Journal of Environmental Chemical Engineering
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2022
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IF 7.968
Yanfang Huang,Kunpeng Shi,Shengpeng Su,Bingbing Liu,Hu Sun,Guihong Han
Selective separation of molybdenum(Mo) and vanadium(V) from hazardous secondary resources containing Mo and V has become a technical bottleneck of its resource utilization. In this work, the selective separation of Mo and efficient recovery of V from simulated leaching solutions of spent hydrodesulfurization (HDS) catalysts were investigated via solvent extraction and chemical precipitation . The result indicates that the D 2 EHPA(P204) exhibits higher selectivity for Mo in strongly acidic conditions. Under optimum experimental conditions of hydrochloric acid of 1 mol/L, extractant concentration of 20 % (v/v), O/A ratio of 1:3 and contact time of 50 min, the single-stage extraction ratio of Mo reached 98.63 %, meanwhile, the co-extraction ratio of vanadium was less than 5 %. Additionally, over 97 % of Mo could be stripped from loaded organic phase at O/A ratio of 1 with 50 g/L NH 4 HCO 3 . The mechanism analysis revealed that selective extraction of Mo was mainly through the cation exchange mechanism. Moreover, the enthalpy changes in the molybdenum extraction were 44.1 kJ mol −1 , which demonstrated that was an endothermic reaction . Furthermore, the Fe(III) was adopted to fabricate FeVO 4 by precipitating vanadium from raffinate, and the precipitation efficiency of vanadium reached 97.71 % at a Fe/V molar ratio of 5/2, meanwhile, the precipitation product was further confirmed by XRD, XPS and SEM-EDS. Ultimately, a conceptual flowsheet for recovering completely Mo and V from simulated leaching solutions of spent HDS catalysts was proposed, which provides theoretical guidance for the resource utilization of containing molybdenum and vanadium secondary resources.
研究领域:
环境科学
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冶金工程
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Yongkui Li,Xianjin Qi,Guohua Li,Hua Wang
Nonferrous smelting wastewaters containing high levels of arsenic and sulfuric acid threaten human health and ecological environments due to insufficient disposal technologies and/or possible leakages during transportation to long-term storage facilities. Chemical precipitation is one important route for arsenic removal and immobilization via the formation of arsenic-stabilized minerals. In this study, we propose a new strategy for the treatment of wastewaters containing high levels of arsenic using pyrite as an in situ S and Fe source to prepare environmentally friendly scorodite and As 2 S 3 precipitates. Dissolved pyrite release (S-II) and Fe (II) ions in highly acidic wastewater, both of which drive arsenic precipitation. Sulfide ions readily react with As(III) to generate the stable As 2 S 3 while Fe(II)/As(III) were oxidized to Fe(III)/As(V) by H 2 O 2 . The reaction between Fe(III) and As(V) took place on the pyrite surface as a nucleation site to form amorphous ferric arsenate that ultimately transformed into crystalline scorodite. Sulfide ions were oxidized to H 2 SO 4 that further promoted pyrite dissolution. Up to 99.4% of arsenic was successfully removed from copper smelting wastewaters with an initial arsenic concentration of 11200 mg/L. The concentration of leached As from the As-bearing precipitate was 1.78 mg/L under optimized conditions, which were: a 1.4 FeS 2 /As molar ratio, an initial solution pH of 2, an H 2 O 2 /As molar ratio of 1%, a reaction temperature of 90 °C, and a reaction time of 12 h. In summary, a prospective process successfully shows arsenic removal and immobilization from smelting wastewater, and further demonstrates the potential for the efficient and affordable disposal of wastewater.
研究领域:
环境科学
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化学工程
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DOI
高影响因子
SOLVENT EXTRACTION AND ION EXCHANGE
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2014
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IF 1.66
Ju-hua Zhang,Wei Zhang,Li Zhang,Song-qing Gu
In the V2O5 production process, purification of vanadium-bearing solution plays an important role in determining the quality of the final product. The choice of purification method depends on the vanadium species, aqueous media, and associated impurities. In this review, the recent research results for the separation and recovery of vanadium from leaching solution with solvent extraction, ion exchange, and chemical precipitation separation are presented. The effects of the main operational parameters on the efficiency of purification with these three methods are compared and discussed respectively, and several problems existing in these processes are proposed.
研究领域:
冶金工程
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材料科学
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DOI
高影响因子
Journal of Water Process Engineering
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2024
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IF 6.3
Mengxiang Geng,Ting Zeng,Xiangyi Deng,Zhenyue Zhang,Chunqiao Xiao,Ru'an Chi
Residual ammonium salt in closed rare earth mining sites leads to elevated levels of ammonia nitrogen in the surrounding environment. To mitigate ammonia nitrogen pollution at its source, a cost-effective and environmentally friendly recycling process was proposed. This process involves leaching residual ammonia nitrogen using a magnesium sulfate solution, followed by chemical precipitation for ammonia nitrogen removal. Additionally, nitrogen can be recovered as ammonia gas through the thermal decomposition of precipitates, allowing for further ammonia nitrogen adsorption from the leachate. The residual ammonium salts leaching rate reached 96.38 % with a 0.1 mol/L magnesium sulfate solution at a flow rate of 0.6 mL/min. The chemical precipitation method achieved a maximum nitrogen removal rate of 86.87 %, with an activation energy of 2.6 kJ/mol, indicating a relatively rapid process. At 190 °C, the ammonia nitrogen release rate of precipitates was 82.5 % after 2 h of thermal decomposition. The adsorption process was consistent with pseudo-second-order kinetics models using thermal decomposition products. Overall, the comprehensive removal rate of residual ammonium salts from the closed rare earth mining site was approximately 83.3 % in recycling process, optimizing the utilization of phosphorus, magnesium, and nitrogen and achieving efficient and environmentally friendly nitrogen removal.
研究领域:
环境科学
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化学工程
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DOI
高影响因子
CHEMOSPHERE
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2019
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IF 5.108
Yanming Jia,Tuokun Zhao,Nan Zhao,Hang Wei,Weihua Zhang,Rongliang Qiu
In natural environments, humic substances (HS) play a key role in the control of Cd stability by forming Cd-HS complexes. In this study, we investigated the influence of the photo-irradiation on the Cd levels remaining in Leonardite humic acid (HA) standard solution after chemical precipitation . The kinetic experiment showed that after the irradiation of ultraviolet light, especially UVC, Cd-HA complexes become more stable. The coexisting Cd in the HA solution under light irradiation seemed to enhance the stability of Cd-HA complexes. Both Fourier transform infrared and X-ray photoelectron spectrometric spectra indicated an increase in the thiol amounts in the HA samples treated by light irradiation. Therefore, we developed a fluorescent method to quantify thiol groups in HA with N-(1-pyrenyl) maleimide (NPM). The HA samples were initially spiked with known amounts of glutathione , the reference containing thiol groups, and then was titrated with various amounts of NPM. The measured thiol amounts in the HA treated by UV were found to significantly increase, and the increment was almost equivalent to those of Cd level in HA solution after chemical precipitation. Therefore, it was concluded that the increased thiol groups in HA induced by ultraviolet irradiation resulted in the formation of more stable Cd-HA complexes in solution.
研究领域:
环境科学
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化学
✓ 已验证
DOI
PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2024
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IF 4.9
Lijuan Wang,Yang Bai,Yanyan Gong
Mercury (Hg) contamination in soil has been a worldwide environmental concern. We prepared and investigated a novel Mg 2 Al layered double hydroxide supported iron sulfide composite (FeS@Mg 2 Al-LDH) for immobilization of mercury in two high-profile Hg-contaminated field soils (TJ soil represents freshly Hg-contaminated soil and GY soil represents historically aged Hg-contaminated soil). Amending the two soils with FeS@Mg 2 Al-LDH effectively immobilized mercury. The addition of 0.02% of FeS@Mg 2 Al-LDH immobilized 97.0% of mercury in TJ soil within 80 d. Similarly, the addition of 0.05% of FeS@Mg 2 Al-LDH immobilized 84.9% of mercury in GY soil. Increasing the FeS@Mg 2 Al-LDH dosage enhanced the immobilization efficiency. Increasing the dosage from 0.02% to 1% boosted the Hg immobilization efficiency in TJ soil from 97.0% to 99.4%. Increasing the dosage from 0.05% to 1% enhanced the Hg immobilization efficiency in GY soil from 84.9% to 86.2%. FeS@Mg 2 Al-LDH reacted with Hg via chemical precipitation and surface complexation, and transformed Hg from more available Hg fractions (exchangeable and carbonate bound fractions) into less available forms (organic and residual fractions), thus, reducing the environmental risk of mercury. The addition of FeS@Mg 2 Al-LDH inhibited the production of methylmercury while enhanced the soil enzyme activities . This study proves the potential and feasibility of FeS@Mg 2 Al-LDH to effectively immobilize mercury in soil.
研究领域:
环境科学
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土壤学
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DOI
高影响因子
Journal of Environmental Chemical Engineering
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2022
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IF 7.968
Bo Wang,Qiaowen Yang
Large amounts of spent selective catalytic reduction (SCR) catalysts were produced in industry after losing their activity. This study developed a clean and effective route of leaching and recovery of vanadium (V) from spent SCR catalyst. First, ascorbic acid (C 6 H 8 O 6 ) as the adjuvant can enhance vanadium leaching in H 2 SO 4 solution. The effect parameters of acid concentration, leaching temperature, leaching time and liquid-solid (L/S) ratio on the leaching efficiency of vanadium were investigated. Then, the enrichment of vanadium in the leachate to obtain the black cake was carried out through adjusting pH value. The effects of vanadium concentration and pH on the precipitation efficiency of vanadium were studied. Finally, after alkaline dissolution and oxidation of the black cake, ammonium chloride (NH 4 Cl) was selected and used as the precipitant to obtain the ammonium poly-vanadate (APV). The final product vanadium pentoxide (V 2 O 5 ) was obtained through roasting APV at 550 ℃ for 1.0 h. The black cake, APV and V 2 O 5 were analyzed by the characterization of XRD or XRF . This study may introduce a new perspective for the effective usage of vanadium from spent SCR catalyst.
研究领域:
环境科学
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材料科学
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DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2018
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IF 3.141
Yang Yu,Huachang Jin,Xindi Jin,Runxin Yan,Li Zhang,Xueming Chen
Electrochemical precipitation has obtained great attentions for water softening in recent years. In order to avoid cathode deactivation, periodical scale detachment is essential. In general, the scale adhered to the cathode is detached by mechanical scraping. Although mechanical scraping is easy operated, elastic scraper must be installed between electrodes, leading to the low softening efficiency and high energy consumption. To overcome such a problem, a new current pulsated electrochemical precipitation process was proposed in this paper. Scale detachment was accomplished by increasing the current density significantly. Experimental results showed that the both high softening and detachment performance were achieved. The precipitation rate was as high as 40.47 g/h/m2. The energy consumption and the total hardness removal efficiency were 8.9–13.2 kWh/kg CaCO3 and 17.8–22.8%, respectively. Repetitive experimental results indicated the current pulsated electrochemical precipitation process could run steadily without any performance decay detected after repetitive operation.
研究领域:
环境科学
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水处理工程
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产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2021
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IF 10.588
Xin Sun,Minlin Mao,Kaibin Lu,Qimei Hu,Weizhen Liu,Zhang Lin
High-level arsenic-containing wastewater (HAW) causes serious environmental pollution . Chemical precipitation is the most widely used technology for treating HAW. However, chemical precipitation generates huge amounts of hazardous solid wastes, which leads to secondary pollution. In this work, an efficient method, producing no secondary pollution was developed for one-step complete removal of As(V) from HAW using a hazardous solid waste namely arsenic-bearing gypsum (ABG). After the treatment, ABG was transformed into highly stable and environment-friendly mineral Johnbaumite. Meanwhile, the arsenic concentration in the wastewater decreased from 10,000 mg L −1 to 0.22 mg L −1 under optimized hydrothermal conditions (ABG dosage of 50 g L −1 , solution pH of 13.5, temperature of 150 °C for 12 h). The mechanism mainly included the following processes: (i) The phase transformation of ABG resulted in the release of calcium and hydrogen arsenate ions in ABG, (ii) Hydrogen arsenate ions transformed into arsenate ions in alkaline environment , and (iii) Under alkaline conditions, calcium ions combined with arsenate ions to form Johnbaumite, whereas the hydrothermal conditions accelerated the crystal growth of Johnbaumite. This study provides a new idea for the synchronous treatment of toxic heavy metal-containing wastewaters and hazardous solid wastes.
研究领域:
环境科学
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化学工程
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产品关联
DOI
PubMed
高影响因子
POWDER TECHNOLOGY
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2020
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IF 4.142
Xiaowen Wang,Bin Mu,Jiang Xu,Aiqin Wang
High-performance bismuth yellow hybrid pigments based on SiO 2 , Al 2 O 3 and MgO were successfully fabricated by chemical precipitation followed by annealing at 700°C. Interestingly, the colors of the hybrid pigments depended on the oxide contents, and the optimal yellow value of +92.07 was obtained at an Al 2 O 3 /SiO 2 /MgO mass ratio of 1:0.375:0.750. X-ray diffraction results indicated the formation of pure monoclinic-scheelite-type BiVO 4 with high crystallinity , suggesting that the incorporated Si, Al and Mg entered the crystal lattice of BiVO 4 . Doping with these elements effectively adjusted the band gap of BiVO 4 , and thus the color of the hybrid pigments could be easily controlled using these oxides. Furthermore, the hybrid pigments also exhibited good suspension properties and chemical stability in acid and alkaline solutions, water and ethanol. Importantly, these pigments were applied in high-grade automotive top finishes and exhibited excellent color and dispersion properties.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2019
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IF 5.589
Chunjie Du,Yuehua Hu,Haisheng Han,Wei Sun,Panpan Hou,Runqing Liu,Li Wang,Yue Yang,Ruohua Liu,Lei Sun,Tong Yue
Traditional chemical precipitation of phosphates from wastewater is somewhat inefficient because it produces some ultrafine hydroxyapatite particles that are difficult to settle. In this study, magnetic seeds with a core–shell structure were prepared by sulfation roasting for magnetic flocculation of those fine particles. Zeta potential measurements show that the hydroxyapatite particles are positively charged at pH 10, whereas the magnetic seeds are negatively charged. The Derjaguin–Landau–Verwey–Overbeek calculation indicates that the van der Waals force between the magnetic seeds and hydroxyapatite particles is always attractive. Moreover, the electrostatic attraction also contributes to aggregation of the magnetic seeds and hydroxyapatite particles. Orthogonal experiments show that the main factor affecting the magnetic flocculation is the dosage of magnetic seeds, and polymeric ferric sulfate also plays an important role. Under the optimal magnetic flocculation experimental conditions, the turbidity of wastewater after magnetic separation was only 16.388 NTU, contributing to the removal of phosphate contaminants. Therefore, magnetic flocculation and magnetic separation may provide an alternative solution for efficient purification of phosphate-containing wastewater.
研究领域:
环境科学
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水处理技术
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2019
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IF 7.65
Ruilin Wang,Dickon H.L. Ng,Shiquan Liu
A facile route was developed to recover nickel ions from a synthetic wastewater. It involved the use of silica xerogel containing amine in the nickel sulphate solution resulting in the formation of a greenish precipitate. It was found that this precipitate was mostly amorphous Ni(OH) 2 spherical aggregate composed of nanosheets. The pH level of the solution was monitored, and it was maintained in the range of 10–10.5 due to the steady release of amine from the xerogel into the waste solution. The prepared silica xerogel would provide a stable environment for the chemical precipitation of metal ions in wastewater during the whole precipitation process. The silica xerogel was collected and reused for two more cycles of recovery. The nickel removal efficiencies (99.34˜99.65%) kept unchanged and higher than those reported earlier. The collected precipitate that contained nickel hydroxide with some residual silica could be utilized as glass colorant.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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