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Addressing climate change requires transitioning to cleaner energy sources and adopting advanced CO2 capture techniques. Clay minerals are effective in CO2 adsorption due to their regenerative properties. Recent advancements in nanotechnology further improve their efficiency and potential for use in carbon capture and storage. This study examines the CO2 adsorption properties of montmorillonite and saponite, which are subjected to a novel microwave-assisted acid treatment to enhance their adsorption capacity. While montmorillonite shows minimal changes, saponite undergoes significant alterations. Furthermore, the addition of silica pillars to smectites results in a new nanomaterial with a higher surface area (653 m2 g−1), denoted as reversed smectite, with enhanced CO2 adsorption capabilities, potentially useful for electrochemical devices for converting captured CO2 into value-added products. [ABSTRACT FROM AUTHOR]

Platinum-based high-entropy-alloy nanoparticles (PHEA-NPs) have been attractive as electrocatalysts due to their excellent electrocatalytic properties. In this work, PHEA-NPs consisting of platinum, iron, copper, cobalt, nickel and manganese were prepared via a facile solvothermal reduction method and further examined for electro-oxidation of formic acid (FA) and glycerol (GLY). The resulting PHEA-NPs exhibited superior activity for FA and GLY electro-oxidation in acidic solutions relative to the commercial Pt/C catalyst. In contrast, PHEA-NPs showed no activity for FA oxidation and mediocre activity for GLY oxidation in alkaline electrolytes. Interestingly, the activity for FA and GLY electro-oxidation in alkaline solutions was enhanced via an acidic treatment, which was attributed to the surface enrichment of platinum element arisen from the structural re-construction of PHEA-NPs. To explore the role of the components, a series of control samples were prepared. It was found that the presence of copper, nickel, and iron is beneficial to the electro-oxidation of FA and GLY in acidic electrolytes. Further CO stripping experiments were conducted to evaluate the poisoning resistance of the samples, which correlates with the catalytic performance. It was found that PHEA-NPs exhibit superior tolerances to CO poisoning compared to Pt/C. The findings from this work may be valuable for fabricating high-performance electrocatalysts for the electro-oxidation of FA and GLY. [Display omitted] • PHEA-NPs show excellent performance for FA and GLY oxidation in acidic electrolytes. • Copper, nickel, and iron contribute played a crucial role for the superior activity. • PHEA-NPs exhibit superior tolerances to CO poisoning compared to Pt/C. • An acid treatment enhanced activities of PHEA in alkaline electrolytes. • Surface Pt enrichment was the main reason for the increased activity. [ABSTRACT FROM AUTHOR]

In this work, the effect of microwave-assisted acid treatments on the morphological and crystallochemical characteristics of chrysotile fibers is investigated. A low concentration of nitric acid (0.2 N) is used to remove Mg2+-species located in the octahedral sheet of its structure, thereby causing a crystallo-chemical change forming a skeleton of non-crystalline amorphous silica. This skeleton maintains an elongated morphology but characterized by rounded -not sharp-edges and porous surfaces whose physical resistance under stress is reduced when compared with the initial fibers of chrysotile, favoring a lower pathogenicity of the fibers. Thus, microwave-assisted acid treatment rise as a low-cost, fast and effective option in avoiding the dangerousness associated with asbestos waste management. [ABSTRACT FROM AUTHOR]

ABSTRACT The electrical properties of acid‐treated CNT were investigated in terms of functional group and microstructure. A mixture of HNO3 and H2SO4 was used to acid treatment of CNT, and acid‐treated CNTs were synthesized by the mixture for 0 to 5 h. In crystal structure analysis, as acid treatment time was increased, the intensity of graphite diffraction peak was decreased and shifted to lower angle. It indicates a decrease in the crystallinity of CNT surface and lattice contraction by loss of carbon atoms. The distribution of oxygen on CNT surface was observed by TEM analysis confirming that functional groups and structural defects were formed. ID/IG ratio and average distance between defects (LD) were calculated using Raman spectroscopy to analyze the structural characteristics of CNT, and the greatest decrease was identified from p‐CNT to 2h‐CNT, resulting in the formation of functional groups and the changes in structural defects on CNT surface by acid treatment in the initial stage. Bonding state on CNT surface was analyzed through XPS analysis, and functional groups such as CO and COH were confirmed in acid‐treated CNT. Sheet resistance was measured to analyze the electrical properties of CNT, and 3h‐CNT showed the lowest sheet resistance at 25.28 Ω. [ABSTRACT FROM AUTHOR]

The effect of acid treatment on TS-1 zeolite prior to alkaline treatment with TPAOH solution is investigated. 1H MAS NMR, UV–Vis, XPS, XRF, N2-sorption and TEM are applied to characterize the acid and/or alkaline treated TS-1 samples. It is found that acid treatment destructs the Si–O-Ti bonds of the framework, and promotes the conversion of 4-coordinated Ti into 6-coordinated Ti. Then in the subsequent alkaline treatment, part of framework Si–O-Si bonds are hydrolyzed and mesopores are formed. Meanwhile, the dissolved Si and Ti species could be incorporated back into the framework directed by TPAOH. Compared with TS-1-A, which is synthesized without acid treatment, TS-1-HA remains more active center and enhanced accessibility. Therefore, it shows high catalytic performance in cyclohexanone ammoximation reaction. [ABSTRACT FROM AUTHOR]

The Si/Al molar ratio of MAZ aluminosilicate zeolite prepared by the direct hydrothermal method is generally less than five, thus giving rise to poor thermal and hydrothermal stability for this low-silica zeolite. With the purpose of enhancing the Si/Al molar ratio of MAZ zeolite, post-synthesized methods including acetic acid treatment and steaming treatment, as well as interzeolite transformation from FAU zeolite, were employed to prepare MAZ zeolite with high silica. It was found that steaming treatment was more effective in increasing the Si/Al molar ratio in comparison with acetic acid treatment, affording a maximum Si/Al molar ratio of 16.9 along with a preserved crystallinity of approximately 75%. Additionally, high-silica MAZ zeolite with a Si/Al molar ratio of up to 7.3 was also capable of being directly hydrothermally synthesized using interzeolite transformation from FAU zeolite. [ABSTRACT FROM AUTHOR]

The current study investigates the evolution of dye adsorption properties of protein-rich soy flour biomass converted to nitrogen-doped biochars. Biochars were synthesized from the single-step pyrolysis of soy flour at different temperatures, 450, 650, and 750 °C, determined from the TG/DTA/DTG studies. The 750 °C pyrolyzed sample was further treated with HNO3 for demineralization. XRD, Raman, and FTIR results revealed that higher pyrolysis temperature led to increased amorphous graphitic carbon and mineral ash content and aromaticity. Treating the synthesized biochar with HNO3 resulted in complete removal of mineral content, emergence of micropores, multifold increase in the surface area, higher oxidation of the surface, and lower pHpzc. From the adsorption study of anionic dye eriochrome black-T (EBT) and the cationic dyes methylene blue (MB) and crystal violet (CV), the best adsorption characteristics were observed for the sample pyrolyzed at 750 °C despite its very low surface area and porosity. The efficiency of adsorption was improved further by treating the sample with HNO3. The adsorption results were explained on the basis of surface chemistry, pHpzc, and pore size of the samples. The maximum dye adsorbed (qe) onto the HNO3-treated sample for MB and EBT was 51.11 and 54.30 mg/g, respectively. For the HNO3-treated sample, the MB and EBT are both adsorbed via two-step chemisorption (pseudo-second-order kinetics) with MB forming multilayers on this sample and EBT forming monolayer as per Freundlich and Langmuir isotherm models, respectively. [ABSTRACT FROM AUTHOR]

Modifying starch allows for improvements in its properties to enable improved uses in food matrices, bioplastics, and encapsulating agents. In this research, four varieties of native potato starch were modified by acid treatment, enzymatic treatment, and ethanol precipitation, and their physicochemical, structural, thermal, and techno-functional characteristics were analyzed. According to FT-IR analysis, no influence of the modified starches on the chemical groups was observed, and by scanning electron microscopy (SEM), spherical and oval shapes were observed in the acid and enzymatic treatments, with particle sizes between 27 and 36 μm. In particular, the ethanolic precipitation treatment yielded a different morphology with a particle size between 10.9 and 476.3 nm, resulting in a significant decrease in gelatinization temperature (DSC) and more pronounced crystallites (XRD). On the other hand, the enzymatic treatment showed higher values for z-potential (ζ), and the acid treatment showed lower mass loss (TGA). Acid and ethanolic treatments affected the dough properties compared to native starches. The techno-functional properties showed a decrease in the water absorption index, an increase in the water solubility index, and varied swelling power behaviors. In conclusion, the modification of potato starches through acid, enzymatic, and ethanolic precipitation treatments alters their physicochemical properties, such as swelling capacity, viscosity, and thermal stability. This in turn affects their molecular structure, modifying morphology and the ability to form gels, which expands their applications in the food industry to improve textures, stabilize emulsions, and thicken products. Furthermore, these modifications also open new opportunities for the development of bioplastics by improving the biodegradability and mechanical properties of starch-based plastic materials. [ABSTRACT FROM AUTHOR]

AbstractRecently, non-wood plants have increasingly gained attention, due to their versatile advantages like cost and fast-growing period. The purpose of this study was to examine the effectiveness of different treatments on Algerian Spart fibers (Lygeum spartum) using sodium hydroxide at various concentrations (8, 10, 15, and 22% NaOH), and sulfuric acid at 30% for 2h at 100 °C. Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were used to characterize the microstructural changes in the treated fibers. The results of FTIR confirmed the presence of cellulose in the raw fibers with a crystallinity index of 49.4%. The FTIR and XRD studies showed that an 8% NaOH treatment eliminated the amorphous constituents and improved the crystallinity index. Also, SEM micrographs confirmed the removal of impurities; for the acid treated fibers a pseudo-lignin was formed and deposited on fibers surfaces in the form of spherical droplets. Moreover, a decrease in the yield of cellulose at high alkali concentrations was noticed. The results suggest the possibility of exploitation of Spart fibers and their application in papermaking and as a reinforcement in composite materials. [ABSTRACT FROM AUTHOR]

Nowadays, oil fields on the territory of the Republic of Tatarstan are developed with application of systems for reservoir pressure maintenance, involving injection of large volumes of water into the formation. Efficiency of waterflooding depends on the quality of the injected agent, and, despite the use of various technologies of preparation and treatment of injected water, with the lapse of time critical matrix porosity and permeability inevitably decreases. In this work the main sources of injection wells critical matrix clogging are considered: mechanical impurities, oil products and scales formation, and the results of the component composition analysis of deposits from cluster pumping stations are given. Using the Oddo-Thomson methodology, it is revealed that injected water is prone to calcite and barite deposition at bottomhole conditions. Physicochemical and core-flooding study of several reagents for removing colmatants: acid compositions, hydrocarbon solvents and complexing agents were carried out and their optimal formulations were determined. The matrix treatment technology, including the sequential injection of compositions based on hydrochloric and mud acids, was substantiated. An algorithm for calculating the optimal reagent volume has been developed on the basis of research data on the mineralogical composition of mechanical impurities and ionic composition of injected water. Four types of matrix treatment technologies were determined for the conditions of injection wells at the Romashkinskoye oil field Devonian formation, taking into account the composition of colmatant, and acid treatment designs were developed.

Surface engineering has been an important strategy in attaining a higher catalytic activity in comparison with pristine samples. CaTiO 3 is a well-known photoactive material but lacks photo-to-electron conversion efficiency. Herein, we demonstrate a simple path-way that could achieve a higher surface area, active site exposure, and oxygen vacancies. The experimental results using different concentrations of HNO 3 illustrated the selective leaching of Ca(II) ions, which leads to the partial conversion of Ti4+ to Ti3+ and the formation of oxygen vacancy. This eventually resulted in an engineered electronic state that modifies the band alignment and improves the charge transfer and migration rate. The optimized photocatalyst (CTO-5) exhibits approximately six times enhanced hydrogen evolution rate of 58.1 μmol∙g−1 h−1 than the pristine CaTiO 3 (8.7 μmol∙g−1 h−1). Our work offers new intuitions into the rational design of photocatalysts with surface-engineering methodology without using any noble metal. [Display omitted] • CaTiO 3 material is synthesized by a simple citrate-gel method. • Surface engineering of CaTiO 3 is performed using dilute HNO 3 treatment. • The acid treatment partially removes Ca(II) and creates Ti3+ as well as oxygen vacancies. • CTO-5 sample shows 6 times higher HER activity than pristine CTO without any co-catalyst. [ABSTRACT FROM AUTHOR]

In order to explore the effects of acid treatment (acid concentration, time and temperature), enzyme preparations (cellulase, xylanase, β-glucanase) on Pleurotus eryngii fungus residue. The experiment used the mushroom residue of Pleurotus eryngii collected in Hebei Province as the raw material, total reducing sugar content as the research index, the factors affecting the acid treatment of P.eryngii residue were analyzed by principal component analysis. At the same time, the effects of enzyme preparation on the reduction of neutral detergent cellulose and acid detergent cellulose were analyzed by orthogonal test. At 40 °C, 2% and 3% acid concentrations would degrade the content of reducing sugar with time. At 60 °C, the increase of acid concentration could slow down the degradation of total reducing sugar. At 80°C, 1% and 2% acid concentrations could promote the degradation of polysaccharides and increase the content of total reducing sugar. According to the principal component analysis, temperature was the most important factor affecting the content of reducing sugar of P.eryngii slag. The orthogonal test results showed that the degradation of xylanase and cellulase were the main factors affecting the reduced amount of neutral detergent cellulose and acid detergent cellulose respectively. The optimal enzymolysis formula was cellulase 85 U/mL, xylanase 220 U/mL and glucanase 40 U/mL.. These results indicated that the bacterial residue after acid and enzyme treatment has nutritional value as a ruminant feed. [ABSTRACT FROM AUTHOR]

The water hyacinth leaf powder (WH) was used to adsorb Cu(II) from wastewater. The WH was modified through sulfuric acid (A-WH) and sodium hydroxide (B-WH) treatments. The biosorption was studied with various initial pH, initial Cu(II) concentrations, and biosorption time. The results show that the biosorption capacities of the biosorbents increase with the initial Cu(II) concentration. The optimum pH for the biosorption was 7.5, 7.0, and 7.5 for the WH, A-WH, and B-WH, respectively. The SEM images of the raw and treated WH revealed that alkali treatment could remove lignin more than the acid treatment, leaving more macropores in the B-WH than in the A-WH. The acid and alkali treatments to the WH leaf increase the biosorption capacity of the WH for Cu (II). The pseudo-second-order kinetic model can represent the dynamic behavior of the biosorption better than the pseudo-first-order model. The Langmuir model is better than the Freundlich model for describing the biosorption isotherm. The maximum biosorption capacities of the biosorbents predicted by the Langmuir model were 14.92 mg g-1, 18.32 mg g-1, and 23.27 mg g-1 for WH, A-WH, and B-WH, respectively. [ABSTRACT FROM AUTHOR]

In this study, natural clinoptilolite was treated with HCl, HNO3, and C2H2O4 at various concentrations (0.1, 0.5, and 1.0 M) at different temperatures (60, 70, and 80 °C) and treatment times (2, 3, and 4 h). The hydrogen adsorption capacity of natural clinoptilolite increased from 0.446 to 3.255 mmol/g after treating with 0.5 M HNO3 at 80 °C for 2 h. The correlation of the newly produced textural and structural properties with hydrogen adsorption ability is explained by characterizing the modified clinoptilolites using X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, and temperature programmed desorption of ammonia (NH3-TPD) measurements. The results show that the hydrogen adsorption capacity of modified clinoptilolites is associated with both the quantity and strength of the strong acid sites, in addition to the enhanced surface area and micropore volume. The hydrogen adsorption data for natural and acid-treated clinoptilolite samples at 77 K obeyed the Freundlich isotherm model. [ABSTRACT FROM AUTHOR]

Copyright of Taiwanese Journal of Agricultural Chemistry & Food Science is the property of Agricultural Chemical Society of Taiwan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biogas production from wheat straw (WS), cow manure (CM), and sewage sludge (SS) have positive impacts on the environment and economy. Therefore, this study investigated the optimization of biogas production from WS and pretreated with H2SO4 during codigesting with SS or CM as co-substrate. The total solids (TS), volatile solids (VS), carbon (C), nitrogen (N), and pH of biomass samples were measured. WS was first treated with different concentrations of H2SO4 and then mixed with different ratios of SS and digested under anaerobic digestion (AD). Both daily and cumulative biogas generated by AD were recorded under mesophilic conditions for 21 days. Chemical analysis indicated that WS and SS showed closely similar values of TS and VS, except CM had the lowest TS and VS. Also, WS had the highest C/N ratio, followed by CM, while the least C/N ratio was observed in SS. The pH values of CM and SS were within the ideal pH range for the AD process. The highest volume of biogas production was observed only in 4% H2SO4 treated WS with 50% SS, followed by 4% H2SO4 treated WS with 10% CM inoculum, whereas the lowest rate of biogas production was found with untreated WS with 10% SS. The highest VS consumed was 64.8% for WS treated with 4% H2SO4 and the lowest VS consumed was 12.75% for untreated WS mixed with SS at ratio of 30:70. Overall, it can be concluded that codigestion of H2SO4 treated WS with SS or CM can greatly enhance the efficiency of biogas production under the AD process. [ABSTRACT FROM AUTHOR]

The Stöber method provides a facile procedure for making carbon spheres with controlled particle sizes and is considered to be low-cost. In this study, a facile method has been established for synthesizing porous carbon spheres with variable pore sizes using a modified Stöber process. The influence of acid treatment and manipulating the carbonization process heating rate on the pore size and morphology of the particles was investigated by nitrogen adsorption, Scanning Electron Microscopy (SEM), Powder X-ray diffraction (XRD), Raman and Fourier Transform Infrared Spectroscopy (FTIR). According to the results, carbon spheres were in the size range between 1 and 7 microns. Pore size characterization shows that the pore diameter has increased by increasing the heating rate as well as by performing acid treatment. Tunable pore sizes from 2.25 to 8 nm have been evidenced by the experiments. These synthesized mesoporous carbons with different pore sizes which facilitate penetration of molecules and ions are promising as effective materials for adsorption, encapsulation and material delivery applications. [ABSTRACT FROM AUTHOR]

Utilizing Ti and Ti alloys as dental materials established a huge spurt in the field of dentistry. Since implantation is an invasive procedure that involves tissue penetration, infection control is mandatory for increasing the success rate of the implant treatment. In this study, we aimed to assess the impact of the surface physicochemical properties of acid-treated Ti on microorganisms specifically bacteria. After investigating the surface morphology and characteristics of acid-treated and untreated Ti sheets, we evaluated their potential to capture Escherichia coli (E. coli.) as well as the latter's survival on the surface of both types of sheets. Finally, we assessed the efficiency of the antibacterial properties exhibited by Ti against the oral microflora. SEM images revealed surface roughening of the acid-treated Ti represented by significantly irregular shape. Moreover, the acid-treated Ti exhibited remarkable hydrophobicity. A quantitative evaluation confirmed that acid-treated Ti has higher bacterial capture and antibacterial properties than untreated Ti. Further experiments showed similar effects of both types of Ti not only on E. coli but also on oral microflora. Results suggest that acid treatment of Ti surface is a potent technique for enhancing the antibacterial properties of Ti-derived materials. [ABSTRACT FROM AUTHOR]

A systematic study on the mechano-thermic reduction of low-grade ilmenite concentrate for the production of high-grade TiO2 powder used in the production of non-oxide ceramics for cutting tool applications has been successfully carried out. Samples were prepared via planetary ball milling and carbothermic reduction processes, and the as-reduced product was subsequently leached in order to improve the synthesized TiO2 by removing the metallic iron in it and other minor soluble impurities dissolved in the iron. The mechano-thermic reduction was achieved by milling a representative mixture of ilmenite and carbon in a molar ratio of 1:1, followed by carbothermic reduction at 1000 °C in a laboratory high-temperature furnace for 60 min. The as-reduced product was subsequently leached at 80 °C for 6 h in a hydrochloric acid solution. It was found that there was a complete reduction of ilmenite to metallic iron and TiO2 at 1000 °C. The results of the FESEM showed there were only two distinct regions of metallic iron (bright region) and titanium dioxide (grey region) with minor traces of unreacted carbon (dark spots), although there was clear regional demarcation between these regions. However, the iron dissolution during the acid treatment was almost 100% as there were no peaks of iron in the as-leached powder. The results of these analyses confirmed the synthesis of high-grade TiO2, which finds application in cutting tool applications and other areas such as in reflective pigment production. [ABSTRACT FROM AUTHOR]

The jarosite waste used during this study consists of minute amount of arsenic that has a potential to be leached into environment when kept in open area. This study tried to recover arsenic from jarosite waste using hydrometallurgical treatment. The comprehensive characterization of jarosite samples was performed using various analytical techniques, including X-ray diffraction (XRD), Fourier transform Infrared (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), and it was characterized as natrojarosite. For optimal removal of arsenic, the response surface methodology (RSM) was applied with the key factors, including dosage (A), time (B), temperature (C), and acid concentration (D) on the recovery of arsenic. The results indicated that the dosage (A) and acid concentration (D) demonstrated significant positive effects on arsenic recovery. As expected, the higher dosage and acid concentration was associated with increased recovery percentages for the arsenic from jarosite. Whereas time (B) and temperature (C) did not exhibit statistically significant recovery of arsenic within the specified experimental range. The contour plots showed the optimal operating conditions for the highest recovery percentage was approximately 52.61% when 2.5 g of jarosite was treated with 10 mol/L acid for 150 min at operating temperature of 80°. Although our study showed very moderate recovery of arsenic, it is first report where arsenic has been removed from jarosite waste. Readjustment of range of operating parameters would provide more insight into the further optimization of the yield. [ABSTRACT FROM AUTHOR]

Little mallow (Malva parviflora L.) is a notorious weed that causes substantial yield losses in winter crops. For effective weed management and seed testing, a deeper understanding of seed dormancy, germination behavior, and dormancy-breaking methods is necessary. Experiments were conducted to determine the effect of seed treatments, i.e., mechanical scarification, acid scarification, hot water treatment, and different germinating temperatures, i.e., 15 °C, 20 °C, or alternating 15–20 °C (16/8 h), on the seed dormancy in M.parviflora. A large proportion of M. parviflora seeds were physically dormant, with just 10.90% germination. Seed treatments had a significant influence on seed germination, seedling dry weight, vigor index, and water absorption (p ≤ 0.01). Among the various treatments, mechanical scarification enhanced germination by 32%, the vigor index by 487% and water uptake by 34%, and decreased percent hard seeds by 34%. Among the various germination temperatures, alternating 15–20 °C temperatures (16/8 h) gave the most significant result for germination and the lowest percent hard seeds. The findings of this study will serve as a valuable reference for seed testing and the development of suitable weed control strategies for M. parviflora. [ABSTRACT FROM AUTHOR]

Acid treatment technology has become widespread in the development of carbonate layers in oil fields. Virtually every well in the history of its production has been acid treated downhole, ultimately providing millions of tons of incremental oil production globally. Despite the considerable amount of theoretical and practical research devoted to this technology, the problem of controlling the efficiency of acid treatments remains topical. In this connection, the purpose of this paper is to study the influence of known and available in field conditions geological and technological parameters on the efficiency of acid stimulation in carbonate reservoirs. Laboratory studies (in free volume, filtration and X-ray tomography tests) using two hydrochloric acid compositions and carbonate rock samples of the same geologic age from oil fields of Perm krai to determine the dependencies were performed. Acid treatments were modeled by varying technological parameters (volume, rate and pressure of injection of acid compositions, reaction time of acid with rock) under thermodynamic conditions corresponding to reservoir properties. Statistical processing of empirically obtained data allowed us to note the predominant role of technological parameters to achieve a successful result of acid stimulation. Multivariate statistical models describing the process of formation of acid treatment efficiency in carbonate reservoirs have been developed. It was found that the reservoir stimulation efficiency varies in direct proportion to the increase in the injection pressure of the acid composition and the volume of agent used due to the development of wormholes. The efficiency of acid treatment at dolomite content in the rock is significantly lower, which requires increasing the rate of composition injection and reaction time to achieve the highest stimulation result. Thus, the paper provides a basis for further development of the process of controlling the effectiveness of acid treatments in carbonate reservoirs of oil fields.

Light-driven water splitting has gained increasing attention as an eco-friendly method for hydrogen production. There is a pressing need to enhance the performance of catalysts for the commercial viability of this reaction. Many methods have been proposed to improve catalyst performance; however, an economical and straightforward approach remains a priority. This paper presents an uncomplicated technique called acid treatment, which augments the catalytic performance of nanoparticles. The method promotes a change in the catalytic reactivity by causing a deficit in electron density of Ti and O on the surface of TiO2 nanoparticles without altering their size, morphology, or crystal structure. In the Eosin Y sensitized photocatalytic hydrogen production system, nitric acid treated TiO2 (16.95 μmol/g) exhibited 1.5 times the hydrogen production compared to bare TiO2 (11.15 μmol/g).

Abstract Background The dissociation of antigen-antibody complexes has been utilized to enhance the accuracy of serological tests for infectious diseases, including Dirofilaria immitis. Currently, the antigen detected by available tests is primarily a glycoprotein found in the reproductive tract of female worms. However, this antigen can become inaccessible when bound to excessive circulating antibodies, leading to reduced test sensitivity and false-negative results. Acid and heat treatments of the sera or plasma have been established as reliable methods for inducing immune complex dissociation (ICD). Previous antigen testing for heartworm infection in dogs and cats has demonstrated that these treatments improve the diagnostic sensitivity without compromising specificity. This study aims to evaluate the performance of four distinct ICD methods in the detection of D. immitis antigen. Methods We utilized twofold serial dilutions of a well-characterized plasma (ranging from 1:2 to 1:4096) obtained from a D. immitis-infected dog to simulate the diverse antigen levels encountered in real-life infected dogs. The presence of antigen in the diluted samples, both without treatment and treated with four ICD protocols, was assessed in triplicate visually using DiroCHEK® by observing color changes. OD values were also obtained using the microplate reader SpectraMax® i Series-Spectramax Id3. A Factorial ANOVA test was conducted to compare the OD values between samples with and without treatments. Results The highest dilution at which color changes were observed was 1:128 for untreated samples and for samples subjected to acid treatments in ICD-3 and the hybrid ICD-4 protocol. In contrast, both heat treatment protocols (ICD-1 and ICD-2) exhibited color changes at a 512-fold dilution. The OD values in samples subjected to heat treatment were significantly higher than those in untreated samples, up to dilutions of 512-fold. Although OD values tended to be higher in samples subjected to acid treatment and the hybrid protocol compared to untreated samples up to a 128-fold dilution, this difference was not significant as the samples underwent further dilution. Conclusions Our findings affirm that heat treatments, rather than acid treatment, efficiently enhance the detection of D. immitis antigen by liberating the sequestered antigen from the immune complexes.

Addressing climate change requires transitioning to cleaner energy sources and adopting advanced CO2 capture techniques. Clay minerals are effective in CO2 adsorption due to their regenerative properties. Recent advancements in nanotechnology further improve their efficiency and potential for use in carbon capture and storage. This study examines the CO2 adsorption properties of montmorillonite and saponite, which are subjected to a novel microwave-assisted acid treatment to enhance their adsorption capacity. While montmorillonite shows minimal changes, saponite undergoes significant alterations. Furthermore, the addition of silica pillars to smectites results in a new nanomaterial with a higher surface area (653 m2 g−1), denoted as reversed smectite, with enhanced CO2 adsorption capabilities, potentially useful for electrochemical devices for converting captured CO2 into value-added products.

Spinel is a type of oxide and is rich in defect sites, which can play a vital role in anchoring noble metals. In this work, we subjected the MgAl2O4 spinel to nitric acid etching to generate more surface defects. Subsequently, low-loading (0.3–0.4 wt %) Au nanoparticle/MgAl2O4 catalysts were obtained by the precipitation method. Analysis of characterization results showed that the nitric acid treatment effectively removed Mg ions, simultaneously creating defects and enhancing the dispersion of Au nanoparticles. Compared to Au/MgAl2O4, Au/MgAl2O4–O (carrier pretreated by nitric acid) exhibited superior formaldehyde (HCHO) oxidation performance, achieving complete HCHO oxidation at 40 °C, due to the enhanced ability to activate H2O. In situ Diffuse Reflectance Infrared Fourier Transform (in situ DRIFT) study revealed that both the Au/MgAl2O4 and Au/MgAl2O4–O catalysts follow the same reaction mechanism: HCHO → DOM (dioxymethylene) → formate → CO2 + H2O, with formate oxidation as the rate-determining step. This study explored the effect of the pretreatment of spinel-supported precious metal catalysts on HCHO oxidation at low temperatures, providing more opportunities for the synthesis of multidefect nanoscale catalysts. [ABSTRACT FROM AUTHOR]

Developers of direct carbon fuel cell (DCFC) technology seek to convert carbon to a pure or highly concentrated carbon dioxide stream that could ultimately be transported and sequestered. Carbon black produced by natural gas cracking processes is very pure and is therefore a candidate for use in DCFCs. In this study the performance of As received and Treated carbon blacks are compared in a planar cell configuration. At a more viable operating temperature of 750 °C, the As received carbon was found to produce a peak power density of 51 mW/cm2 at a current density of 104 mA/cm2. The performance then increased to 105 mW/cm2 at a current density of 145 mA/cm2 at 850 °C. Acid treatment of the carbon was found to improve performance of the DCFC at 750 °C by 35% (69 mW/cm2 at 160 mA/cm2) and only by 5% at 850 °C (111 mW/cm2 at 201 mA/cm2). • A commercial carbon black was used to fuel a planar, direct carbon fuel cell (DCFC). • An acid treatment method applied to the carbon black increased its wettability. • A DCFC output higher power density with Treated than with As received carbon black. [ABSTRACT FROM AUTHOR]

The transition-metals carbon catalysts belong to intensively studied alternatives to the Pt-based catalysts promoting the oxygen reduction reaction (ORR) in electrochemical fuel cells (FCs). Commonly studied Fe,Co–N–C composites are usually obtained through pyrolysis and used as such or after a chemical post-treatment with an oxidizing agent. This treatment is applied to remove inactive metal species, thus, promoting the electrochemical activity. The impact of an oxidizing agent is poorly addressed in the literature, while its nature may negatively affect the catalyst's performance. Herein we report the first comparative study on the effect of post-treatment with the most common oxidizing agents such as HCl, HNO 3 , H 2 SO 4 and H 2 O 2 , on the structural and electrochemical properties of the Fe,Co–N–C catalyst. The catalyst is made by pyrolysis of the Co,Zn-ZIF metal-organic framework enriched with iron and nitrogen. Its structure was observed withstanding the action of mineral acids but suffers from hydrogen peroxide. The treatment with either nitric or chloric acid may improve the electrochemical performance up to 4%, while other agents decrease that by 6% and slow down the ORR rate. These findings are useful for the careful design of post-treatment procedures for carbon catalysts. • The Fe,Co–N–C carbon-based catalyst was obtained from Fe,Co-ZIF-8 MOF via pyrolysis at 700 °C in an inert atmosphere. • The Fe,Co–N–C catalyst was treated with four oxidizing agents - chloric, nitric and sulfuric acids, and hydrogen peroxide. • Structural and compositional changes were assessed with multi-technique characterization of the catalysts. • The catalysts treated with nitric and chloric acids demonstrated improved performance for ORR in an acidic medium. [ABSTRACT FROM AUTHOR]

Algerian kaolinite, sourced from Djebel Debbagh nuance 3 (DD3), was used as a low-cost adsorbent to remove methylene blue (MB) dye from water. Its adsorption capacity was enhanced through sulfuric acid treatment (treated-DD3). In response to the urgent demand for clean water, various technologies have been developed to address dye removal from wastewater. This study, specifically delving into the treatment of textile wastewater, examined the efficacy of treated-DD3 through adsorption processes. The acid treatment increased the surface area and pore volume of DD3. X-ray diffraction showed crystalline phases in both, with treated-DD3 having higher crystallinity. Fourier-transform infrared spectroscopy found no significant differences post-acid treatment. Scanning electron microscopy revealed DD3 had large, stacked particles with low surface area, while treated-DD3 had increased porosity and a smoother surface. Various parameters affecting MB adsorption were studied. The Langmuir and Freundlich models were used for isotherm parameters. Treated-DD3 exhibited a higher MB adsorption capacity (64.58 mg/g according to the Langmuir model) than DD3 (44.48 mg/g). Thermodynamic analysis indicated spontaneous and endothermic MB adsorption onto both DD3-BM and treated-DD3-BM systems under different pH conditions. Treated-DD3 effectively reduced chemical oxygen demand (from 304.056 mg/L to 34.44 mg/L) and biological oxygen demand (from 80 mg/L to 20 mg/L) in real textile wastewater. The adsorbent exhibited rapid removal and decolorization, surpassing 93% within the first 7 min of the experiment. The Gaussian process regression and particle swarm optimization (GPR–PSO) predicted MB adsorption capacity effectively (R = 0.9989, R2 = 0.9978, adj-R2 = 0.9978, RMSE = 1.1390, and MAE = 0.3926). [ABSTRACT FROM AUTHOR]

Acid treatment can increase the sludge calorific value to some extent by separating inorganic elements. In order to determine the mechanism by which acidification affects the sludge calorific value from an organic perspective, we investigated the changes in organic matter and dewaterability under different pH conditions. The results of this study showed that acidification conditioning retained organic matter while removing a greater amount of inorganic elements. Furthermore, acid treatment significantly increased the zeta potential and particle size of sludge particles and facilitated the precipitation of biological organic components from the supernatant to the surface of sludge particles. Acid-treated sludge exhibited a lower moisture content and a higher proportion of organic matter, and sludge treated with H2SO4, HCl, and HNO3 exhibited respective increases in calorific values of 12.14%, 7.92%, and 8.01% under pH 2. The calorific value of the acid-treated sludge was higher, making it more suitable for subsequent incineration. The findings of this study serve as a reference and foundation for efficient sludge incineration. [ABSTRACT FROM AUTHOR]

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The catalytic activity of an iron–containing nanoscale chitosan-based catalyst in the Fischer–Tropsch synthesis (FTS) and the features of the formation of the structure of such a catalyst have been studied. It is shown that the nature of the acids used in the preparation stage—nitric, acetic or citric, has a significant effect on the structure obtained by partial destruction of chitosan and the size of the nanocrystallites of the active phase, which, in turn, leads to significant changes in the activity of the catalyst and productivity for the target products—C5+ hydrocarbons. The best performance of catalyst in FTS observed for the sample, obtained with use of nitric acid: С5+ productivity reached to 2136 g С5+/kgFe/h. [ABSTRACT FROM AUTHOR]

To address the issue of surface enrichment of A-site ions in perovskite and the resulting suppression of catalytic activity, the La0.8Sr0.2Mn0.8Cu0.2O3 was modified by treatment with dilute nitric acid (2 mol/L) and dilute acetic acid (2 mol/L). The results show that the effect of dilute nitric acid treatment on the morphology and catalytic activity of the catalyst is more significant. The specific surface area of the catalyst after dilute nitric acid treatment (268.78 m2/g) is seven times higher than before treatment (37.55 m2/g). The low-temperature catalytic oxidation activity of HCHO of the catalyst after dilute nitric acid treatment is significantly improved, achieving a 50% HCHO oxidation efficiency at 80 °C, while the original sample requires 127 °C to achieve a 50% HCHO conversion. The excellent catalytic activity of the catalyst after dilute nitric acid treatment is related to its large specific surface area, high surface-active site density, and abundant Mn4+ ions. Stability and water resistance experiments show that the catalyst after dilute nitric acid treatment has excellent reaction stability and good water resistance ability. The mechanism of the formaldehyde oxidation reaction is that formaldehyde is first oxidized to a dioxymethylene (DOM) intermediate and DOM dehydrogenation reaction is responsible for the formation of formate species (HCOO-). [ABSTRACT FROM AUTHOR]

Background: The dissociation of antigen-antibody complexes has been utilized to enhance the accuracy of serological tests for infectious diseases, including Dirofilaria immitis. Currently, the antigen detected by available tests is primarily a glycoprotein found in the reproductive tract of female worms. However, this antigen can become inaccessible when bound to excessive circulating antibodies, leading to reduced test sensitivity and false-negative results. Acid and heat treatments of the sera or plasma have been established as reliable methods for inducing immune complex dissociation (ICD). Previous antigen testing for heartworm infection in dogs and cats has demonstrated that these treatments improve the diagnostic sensitivity without compromising specificity. This study aims to evaluate the performance of four distinct ICD methods in the detection of D. immitis antigen. Methods: We utilized twofold serial dilutions of a well-characterized plasma (ranging from 1:2 to 1:4096) obtained from a D. immitis-infected dog to simulate the diverse antigen levels encountered in real-life infected dogs. The presence of antigen in the diluted samples, both without treatment and treated with four ICD protocols, was assessed in triplicate visually using DiroCHEK® by observing color changes. OD values were also obtained using the microplate reader SpectraMax® i Series-Spectramax Id3. A Factorial ANOVA test was conducted to compare the OD values between samples with and without treatments. Results: The highest dilution at which color changes were observed was 1:128 for untreated samples and for samples subjected to acid treatments in ICD-3 and the hybrid ICD-4 protocol. In contrast, both heat treatment protocols (ICD-1 and ICD-2) exhibited color changes at a 512-fold dilution. The OD values in samples subjected to heat treatment were significantly higher than those in untreated samples, up to dilutions of 512-fold. Although OD values tended to be higher in samples subjected to acid treatment and the hybrid protocol compared to untreated samples up to a 128-fold dilution, this difference was not significant as the samples underwent further dilution. Conclusions: Our findings affirm that heat treatments, rather than acid treatment, efficiently enhance the detection of D. immitis antigen by liberating the sequestered antigen from the immune complexes. [ABSTRACT FROM AUTHOR]

The direct cracking of Bach Ho crude oil, having API gravity of 41°, over equilibrium FCC catalyst (Ecat), modified FCC catalyst (HT-FCC) and ZSM-5 additive were studied at 620–650 °C using short-contact-time micro activity testing unit. HT-FCC catalyst was prepared by the treatment of Ecat with oxalic acid in reflux condition. This treatment largely improves the porosity while keeping the particle size of Ecat. Hence, it leads to an important enhancement in catalytic cracking activity. Due to high activity of HT-FCC catalyst, the direct cracking of crude oil can be performed at a low catalyst-to-oil ratio (C/O) which helps to decrease the yield of dry gas. At 620–650 °C, C/O of 1.5–2.5, 18–23 wt.% of light olefins, 3–6 wt.% of dry gas together with 51–59 wt.% of gasoline yields can be obtained with HT-FCC catalyst. ZSM-5 addition favors the conversion of gasoline to light olefins. Compared to the results reported in literature, the use of HT-FCC and ZSM-5 catalysts at 650 °C, low C/O of 1.5 shows promising performances: (i) much lower dry gas yield (8%), (ii) high light-olefins yield (32%) while maintaining high gasoline yield (43%), and (iii) high BTXs content in gasoline (45%). [ABSTRACT FROM AUTHOR]

Acid treatment has been proven to effectively reduce the fracture initiation pressure in reservoirs, making it a viable method for stimulating deep tight sandstone reservoirs. However, the underlying mechanism of how sandstone pore structure and mechanical properties vary with acid treatment time remains unknown. Understanding this mechanism is crucial for studying the fracture initiation and propagation in tight sandstone reservoirs. In this study, to quantitatively analyze the changes in pore structure and mechanical properties of sandstone samples treated with acid for different times (0 h, 1 h, 2 h, 4 h, 6 h, 12 h, 24 h, 48 h, 72 h, 120 h, and 168 h), nuclear magnetic resonance and uniaxial compression tests were employed to examine these changes. The results revealed that the number of mesopores and macropores increased rapidly after 6 h and 48 h of acid treatment, respectively. Additionally, the permeability showed a significant increase after 24 h of acid treatment. This can be attributed to the gradual dissolution of intergranular cement, leading to the formation of new pores that connect with the existing pore network. The peak strength of sandstone undergoes stepwise changes with acid treatment time, which can be divided into three stages: stage I (0–6 h), stage II (12–72 h), and stage III (120–168 h). Under the influence of acid treatment and uniaxial compression, the damage and damage change rate of sandstone treated with acid for 24 h reached the minimum. Moreover, a variation mechanism for sandstone after acid treatment was proposed. [ABSTRACT FROM AUTHOR]

Increasing energy demands and growing environmental concerns regarding the consumption of fossil fuels are important motivations for the development of clean and sustainable energy sources. A triboelectric nanogenerator (TENG) is a promising energy technology that harnesses mechanical energy from the ambient environment by converting it into electrical energy. In this work, the enhancement of the energy conversion performance of a natural rubber (NR)-based TENG has been proposed by using modified activated carbon (AC). The effect of surface modification techniques, including acid treatments and plasma treatment for AC material on TENG performance, are investigated. The TENG fabricated from the NR incorporated with the modified AC using N2 plasma showed superior electrical output performance, which was attributed to the modification by N2 plasma introducing changes in the surface chemistry of AC, leading to the improved dielectric property of the NR-AC composite, which contributes to the enhanced triboelectric charge density. The highest power density of 2.65 mW/m2 was obtained from the NR-AC (N2 plasma-treated) TENG. This research provides a key insight into the modification of AC for the development of TENG with high energy conversion performance that could be useful for other future applications such as PM2.5 removal or CO2 capture. [ABSTRACT FROM AUTHOR]

The acidity of supports can have a positive effect on their catalytic behaviors. Herein, the effects of HCl treatment of TiO2 on its acidic properties and catalytic activity were investigated. TiO2 was treated with various molar concentrations of HCl. Subsequently, Pd was deposited on the treated TiO2 via the deposition–precipitation method; here, the catalysts were denoted as Pd/xH-T, where X is the molar concentration of HCl. Evidently, the amount of strong acid in TiO2 increased with HCl treatment, whereas that in TiO2 treated with a high concentration (5 M) of HCl decreased. After Pd was supported, the amount of acid slightly decreased compared with that on the TiO2 support; however, the order of the acid amounts was similar. The strong acid density increased such that Pd/2H-T had the highest acid content, whereas Pd/5H-T had the lowest. The Pd/2H-T catalyst exhibited the highest selectivity for THFA (95.4%), thus confirming that the selectivity for THFA is correlated with the amount of strong acid. Thus, THFA selectivity is affected by the number of strongly acid sites. [ABSTRACT FROM AUTHOR]

In this study, the effects of different types of acid treatments (H3PO4, H2SO4, and HCl) on the physicochemical properties and catalytic activity of the microporous HZSM-5 catalyst were investigated in methanol to olefins (MTO) reaction. The synthesized catalysts were characterized by XRD, N2 adsorption/desorption, ICP-MS, SEM, TEM, and pyridine-adsorbed DRIFT techniques. The characterization analyses indicated that each acid treatment led to the removal of differently positioned Al atoms in the HZSM-5 framework. Consequently, these acid treatments tuned the physicochemical properties, enhanced mesoporosity, and adjusted the Lewis Acid Site/Brønsted Acid Site (LAS/BAS) ratio of the catalysts by increasing the Si/Al ratio based on the removed Al atoms positioned in the HZSM-5 structure. In the activity tests of the catalysts, acid-treated HZSM-5 catalysts showed more stable and higher average methanol conversion, ethylene, and propylene selectivity compared to the parent catalyst. Among the acid-treated catalysts, the highest total light olefin selectivity (53%) was obtained over phosphoric acid-treated HZSM-5 due to the formation of silicoaluminophosphate-like structures, the generation of mesopores, and the adjusted acidity caused by the altered Si/Al ratio. TOS results showed that the amount of total light olefin selectivity obtained from the parent HZSM-5 was increased by 33% after phosphoric acid treatment. Acid treatments decreased coke deposition over the catalyst from 9.5 to 1.3%. Thus, it is noteworthy to say that the use of phosphoric acid-treated HZSM-5 in the MTO reaction is recommendable. [ABSTRACT FROM AUTHOR]

In this study, unlike porous carbon as a conventional catalyst support material in fuel cells, nonporous carbon was synthesized in the presence of different HCl concentrations (0.2 M-1 M) and investigated as a support material for platinum (Pt) catalysts in the oxygen reduction reaction (ORR). Since the micropore volume of the synthesized carbons is negligible, the detected surface areas with Brunauer-Emmett-Teller (BET) method were between the range of 19-23 m2 /g. Among the support materials, the carbon-supported Pt catalyst synthesized in the presence of 1 M HCl was investigated electrochemically in terms of hydrogen oxidation (HOR) and ORR half-cell reactions in the three-electrode system. The Pt catalyst supported with nonporous carbon, synthesized using 1 M HCl, reached the maximum limiting current value of -1.2 mA/cm2 (@1600 rpm, 5 mV/s) at ORR hydrodynamic curves. Low internal and charge transfer resistances of the same catalyst in electrochemical impedance spectroscopy (EIS) analysis are attributable to its nonporous structure. [ABSTRACT FROM AUTHOR]

Acid treatment of sepiolite under different molarity of HCl at various times was studied to find the best acid treatment conditions for obtaining anhydrous sepiolite without structural folding and with fully open and empty channels. It was found that high molarity (e.g., 3 M) acid treatment causes severe acid attack and heterogeneous magnesium dissolution from sepiolite particles. In contrast, the low molarity (e.g., 0.5 M) acid treatment dissolves magnesium homogeneously through the particles. This, in turn, affects the behavior of sepiolite upon calcination at 450ºC in that homogeneous magnesium dissolution gives better structural stability and consequently higher amount of open channels with the least amount of magnesium removal (25%). This is verified by rehydration behavior and specific surface area measurements after the calcination, where over 90% of the surface area could be preserved after the calcination of the low molarity acid-treated samples. No change in the morphology of sepiolite fibers was observed after acid treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • N -doped carbon coated nickel (Ni@NC) is prepared for electrochemical CO 2 reduction (ECRR). • There is a synergistic effect between Ni and N to ECRR activity. • The effect of pickling on ECRR performance of Ni@NC is revealed. • The adsorbed Cl on Ni@NC surface after pickling improves the ECRR performance. • The origin of the activity and selectivity of the pickling Ni@NC for ECRR is elucidated. Converting CO 2 into valuable chemicals and fuels through clean and renewable energy electricity provides a way to achieve sustainable development for human societies. In this study, carbon coated nickel catalysts (Ni@NCT) were prepared by solvothermal and high-temperature pyrolysis methods. A series of Ni@NC-X catalysts were obtained by pickling with different kinds of acids for electrochemical CO 2 reduction reaction (ECRR). The results show that Ni@NC-N treated with nitric acid has the highest selectivity but lower activity, Ni@NC-S treated with sulfuric acid has the lowest selectivity, and Ni@NC-Cl treated with hydrochloric acid shows the best activity and good selectivity. At –1.16 V, Ni@NC-Cl has a considerable CO yield of 472.9 μmol h−1 cm−2, which is significantly superior to Ni@NC-N (327.5), Ni@NC-S (295.6) and Ni@NC (270.8). The controlled experiments show that there is a synergistic effect between Ni and N. The chlorine adsorbed on the surface can promote the performance of ECRR. The poisoning experiments indicate that the contribution of surface Ni atoms to the ECRR is very small, and the increase of activity is mainly due to the nitrogen doped carbon coated Ni particles. The relationship between activity and selectivity of ECRR on different acid-washed catalysts was correlated by theoretical calculations for the first time, which is also in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The accurate calculation of the contribution which provided by clay minerals in coal on methane adsorption not only bares a significant importance for evaluating the effectiveness of acid stimulation in improving permeability and estimating the coalbed methane reserves but also serves a guide for the governance and utilization of methane resources. In this study, hydrochloric acid (HCl) and hydrofluoric acid (HF) were used to remove specific minerals in Qingdong coal samples. We firstly analyzed the mineral compositions of coal samples with different acidification treatments based on the X-ray diffraction (XRD) experiments, together with analysis of the changes in pore morphology and adsorption capacity. The results showed that acidification did not significantly change the shape of the pores, which remained slit-/plate-like pore. However, the altered adsorption capacity of the coal samples was attributed to changes in pore structure and mineral distribution. Acid erosion of mesopores promoted the transition from mesopores to macropores, contributing to an increase of 8.4% and 24.36% in the percentage of macropores in coal samples treated with HCl and HF, respectively. Fractal dimension D1 grew from 2.2193 to 2.3888 and 2.2572, respectively, but D2 decreased from 2.6146 to 2.5814 and 2.5433, indicating an increment in pore surface roughness and a simplification of the pore structure. The mineral richness of the coal seams should be taken into consideration when applying acid stimulation to increase permeability due to that the acidification products may block the passage of gas migration when the mineral content is slight, which can hinder gas extraction. The aim of this study is to quantitatively determine the contribution rate of clay minerals in coal to methane adsorption with a calculation method is provided by combining pore parameters and limit adsorption capacity, resulting in a contribution rate of 15%. [ABSTRACT FROM AUTHOR]

As the performance of natural rubber (NR) and halloysite nanotube (HNT) composites is uncertain due to low compatibility between the materials, malleated natural rubber (MNR) is then used as a compatibilizer to encourage filler–rubber compatibility. However, the properties of these composites remain unsatisfactory, and the treatment of HNT requires further improvement. Therefore, this study introduced acid treatment and silane coupling agents to increase the interactions between NR and HNT. Besides, this study also introduced the methods of compounding the rubber composites, either with single-stage or two-stage treatments. The application of a two-stage treatment to acid-treated HNT has given tensile strength a 26.5% improvement. Two-stage treatment enabled better silanization, while acid-treated HNT provided effective silanols for such interactions. The use of silane with acid-treated HNT was found to enhance the tensile strength, modulus, and tear strength of the composites, which was clearly due to better filler–rubber interactions. The Payne effect, which decreased up to 64.03% after applying a two-stage treatment, served as further confirmation of better filler–rrubber interactions. This conclusively proved that modifying both the rubber matrix and HNT enhances the performance of NR/HNT composites. [ABSTRACT FROM AUTHOR]