSZ powders ,Tetragonal phase content ,Average particle size ,Microwave sintering - Abstract
Partially stabilized Y₂O₃–ZrO₂ (Y-PSZ) is often used as a material in the field of oxygen sensors and batteries. However, the presence of a tetragonal phase will seriously reduce the conductivity of Y-PSZ materials. As a sintering aid, Bi₂O₃ can be used to sinter materials with high oxygen ion conductivity at low temperatures. It is the first choice for the Y-PSZ doped system. A new microwave sintering technique prepared Bi₂O₃–Y-PSZ powders. The effects of doping amount of Bi₂O₃ on the microstructure, phase transition, and tetragonal phase content of Y-PSZ during sintering were researched. The results displayed that doping Bi₂O₃ improved the tetragonal phase content of the ZrO₂. The tetragonal phase content of the samples increased from 59.72% to 94.69% after sintering at 750 °C for 1 h. After doping Bi₂O₃, the aggregation of the samples reduced gradually, and the particles dispersed evenly. The average particle sizes of raw material and samples doped with different amounts of Bi₂O₃ were 0.0794 μm, 0.0638 μm, 0.0629 μm, 0.0794 μm, 0.1116 μm, respectively. Therefore, in the doping amount (1 mol%-4 mol%), the Bi₂O₃ doped Y-PSZ system with 2 mol% has the highest tetragonal phase content, the best dispersion, the smallest average particle size, and the most uniform particle distribution.
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- 2023
14. Drying characteristics of ammonium polyvanadate under microwave heating based on a thin-layer drying kinetics fitting model
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Huang, W. (Weiwei), Zhang, Y. (Yanqiong), Qiu, H. (Hongju), Huang, J. (Junzheng), Chen, J. (Jin), Gao, L. (Lei), Omran, M. (Mamdouh), Chen, G. (Guo), Huang, W. (Weiwei), Zhang, Y. (Yanqiong), Qiu, H. (Hongju), Huang, J. (Junzheng), Chen, J. (Jin), Gao, L. (Lei), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Abstract
The dried ammonium polyvanadate (APV) can be used to produce high-purity Vanadium pentoxide (V₂O₅) by calcination. Therefore, drying is a necessary process. The advantages of microwave drying are uniform heating, selective heating, high heating efficiency and the operation process is clean and hygienic. This study uses a microwave to dry APV and discusses the effect of the initial mass, microwave power, initial moisture content on the drying efficiency of APV. The results display that the average drying rate is positively correlated with the microwave output power. When the initial mass is 35 g, the average rate is shown as 0.000263%/s. As the initial moisture content and power of APV increases to 25% and 560W, the average drying rate increases to 0.00036231%/s and 0.003125%/s, respectively. At the same time, through the analysis of APV drying kinetics and the fitting of experimental data, it is found that the APV microwave drying process can be precisely described by the Modified Page model. The microwave heating process saves energy and time, directly penetrates the product, and has certain advantages in green metallurgy.
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- 2022
15. Enhancement effects of distiller's dried grains as reducing agents on the kinetics and leaching of pyrolusite from manganese ore
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Liu, D. (Dongjie), Gao, L. (Lei), Chen, G. (Guo), Zhou, J. (Junwen), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, J. (Jin), Liu, D. (Dongjie), Gao, L. (Lei), Chen, G. (Guo), Zhou, J. (Junwen), Guo, S. (Shenghui), Omran, M. (Mamdouh), and Chen, J. (Jin)
- Abstract
To solve the problem of environmental pollution, Distiller’s dried grains (DDGS), a biomass, is used as a clean reducing agent for the leaching process of pyrolusite. Experimental results have shown that the leaching rate of manganese can reach 92.1% with the optimized conditions including a sulfuric acid concentration of 3.5 mol/L, a DDGS to pyrolusite ratio of 0.4, a liquid–solid ratio of 3 mL/g, a temperature of 363K, a time of 3 h, and a rotation speed of 400 rpm. This article explored the mechanism of the entire leaching process: the crude fiber in DDGS is hydrolyzed into reducing sugars, and the MnO₂ in pyrolusite undergoes an oxidation–reduction reaction to generate Mn²⁺ and studied the kinetics of the leaching process following the unreacted shrinkage nuclear reaction model controlled by the surface chemical reaction (\(1-(1-X)^{1/3}=\text{kt}\)). The equation of leaching kinetics is \(1−1-\text{X}^{\frac{1}{3}} = 3738.06 \cdot [\text{H}_{2}\text{SO}_{4}]^{0.57} \cdot \left[\frac{L}{S}\right]^{0.78} \cdot \left[\frac{DDGS}{\text{pyrolusite}}\right]^{0.25} \cdot [rpm]^{0.09} \cdot \exp(-48.448/(RT)\) This work provides a green and effective leaching process for the leaching of pyrolusite.
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- 2022
16. Effects of sodium selenite and coated sodium selenite on lactation performance, total tract nutrient digestion and rumen fermentation in Holstein dairy cows
- Author
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Zhang Shuanlin, Y.L. Zhang, Wang Chao, Z.D. Zhang, H.S. Du, Pei Caixia, Junzhen Zhang, Huo Wenjie, Q. Liu, and G. Guo
- Subjects
Rumen ,Population ,milk performance ,Feed conversion ratio ,SF1-1100 ,Sodium Selenite ,Animal science ,Pregnancy ,Lactation ,Ruminococcus ,medicine ,Animals ,Dry matter ,ruminal microbiota ,education ,selenium ,education.field_of_study ,Fibrobacter succinogenes ,biology ,Chemistry ,Nutrients ,biology.organism_classification ,Animal Feed ,Diet ,Animal culture ,medicine.anatomical_structure ,Dietary Supplements ,Fermentation ,nutrient digestibility ,Cattle ,Digestion ,Female ,Animal Science and Zoology ,Sample collection ,Fibrobacter ,microbial enzymatic activity - Abstract
Se can enhance lactation performance by improving nutrient utilization and antioxidant status. However, sodium selenite (SS) can be reduced to non-absorbable elemental Se in the rumen, thereby reducing the intestinal availability of Se. The study investigated the impacts of SS and coated SS (CSS) supplementation on lactation performance, nutrient digestibility, ruminal fermentation and microbiota in dairy cows. Sixty multiparous Holstein dairy cows were blocked by parity, daily milk yield and days in milk and randomly assigned to five treatments: control, SS addition (0.3 mg Se/kg DM as SS addition) or CSS addition (0.1, 0.2 and 0.3 mg Se/kg DM as CSS addition for low CSS (LCSS), medium CSS (MCSS) and high CSS (HCSS), respectively). Experiment period was 110 days with 20 days of adaptation and 90 days of sample collection. Dry matter intake was higher for MCSS and HCSS compared with control. Yields of milk, milk fat and milk protein and feed efficiency were higher for MCSS and HCSS than for control, SS and LCSS. Digestibility of DM and organic matter was highest for CSS addition, followed by SS addition and then control. Digestibility of CP was higher for MCSS and HCSS than for control, SS and LCSS. Higher digestibility of ether extract, NDF and ADF was observed for SS or CSS addition. Ruminal pH decreased with dietary Se addition. Acetate to propionate ratio and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was greater for SS, MCSS and HCSS than control. Ruminal H ion concentration was highest for MCSS and HCSS and lowest for control. Activities of cellobiase, carboxymethyl-cellulase, xylanase and protease and copies of total bacteria, fungi, Ruminococcus flavefaciens, Fibrobacter succinogenes and Ruminococcus amylophilus increased with SS or CSS addition. Activity of α-amylase, copies of protozoa, Ruminococcus albus and Butyrivibrio fibrisolvens and serum glucose, total protein, albumin and glutathione peroxidase were higher for SS, MCSS and HCSS than for control and LCSS. Dietary SS or CSS supplementation elevated blood Se concentration and total antioxidant capacity activity. The data implied that milk yield was elevated due to the increase in total tract nutrient digestibility, total VFA concentration and microorganism population with 0.2 or 0.3 mg Se/kg DM from CSS supplementation in dairy cows. Compared with SS, HCSS addition was more efficient in promoting lactation performance of dairy cows.
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- 2020
17. Effect of microwave heating duration on the stability of the partially stabilised zirconia doped with CaO
- Author
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Li, Q. (Qiannan), Ling, Y. (Yeqing), Zheng, H. (Hewen), Omran, M. (Mamdouh), Li, K. (Kangqiang), Gao, L. (Lei), Zhang, M. (Mingyuan), Chen, J. (Jin), and Chen, G. (Guo)
- Subjects
holding time ,microwave heating ,calcium oxide ,stability ,zirconia - Abstract
In this paper, the stability of CaO doped partially stabilised zirconia (CaO-PSZ) prepared by electrofusion method was improved from 88.14% to 95% within one hour using the microwave heating method. The increase of the stability rate was because of the microwave heating method’s advantages, including selective heating and fast heating. Analysis techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM), were used to analysis the influences of the holding time (1–4 h) on the CaO doped PSZ samples at a heating temperature of 1100 °C to understand the fundamental mechanism of the optimisation process. The Raman and XRD spectra were fitted by the Gaussian method to further analysis the effect of holding time on the microstructure evolution of the samples. The fitting results indicated that the sample’s crystal quality and stability were improved after microwave heating, and the optimised holding time is 2h.
- Published
- 2021
18. Controlled sintering and phase transformation of yttria-doped tetragonal zirconia polycrystal material
- Author
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Li, Q. (Qiannan), Hao, X. (Xiandong), Gui, Y. (Yuxi), Qiu, H. (Hongju), Ling, Y. (Yeqing), Zheng, H. (Hewen), Omran, M. (Mamdouh), Gao, L. (Lei), Chen, J. (Jin), and Chen, G. (Guo)
- Subjects
Pressureless sintering ,Yttria doped zirconia ,Phase transformation ,Microstructure ,Roasting temperature - Abstract
In this paper, 3 mol% yttria-doped tetragonal zirconia polycrystal material (3 mol% Y₂O₃–ZrO₂) was prepared using an optimised pressureless sintering process. The phase change and particle size distribution of Y₂O₃–ZrO₂ during sintering were studied, and the effect of sintering temperature on the properties of Y₂O₃–ZrO₂ was analysed. The raw materials and prepared samples were analysed using XRD, Raman spectroscopy, SEM, and Gaussian mathematical fitting. The results show that sintering encourages the transformation of the monoclinic phase into the tetragonal phase, thus improving the crystallinity of the sample. The relative content of the tetragonal phase in the sample increased from 57.43% to 99.80% after sintering at 1200 °C for 1 h. In the range of sintering temperatures studied in this paper (800–1200 °C), the zirconia material sintered at 1000 °C presented the lowest porosity and the best density.
- Published
- 2021
19. Microwave-assisted method investigation for the selective and enhanced leaching of manganese from low-grade pyrolusite using pyrite as the reducing agent
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Lin, S. (Shunda), Li, K. (Kangqiang), Yang, Y. (Yong), Gao, L. (Lei), Omran, M. (Mamdouh), Guo, S. (Shenghui), Chen, J. (Jin), and Chen, G. (Guo)
- Subjects
Environmentally friendly ,Microwave heating ,Pyrolusite ,Dipole rotation ,Enhanced leaching - Abstract
The recovery mechanism of manganese from low-grade pyrolusite was studied through microwave and conventional leaching, respectively, and pyrite was used as the reducing agent. An improvement on the manganese leaching rate with microwave heating was noticed which may be caused by the suppressing of the formation of sulfur passivation layer by the unique dipole rotation heating mechanism of microwave energy. To confirm this hypothesis, the leaching time, the amount of reducing agent, and the concentration of sulfuric acid were studied, and the surface compositions of the leaching residues were analyzed. The results evidenced that the sulfur content on the surface of residue produced by microwave leaching was significantly reduced compared to the results produced by conventional heating, which proved the rationality of the hypothesis. The recovery of leaching assisted with microwave heating was improved compared to that assisted with conventional heating under the same experimental conditions (liquid-solid ratio: 10:1, leaching temperature: 90 ℃, M(pyrite)/M(pyrolusite): 0.2, sulfuric acid concentration: 1.2 mol/L, stirring speed: 400 rpm). The corresponding peak value of the leaching rate was 95.07 % and 75.08 %. Additionally, microwave leaching is very environmentally friendly since it significantly reduces the amount of reducing agent and sulfuric acid as well as reaction time.
- Published
- 2021
20. Phase stability and microstructure morphology of microwave-sintered magnesia-partially stabilised zirconia
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Chen, G. (Guo), Li, Q. (Qiannan), Ling, Y. (Yeqing), Zheng, H. (Hewen), Chen, J. (Jin), Jiang, Q. (Qi), Li, K. (Kangqiang), Peng, J. (Jinhui), Omran, M. (Mamdouh), and Gao, L. (Lei)
- Subjects
MgO-PSZ ,Microwave heating ,Phase stability ,Microstructure morphology - Abstract
In this work, microwave heating approach was introduced into the preparation process of zirconia materials to overcome the tricky technical defects during the traditional electric arc furnace method. Magnesia-partially stabilised zirconia (MgO-PSZ) with enhanced stability and a uniform microstructure was prepared via microwave heating of a ZrO₂ sample manufactured by the electric arc furnace method. The effects of microwave heating on the phase stability properties, microstructure, and surface morphology of the prepared MgO-PSZ sample were evaluated via X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and Scanning electron microscopy, and the obtained results suggested that the stability rate of the MgO-PSZ sample improved from the initial value of 81.19%–94.82% after microwave heating at 1300 °C for 1 h. As a result of the martensitic conversion of ZrO₂ material, the m-ZrO₂ diffraction peaks were suppressed at the same time. Additionally, a similar changing trend was noticed in the XRD pattern, Raman spectrum, and FT-IR spectrum, indicating a decrease in the m-ZrO₂ phase content in the microwave treated products. Furthermore, the microstructure on the surface of the microwave-sintered MgO-PSZ sample was improved in contrast to the raw MgO-PSZ sample, and became relatively more uniform and smooth. This study determined the optimal microwave heating conditions for the preparation of MgO-PSZ material with enhanced performance, and can provided as a good foundation for developing the further related research on zirconia materials preparing by microwave heating technology.
- Published
- 2021
21. Research on microwave drying technology in the procedure of preparation of V₂O₅ from ammonium polyvanadate (APV)
- Author
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Zheng, H. (Hewen), Li, Q. (Qiannan), Ling, Y. (Yeqing), Omran, M. (Mamdouh), Gao, L. (Lei), Chen, J. (Jin), and Chen, G. (Guo)
- Subjects
Dynamic mechanism ,Microwave heating ,Factors optimisation ,Ammonium polyvanadate (APV) ,Vanadium pentoxide - Abstract
High-quality vanadium pentoxide powder is an important product of the vanadium industry and was usually prepared from ammonium polyvanadate (APV) using a roasting process combined with a drying pretreatment. Conventional hot air drying is usually used for the drying of APV, the heat transfer of which is from outside to inside thus limited the efficiency of the drying pretreatment. In the present paper, microwave heating was applied as an alternative heating method for the drying of APV because of its advantages including selective heating, high heating efficiency, low energy consumption, and green environmental protection. An experimental comparison between hot air drying and microwave drying is provided, and the results show that microwave drying is more energy-saving and faster. The drying characteristics of APV under the irradiation of microwave energy were investigated. The influences of factors including microwave power, material quality, and initial moisture content on microwave drying were studied. The results show that the microwave power, initial moisture content, and initial mass are positively proportional to the microwave drying efficiency of APV. Additionally, the Page model was robust in describing the kinetics of microwave drying and hot air drying of APV. This study provides fundamental knowledge on the microwave drying process and provides the trial for the industrial applications of microwave heating on the preparation of V₂O₅.
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- 2021
22. Optimisation on the stability of CaO-doped partially stabilised zirconia by microwave heating
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Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Omran, M. (Mamdouh), Gao, L. (Lei), Chen, J. (Jin), and Chen, G. (Guo)
- Subjects
Calcium oxide doped partially stabilised zirconia ,Microwave heating ,Stability ratio ,Phase transition - Abstract
Partially stabilised zirconia has advantages for the applications in the metallurgical processes which have special requirements in corrosion resistance and high-temperature performance. In the present work, controllable microwave heating was used for the uniform thermal field and consequent microstructure improvement to further improve the stability of partially stabilised zirconia, which was 88.14% prepared by electric arc melting. Analyses including X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman) were used to study the effect of temperature change on the phase composition and structure of the samples. After heating at temperatures of 900 °C, 1000 °C, 1100 °C, 1200 °C and 1300 °C for 1h, the stabilities of the heated product were 88.51%, 95.02%, 95.17%, 96.31% and 97.64%, respectively. From the phase transformations based on the experimental results, the discussion indicates that the martensitic transformation temperature of zirconia from m-ZrO₂ to t-ZrO₂ during the heating stage was reduced under the radiation of microwave energy.
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- 2021
23. Stability properties and microstructure properties of microwave-sintered CeO₂ doped zirconia ceramics
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Ling, Y. (Yeqing), Hao, X. (Xiandong), Gui, Y. (Yuxi), Qiu, H. (Hongju), Li, Q. (Qiannan), Zheng, H. (Hewen), Omran, M. (Mamdouh), Gao, L. (Lei), Chen, J. (Jin), and Chen, G. (Guo)
- Subjects
Transformation and evolution ,Ce–ZrO2 ceramics ,Microwave sintering ,Phase transformation - Abstract
Nanosized CeO₂–ZrO₂ powders prepared by atmospheric pressure pyrolysis were used as raw materials to prepare CeO₂–ZrO₂ ceramics using microwave sintering. The samples were characterised using bulk density measurements, X-ray diffraction (XRD), Fourier Transform Infrared Spectrometer (FT-IR), Raman, and scanning electron microscopy (SEM). The purpose was to determine the optimised microwave sintering process for CeO₂–ZrO₂ ceramics and reveal the corresponding mechanism. The results show that with a CeO₂ addition content above 5 mol%, the tetragonal phase peak appeared obviously in the sample. The results show that the tetragonal phase peak appears when the CeO₂ content is more than 5 mol%. The dopants, namely CeO₂, have reduced the solid solution’s phase transformation temperature with the assistance of microwave heating. Additionally, the grain size of the CeO₂–ZrO₂ ceramics has shown a negative relationship with Ce content at a temperature of 900 °C. The reason is that the rapid sintering due to microwave sintering and the oxygen vacancies generated by CeO₂ can effectively inhibit grain growth. The regulation mechanism on microwave sintering of CeO₂–ZrO₂ ceramic was clarified, and the technical prototype of controlled prepared CeO₂–ZrO₂ ceramics by microwave sintering was constructed.
- Published
- 2021
24. Drying kinetics and microstructure evolution of nano-zirconia under microwave pretreatment
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Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Omran, M. (Mamdouh), Gao, L. (Lei), Li, K. (Kangqiang), and Chen, G. (Guo)
- Subjects
kinetics ,microwave drying ,surface diffusion ,zirconia - Abstract
The effects of microwave power and sample quality on microwave drying kinetics and characteristics of zirconia were studied. It is found that by increasing the microwave power and decreasing the sample mass, the surface diffusion coefficient (Deff) appears to an upward tendency. The corresponding value Deff at a sample mass of 10, 20, 30, and 40g are 1.849E-14, 2.443E-14, 3.210E-14, and 3.278E-14 m²/s, respectively. The corresponding value Deff at a microwave power of 300, 400, 500, 600, and 700W are 1.270E-14, 1.784E-14, 2.619E-14, 3.392E-14, and 4.497E-14 m²/s, respectively. Besides, the materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR) to evaluate the changes of materials before and after drying. The results show that microwave accelerates the drying of zirconia and increases its dispersibility. The heat conduction direction of microwave drying is the same as that of moisture diffusion, which avoids being affected by heat inertia and heat transfer loss. The drying process is fast and efficient, and the microwave directly penetrates the product, avoiding the disadvantage of slow evaporation caused by the temperature gradient.
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- 2021
25. Study on thermochemical characteristics properties and pyrolysis kinetics of the mixtures of waste corn stalk and pyrolusite
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Du, J. (Jinjia), Gao, L. (Lei), Yang, Y. (Yong), Chen, G. (Guo), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, J. (Jin), and Ruan, R. (Roger)
- Subjects
Waste biomass ,Non-isothermal models ,Thermodynamic analysis ,Pyrolusite ,Mixed pyrolysis kinetics - Abstract
As an alternative energy source for fossil energy, use of biomass pyrolysis to reduce pyrolusite is of great significance for energy conservation, emission reduction and environmental protection. Kinetics and thermodynamics of reducing pyrolusite using biomass pyrolysis was studied using thermogravimetric analysis analysis. Five non-isothermal methods, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Distributed Activation Energy Model, Starink and Friedman, were employed to calculate the pyrolysis kinetics and thermodynamic parameters. The results showed that pyrolusite reduction by biomass pyrolysis can be divided into four stages: drying stage (30–175 °C), rapid pyrolysis reduction stage (175–350 °C), slow pyrolysis reduction stage (350–680 °C) and char formation stage (680–900 °C). The apparent activation energy, reaction enthalpy, Gibbs free energy and entropy change of pyrolusite reduction by biomass pyrolysis was calculated ranges from 170 to 180 kJ/mol, 164 to 174 kJ/mol, 136.97 to 137.25 kJ/mol and 45.67 to 61.91 J/mol·K, respectively. This work provides theoretical basis and practical guidance for the reduction of pyrolusite by waste corn stalk.
- Published
- 2021
26. Phase microstructure and morphology evolution of MgO-PSZ ceramics during the microwave sintering process
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Li, Q. (Qiannan), Ling, Y. (Yeqing), Zheng, H. (Hewen), Chen, G. (Guo), Chen, J. (Jin), Koppala, S. (Sivasankar), Jiang, Q. (Qi), Li, K. (Kangqiang), Omran, M. (Mamdouh), Gao, L. (Lei), Li, Q. (Qiannan), Ling, Y. (Yeqing), Zheng, H. (Hewen), Chen, G. (Guo), Chen, J. (Jin), Koppala, S. (Sivasankar), Jiang, Q. (Qi), Li, K. (Kangqiang), Omran, M. (Mamdouh), and Gao, L. (Lei)
- Abstract
In the present study, controllable microwave sintering was applied to prepare partially stabilised zirconia ceramics with enhanced phase composition and a more uniform structure. To reveal the phase interface properties and structural changes of PSZ ceramics during the microwave sintering process, XRD, FT-IR, Raman, and SEM characterisations were utilised. XRD analysis and Raman analysis demonstrated that the increase of sintering temperature promoted the martensite conversion. However, prolonging duration time was unconducive to the retention of the stable phase. Additionally, the FT-IR characteristic peak movement caused by the reversible phase martensite transformation was observed. Furthermore, SEM analysis found that microwave treatment improved the grain size and structure distribution of the as-received MgO-PSZ sample. This work constructed a controllable technical prototype of preparing PSZ ceramics via microwave sintering, which can provide a theoretical basis and experimental basis for further industrial production.
- Published
- 2021
27. Dielectric characterisation and reduction properties of the blending mixtures of lowgrade pyrolusite and waste corn stalks in the microwave field
- Author
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Du, J. (Jinjia), Gao, L. (Lei), Yang, Y. (Yong), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, J. (Jin), Chen, G. (Guo), Du, J. (Jinjia), Gao, L. (Lei), Yang, Y. (Yong), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, J. (Jin), and Chen, G. (Guo)
- Abstract
Recently, pyrometallurgical reduction of low-grade pyrolusite is one of the potential techniques for expanding the resources for manganese. However, the process has a high cost on fossil energy and produces a large amount of greenhouse gases. This work proposed a novel method of using biomass, namely corn stalks, to reduce and roast low-grade pyrolusite under microwave field to provide positive alternatives for fossil energy. The microwave-assisted reduction was studied systematically, and the corresponding mechanism was also studied by thermodynamic analysis and dielectric properties analysis. Results indicated that co-pyrolysis reduction characteristics of the mixtures were mainly divided into three stages: the pre-reaction stage (25 °C–196 °C), activated pyrolysis reduction stage (196 °C–480 °C), and carbonisation stage (>430 °C). The mechanism of MnO₂ reduction is attributed to reductive volatiles (H₂, CO, CH₄) and the fixed carbon (C) produced by biomass pyrolysis. Meanwhile, the reduction efficiency of Mn can achieve 97.2% at 650 °C for 60 min with 25% corn stalks, indicating efficient pyrolusite reduction by microwave heating. These results enrich the fundamental knowledge on the corresponding industrial technology development.
- Published
- 2021
28. Kinetics characteristics and microwave reduction behavior of walnut shell-pyrolusite blends
- Author
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Li, K. (Kangqiang), Jiang, Q. (Qi), Chen, G. (Guo), Gao, L. (Lei), Peng, J. (Jinhui), Chen, Q. (Quan), Koppala, S. (Sivasankar), Omran, M. (Mamdouh), Chen, J. (Jin), Li, K. (Kangqiang), Jiang, Q. (Qi), Chen, G. (Guo), Gao, L. (Lei), Peng, J. (Jinhui), Chen, Q. (Quan), Koppala, S. (Sivasankar), Omran, M. (Mamdouh), and Chen, J. (Jin)
- Abstract
Combining biomass pyrolysis with microwave heating technologies provides a novel and efficient approach for low-grade pyrolusite reduction. The microwave reduction behavior and pyrolysis kinetic characteristics of walnut shell-pyrolusite blends were explored. Results indicated the optimal reduction parameters were: reduction temperature of 650 °C, holding time of 30 min, Mbio/More of 1.8:10, and microwave power of 1200 W. The co-pyrolysis characteristics of the blends included four stages: dehydration, pre-pyrolysis, intense pyrolysis and reduction, and slow pyrolysis and reduction. Fitting analysis based on Coats-Redfern method revealed that chemical reaction was the control step of the process of reducing pyrolusite by biomass, which the finding matched to the isothermal kinetic analysis results determined through unreacted shrinking nuclear model. The activation energies and pre-exponential factors were determined at 5.62 kJ·mol⁻¹–16.69 kJ·mol⁻¹ and 0.0426 min⁻¹–0.515 min⁻¹. The work provides sound references for promoting the industrial application of the combined method on minerals reduction.
- Published
- 2021
29. Optimisation on the microwave drying of ammonium polyvanadate (APV):based on a kinetic study
- Author
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Zheng, H. (Hewen), Li, Q. (Qiannan), Ling, Y. (Yeqing), Omran, M. (Mamdouh), Gao, L. (Lei), Chen, G. (Guo), Zheng, H. (Hewen), Li, Q. (Qiannan), Ling, Y. (Yeqing), Omran, M. (Mamdouh), Gao, L. (Lei), and Chen, G. (Guo)
- Abstract
Vanadium pentoxide (V₂O₅) is one of the fundamental materials applied in the productions of batteries, vanadium-aluminium alloys, biomedicine, catalysis, etc. High purity V₂O₅ can be prepared from an intermediate product, namely ammonium polyvanadate (APV), using roasting after a drying process. In this paper, microwave heating was used as an alternative drying option for APV, which has advantages including selective heating, high heating efficiency, energy-saving, and environmental protection. The authors investigated the microwave heating characteristics of APV and discussed the effects of microwave power, the mass of APV, and initial water content on the efficiency of microwave drying. The dynamic analysis of the APV microwave drying process was also carried out. Four groups of thin-layer drying dynamic models, namely Modified-Page model, Verma model, Sickmplified-Fick’s-diffusion model, and Two-term-exponential model, were fitted with the experimental data. Through comparison, the Modified Page model could better describe the microwave drying process of APV.
- Published
- 2021
30. Investigations on the microwave absorption properties and thermal behavior of vanadium slag:improvement in microwave oxidation roasting for recycling vanadium and chromium
- Author
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Li, K. (Kangqiang), Jiang, Q. (Qi), Gao, L. (Lei), Chen, J. (Jin), Peng, J. (Jinhui), Koppala, S. (Sivasankar), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Subjects
microwave oxidation roasting ,microwave absorption properties ,chromium ,thermal behavior ,vanadium slag - Abstract
Vanadium slag contains high contents of vanadium and chromium with complex and dense structures, hence microwave heating instead of conventional methods is expected to destroy the dense structure and further to improve the extraction rate of vanadium and chromium, and exploring its dielectric properties is the prerequisite work. Microwave absorption properties and thermal behavior of vanadium slag were investigated. Results indicated that vanadium slag endowed excellent microwave absorption properties, with minimum εr′ value of 34.447 (F/M). Dielectric properties of vanadium slag varied with temperature, which changing trend was matched to the three stages of microwave heating characteristics identified by heating rates. Meanwhile, the changing process of dielectric properties also corresponded to the three processes of thermogravimetric characteristics: dehydration stage (30 °C-280 °C), oxidation decomposition of olivine phase and normal spinel phase (280 °C-650 °C), and oxidation decomposition of vanadium chromium spinel (650 °C-950 °C). Moreover, the maximum dielectric constant and highest microwave heating rate of vanadium slag both appeared at the temperature regime of 500 °C-550 °C, which was also the main temperature regime for oxidation decomposition of olivine phase and normal spinel phase in vanadium slag, demonstrating the appropriate process temperature for microwave heating technology to recycle vanadium slag.
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- 2020
31. One-step preparation of CaO-doped partially stabilized zirconia from fused zirconia
- Author
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Li, K. (Kangqiang), Chen, J. (Jin), Peng, J. (Jinhui), Koppala, S. (Sivasankar), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Subjects
Fused zirconia ,Phase structure ,Partially stabilized zirconia ,Stability properties - Abstract
Partially stabilized zirconia (PSZ) replaces the widespread applications of full stabilized zirconia (FSZ) on ceramics materials and refractories materials, attributed to its excellent properties including small coefficient of thermal expansion, low thermal conductivity and good thermal shock resistance. In this work, CaO-doped partially stabilized zirconia (CaO-PSZ) was optimizedly prepared from fused zirconia through conventional roasting. Meanwhile, the effects of roasting temperature and duration time on stability properties were explored to determine the stability parameters of the prepared CaO-PSZ. Results indicated that the zirconia stability rate synchronously improved with the decrease of roasting temperature and duration time, which was attributed to that the martensitic transformation of fused zirconia with volume change plays a toughening effect, further rendering the change of zirconia stability properties. XRD patterns verified the martensitic transformation, representing by cubic ZrO₂ phase (c-ZrO₂) in raw fused zirconia was partially transformed into monoclinic ZrO₂ phase (m-ZrO₂) at 1450 °C for 4 h. Moreover, the phase transition law of fused zirconia was revealed through SEM and EDAX characterization for the raw fused zirconia and the prepared CaO-PSZ. SEM patterns showed acicular patterns of grains and round fine particles clustered at grain boundaries, indicating that CaO stabilizer precipitated on grain boundaries and rendered the crystal structure enhanced, which the result was consistent with EDAX analysis. This work can lay a significant foundation for applications of microwave heating on the preparation of partially stabilized zirconia (PSZ) from fused zirconia.
- Published
- 2020
32. The controlled preparation and stability mechanism of partially stabilized zirconia by microwave intensification
- Author
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Li, K. (Kangqiang), Jiang, Q. (Qi), Chen, J. (Jin), Peng, J. (Jinhui), Li, X. (Xinpei), Koppala, S. (Sivasankar), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Subjects
Fused zirconia ,Structure ,Microwave sintering ,CaO-PSZ ceramics - Abstract
Partially stabilized zirconia (PSZ) occupies an important application portion in ceramics materials and refractories materials. In this work, calcium oxide-partially stabilized zirconia (CaO-PSZ) ceramics were prepared from fused zirconia by microwave sintering, with its microstructure and stability properties characterized by XRD and SEM. Results indicated that the heating rate, cooling rate, quenching temperature and isothermal treatment time rendered different influence on the stability properties, which was mainly ascribed to the reversible martensitic transformation of zirconia ceramics. Additionally, a mixed-phase composed by cubic phase ZrO₂ (c-ZrO₂) and monoclinic phase ZrO₂ (m-ZrO₂) appeared after fused zirconia treated by microwave sintering at 1450 °C for 2 h, indicating the formation of CaO-PSZ ceramics, which the finding was consistent with the SEM and EDAX analysis. Meanwhile, CaO stabilizer precipitated behavior at the crystal boundary, with the formation of acicular grains and fine particles, further rendering a toughening effect to CaO-PSZ ceramics. This work can provide important theoretical and practical significance for applications of microwave sintering to prepare CaO-PSZ ceramics material, even extending further applications in functional materials and structural materials.
- Published
- 2020
33. Microstructure and enhanced volume density properties of FeMn78C8.0 alloy prepared via a cleaner microwave sintering approach
- Author
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Chen, G. (Guo), Li, K. (Kangqiang), Jiang, Q. (Qi), Li, X. (Xinpei), Peng, J. (Jinhui), Omran, M. (Mamdouh), and Chen, J. (Jin)
- Subjects
FeMn78C8.0 alloy ,Microwave sintering ,Volume density ,Ferromanganese powder ,Microstructure - Abstract
Smelting fine ore into a block with the lower phosphorus content before entering the furnace can achieve cleaner production and value-added efficiency for ferromanganese alloy enterprises, and microwave sintering technology shows bright application prospects in the secondary utilization of waste materials and environmental-friendly preparation of high-performance alloy materials. In this work, FeMn78C8.0 grade bulk alloy with enhanced volume density properties was efficiently prepared via an environmental-friendly microwave sintering approach, using high-carbon ferromanganese powder with low processing efficiency in factories as the raw material. Results indicate that adding certain carbon can prevent the oxidation behavior of Mn and Fe elements during the sintering process, and the qualified FeMn78C8.0 alloy can be obtained by controlling sintering temperature and duration time, with the optimum sintering conditions determined at 1168 °C for 11 min and with the alloy powder of
- Published
- 2020
34. Dielectric properties and thermal behavior of electrolytic manganese anode mud in microwave field
- Author
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Li, K. (Kangqiang), Chen, J. (Jin), Peng, J. (Jinhui), Ruan, R. (Roger), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Subjects
Manganese anode mud ,Heating characteristics ,Microwave heating ,Dielectric properties ,Thermochemical behavior - Abstract
Exploring the dielectric properties of a material can provide guidance for applications of microwave technology to the material. In this work, dielectric properties and thermal behavior of manganese anode mud and pure MnO₂, CaSO₄ and PbSO₄ components were systematically investigated. Results indicated that manganese anode mud showed excellent responsiveness to microwaves, with εr′ value of 17.971 (F/M) at room temperature and a maximum value of 20.816 (F/M) at 150 °C, rendering it took only 5.5 min for manganese anode mud to be heated from room temperature to 1000 °C. The dielectric properties of manganese anode mud were related to its thermal behavior, mainly affected by MnO₂ component. Moreover, the heating process of manganese anode mud was divided into four stages identified by temperatures: less than 200 °C, 200 °C–700 °C, 700 °C–900 °C, greater than 900 °C, corresponding to the five stages of thermal behavior: the removal of absorption water and combined water, the decomposition reaction of Pb₂Mn₈O16, and the deoxidation reactions of PbO₂, MnO₂ and Mn3O₄. The work highlights the feasibility of processing manganese anode mud by microwave heating.
- Published
- 2020
35. Simultaneous removal of Cr(III) and V(V) and enhanced synthesis of high-grade rutile TiO₂ based on sodium carbonate decomposition
- Author
-
Chen, G. (Guo), Jiang, Q. (Qi), Li, K. (Kangqiang), He, A. (Aoxi), Peng, J. (Jinhui), Omran, M. (Mamdouh), and Chen, J. (Jin)
- Subjects
Chromium ,Titanium slag ,Rutile TiO2 ,Vanadium ,Sodium carbonate decomposition - Abstract
Rutile TiO₂ is widely applied as the raw material to produce titanium dioxide and titanium sponge, whereas the Cr (III) and V (V) impurities in rutile TiO₂ significantly affect the performance of related products. In the present work, the sodium carbonate decomposition treatment on Panzhihua titanium slag was attempted, to improve the preparation process of rutile TiO₂ with high crystallinity and simultaneously reduce the chromium (Cr) and vanadium (V) content as hazardous elements. Effects of sodium carbonate decomposition treatment on the crystal composition, microstructure of rutile TiO₂ were determined using XRD, SEM and Raman characterization. The recovery of Cr(III) and V(V) was achieved through leaching the roasted titanium slag by dilute sulfuric acid, with the chromium and vanadium content in the residue decreasing up to 0.03 % and 0.04 %, respectively, followed by the final product rutile TiO₂ was produced by the leaching residue calcined at 1323.15 K with a duration time of 120 min, with 85.56 % of TiO₂ grade. The work highlights the feasibility of synchronously preparing rutile TiO₂ and removing hazardous Cr (III) and V (V) impurities from titanium slag using sodium carbonate decomposition.
- Published
- 2020
36. Crystal structure and thermomechanical properties of CaO-PSZ ceramics synthesised from fused ZrO₂
- Author
-
Chen, G. (Guo), Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Li, K. (Kangqiang), Jiang, Q. (Qi), Chen, J. (Jin), Omran, M. (Mamdouh), and Gao, L. (Lei)
- Subjects
Thermomechanical properties ,Fused ZrO2 ,Crystal structure ,CaO-PSZ ceramics - Abstract
Partially stabilised zirconia (PSZ) ceramics have attracted much interest because of their outstanding properties. In this study, fused ZrO₂ was treated as a raw resource for the synthesis of CaO-PSZ ceramic materials through a facile sintering process. The crystal structure and thermomechanical properties of the synthesised CaO-PSZ ceramic samples were determined using XRD and SEM. The results revealed that various process parameters had different effects on the zirconia stability rate, including the temperature changing rate during the heating and cooling stages and the temperature and isothermal time during the quenching treatment; this was primarily a result of the thermodynamic characteristics of the martensitic conversion of ZrO₂ ceramics. Secondly, the martensitic conversion process was revealed by XRD patterns, expressed as the partial conversion of c-ZrO₂ to m-ZrO₂. Meanwhile, SEM-EDAX analysis highlighted the precipitation behaviour of the CaO stabiliser and the successful preparation of CaO-PSZ ceramics by sintering, represented by the gathering phenomenon of the acicular grains and particles, as the findings matched the stability rate analysis. This study can supply a sound reference for the synthesis of CaO-PSZ ceramics from fused ZrO₂.
- Published
- 2020
37. Synthesis of rutile TiO₂ powder by microwave-enhanced roasting followed by hydrochloric acid leaching
- Author
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Kang, J. (Juanxue), Gao, L. (Lei), Zhang, M. (Mingyuan), Pu, J. (Jing), He, L. (Lin), Ruan, R. (Rongsheng), Omran, M. (Mamdouh), Peng, J. (Jinhui), and Chen, G. (Guo)
- Subjects
Na₂CO₃ ,Rutile TiO₂ ,Hydrochloric acid ,Phase transformation ,Microwave roasting - Abstract
In this paper, the preparation of rutile TiO₂ powder from titanium slag by microwave-assisted activation roasting followed by hydrochloric acid leaching was investigated. The effects of the additive Na₂CO₃ on the crystal form, cell, crystallinity, phase transformation, surface functional groups and micro-surface structure of the calcined product were systematically studied using X-ray powder diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The results confirmed that the strongest characteristic Raman bands of rutile TiO₂ and the weakest FT-IR bands of (CO₃)⁻² were found when the Na₂CO₃ mass ratio was 0.4. Accordingly, the crystallinity for the product, namely short rod structure rutile TiO₂ powder, reached its peak value of 99.21% with a corresponding average grain size of 43.5 nm. The excessive Na₂CO₃ was found to be disadvantageous for the crystallinity of the product, since it formed a coverage on the surface of titanium slag which prevented the oxidation reaction for the decomposition of anosovite.
- Published
- 2020
38. Stability properties and structural characteristics of CaO-partially stabilized zirconia ceramics synthesized from fused ZrO₂ by microwave sintering
- Author
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Chen, G. (Guo), Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Li, K. (Kangqiang), Jiang, Q. (Qi), Gao, L. (Lei), Omran, M. (Mamdouh), Peng, J. (Jinhui), and Chen, J. (Jin)
- Subjects
Structural characteristics ,Microwave sintering ,CaO-PSZ ceramics ,Stability properties - Abstract
Partially stabilized zirconia (PSZ) ceramics play a significant role as fundamental ceramics and refractory materials. In this work, a CaO-PSZ ceramics material was synthesized from fused ZrO₂ by microwave sintering. The stability properties and structural characteristics of the products were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that in a microwave field, the duration and sintering temperature presented similar influence trends for the stability properties of ZrO₂ ceramics materials, which the finding was assigned to the phase transformation of ZrO₂ with temperature change. In addition, following the microwave treatment of the fused zirconia sample at 1450 °C for 2.0 h, a cubic and monoclinic mixed phase was formed. These outcomes corresponded to the results from the SEM and energy dispersive X-ray (EDAX) analysis, demonstrating the successful preparation of the CaO-PSZ ceramics. The toughness of the ceramics was improved, which could be attributed to the formation of CaO-stabilizer-precipitated acicular crystals. The theoretical fundamentals and the practical cases presented in this paper are beneficial for the application of the microwave sintering technology in the synthesis of CaO-PSZ ceramics.
- Published
- 2020
39. Efficiency and sustainable leaching process of manganese from pyrolusite-pyrite mixture in sulfuric acid systems enhanced by microwave heating
- Author
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Lin, S. (Shunda), Gao, L. (Lei), Yang, Y. (Yong), Chen, J. (Jin), Guo, S. (Shenghui), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Subjects
Pyrolusite-pyrite mixture ,Conventional heating ,Leaching kinetics ,Microwave heating ,Dielectric properties ,Reductive leaching - Abstract
Recently, with the decrease in the quality of manganese resources, the efficient use of low-quality manganese ore resources has attracted widespread attention. At present, pyrite is often used as reducing agent to recover Mn(IV) in industrialization. However, the passivation of pyrite in the leaching reaction process will lead to a decreased reaction efficiency. Hence, in this study, microwave heating was applied in the reduction system in order to remove the inhibition of the passivation layer and accelerate the dissolution of pyrite, indicating an improvement in the corresponding Mn(IV) reduction efficiency. The results show that the leaching rate assisted by microwave heating was 95.07%, approximately 20% higher than that of conventional heating (75.08%), and the amount of sulfuric acid and pyrite was reduced by 14% and 20%, respectively. XPS analysis shows that there was an obvious sulfur elemental peak at 164.3 eV under traditional heating conditions, but it was absent when microwave heating was applied, and the elemental sulfur under conventional heating is 11.63%, which is higher than that under microwave heating (4.80%). Through scanning electron microscopy, it was noted that there are a large number of voids on the mineral surface under microwave heating, which can increase the solid-liquid contact area, effectively reducing the formation of the sulfur passivation layer and accelerating the dissolution of Mn (IV). In addition, the measurement of the dielectric constant of the solution mixture shows that the dielectric constant of the solution with mineral addition was increased from 36.533 (F/M) to 37.717 (F/M) and the loss tangent angle was increased from 8.61 × 10⁻³ to 9.21 × 10⁻³. It can be inferred that microwaves act directly on the mineral itself through the solution. Thus, the application of pyrite and microwave heating in the recovery of Mn(IV) is expected to effectively reduce the use of sulfuric acid, and achieve green, environmentally friendly and efficient leaching of manganese.
- Published
- 2020
40. Efficient improvement for dissociation behavior and thermal decomposition of manganese ore by microwave calcination
- Author
-
Li, K. (Kangqiang), Chen, J. (Jin), Peng, J. (Jinhui), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Subjects
Dissociation behavior ,Phase structure ,Microwave calcination ,Thermal decomposition ,Manganese ore - Abstract
Traditional smelting process of manganese ore was plagued with high consume of power and coke, and spraying and slag turning accidents caused by violent decomposition of carbonates and manganese oxides in manganese ore. In the present work, the thermal decomposition mechanism and phase structures of manganese ore were systematically investigated, calcined through microwave calcination approach and characterized by XRD, SEM and EDAX. Results indicated that microwave calcination had a significantly better effect than conventional calcination for manganese ore. An increase in calcination temperature was found to present a more profound effect than calcination duration. The optimum calcination temperature was identified to be 950 °C, with the calcination duration being 30 min, and manganese ore grade increased from initial 30% to 39%–42%, with the pulverization ratio being 8%–9%. Peak intensities of Mn3O4 phase enhanced with calcination temperature increasing, and irregular cracks and pits appeared on the surface of the microwave calcined manganese ore. Meanwhile, the feasibility of decomposition reactions of manganese ore at the considered temperature regime was confirmed by thermodynamics analysis. The upgrading and modified manganese ore by microwave calcination can realize the direct smelting of the concentrate. The work proposes an efficient calcination idea for manganese ore by microwave calcination.
- Published
- 2020
41. The adsorption removal of tannic acid by regenerated activated carbon from the spent catalyst of vinyl acetate synthesis
- Author
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Ma, A. (Aiyuan), Zheng, X. (Xuemei), Li, K. (Kangqiang), Omran, M. (Mamdouh), Chen, G. (Guo), Ma, A. (Aiyuan), Zheng, X. (Xuemei), Li, K. (Kangqiang), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Abstract
Activated carbon can remove humic acid organic pollutants to reduce trihalomethanes carcinogens generated in the chlorination disinfection process. In this study, regenerated activated carbon (RAC) was recycled from the spent catalyst of vinyl acetate synthesis via a thermal regeneration method. The influences of regeneration temperature and time on the regeneration rate and iodine adsorption value of the RAC samples were determined, the nitrogen adsorption isotherms and pore structure characteristics of RAC samples were characterised, and the effects of RAC additive amount, pH, adsorption temperature, and time on tannic acid removal rate were investigated. Results indicated that regeneration time and temperature presented pronounced influences on the regeneration rate and iodine adsorption performance of RAC samples. For the RAC sample optimally prepared at 900 °C for 2 h, the iodine adsorption value, BET surface area, and the regeneration rate were 817 mg/g, 1346 m²/g, and 65.9%, respectively. Under the optimal conditions including RAC additive amount of 3.5 g, temperature of 25 °C, adsorption time of 200 min and pH of 4.0, and tannic acid concentration of 50 mg/L, the tannic acid removal rate reached 89.96%. The adsorption kinetic characteristics for tannic acid onto RAC matched to Pseudo-second-order model, meanwhile the analysis of Boyd dynamic equation and Intraparticle diffusion model denoted the absorption process was mainly controlled by film diffusion. This work provides a technology aiming at the joint treatment of hazardous waste resources, which involve the regeneration activated carbon from spent catalysts and the absorption removal of tannic acid organic pollutants.
- Published
- 2020
42. Dielectric properties and high temperature thermochemical properties of the pyrolusite-pyrite mixture during reduction roasting
- Author
-
Lin, S. (Shunda), Gao, L. (Lei), Yang, Y. (Yong), Chen, J. (Jin), Guo, S. (Shenghui), Omran, M. (Mamdouh), Chen, G. (Guo), Lin, S. (Shunda), Gao, L. (Lei), Yang, Y. (Yong), Chen, J. (Jin), Guo, S. (Shenghui), Omran, M. (Mamdouh), and Chen, G. (Guo)
- Abstract
Manganese sulfate is widely used in electrolytic manganese production, catalysts, batteries, and other fields. However, the preparation of manganese sulfate from conventional roasting process of pyrolusite with additive of pyrite has disadvantages including long roasting time and low efficiency. Thus, microwave heating is used as an alternative for the preparation of manganese sulfate instead of traditional heating to destroy the dense structure of minerals and to further improve the heating efficiency which is dominating by dielectric properties of the material. Therefore, to evaluate the mechanism of preparation of manganese sulfate with microwave heating, experiments were carried out to explore the dielectric and thermochemical properties of pyrolusite-pyrite mixture at high temperature. The dielectric properties of pyrolusite-pyrite mixtures with different ratios were measured at high temperature using the resonant cavity perturbation technique, which has been widely used to study the dielectric properties of different metallurgical materials. It was found that with the increase of temperature, the microwave absorption properties of pure pyrolusite decreased from 28.173 F/M to 25.931 F/M. The wave-absorbing property of the soft pyrite/pyrite mixture increased to 41.218 F/M, indicating that pyrite can obviously improve the wave-absorbing property of the mixture. In addition, the characteristics of pyrolysis and reduction were studied systematically, and the pyrolysis and reduction process was divided into four stages according to the difference of temperature: 30 ℃-200 ℃, 200 ℃-400 ℃, 400 ℃-600 ℃, 600 ℃-900 ℃, corresponding to the separation of adsorbed water and bound water, MnO₂ decomposition, desulfurization redox reaction of FeS₂ and desulfurization redox reaction of Fe(1-x) S, respectively. This work highlights the possibility of reducing manganese ore by microwave heating with an additive of pyrite and finds that pyrite can modify the microwave abs
- Published
- 2020
43. Highly efficient oxidation of Panzhihua titanium slag for manufacturing welding grade rutile titanium dioxide
- Author
-
Chen, G. (Guo), Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Jiang, Q. (Qi), Li, K. (Kangqiang), Gao, L. (Lei), Omran, M. (Mamdouh), Chen, J. (Jin), Chen, G. (Guo), Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Jiang, Q. (Qi), Li, K. (Kangqiang), Gao, L. (Lei), Omran, M. (Mamdouh), and Chen, J. (Jin)
- Abstract
Because of the shortage of natural rutile, synthetic rutile is a widely used substitute welding materials for natural rutile owing to its excellent mechanical and thermal properties. In this work, rutile TiO2 was prepared from oxidation roasting titanium slag, which can be used as special welding materials. The phase microstructure characteristics of the raw materials and the roasted samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopic analysis. Results indicated that the contents of sulfur (S) and carbon (C) in titanium slag decreased during oxidation roasting process, and the decreases of sulfur and carbon contents were mainly ascribed to the formation of corresponding oxides. XRD and FT-IR results revealed the formation of rutile TiO₂ phase after titanium slag through oxidization roasting; additionally, observed from SEM patterns, the rutile TiO₂ phase with a complex short rod-like crystal appeared in the products. Since the contents of sulfur (S), phosphorus (P) and carbon (C) element were all below 0.030% in the prepared rutile TiO₂ with the recommended roasting approach (roasted at 1100 °C for 120 min), the present work highlights that Panzhihua titanium slag is a potential resource of titanium for the manufacture of high-quality rutile TiO₂ applicable for special welding materials industry.
- Published
- 2020
44. Investigation on microwave carbothermal reduction behavior of low-grade pyrolusite
- Author
-
Chen, G. (Guo), Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Jiang, Q. (Qi), Li, K. (Kangqiang), Chen, J. (Jin), Peng, J. (Jinhui), Gao, L. (Lei), Omran, M. (Mamdouh), He, F. (Fei), Chen, G. (Guo), Ling, Y. (Yeqing), Li, Q. (Qiannan), Zheng, H. (Hewen), Jiang, Q. (Qi), Li, K. (Kangqiang), Chen, J. (Jin), Peng, J. (Jinhui), Gao, L. (Lei), Omran, M. (Mamdouh), and He, F. (Fei)
- Abstract
Applying microwave heating, in substitution for conventional industrial process heating, renders energy-saving and clean efficient for mineral reduction. In this work, the behavior of low-grade pyrolusite during microwave-assisted heating was systematically investigated, and the phase transformation of pyrolusite during the reduction process was characterized by TG-DTG-DSC and XRD; meanwhile, a model for the reduction mechanism was proposed, with a three-stage reduction process identified. Results indicated that manganese oxide (MnO) powder can be efficiently prepared, and the reduction ratio presented positive relationships with reduction temperature and heating time, obtaining with a high reduction ratio value of 94.4% achieved at 600 °C within a duration time of 40 min. XRD analysis confirmed that the phase transformation during the reduction process followed the conversion sequence as MnO2→Mn2O3→Mn3O4→MnO, and the iron oxides was almost converted to Fe3O4. It was proved that low-grade pyrolusite can be reduced effectively and efficiently to manganese oxide at lower temperature and shorter duration time by microwave heating.
- Published
- 2020
45. High-temperature dielectric properties and pyrolysis reduction characteristics of different biomass-pyrolusite mixtures in microwave field
- Author
-
Li, K. (Kangqiang), Chen, G. (Guo), Li, X. (Xiteng), Peng, J. (Jinhui), Ruan, R. (Roger), Omran, M. (Mamdouh), and Chen, J. (Jin)
- Subjects
Low-grade pyrolusite ,Heating characteristics ,Microwave heating ,Dielectric properties ,Biomass pyrolysis - Abstract
Exploring the dielectric properties of mineral-biomass mixtures is fundamental to the coupled application with biomass pyrolysis and microwave technology to mineral reduction. In this work, the microwave dielectric properties of five pyrolusite-biomass mixtures were measured by resonant cavity perturbation technique and the pyrolysis reduction characteristics were systematically investigated, including poplar, pine, ageratina adenophora, rapeseed shell and walnut shell. Results indicated that the dielectric properties commonalities of five mixtures with temperature represented by increasing firstly, dropping intensely and finally rising slightly, with excellent responsiveness to microwaves; which the change trend was mainly attributed to the crystal transformation of amorphous MnO₂ and pyrolusite reduction reactions by biomass pyrolysis. Meanwhile, the heating characteristics successfully matched the dielectric properties of the mixtures, and the pyrolusite reduction process by biomass can be divided into two stages: biomass pyrolysis and pyrolusite reduction. The work highlights the universal feasibility of the novel coupled method for mineral reduction.
- Published
- 2019
46. China–Africa and China–Asia Collaboration on Schistosomiasis Control
- Author
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Qing Yu, Simon L. Croft, Xiao-Nong Zhou, Qian Wang, Jing Xu, Rosanna W. Peeling, Ying-Jun Qian, R. Bergquist, and J.-G. Guo
- Subjects
0301 basic medicine ,Economic growth ,medicine.medical_specialty ,business.industry ,Public health ,030231 tropical medicine ,Environmental resource management ,Schistosomiasis ,030108 mycology & parasitology ,medicine.disease ,Southeast asia ,03 medical and health sciences ,0302 clinical medicine ,Geography ,Schistosomiasis control ,parasitic diseases ,medicine ,China ,business ,SWOT analysis - Abstract
Schistosomiasis, a disease caused by a trematode, parasitic worm, is a worldwide public health problem. In spite of great progress with regard to morbidity control, even elimination of this infection in recent decades, there are still challenges to overcome in sub-Saharan Africa and endemic areas in Southeast Asia. Regarded as one of the most successful countries with respect to schistosomiasis control, The People's Republic of China has accumulated considerable experience and learnt important lessons in various local settings that could benefit schistosomiasis control in other endemic countries. Based on an analysis of conceived strengths, weaknesses, opportunities and threats (SWOT) of potential collaborative activities with regard to schistosomiasis in Africa and Asia, this article addresses the importance of collaborative efforts and explores the priorities that would be expected to facilitate the transfer of Chinese experience to low- and middle-income countries in Africa and Asia.
- Published
- 2016
47. Fetal Minamata DiseaseCongenital Methylmercury Poisoning
- Author
-
L Chang and G Guo
- Subjects
Fetus ,business.industry ,Methylmercury poisoning ,Medicine ,Physiology ,business - Published
- 1998
48. Fractal geometry of fingering front morphologies of water and NAPL flow in homogeneous porous media: A comparison study.
- Author
-
Li H, Shen Z, Zhang X, Huang X, Li F, Du X, Li Y, and Guo G
- Abstract
Fingering front morphologies for water and non-aqueous phase liquids (NAPLs) infiltrating into homogeneous unsaturated porous media were quantitatively described based on the fractal assumption. Correlations of fractal dimensions with physical properties of the fluids were studied. The implications of fractal dimensions for environmental systems are further discussed. Fingering front morphologies had fractal properties, and diesels which with high capillary numbers experienced high fractal dimensions than water. Fractal dimension was suggested as an indicator for dye coverage and infiltration depth, which represent pollution area and depth, respectively. The pollution areas showed positive correlations with fractal dimensions while the infiltration depths showed negative correlations. This information is useful for contaminated soil risk management and important in the effective design of recovery and remediation schemes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)
- Published
- 2024
- Full Text
- View/download PDF
49. A comprehensive risk assessment of microplastics in soil, water, and atmosphere: Implications for human health and environmental safety.
- Author
-
Wang Y, Zhu Y, Guo G, An L, Fang W, Tan Y, Jiang J, Bing X, Song Q, Zhou Q, and He Z
- Abstract
Microplastics (MPs) are pervasive across ecosystems, likely posing significant environmental and health risks based on more and more evidence. In this study, we searched through the Web of Science Core Collection and obtained 1039 papers for visualization and analysis. In order to discuss the chemical composition, migration, transformation and potential risk of MPs, 135 sets of relevant data in soil, water, and atmosphere were collected in China as a typical region, which is a hotspot region for investigation of MPs. The results showed that the primary polymer categories of MPs in the environment to be polypropylene, polyethylene, and polystyrene. The soil contains a significant quantity of MPs, averaging at 12,107.42 items·kg
dw -1 , while water contains averaging at 97,271.18 items m-3 . The total pollution load indexes for all three environments are at risk level I. Based on current risk assessment methods, the potential ecological risk of MPs is low. However, based on the polymer components, migration and transformation patterns, and especially the complexes with other pollutants, it indicates an increasing indirect risk. Interactions with some other pollutants are likely amplify the ecological and health risks associated with MPs. Aggregative results showed that the present risk assessment models could not assess the risks of MPs well. Thus, we suggested develop a risk assessment methodology for MPs based on relevant research progress. Some factors such as the size and form of MPs, sources and distribution, bioaccumulation, social acceptance and economic costs could be considered adding in the present risk assessment models. Finally, promotion of development and application of green chemically synthesized bioplastics such as using synthetic biology to help degrade plastics would be an alternative and sustainable option to relieve the adverse environmental and health concerns of MPs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
50. Accurate prediction of spatial distribution of soil potentially toxic elements using machine learning and associated key influencing factors identification: A case study in mining and smelting area in southwestern China.
- Author
-
Li K, Guo G, Zhang D, Lei M, and Wang Y
- Abstract
Accurate prediction of spatial distribution of potentially toxic elements (PTEs) is crucial for soil pollution prevention and risk control. Achieving accurate prediction of spatial distribution of soil PTEs at a large scale using conventional methods presents significant challenges. In this study, machine learning (ML) models, specially artificial neural network (ANN), random forest (RF), and extreme gradient boosting (XGB), were used to predict spatial distribution of soil PTEs and identify associated key factors in mining and smelting area located in Yunnan Province, China, under the three scenarios: (1) natural + socioeconomic + spatial datasets (NS), (2) NS + irrigation pollution index (IPI) datasets, (3) NS + IPI + deposition (DEPO) datasets. The results highlighted the combination of NS+IPI+DEPO yielded the highest predictive accuracy across ML models. Particularly, XGB exhibited the highest performance for As (R
2 =0.7939), Cd (R2 =0.6679), Cu (R2 =0.8519), Pb (R2 =0.8317), and Zn (R2 =0.7669), whereas RF performed the best for Ni (R2 =0.7146). The feature importance and Shapley additive explanation (SHAP) analysis revealed that DEPO and IPI were the pivotal factors influencing the distribution of soil PTEs. Our findings highlighted the important role of DEPO in spatial distribution prediction of soil PTEs, which has often been ignored in previous studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)- Published
- 2024
- Full Text
- View/download PDF
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