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Clarifying the occurrence state and embedding characteristics is the primary task to investigate the leaching behavior of the main metals in decopperized anode slime. Electron probe microanalysis, thermodynamic analysis, and leaching experiments were used to determine the optimum conditions for efficient one-step separation of the scattered and precious metals (SPMs) from base metals. The result shows that the leaching efficiencies of Te, Au, Pt, and Pd were 97.69%, 100.79%, 94.47%, and 100.38%, respectively. Moreover, there was scarcely leaching of Pb, Sn, Sb, and Ag, with most of Bi and As remaining in the residue. Te, Au, Pt, and Pd enriched in a targeted manner. This work presents that it is useful in the analysis of the phenomena in copper anode slime hydrometallurgy and provides a short process technology for treating the decopperized anode slime. [ABSTRACT FROM AUTHOR]

Cyanide leaching technology was studied for low-grade oxidized gold ores in Guangxi Province. The gold grade of the raw ores was 1.32 g/t. The gold leaching rate was 90.91% under the optimal conditions for the following conventional leaching process: using steel forging as the grinding medium, a grinding fineness of −0.074 mm accounting for 92.53%, a stirring speed of 1500 r/min, a pulp leaching concentration of 28.57%, a pH value of 10.5, a temperature of 25 °C, a leaching time of 24 h, and a potassium cyanide consumption of 4 kg/t. A new type of mixed aid-leaching agent (0.6 kg/t) was used, with a dosage of potassium cyanide of 2 kg/t. All else being equal, the gold leaching rate increased by 2.17% to 93.20% after 18 h of aid leaching compared to that of conventional leaching for 28 h. Meanwhile, the amount of potassium cyanide used was reduced by 50%. The aid-leaching agents restored the surface activity of passivated gold particles and depressed the adsorption of gold and its complexes by gangue minerals. This approach could shorten the leaching time and increase the gold leaching rate. [ABSTRACT FROM AUTHOR]

Copyright of Iron Steel Vanadium Titanium is the property of Iron Steel Vanadium Titanium Editorial Office 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.)

Benzovindiflupyr is a succinate dehydrogenase inhibitor fungicide that targets mitochondrial function for disease control. In this study, we investigated the adsorption–desorption and leaching behavior of benzovindiflupyr in eight soil types using the batch equilibrium method and the soil column leaching method. A Freundlich model (r2 > 0.9959) was used to better characterize the adsorption-desorption process in eight soil types, with adsorption coefficients (KF-ads) ranging from 2.303 to 17.886. KF-ads was significantly and positively correlated (p < 0.05) with the organic carbon content. High temperatures and increased initial pH of aqueous solutions led to a decrease in benzovindiflupyr adsorption in the soil. The adsorption was also influenced by factors such as ionic strength, humic acid, surfactant type, microplastic type, and particle size and concentration. Moreover, benzovindiflupyr exhibited low leachability in all four soils selected, but different leaching solutions affected the risk of benzovindiflupyr migration to groundwater. Overall, this study provides insights into the adsorption characteristics of benzovindiflupyr in different soils and provides key information for environmental risk assessment.

Harsh environments such as saline and alkaline environments will affect solidification/stabilization quality, especially considering the long-term service cycle. To investigate the environmental influence on the leaching behavior of solidified/stabilized soils, the Pb2+ leaching behaviors of cement-stabilized contaminated clay (CSC) and ternary binder (CSG)-stabilized contaminated clay (CSGSC) under the endo/exogenous saline and alkaline attacking environment were discussed. Note that, the ternary CSG binder, consisting of cement, silica fume (SF), and desulfurization gypsum powder (DGP) in a ratio of 1:0.25:0.19, underwent pre-screening based on its unconfined compressive strength (UCS). Scanning electron microscopy was employed to reveal the environment-resisting mechanism. The leaching concentration of Pb2+ in the leachate from CSGSC was lower than that from CSC in both saline and alkaline environments with a same incorporation ratio (15%) to dry soils, indicating CSG’s efficiency. Under the exogenous environment, the Pb2+ cumulative leaching mass from the stabilized clays in saline environment was more than that in deionized water, while that under the endogenous environment was opposite. Microstructure analysis indicated that the SF and DGP in CSG facilitated the formation of calcium silicate hydrate and ettringite, resulting in a denser structure that greatly enhances the physical encapsulation and chemical fixation of Pb2+ cation. At the end, the different mechanism under endo/exogenous attacking environments was attributed to the cation influence on clay minerals and the formation of new substance. These findings provide a guidance for the remediation of contaminated soil in harsh environments. [ABSTRACT FROM AUTHOR]

In this study, the structure and phase transition of kaolin lithium clay at different calcination temperatures were studied and discussed; subsequently, the effects of Li leaching with sulfuric acid under various factors were investigated in detail. The experimental results indicated that an optimal Li leaching rate of 81.1% could be achieved when kaolin lithium clay was calcined at 600 °C for 1 h, followed by leaching with 15.0% sulfuric acid at 80 °C for 2 h. The TG-DSC, XRD, and SEM analyses showed that the layered structure of the clay was not destroyed during the leaching and calcination processes. During the process of calcination, kaolinite was converted to metakaolinite via dehydroxylation. During the process of leaching, the Al on the surface of the metakaolinite was dissolved by sulfuric acid, resulting in the destruction of the Al-O structure; then, Li+ was exchanged for H+ to the surface of the mineral and entered the solution under the action of diffusion. The leaching kinetics showed that the leaching process was controlled by a diffusion model, and the activation energy (Ea) was 41.3 kJ/mol. The rapid extraction of Li from calcined kaolin lithium clay with sulfuric acid leaching offers a high-efficiency, low-energy-consumption strategy for the utilization of new lithium resources. [ABSTRACT FROM AUTHOR]

Evaluating the corrosion behavior of borosilicate glass after irradiation holds vital importance for the safe geological disposal of high‐level radioactive waste. This study examined the leaching properties of three kinds of sodium‐borosilicate (RNa2O‒B2O3‒KSiO2, denoted as "NBS") glasses with the same R but varying K under 5 MeV Xe‐ion radiation to decipher the correlation between the corrosion mechanism and glass composition. After Xe‐ion radiation, an increase in [BO3] units was observed, indicative of the glass network depolymerization. Irradiated glasses exhibited a more significant change in [BO3] units over the leaching time compared to their pristine counterparts. There is a strong correlation between the initial dissolution rates of pristine glasses, the K value, and the proportion of Na. Additionally, the initial Si dissolution rate of the NBS glasses has been accelerated by heavy ion irradiation. For the same R value over the glass series, the initial Si dissolution rates in ternary borosilicate glasses change at similar rates after irradiation. This study concluded that the variation trend in the initial dissolution rate of Si and Na differs under ion radiation. [ABSTRACT FROM AUTHOR]

Municipal solid waste incinerator (MSWI) fly ash poses intricate compositional challenges and potential environmental hazards. Effective management of such hazardous waste is imperative to mitigate the release of toxic compounds into the environment. Solidification/stabilization (S/S) processes have emerged as a viable strategy to transform MSWI fly ash from incineration waste into a safer and more environmentally benign material. This study aims to comprehensively investigate the potential of utilizing cow bone waste to stabilize heavy metals, focusing on Pb, within municipal solid waste incineration fly ash. Experimental investigations encompassed cow bone-to-fly ash weight ratios ranging from 0.0 (control group) to 7:3, a settling time of 2 h, and a liquid-to-solid (L/S) ratio of 1.0 mL/g. Cow bone waste exhibited pronounced efficacy, particularly within the short settling time, yielding a remarkable Pb removal efficiency of up to 99% at a cow bone waste dose of merely 2% and an L/S ratio of 1.0 mL/g. Concurrently, other heavy metals such as Cd, Cu, and Zn were effectively stabilized with a cow bone waste dose of 1.5% during the same 2-h settling period. The results underscore the pivotal roles of ash/bone ratio and settling time in augmenting Pb stabilization in MSWI fly ash. The application of cow bone waste is anticipated to offer a cost-effective and environmentally sound approach, aligning with sustainable waste management principles. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office 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.)

There is a recognized need to address the mismanagement of industrial by-products, as their accumulation severely threatens the environment. Efficient reutilizing of industrial waste is indispensable in realizing environment-friendly sustainable development. Towards this end, supervised adoption of controlled low-strength materials (CLSM) can be a solution. CLSM are cement-based materials which are environmentally safe, with self-levelling and self-consolidating properties. CLSM's long-term sustainable applications exclusively depend on its geo-environmental properties during and after the construction phase. This comprehensive review explores the impact of geo-environmental properties on the plastic and in-service properties of industrial by-products used for CLSM creation. It critically examines various geo-environmental properties of CLSM comprising interlaced aspects of chemical composition, mineralogical composition, leaching behavior, pH value, and thermal conductivity. It is shown that the geo-environmental properties of CLSM are determined mainly by the characteristics and content of raw materials, wastes, and the quantity of water used in the final blend. Further, the review accentuates the geo-environmental properties' detrimental effects on the plastic and in-service properties of CLSM. The comprehensive review can aid in effectively utilizing CLSM to reduce environmental concerns while achieving sustainable development. [ABSTRACT FROM AUTHOR]

At present, the pollution of arsenic (As) and lead (Pb) is becoming increasingly serious. The pollution caused by the release of As and Pb from lead–zinc mines has seriously affected the water and soil environment and threatened human health. It is necessary to reveal the release characteristics of As and Pb. The actual scene of mine drainage (MD) and rainwater (RW) leaching waste rocks is the one of the main reasons for the release of As and Pb. However, the leaching behavior of As and Pb in these waste rocks under MD and RW suffered from a lack of in-depth research. In this study, we investigated the occurrence of As and Pb in waste rocks (S1–S6) by using X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (TOF-SIMS), and then, the changes in As and Pb concentration and the hydrochemical parameter in leaching solution were systematically studied. Furthermore, the correlation between the release of As and Pb and mineral composition was also evaluated. Results showed that these waste rocks were mainly composed of carbonate and sulfide minerals. As and Pb were mainly bounded or associated with sulfide minerals such as arsenopyrite, pyrite, chalcopyrite, and galena in these waste rocks, and small parts of As and Pb were absorbed or encased by clay minerals such as kaolinite and chlorite. Under MD and RW leaching, the pH, redox potential (Eh), and electric conductivity (EC) of each waste rock tended to be consistent due to their buffering ability; the leachate pH of waste rocks with more carbonate minerals was higher than that of sulfide minerals. Both As and Pb were released most under MD leaching in comparison to RW, reaching 6.57 and 60.32 mg/kg, respectively, due to MD's low pH and high Eh value. However, As in waste rock released more under alkaline conditions because part of the arsenic was in the form of arsenate. As and Pb release were mainly positively correlated with the proportions of sulfide minerals in these waste rocks. MD leaching significantly promoted the release of As and Pb from waste rocks, which would cause a great threat to the surrounding environment, and control measures were imperative. This paper not only reveals the As and Pb pollution mechanism around the lead–zinc mining area but also provides a theoretical basis for the prevention and control of As and Pb pollution in the future. [ABSTRACT FROM AUTHOR]

Cyanide leaching technology was studied for low-grade oxidized gold ores in Guangxi Province. The gold grade of the raw ores was 1.32 g/t. The gold leaching rate was 90.91% under the optimal conditions for the following conventional leaching process: using steel forging as the grinding medium, a grinding fineness of −0.074 mm accounting for 92.53%, a stirring speed of 1500 r/min, a pulp leaching concentration of 28.57%, a pH value of 10.5, a temperature of 25 °C, a leaching time of 24 h, and a potassium cyanide consumption of 4 kg/t. A new type of mixed aid-leaching agent (0.6 kg/t) was used, with a dosage of potassium cyanide of 2 kg/t. All else being equal, the gold leaching rate increased by 2.17% to 93.20% after 18 h of aid leaching compared to that of conventional leaching for 28 h. Meanwhile, the amount of potassium cyanide used was reduced by 50%. The aid-leaching agents restored the surface activity of passivated gold particles and depressed the adsorption of gold and its complexes by gangue minerals. This approach could shorten the leaching time and increase the gold leaching rate.

To remediate historically polluted sites before their land-use changes, it is essential to understand the concentration distribution, geochemical fraction, and migratory behavior of As in soil with varied particle sizes for the use of a sieving procedure. This study investigated the amount and percentage of As in soil with different particle sizes (0.25, 0.25–1, and 1–2 mm) as well as its toxicity characteristic in leaching procedure at four previously contaminated sites in the Beijiang River Basin, South China. The results showed that the total As concentration in the collected soils ranged from 70.1 to 402.8 mg/kg, and only a few percent of soil particle samples had As contents below the local risk threshold value of 60 mg/kg. The amorphous hydrous oxide bound, crystalline hydrous oxide bound, and residual fractions (F3–F5) of the geochemical fraction of As in soil of polluted sites accounted for 82.2–95.7% of the total As distribution. However, the concentration of As in non-specifically bound fractions increased with the mass ratio of soil with coarse particle sizes due to the negative correlation of Fe-bearing minerals concentration with the mass ratio of soil with coarse particle size. According to redundancy analysis, soil with coarse particle sizes and non-specifically bound As were mostly responsible for the As concentration in the leachate. These findings confirmed that a sieving process was not suitable for the remediation of soil As at four historically contaminated sites in the Beijiang River Basin due to the high concentration of As in soil and non-negligible environmental risk of labile extractable As in soil with coarse particle size. [ABSTRACT FROM AUTHOR]

Copyright of Low-Carbon Materials & Green Construction is the property of Springer Nature 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.)

In this study, the structure and phase transition of kaolin lithium clay at different calcination temperatures were studied and discussed; subsequently, the effects of Li leaching with sulfuric acid under various factors were investigated in detail. The experimental results indicated that an optimal Li leaching rate of 81.1% could be achieved when kaolin lithium clay was calcined at 600 °C for 1 h, followed by leaching with 15.0% sulfuric acid at 80 °C for 2 h. The TG-DSC, XRD, and SEM analyses showed that the layered structure of the clay was not destroyed during the leaching and calcination processes. During the process of calcination, kaolinite was converted to metakaolinite via dehydroxylation. During the process of leaching, the Al on the surface of the metakaolinite was dissolved by sulfuric acid, resulting in the destruction of the Al-O structure; then, Li+ was exchanged for H+ to the surface of the mineral and entered the solution under the action of diffusion. The leaching kinetics showed that the leaching process was controlled by a diffusion model, and the activation energy (Ea) was 41.3 kJ/mol. The rapid extraction of Li from calcined kaolin lithium clay with sulfuric acid leaching offers a high-efficiency, low-energy-consumption strategy for the utilization of new lithium resources.

The MgO-based binder is a novel and effective material for solidifying municipal solid waste incineration fly ash (MSWI FA). In this study, the effect of MgO-based binders with different MgO contents on the solidification and stabilization of MSWI FA was investigated by adjusting the proportions of MgO, silica fume, and MSWI FA in the solidified system. The leaching behavior and immobilization mechanisms of Cd and Pb in the solidified bodies were focused on. The hydration products generated were characterized by XRD, FTIR, and TG analysis. The results demonstrated that the compressive strength of the solidified bodies and the immobilization efficiencies of heavy metals improved with the increase in MgO addition. The MSWI FA solidified by MgO-based binders could maintain low leaching toxicity over a wider pH range. The generated Mg-containing hydration products, including Mg(OH) 2 and M-C-S-H gels, were believed to contribute to the reduction of the leaching concentrations of heavy metals. The immobilization mechanisms of Pb and Cd were different: the immobilization of Pb came from chemical chelation, and Cd was stabilized from alkaline precipitation. In conclusion, this work provides new insights into applying MgO-based binders in MSWI FA solidification. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology 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.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology 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.)

Objectives The objectives of this study were to investigate gamma radiation induced degradation and leaching behavior of nuclide and/or organic complexing agent adsorbed ion exchange resin. Methods Cation exchange resin (IRN 77) and anion exchange resin (IRN 78) widely used in nuclear power plants were purchased. Cobalt ion and EDTA were used to represent nuclide and organic complexing agent adsorbed to ion exchange resins. Cation and anion exchange resin adsorbed cobalt ion and/or EDTA were radiated by 60Co nuclide. The radiation dose rate was 10 kGy/hr and total doses were 0, 300, 500, and 700 kGy. Results and Discussion The sulfone and quaternary ammonium functional groups of gamma radiated ion exchange resin were degraded, indicating nuclide/organic complexing agent would be leached from ion exchange resin. It was shown that degradation of anion exchange resin was worse than that of cation exchange resin. While the high concentrations of cobalt ion and organic matter were observed in leachate from anion exchange resin, those in leachate from cation exchange resin were very low. For mixed cation and anion exchange resin, the leaching behavior of mixed resin was improved. This shows that disposal in the form of a mixed ion exchange resin was evaluated as a safer method than that of a cation or anion exchange resin alone. Conclusion The adsorbed nuclide and organic complexing agent were leached from ion exchange resin by gamma irradiation. The leaching behavior of cation and anion exchange resin was improved by using mixed ion exchange resin.

Purpose: As one of the most critical sources of pollution from detrimental elements, smelting slags pose a huge threat to the surrounding environment. A comprehensive environmental risk evaluation of slag is beneficial to propose more rational suggestions on their management and treatment. Therefore, the aim of this study was to assess the potential environmental hazard of toxic elements in non-ferrous metal slags from Guangxi (GX) and Yunnan (YN) by comparing the leaching behavior and geochemical characteristics. Methods: The pHstat and semi-dynamic leaching tests were used to study the leaching behavior of metal(loid)s at different pH and simulate local rainfall, respectively. The potential mobility, bioavailability, and bioaccessibility of metal(loid)s were determined through a series of extraction experiments. In addition, a combination of leachability, mobility, bioavailability, and bioaccessibility is used to explore the potential environmental risk implications of slags. Results: The release of metal(loid)s showed a strong dependence on pH. Most metal(loid)s release decreased with increasing pH, while some metal(loid)s release increased under alkaline conditions. Variation in metal(loid)s concentrations induced by pH changes is due to the dissolution/precipitation and the adsorption/desorption processes of minerals. The results of the simulated rainfall indicate different trends in metal(loid)s release due to the differences in slag composition, rainfall, and pH between the two regions. The leaching of metal(loid)s decreases with increasing rainfall, which is due to the depletion of the slag surface. The mobility, bioavailability, and bioaccessibility of Cd, Cu, and Zn in GX were higher than in YN, while As and Pb were lower than in YN. These metal(loid)s are more likely to enter the environment and pose a greater threat to plants and humans. The correlation analysis showed that the exchange and carbonate-bound fractions of metal(loid)s have a positive effect on their bioavailability and bioaccessibility. Conclusion: The results show that among the elements studied, the potential environmental risks of Cd, Cu, and Zn in GX are greater than those of YN, while As and Pb are less than those of YN. The toxic elements in the slags may pose a potential risk to the surrounding environment. [ABSTRACT FROM AUTHOR]

This research focused on the hazardous elements in the main coal seam of Huaibei coalfield, China. Through collecting 20 feed coal samples from different coal seams of nine coal mines in the region, and combining with XRF, XRD, ICP-MS, and sequential chemical extraction, the mineral composition and the contents of major elements and HEs for feed coal were analyzed. Compared with previous research results, the enrichment characteristics of HEs in feed coal were revealed. The leaching behaviors of Se, Hg, and Pb in feed coal and coal ash under different leaching conditions were analyzed in depth by using a leaching device independently developed. Results showed that, compared with Chinese coals and World coals, the content of other elements, except Se, Sb, Hg, and Pb, in feed coal of Huaibei coalfield were at the "Normal" level, and no "Low" level elements were found; as the acidity of leaching solution decreased, the relative leaching rate of Se (LSe) was gradually increasing, while the LHg and LPb were not obvious; the LSe in feed coal and coal ash had a great relationship with the modes of occurrence of Se. The difference in the Hg content in the ion exchange state in feed coal may be an important reason for the difference in Hg leaching behavior. However, the content of Pb in feed coal had little influence on its leaching behavior. The modes of occurrence of Pb determined that the LPb in feed coal and coal ash was not high. The LSe increased with the increase in acidity of leaching solution and leaching time. The leaching time was the main influencing factor of the LHg and LPb. [ABSTRACT FROM AUTHOR]

Phosphoric acid manufacturing generates large amounts of phosphogypsum (PG); a by-product generally disposed in the surface or evacuated in the seawater without any pretreatment. Phosphogypsum may host non-negligible amounts of valuable elements such as rare earth elements (REEs), which are critical elements on the global market. Surface disposal of PG may be a sustainable option to allow further processing in order to recover valuable elements. However, surface disposal exposes PG to atmospheric conditions (e.g., water, oxygen) which may increase their reactivity and accelerate the release rate of chemical species. This study aims to evaluate the trace element release rate from PG at atmospheric conditions. The studied PG samples were collected from a Moroccan phosphate treatment plant. The samples were characterized for their (i) chemical composition using inductively coupled plasma optical emission spectrometry (ICP-OES) for major elements and inductively coupled plasma mass spectrometry (ICP-MS) for trace elements; (ii) mineralogical composition by X-ray diffraction (XRD), scanning electron microscope equipped with energy-dispersive spectrometer (SEM–EDS), laser-induced breakdown spectroscopy (LIBS), and the mineral chemical composition was analyzed by electron probe microanalyzer (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS); and (iii) chemical species release rate using leaching tests over 24 h at 25 and 60 °C. Chemically, the PG samples were mainly composed of Ca (23.03–23.35 wt.%), S (17.65–17.71 wt.%), and Si (0.75–0.82 wt.%), and non-negligible amounts of trace elements: REE (344–349 ppm), Cd (3.5–7.4 ppm), U (9.3–27.4 ppm). Mineralogically, the PGs are mainly formed by gypsum (94.2–95.9 wt.%) and quartz (1.67–1.76 wt.%). In terms of chemical species release, the PGs showed a higher reactivity at 60 °C compared to room temperature with a higher release rate at the beginning of the leaching tests. Quantitatively, the PG samples released 3.57–4.11 µg/L/day of REE, 3.18–17.29 µg/L/day of U, and 1.67–5.49 µg/L/day of Cd. Based on the leaching results, we concluded that the trace elements (e.g., U, Cd, REE) are incorporated in PG crystal lattice, which may explain their low concentrations in the leachates. Consequently, total digestion of PG matrix is required to solubilize REE. [ABSTRACT FROM AUTHOR]

This study investigated the influence of the interaction between Fe-based substances and thermal treatment parameters on the leaching behavior of Cr in hazardous waste incineration fly ash (HWIFA) after thermal treatment. The results revealed that the interaction between the addition of Fe-based substance and the thermal treatment parameters and their effects on static and dynamic leaching behaviors of Cr had significant differences when Fe2O3, Fe3O4, and Fe were added, respectively. Specifically, when Fe2O3 or Fe was added, the thermal treatment temperature was the most significant factor affecting the static leaching of Cr in thermal treated HWIFA, and the interaction effect of other factors was not significant. The most important influence on the dynamic leaching behavior of Cr was the interaction between the thermal treatment temperature and the addition of Fe2O3. Different from the addition of Fe2O3, the effect of the addition of Fe3O4 on the static leaching of Cr in thermal treated HWIFA was more significant than that of thermal treatment temperature; meanwhile, the interaction between the thermal treatment temperature and the addition of Fe3O4 was also significant. However, when Fe3O4 was added, the effect of interaction between factors on the dynamic leaching of Cr in thermal treated HWIFA was consistent with that when Fe2O3 was added. [ABSTRACT FROM AUTHOR]

Coal mining produces a large amount of gangue that pollutes the environment, causing surface subsidence and damaging the groundwater systems. Backfill mining is an effective technology used to solve this problem, but there is a risk of polluting the groundwater due to the heavy metal ions present in the backfill material. Pb2+ has been determined to be a representative element because of its existence in coal gangue samples but not in fly ash. The risk of gangue-based cemented backfill causing groundwater pollution can be evaluated by studying the Pb2+ leaching from gangue under various conditions. When comparing the leaching amounts of Pb2+ from the coal gangue particles and the test blocks, it was found that cement filling has an obvious consolidation effect on the Pb2+ in coal gangue. The above process shows that cemented backfill has an obvious consolidation effect on the Pb2+ in gangue. The results of the theoretical analysis, X-ray, and SEM show that the consolidation mechanism can be divided into four modes: physical encapsulation, ion exchange, ion adsorption, and chemical reaction. The results are of great significance for revealing the leaching mechanism of the heavy metals in coal gangue, assessing the risk of heavy metal pollution in groundwater via gangue-cemented backfill, and improving the mining theory of the gangue-cemented filling and groundwater protection. [ABSTRACT FROM AUTHOR]

At present, the pollution of arsenic (As) and lead (Pb) is becoming increasingly serious. The pollution caused by the release of As and Pb from lead–zinc mines has seriously affected the water and soil environment and threatened human health. It is necessary to reveal the release characteristics of As and Pb. The actual scene of mine drainage (MD) and rainwater (RW) leaching waste rocks is the one of the main reasons for the release of As and Pb. However, the leaching behavior of As and Pb in these waste rocks under MD and RW suffered from a lack of in-depth research. In this study, we investigated the occurrence of As and Pb in waste rocks (S1–S6) by using X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (TOF-SIMS), and then, the changes in As and Pb concentration and the hydrochemical parameter in leaching solution were systematically studied. Furthermore, the correlation between the release of As and Pb and mineral composition was also evaluated. Results showed that these waste rocks were mainly composed of carbonate and sulfide minerals. As and Pb were mainly bounded or associated with sulfide minerals such as arsenopyrite, pyrite, chalcopyrite, and galena in these waste rocks, and small parts of As and Pb were absorbed or encased by clay minerals such as kaolinite and chlorite. Under MD and RW leaching, the pH, redox potential (Eh), and electric conductivity (EC) of each waste rock tended to be consistent due to their buffering ability; the leachate pH of waste rocks with more carbonate minerals was higher than that of sulfide minerals. Both As and Pb were released most under MD leaching in comparison to RW, reaching 6.57 and 60.32 mg/kg, respectively, due to MD’s low pH and high Eh value. However, As in waste rock released more under alkaline conditions because part of the arsenic was in the form of arsenate. As and Pb release were mainly positively correlated with the proportions of sulfide minerals in these waste rocks. MD leaching significantly promoted the release of As and Pb from waste rocks, which would cause a great threat to the surrounding environment, and control measures were imperative. This paper not only reveals the As and Pb pollution mechanism around the lead–zinc mining area but also provides a theoretical basis for the prevention and control of As and Pb pollution in the future.

Pollucite has been proposed as an ideal candidate material for addressing the critical challenge of the safe trapping of the 137Cs radionuclide. However, its detailed corrosion mechanism remains elusive. In this work, we performed reactive and ab initio molecular simulations to explore the leaching behavior of Cs+ from pollucite glass–ceramics at the initial stage. The nonbridging oxygen ions on the surface are protonated at first, followed by the release of Cs+ associated with these oxygen ions. For the glass phase, the inner Cs+ could leach out due to the interaction with water molecules, whereas only the Cs+ present at the surface leach out for pollucite, confirming its remarkable chemical stability. The hydrolysis of Si/Al–O bonds in pollucite is thermodynamically unfavorable, and Al–O bonds are the weak spots. Moreover, the migration barriers of Cs+ in pollucite were calculated by the climbing image nudged elastic band method, and the high barriers reveal that pollucite immobilizes Cs+ stably. This study paves the way for predicting the long‐term safety of a nuclear waste immobilization repository. [ABSTRACT FROM AUTHOR]

The Kaldor furnace smelting process is currently the mainstream process for treating copper anode slime, but the existence of copper, tellurium and other impurities has adverse effects on the recovery of gold and silver during the Kaldor furnace smelting stage. Therefore, it is necessary to pretreat the copper anode slime to remove these impurities before Kaldor furnace reduction smelting. However, the current pretreatment process of copper anode slime generally has the problem of low removal efficiency of copper and tellurium, and little research on the occurrence state of main metals in copper anode slime. Therefore, this study quantitatively determined the phase composition of Cu, Te, Pb, Bi, As, Sb, Se, Ag and Au, and hydrogen peroxide was introduced to enhance the leaching of impurities. The leaching behavior of each metal in copper anode slime was investigated in detail. The results demonstrate that Cu and Te in the copper anode slime mainly exist in the form of CuO and CuSO4 and Te and AuTe2, respectively. More than 99% of the Cu and 97% of the Te were leached out using 250 g/L H2SO4 and 28.8 g/L H2O2 with a leaching pressure of 0.8 MPa at 150 °C for 2 h, while the leaching of Au and Ag was both < 0.03%. The removal of Cu and Te and the enrichment of precious metals were achieved. This study provides a rich theoretical reference for the optimization of the Kaldor furnace process. [ABSTRACT FROM AUTHOR]

Benzovindiflupyr is a succinate dehydrogenase inhibitor fungicide that targets mitochondrial function for disease control. In this study, we investigated the adsorption–desorption and leaching behavior of benzovindiflupyr in eight soil types using the batch equilibrium method and the soil column leaching method. A Freundlich model (r 2 > 0.9959) was used to better characterize the adsorption-desorption process in eight soil types, with adsorption coefficients (K F-ads) ranging from 2.303 to 17.886. K F-ads was significantly and positively correlated (p < 0.05) with the organic carbon content. High temperatures and increased initial pH of aqueous solutions led to a decrease in benzovindiflupyr adsorption in the soil. The adsorption was also influenced by factors such as ionic strength, humic acid, surfactant type, microplastic type, and particle size and concentration. Moreover, benzovindiflupyr exhibited low leachability in all four soils selected, but different leaching solutions affected the risk of benzovindiflupyr migration to groundwater. Overall, this study provides insights into the adsorption characteristics of benzovindiflupyr in different soils and provides key information for environmental risk assessment. [Display omitted] • Study of the adsorption-desorption and leaching behavior of benzovindiflupyr in soil. • The adsorption-desorption process can be better described by the Freundlich model. • First study of benzovindiflupyr adsorption on microplastic-soil mixtures. • Risk of benzovindiflupyr migration to groundwater as affected by drench solutions. • The adsorption mechanism of benzovindiflupyr in soil was evaluated. [ABSTRACT FROM AUTHOR]

Developing a low-cost and eco-friendly alternative to cement is of great significance for reducing CO 2 emissions. Mine tailings (MTs) rich in Si and Al can be served as a promising precursor for geompolymer preparation only when the severe defect in the low reactivity is overcame. Alkali-hydrothermal activation technology was used to enhance the reactivity of MTs, and then activated tailings (ATs) and slag served as the precursors for the one-part geopolymer (OPG) preparation. Activation mechanism of MTs, workability, compressive strength, and hydration reactions of OPG samples were studied. The crystalline mineral phases in the MTs reacted with NaOH to form the amorphous sodium aluminosilicate, thus increasing the amorphization degree. High NaOH content favored the MTs activation, and the ATs with high NaOH content tended to create a higher initial pH and release more active species (Si and Al) for the slag hydration. The increase of NaOH content shortened the setting time, decreased the fluidity, and increased the strength of OPG samples. This was because the duration of the induction period was shortened and the hydration rate in the acceleration period of OPG samples was improved with increasing NaOH content, which generated large amounts of calcium–sodium aluminosilicate hydrate (C(N)-A-S-H) gel and yield the compact microstructure. However, excessive NaOH content resulted in a poor microstructure, and it is likely responsible for the reduction in strength. [ABSTRACT FROM AUTHOR]

The mining industry produces a large amount of stone waste and tailings, which poses a threat to the environment. Dumping is the most common means of disposing of this industrial waste, contributing to soil degradation and water pollution with the acquisition of valuable land. Fortunately, it can be recycled in a variety of technologies, including the promising geopolymerization technology, which turns waste into value. This review paper presents recent advances in the production of mine tailings-based geopolymer composites from industrial waste as a potential sustainable building material. This article also provides in-depth studies on the behaviors and characteristics of mine tailings composites utilized in geopolymer production, such as physical properties, mechanical properties, durability properties, microstructural properties, thermal properties, leaching behavior, and potential applications. Besides, study developments are moving towards a comprehensive understanding of the environmental footprints and economic benefits of mine tailings-based geopolymer composites for building applications utilizing mine tailings as suitable concrete material. This review paper also highlights knowledge gaps that must be overcome to progress mine tailings composites for geopolymers, as well as future study opportunities based on prior research and existing challenges. [ABSTRACT FROM AUTHOR]

Municipal solid waste incineration (MSWI) fly ash (FA) is a typical hazardous waste due to its high contents of toxic heavy metals, and hence its disposal has attracted global concern. In this work, it was recycled into environmental-friendly CaO–Al 2 O 3 –SiO 2 system glass-ceramics via adding coal fly ash (CFA) and waste glass (WG). The effects of CaO/SiO 2 ratios and sintering temperatures on the crystalline phases, morphologies, mechanical and chemical properties, heavy metals leaching and potential ecological risks of glass-ceramics were investigated. The results showed that wollastonite (CaSiO 3), anorthite (CaAl 2 Si 2 O 8) and gehlenite (Ca 2 Al 2 SiO 7) were the dominant crystals in the glass-ceramics, which were not affected by CaO/SiO 2 ratio and sintering temperature. The compressive strength increased, while the Vickers hardness and microhardness decreased as increasing the sintering temperatures from 850 to 1050 °C, which reached their maximum values of 660.69 MPa, 6.14 GPa, and 7.43 GPa, respectively. However, the increase of CaO/SiO 2 ratio resulted into the reduction of the three mechanical parameters. As varying CaO/SiO 2 ratio from 0.48 to 0.86, the maximum compressive strength, Vickers hardness and microhardness were 611.80 MPa, 5.43 GPa, and 6.56 GPa, respectively. Besides, all the glass-ceramics exhibited high alkali resistance of >97%. The extremely low heavy metals leaching concentrations and low potential ecological risk of glass-ceramics further revealed its environmentally friendly property and potential application feasibility. [ABSTRACT FROM AUTHOR]

The feasibility of soil washing for remediating PFAS-contaminated clay soil using various water-organic solvents was systematically investigated based on the combination of batch and column tests. Batch tests using 22 types of solvents highlighted that 0 % (water) and 5 % solvents could effectively extract PFCAs (≤ C9), while long-chain PFCAs (≥ C10) and PFSAs required 80 % solvents for optimal extraction, with efficiency in the order of EtOH ≤ MeOH < Acetonitrile (ACN), suggesting a strong correlation with carbon chain lengths and functional head groups. Column tests with six selected washing solutions indicated rapid desorption of PFOA and PFOS initially, peaking at liquid-to-solid (L/S) ratios of 3-4 for 0 % and 5 % solutions, and at an L/S ratio of 1 for 80 % solutions. To remediate 1 kg-dry soil to meet the legislatively permissible levels for groundwater in Japan (PFOA + PFOS < 50 ng/L), 11 L of 0 % solution (water) or 5 L of 80 % ACN are required for washing out PFOA, while 62 L of 0 % solution (water) or 53 L of 80 % ACN for PFOS. Future research should address the treatment of PFAS-rich wastewater generated from washing PFAS-contaminated soils and the impacts of washing solutions on soil., 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 Elsevier B.V. All rights reserved.)

Sensory deterioration exists in marketed cooked rice. The migration and interaction of intrinsic components occur under multiple conditions in each industrial production process and cause relevant physicochemical changes in cooked rice. This review aims to establish a scientific knowledge system of intrinsic component transition and migration in cooked rice kernel during processing to solve qualitative deficiencies in cooked rice products. The main influencing factors of intrinsic component structural change in cooked rice and the quality control points that should be considered are summarized. Further studies are needed to establish proper evaluation standards for cooked rice products to meet the growing consumer demands., 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 Elsevier Ltd. All rights reserved.)

Dewatering is an indispensable link in sludge treatment, but its effect on the microplastics (MPs) remains inadequately understood. This study investigated the physicochemical changes and leaching behavior of MPs during the mechanical dewatering of sludge, as well as the impact of MP leachates on activated sludge (AS). After sludge dewatering, MPs exhibit rougher surfaces, decreased sizes and altered functional groups due to the addition of dewatering agents and the application of mechanical force. Meanwhile, plastic additives, depolymerization products, and derivatives of their interactions are leached from MPs during sludge dewatering process. The concentration of MP-based leachates in sludge is 2-25 times higher than that in water. The enhancement of pH and ionic strength caused by dewatering agents induces the release of MP leachates enriched with protein-like, fulvic acid-like, and soluble microbial by-product-like substances. The reflux of MP leachates in sludge dewatering liquor to the wastewater treatment system negatively impacts AS, leading to a decrease in COD removal rate and inhibition of the extracellular polymeric substances secretion. More importantly, MP leachates cause oxidative stress to microbial cells and alter the microbial community structure of AS at the phylum and genus levels. These findings confirm that MPs undergo aging and leaching during sludge dewatering process, and MP leachates may negatively affect the wastewater treatment system., 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 Elsevier Ltd. All rights reserved.)

Neutralization enrichment residues containing As,Sb and Bi is an important intermediate product in the hydrometallurgy process of anode slime, which is rich in valuable metals such as Bi and Sb with a high recovery value. However, the efficient extraction of Bi and other valuable metals faces challenge due to existence of multiple metals and complex occurrence behaviors. In view of this, hydrochloric acid total leaching process was proposed to treat the enrichment residue. The effects of HCl concent ration, liquid-to-solid ratio, reaction temperature and reaction time on the leaching rate of Bi, Cu, Pb, As and Sb were investig ated. Moreover, the leaching kinetics of the Bi was also explored at the same time. The results show that the leaching rate of Bi, Cu, Pb, As and Sb are 97.4 %,96.1 %, 75.9 %, 93.6 %, and 96.0 % respectively under 6.0 mol/L HCl with liquid-to-solid ratio ( mL/ g) of 6 at 80 °C for 15 min. It is determined that the kinetic control conditions of Bi in the hydrochloric acid leaching process can be divided into two stages. The early stage of the leaching process is affected by interface mass transfer and diffusion. The leaching of Bi is controlled by the chemical reaction in the later stage. The activation energy of the reaction is 14. 50 kJ/ mol and 82. 80 kJ/ mol in these two stages, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Analyzed physical and chemical properties and performed quantitative phase analysis of HAHCA at different coal combustion temperatures. • Clarified the relation between the leaching behavior of 28 valuable elements and coal combustion temperatures under acidic and alkaline conditions. • Most metals easily leached from HAHCA under acidic conditions when coal combustion at 600 °C–800 °C. • Only Mo achieved a high leaching rate under acidic and alkaline conditions. The evaluation of the application potential of high-alumina coal fly ash (HACFA) resources relies on the assessment of the phase composition and leaching behavior of valuable elements. Herein, we systematically investigated the particle size, specific surface area, and morphology of high-alumina high-temperature coal ash (HAHCA) produced under laboratory conditions at different temperatures and quantitatively analyzed phase transformations using the Rietveld method. The results revealed that the HAHCA particle size gradually increased, specific surface area gradually decreased, and pores became lesser with the increasing coal combustion temperature of high-alumina coal (HAC) from 400 °C to 1300 °C. Furthermore, HAHCA phases sequentially changed across various temperatures, its main phases at a coal combustion temperature of 400 °C included 29.8 % kaolinite, 6.9 % boehmite, and 5.4 % calcite, but the crystalline phases were the most abundant and turned into 41.2 % mullite, 13.7 % corundum, and 11.6 % plagioclase when the coal combustion temperature reached 1300 °C. Additionally, the leaching behavior of 28 major and trace valuable elements of HAHCA under acidic and alkaline conditions was investigated. Most metal elements easily leached from HAHCA under acidic conditions at coal combustion temperatures of 600 °C–800 °C: the optimal leaching efficiencies of Al, Li, K, Rb, Mg, Ca, Sr, and Ba were 67.64 %, 92.71 %, 76.67 %, 73.46 %, 86.74 %, 98.87 %, 98.42 %, and 61.19 %, respectively. Si, a nonmetallic element, achieved a high leaching efficiency of 48.27 % under alkaline conditions at a coal combustion temperature of 1300 °C. Interestingly, only Mo exhibited a high leaching efficiency of approximately 98 % under acidic and alkaline conditions. [ABSTRACT FROM AUTHOR]

Municipal solid waste incineration (MSWI) fly ash is a significant byproduct of waste-to-energy processes, and poses substantial environmental and health hazards if not treated properly. The process of Stabilization/Solidification (S/S) efficiently immobilizes hazardous elements present in the fly ash through a combination of physical and chemical mechanisms. The objective of this research is to thoroughly examine the feasibility of using chicken eggshell waste powder as a stabilizing agent for heavy metals, specifically targeting Pb, in MSWI fly ash. Experimental analysis involved varying eggshell waste to fly ash weight proportions, extending from 0.0 (control group), 7:3 up to 9.5:0.5 ratio, with designated curing durations of 2 and 72 hours, and maintaining a liquid-to-solid (L/S) ratio at 1.0 mL/g. In the two-hour curing period, the immobilization efficiency of Pb reached 100% with the addition of only 1.5% eggshell waste. Optimal ratios for Pb stabilization in MSWI fly ash were identified: maximum 2% eggshell waste for 2-hour curing and 1.5% for 72 hours due to elevated Pb and Cd levels of 7:3 ratio. Adding CaO mitigated these levels, enhancing stabilization and compliance with landfill criteria. The results demonstrated that the addition of CaO led to efficient immobilization of Pb, achieving approximately 99%. In addition, the observed enhancement in compressive strength resulting from the incorporation of CaO highlights its effectiveness in enhancing the stabilizing process of MSWI fly ash. By demonstrating the effectiveness of eggshell waste and CaO in stabilizing hazardous elements, this study advocates for scalable solutions and further research on long-term stability and environmental impacts. [Display omitted] • Chicken eggshell waste shows high potential as a stabilizing agent for Pb in MSWI fly ash. • A mere 1.5% addition of eggshell waste can achieve 100% immobilization of Pb, complying with landfill limit requirements. • The addition of CaO to the eggshell and fly ash mix achieves 99% immobilization of Pb with only 6.5% of CaO. • This innovative method also enhances compressive strength, presenting an eco-friendly solution for recycling eggshell waste. [ABSTRACT FROM AUTHOR]

Coal combustion is the major contributor to global toxic selenium (Se) emissions. Inorganic elements in coals significantly affect Se partitioning during combustion. This work confirmed that the calcium (Ca) in ash had a stronger relationship with Se retention at 1300 °C than other major elements. Ca oxide chemically reacted with gaseous Se, and its sintering densification slightly affected Se adsorption capacities (44.45 −1840.71→35.17 −1540.15 mg/kg) at 300 − 1300 °C. Therefore, Ca in coals was identified as having potential for hindering gaseous Se emissions, and coals with increased Ca contents (2.74→5.19 wt%) were used in a 350 MW unit. The decreased Se mass distribution (3.54%→2.63%) in flue gas at air preheater inlet (320 −362 °C) confirmed the effectiveness of increased Ca content on gaseous Se emission reduction. More gaseous Se further condensed and was chemically adsorbed by fly ash when passed through an electrostatic precipitator, resulting in a significant increase in the Se content of fly ash. Additionally, the corresponding Se leaching ratio decreased from 4.88 − 35.74% to 1.87 − 26.31%, indicating enhanced stability of Se enriched in fly ash. This research confirmed the feasibility and environmental safety of sequestration of gaseous Se from flue gas to fly ash by increasing the Ca content in coals. [Display omitted] ● Se retention at 1300 °C is associated with Ca content in ash. ● Ca oxide removes more gaseous Se via chemical reaction during flue gas cooling. ● Coals with higher Ca contents will release less gaseous Se into flue gas. ● A higher Ca content in fly ash can enhance the stability of Se within. ● Electrostatic precipitator induces Se emission reduction with increased Ca content. [ABSTRACT FROM AUTHOR]