Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a seri...Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.展开更多
The solvent of P350 was applied to extract and separate the oxalic acid from the mother-liquor originated from the precipitation of cobalt by oxalic acid,and its extraction mechanism was deduced.Some factors,including...The solvent of P350 was applied to extract and separate the oxalic acid from the mother-liquor originated from the precipitation of cobalt by oxalic acid,and its extraction mechanism was deduced.Some factors,including the concentration of P350, the concentration of hydrochloric acid and the concentration of oxalic acid were investigated to determine the best distribution coefficient of the oxalic acid.In the case of phase ratio(O/A)at 2.0,the extraction of the oxalic acid was more than 95%and its concentration in the extraction raffinate was lower than 0.004 0 mol/L after six-stage counter-current extraction.While the phase ratio(O/A)of the stripping was at 1.0,the recovery of oxalic acid attained more than 95%after ten-stage counter-current stripping.展开更多
The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using ...The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using 0.1–1.5 mol L^(-1) oxalic acid concentration was studied at 60℃–90℃.V and Fe were preferentially released(65%and 81%)compared with Al,Ti and W within 5 min due to the redox reactions of oxalic acid.The dissolved fractions of Fe,V,Al,Wand Ti increased with the increase of oxalic acid concentration and reaction temperature.The dissolution kinetic experiments were analysed and controlled diffusion with n<0.5 according to the Avrami dissolve reaction model(R^(2)>0.92).The Arrhenius parameters of the Ea values of Ti,W,V,Fe and Al from SDC with oxalic acid were 30,26,20,19 and 11 kJ mol^(-1),respectively.The obtained Avrami equation of V and Fe was successfully used to predict their leaching behaviour in oxalic acid.Toxicity characteristic leaching procedure revealed that the toxicity risk of Vand Fe metals from SDC after leaching with oxalic acid decreased to below 5 mg kg^(-1) residua.Overall,the leaching residua by oxalic acid indicated its safety for the environment.展开更多
We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the sol...We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt%based on all the reactants can be achieved with excellent hydrogen generation kinetics.展开更多
A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 ...A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 and 3.0 mmol kg-1 soil), oxalic acid (OA) at 3 rates (0, 1.5 and 3.0mmol kg-1 soil) and citric acid combined with oxalic acid (1.5 mmol citric acid combined with 1.5 mmol oxalic acid kg-1). Two types of soil were chose in the experiment. One was collected from the agricultural soil near a battery-recycling factory in Anhui province, China (site A) and the other was collected from a Pb-Zn mine residues in Hunan province, China (site B). The results showed that soil pH varied with the different treatment of citric and oxalic acids. However, there were no differences in all the treatments. 3.0mmol CA kg-1 soil addition significantly increased the concentrations of the CaCI2-extractable Pb and Zn and other treatments have no significantly increased. The highest shoot concentrations of Pb and展开更多
The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution.The effect of main factors affecting the process rate,including th...The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution.The effect of main factors affecting the process rate,including the oxalic-acid-to-sulfuric-acid ratio,stirring rate,grain size,temperature,and the initial concentration of synergic acid,was precisely evaluated.The results confirmed the acceptable efficiency of dissolving indium in the presence of oxalic acid.The shrinking-core model with a chemical-reaction-controlled step can correctly describe the kinetics of indium dissolution.On the basis of an apparent activation energy of 44.55 kJ/mol and a reaction order with respect to the acid concentration of 1.14,the presence of oxalic acid was found to reduce the sensitivity to temperature changes and to increase the effect of changes in acid concentration.Finally,the equation of the kinetic model based on the factors under study is presented.展开更多
Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the electrocatalytic reduction of oxalic acid to glycolic acid, allowing the development of a renewable energy-driven process ...Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the electrocatalytic reduction of oxalic acid to glycolic acid, allowing the development of a renewable energy-driven process for producing an alcoholic compound from an organic acid at low potential and room temperature. Coupled with the electrochemical synthesis of the oxalic acid from CO_(2),this process represents a new green and low-carbon path to produce added value chemicals from CO_(2). Various electrodes prepared by anodic oxidation of Ti foils were investigated. They were characterized by the presence of a TiO_(2) nanotube array together with the presence of small patches, debris, or TiO_(2) nanoparticles. The concentration of oxygen vacancies, the amount of Ti^(3+) measured by X-ray photoelectron spectroscopy(XPS) and the intensity of the anodic peak measured by cyclic voltammetry, were positively correlated with the achieved oxalic acid conversion and glycolic acid yield. The analysis of the results indicates the presence of small amorphous TiO_(2) nanoparticles(or surface patches or debris) interacting with TiO_(2) nanotubes, the sites responsible for the conversion of oxalic acid and glycolic acid yield. By varying this structural characteristic of the electrodes, it is possible to tune the glycolic acid to glyoxylic acid relative ratio. A best cumulative Faradaic efficiency(FE) of about 84% with FE to glycolic acid around 60% and oxalic conversion about 30% was observed.展开更多
It was found that micro amounts of oxalate showed a very strong catalytic effect on the slow reaction between K 2Cr 2O 7 and Orange Ⅳ in a diluted sulfuric acid medium in a water bath at 70 ℃ . Orange Ⅳ exhibited a...It was found that micro amounts of oxalate showed a very strong catalytic effect on the slow reaction between K 2Cr 2O 7 and Orange Ⅳ in a diluted sulfuric acid medium in a water bath at 70 ℃ . Orange Ⅳ exhibited a sensitive second order derivative polarographic wave at -0 50 V( vs . SCE). This provides the basis for a sensitive and selective catalytic kinetic method for oxalate determination with second order derivative oscillopolarography. The effects of sulphuric acid, K 2Cr 2O 7, and orange Ⅳ concentrations, reaction temperature and reaction time were investigated. A calibration curve of oxalate in the range of 0 1-2 0 μg/mL was obtained by the fixed time procedure. The detection limit was 0 03 μg/ mL. The possible interference from co existing substances or ions was examined. The new method has a high sensitivity and a good selectivity compared to other existing methods for oxalic acid determination. It has been applied to the determination of micro amounts of oxalate in real urine samples with satisfactory results.展开更多
We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixtu...We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt% based on all the reactants can be achieved with excellent hydrogen generation kinetics.展开更多
Objective To analyze and identify the differentially expressed proteins in human renal tubular epithelial ceils ( HK-2) after injury caused by oxalic acid and calcium oxalate monohydrate ( COM ) crystal,and to explore...Objective To analyze and identify the differentially expressed proteins in human renal tubular epithelial ceils ( HK-2) after injury caused by oxalic acid and calcium oxalate monohydrate ( COM ) crystal,and to explore the potential role of renal tubular cell injury in kidney stone formation. Methods Normal HK-2 cells展开更多
A simplistic and novel leaching process is developed to dispose spent lithium iron phosphate(LiFePO_(4))batteries.In this paper,oxalic acid is selected as a leaching reagent to recover lithium as a resource and remove...A simplistic and novel leaching process is developed to dispose spent lithium iron phosphate(LiFePO_(4))batteries.In this paper,oxalic acid is selected as a leaching reagent to recover lithium as a resource and remove phosphorus from LiFePO_(4) batteries,benefiting from its low natural effects.The physical properties of spent cathode materials(before leaching)and residues(after leaching)are identified by X-ray diffraction(XRD)and scanning electronic microscopy(SEM)with energy dispersive X-ray spectroscopy(EDS).The total amounts of Li and Fe are analyzed by inductively coupled plasma-atomic emission spectroscopy(ICP-AES).The process occurs under conditions of a 0.3 mol·L^(-1) oxalic acid concentration,a temperature of 80℃,a reaction time of 60 min and a solid/liquid ratio of 60 g·L^(-1).It can effectively precipitate92%ferrum in terms of FeC_(2)O_(4)·2H_(2)O from LiFePO4,with the leaching efficiency of Li achieving up to 98%.This method demonstrates a new strategy for dealing with spent lithium iron phosphate batteries with a low cost and low environmental impact.展开更多
Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdF...Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdFeB waste with oxalic acid was developed.The high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic benefit.Results of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,respectively.Rare earth oxalate and Fe(C_(2)O_(4))3^(3-) were left in the residue and the leaching solution,respectively.The leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical reaction.The leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt electrolysis.For the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC_(2)O_(4)-2H_(2)O).展开更多
Solution equilibrium calculations were performed in this study to understand the impact of contaminant metal ions on the precipitation efficiency of selected rare earth elements(Ce^(3+),Nd^(3+),and Y^(3+))using oxalic...Solution equilibrium calculations were performed in this study to understand the impact of contaminant metal ions on the precipitation efficiency of selected rare earth elements(Ce^(3+),Nd^(3+),and Y^(3+))using oxalic acid as a precipitant.Trivalent metal ions,Al^(3+) and Fe^(3+),are found to considerably affect the precipitation efficiency of REEs.When Al^(3+) and Fe^(3+)concentrations are increased by 1×10^(−4) mol/L,in order to achieve an acceptable cerium recovery of 93%from solutions containing 1×10^(−4) mol/L Ce^(3+),oxalate dosage needs to increase by 1.2×10^(−4) and 1.68×10^(−4) mol/L,respectively.Such great impacts on the required oxalate dosage are also observed for Nd^(3+) and Y^(3+),which indicates that oxalic acid consumption and cost will be largely increased when the trivalent metal ions exist in REE-concentrated solutions.Effects of the divalent metal ions on the oxalate dosage are minimal.Furthermore,solution equilibrium calculation results show that the precipitation of Fe^(3+) and Ca^(2+)(e.g.,hematite and Ca(C_(2)O_(4))∙H_(2)O(s))likely occurs during the oxalate precipitation of REEs at relatively high pH(e.g.,pH 2.5),which will reduce rare earth oxalate product purity.In addition to the metal ions,anionic species,especially SO_(4)^(2-),are also found to negatively affect the precipitation recovery of REEs.For example,when 0.1 mol/L SO_(4)^(2-) occurs in a solution containing 1×10^(−4) mol/L Ce^(3+) and 4×10^(−4) mol/L oxalate,the pH needs to be elevated from 2.0 to 3.3 to achieve the acceptable recovery.Overall,findings from this study provide guidance for the obtainment of high-purity rare earth products from solutions containing a considerable amount of contaminant metal ions by means of oxalic acid precipitation.展开更多
The current study evaluated the effects of oxalic acid(OA)application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese(Mn)-contaminated soils sample...The current study evaluated the effects of oxalic acid(OA)application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese(Mn)-contaminated soils sampled from an unexplored area(US),an explored area(ES)and a tailing area(TS)of the Ertang Mn mine,South China.The supplied levels of OA were 0(control),1(low level),3(medium level),and 9(high level)mmol/kg,referred to as CK,OA1,OA3 and OA9,respectively.The results revealed that the average water-extractable Mn concentrations US,ES and TS amended with OA increased by 214.13,363.77 and 266.85%,respectively.All OA supply levels increased plant growth and Mn concentrations in US.The low OA supply level increased plant growth in ES and TS;however,contrasting results were found for the medium and high OA supply levels.Plant Mn concentrations and total Mn increased in ES and TS in response to all OA supply levels.Total Mn in the aerial parts increased by 81.18,44.17 and 83.17%in US,ES and TS,respectively;the corresponding percentages for the whole plants were 81.53,108.98 and 77.91%,respectively.The rate of·O_(2)^(−)production and malondialdehyde(MDA)concentrations increased in response to OA amendment,especially the medium and high OA supply levels in ES and TS.In general,antioxidant enzymes might play a vital role in alleviating Mn stress in plants cultivated in US,while non-enzymatic antioxidants might be the main factor for plants cultivated in ES and TS.展开更多
Dye desalination is a challenge in the treatment of textile wastewater with high salt concentration. It is imperative to develop salt resistance membrane that is from sustainable materials to effectively treat dye/sal...Dye desalination is a challenge in the treatment of textile wastewater with high salt concentration. It is imperative to develop salt resistance membrane that is from sustainable materials to effectively treat dye/salt mixtures. And most polymer membrane materials are non-renewable petrochemical resources.In this paper, a green hydrogel membrane(CMCS-OA-Na Alg) was prepared by non-metallic ions of oxalic acid(OA) cross-linking of two natural macromolecules of sodium alginate(Na Alg) and carboxymethyl chitosan(CMCS). The membrane showed excellent anti-swelling at high salt concentration(swelling rate less than 8.0% in 10.0 wt% Na Cl solution) and good anti-fouling performance. The membrane exhibited a rejection higher than 95.0% for dyes(bright blue, direct black, direct red, and Congo red) and lower than7.0% for Na Cl, which can achieve better dye/Na Cl separation performance. This study provides a promising membrane material for high salt textile wastewater treatment only using water and carbohydrates as raw materials without any organic solvents.展开更多
In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were inve...In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.展开更多
The use of trichlorphon in large quantities causes a large number of organic pollutants to enter water, sediments, and soils. Phyllosilicate minerals are considered effective adsorbents for organic pollutants. However...The use of trichlorphon in large quantities causes a large number of organic pollutants to enter water, sediments, and soils. Phyllosilicate minerals are considered effective adsorbents for organic pollutants. However, the adsorption behavior of organic pollutants on soil minerals affected by low-molecular-weight organic acids(LMWOAs) is not fully understood. In this study, the effect of LMWOAs on the adsorption behavior of trichlorphon on phyllosilicate minerals was investigated using a combination of adsorption measurements and molecular spectroscopic techniques(attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR) and X-ray photoelectron spectroscopy(XPS)). The adsorption of trichlorphon onto kaolinite(KAO) and montmorillonite(MON) was suppressed by increasing pH, indicating that electrostatic interaction played a key role in adsorption, especially at low pH. In the presence of citric acid(CA), there was an obvious promotion of trichlorphon adsorption on KAO and MON. In the presence of oxalic acid(OA), the adsorption of trichlorphon on KAO was promoted, whereas the adsorption on MON was inhibited, especially at pH 4.0. The presence of CA and OA increased the adsorption by increasing the exposure of hydrophobic sites of KAO and MON. The results from ATR-FTIR and XPS also indicated that the hydrophobic Si–O sites of phyllosilicate minerals were the preferred adsorption sites for trichlorphon in the presence of CA and OA, probably driven by the hydrophobic effect. However, the weak effect of OA on MON caused an increase in the electrostatic repulsion between MON and trichlorphon molecules, thus inhibiting adsorption. This study is significant for a deeper understanding of self-purification of soil and sediment systems in the presence of organic pollutants.展开更多
An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas.The desorption effect of As,Cd,Sb and Pb was investigated utilizing...An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas.The desorption effect of As,Cd,Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques.It was found that the heavy metals concentration increased with decreasing particle size.The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides,while the maximum proportion of As,Sb and Pb were in the residual.The optimal solid-liquid ratio of the hydrocyclone was 1:20,and the corresponding separation efficiency and flow rate were 84.7%and 1.76 m^(3)/hr,respectively.The grade efficiency of soil particle separation increases with particle size and exceeds 99%for particles above 1,000μm.Leaching experiments have revealed that oxalic acid(OA)and a combination of oxalic acid and EDTA(OAPE)were more efficient than citric acid(CA)and a combination of citric acid and EDTA(CAPE)for the desorption of heavy metals,respectively.The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%,7.5%,7.2%and 7.8%for As,Cd,Sb and Pb compared to the former,respectively.The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals.It is expected to provide technical support for soil remediation with reduced usage of leaching agents.展开更多
The recovery of rare earth elements(REEs)from NdFeB slurry by traditional hydrometallurgy has been limited becuase a large number of REEs are lost during separation together with iron.In this paper,a simple and sustai...The recovery of rare earth elements(REEs)from NdFeB slurry by traditional hydrometallurgy has been limited becuase a large number of REEs are lost during separation together with iron.In this paper,a simple and sustainable method is proposed to efficiently separate and recover REEs and iron from NdFeB slurry.REEs were recovered by one-step selective precipitation in phosphoric acid,and the dissolved iron was recovered by oxalic acid.Phosphoric acid leaching results show that under the conditions of 4 mol/L phosphoric acid,80℃,L/S of 30:1 and 90 min,the leaching efficiencies of Fe and REEs reach 98.76%and1.09%,respectively.While the rest of REEs remained in the leaching residue in the form of REEPO_(4)·nH_(2)O precipitation.Subsequently.the mixed rare earth oxide(rare earth oxalate roasted at 800℃)and FeC_(2)O_(4)·2 H_(2)O are obtained by oxalic acid precipitation with purities of 99.49%and 97.17%from the REEPO4·nH_(2)O dissolving solution and the phosphoric acid leaching solution.Moreover,the phosphoric acid is regenerated while recovering iron,and it can be reused in the phosphoric acid leaching step after removing the impurity C_(2)O_(4)^(2-).In summary,this work provides an efficient and environmentally friendly method for recovering REEs and iron from NdFeB slurry waste.展开更多
This study focused on metal release from technosols induced by synthetic root exudate(SRE).The effect of SRE composition on metal release was studied using six technosols.This was done by treating the technosols with ...This study focused on metal release from technosols induced by synthetic root exudate(SRE).The effect of SRE composition on metal release was studied using six technosols.This was done by treating the technosols with SRE solutions having varying concentrations of low molecular weight organic acids (LMWOAs),namely oxalic,citric,and malic acids.Consequently,the physico-chemical parameters (p H and electric conductivity),Ca,Mg,Fe,Zn,and Cu release (by atomic absorption spectroscopy,AAS),chemical changes (by Fourier transform infrared,FT-IR),and organic parameters (by fluorescence) were investigated.Metal release showed to be dependent on the SRE composition and technosol characteristics.Citric acid selectively released Ca,Mg,Zn,and Cu from technosols in a concentration-dependent manner;oxalic acid showed a significant role in the release of Mg and Fe.Under relatively high LMWOA concentrations,particulate organo-mineral complexes precipitated.Additionally,technosol weathering was seen by the dissolution of humic substances and ferriallophanes,which in turn caused metal release.However,re-precipitation of these phases showed to re-sorb metals,thus underestimating the role of LMWOAs in metal release.Therefore,the selective metal leaching was highly dependent on the SRE composition and LMWOA concentrations on one hand,and on the mineral,organic,and organo-mineral components of the technosols on the other.The understanding of such processes is crucial for proposing and implementing environmental management strategies to reduce metal leaching or for the beneficial re-usage of metals (e.g.,for agromining) from technosols.展开更多
基金financially supported by the Young Scientists Fund of the National Natural Science Foundation of China(Nos.52104395 and 52304365)the Science and Technology Planning Project of Guangzhou,China(Nos.202102021080 and 2024A04J10006)+1 种基金the National Key R&D Program of China(No.2021YFC2902605)the Natural Science Foundation of Guangdong Province,China(Nos.2023A1515030145 and 2023A1515011847)。
文摘Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.
文摘The solvent of P350 was applied to extract and separate the oxalic acid from the mother-liquor originated from the precipitation of cobalt by oxalic acid,and its extraction mechanism was deduced.Some factors,including the concentration of P350, the concentration of hydrochloric acid and the concentration of oxalic acid were investigated to determine the best distribution coefficient of the oxalic acid.In the case of phase ratio(O/A)at 2.0,the extraction of the oxalic acid was more than 95%and its concentration in the extraction raffinate was lower than 0.004 0 mol/L after six-stage counter-current extraction.While the phase ratio(O/A)of the stripping was at 1.0,the recovery of oxalic acid attained more than 95%after ten-stage counter-current stripping.
基金The authors are grateful for the financial support of the National Natural Science Foundation of China(No.51574214).
文摘The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using 0.1–1.5 mol L^(-1) oxalic acid concentration was studied at 60℃–90℃.V and Fe were preferentially released(65%and 81%)compared with Al,Ti and W within 5 min due to the redox reactions of oxalic acid.The dissolved fractions of Fe,V,Al,Wand Ti increased with the increase of oxalic acid concentration and reaction temperature.The dissolution kinetic experiments were analysed and controlled diffusion with n<0.5 according to the Avrami dissolve reaction model(R^(2)>0.92).The Arrhenius parameters of the Ea values of Ti,W,V,Fe and Al from SDC with oxalic acid were 30,26,20,19 and 11 kJ mol^(-1),respectively.The obtained Avrami equation of V and Fe was successfully used to predict their leaching behaviour in oxalic acid.Toxicity characteristic leaching procedure revealed that the toxicity risk of Vand Fe metals from SDC after leaching with oxalic acid decreased to below 5 mg kg^(-1) residua.Overall,the leaching residua by oxalic acid indicated its safety for the environment.
基金Funded by the Ministry of Science and Technology(MOST)of China(No.2018YFB1502104)the National Natural Science Foundation of China(No.21771006)the Equipment Development Department of People’s Republic of China Central Military Commission(Pre-research Project of the Thirteenth FiveYear Plan)(No.41421020103)。
文摘We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt%based on all the reactants can be achieved with excellent hydrogen generation kinetics.
文摘A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 and 3.0 mmol kg-1 soil), oxalic acid (OA) at 3 rates (0, 1.5 and 3.0mmol kg-1 soil) and citric acid combined with oxalic acid (1.5 mmol citric acid combined with 1.5 mmol oxalic acid kg-1). Two types of soil were chose in the experiment. One was collected from the agricultural soil near a battery-recycling factory in Anhui province, China (site A) and the other was collected from a Pb-Zn mine residues in Hunan province, China (site B). The results showed that soil pH varied with the different treatment of citric and oxalic acids. However, there were no differences in all the treatments. 3.0mmol CA kg-1 soil addition significantly increased the concentrations of the CaCI2-extractable Pb and Zn and other treatments have no significantly increased. The highest shoot concentrations of Pb and
文摘The present study evaluates the reductive leaching of indium from indium-bearing zinc ferrite using oxalic acid as a reducer in sulfuric acid solution.The effect of main factors affecting the process rate,including the oxalic-acid-to-sulfuric-acid ratio,stirring rate,grain size,temperature,and the initial concentration of synergic acid,was precisely evaluated.The results confirmed the acceptable efficiency of dissolving indium in the presence of oxalic acid.The shrinking-core model with a chemical-reaction-controlled step can correctly describe the kinetics of indium dissolution.On the basis of an apparent activation energy of 44.55 kJ/mol and a reaction order with respect to the acid concentration of 1.14,the presence of oxalic acid was found to reduce the sensitivity to temperature changes and to increase the effect of changes in acid concentration.Finally,the equation of the kinetic model based on the factors under study is presented.
基金funding from the European Union’s Horizon 2020 research and innovation program under grant agreement ID 767798 (OCEAN)MIUR PRIN 2017 project CO_(2) ONLY project nr. 2017WR2LRS。
文摘Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the electrocatalytic reduction of oxalic acid to glycolic acid, allowing the development of a renewable energy-driven process for producing an alcoholic compound from an organic acid at low potential and room temperature. Coupled with the electrochemical synthesis of the oxalic acid from CO_(2),this process represents a new green and low-carbon path to produce added value chemicals from CO_(2). Various electrodes prepared by anodic oxidation of Ti foils were investigated. They were characterized by the presence of a TiO_(2) nanotube array together with the presence of small patches, debris, or TiO_(2) nanoparticles. The concentration of oxygen vacancies, the amount of Ti^(3+) measured by X-ray photoelectron spectroscopy(XPS) and the intensity of the anodic peak measured by cyclic voltammetry, were positively correlated with the achieved oxalic acid conversion and glycolic acid yield. The analysis of the results indicates the presence of small amorphous TiO_(2) nanoparticles(or surface patches or debris) interacting with TiO_(2) nanotubes, the sites responsible for the conversion of oxalic acid and glycolic acid yield. By varying this structural characteristic of the electrodes, it is possible to tune the glycolic acid to glyoxylic acid relative ratio. A best cumulative Faradaic efficiency(FE) of about 84% with FE to glycolic acid around 60% and oxalic conversion about 30% was observed.
文摘It was found that micro amounts of oxalate showed a very strong catalytic effect on the slow reaction between K 2Cr 2O 7 and Orange Ⅳ in a diluted sulfuric acid medium in a water bath at 70 ℃ . Orange Ⅳ exhibited a sensitive second order derivative polarographic wave at -0 50 V( vs . SCE). This provides the basis for a sensitive and selective catalytic kinetic method for oxalate determination with second order derivative oscillopolarography. The effects of sulphuric acid, K 2Cr 2O 7, and orange Ⅳ concentrations, reaction temperature and reaction time were investigated. A calibration curve of oxalate in the range of 0 1-2 0 μg/mL was obtained by the fixed time procedure. The detection limit was 0 03 μg/ mL. The possible interference from co existing substances or ions was examined. The new method has a high sensitivity and a good selectivity compared to other existing methods for oxalic acid determination. It has been applied to the determination of micro amounts of oxalate in real urine samples with satisfactory results.
基金Funded by the Ministry of Science and Technology(MOST)of China(No.2018YFB1502104)the Natural Science Foundation of China(No.21771006)the Equipment Development Department of People’s Republic of China Central Military Commission(Preresearch Project of the Thirteenth Five-Year Plan,No.41421020103)。
文摘We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt% based on all the reactants can be achieved with excellent hydrogen generation kinetics.
文摘Objective To analyze and identify the differentially expressed proteins in human renal tubular epithelial ceils ( HK-2) after injury caused by oxalic acid and calcium oxalate monohydrate ( COM ) crystal,and to explore the potential role of renal tubular cell injury in kidney stone formation. Methods Normal HK-2 cells
基金This work was supported by the International Science and Technology Cooperation Program of China(No.2016YFE0102200)SGCC’s Science&Technology Program(No.DG71-14-044).
文摘A simplistic and novel leaching process is developed to dispose spent lithium iron phosphate(LiFePO_(4))batteries.In this paper,oxalic acid is selected as a leaching reagent to recover lithium as a resource and remove phosphorus from LiFePO_(4) batteries,benefiting from its low natural effects.The physical properties of spent cathode materials(before leaching)and residues(after leaching)are identified by X-ray diffraction(XRD)and scanning electronic microscopy(SEM)with energy dispersive X-ray spectroscopy(EDS).The total amounts of Li and Fe are analyzed by inductively coupled plasma-atomic emission spectroscopy(ICP-AES).The process occurs under conditions of a 0.3 mol·L^(-1) oxalic acid concentration,a temperature of 80℃,a reaction time of 60 min and a solid/liquid ratio of 60 g·L^(-1).It can effectively precipitate92%ferrum in terms of FeC_(2)O_(4)·2H_(2)O from LiFePO4,with the leaching efficiency of Li achieving up to 98%.This method demonstrates a new strategy for dealing with spent lithium iron phosphate batteries with a low cost and low environmental impact.
基金Project supported by the National Natural Science Foundation of China(51564019,51674125)the Science and Technology Project of Jiangxi Province Education Department(GJJ181501)。
文摘Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdFeB waste with oxalic acid was developed.The high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic benefit.Results of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,respectively.Rare earth oxalate and Fe(C_(2)O_(4))3^(3-) were left in the residue and the leaching solution,respectively.The leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical reaction.The leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt electrolysis.For the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC_(2)O_(4)-2H_(2)O).
文摘Solution equilibrium calculations were performed in this study to understand the impact of contaminant metal ions on the precipitation efficiency of selected rare earth elements(Ce^(3+),Nd^(3+),and Y^(3+))using oxalic acid as a precipitant.Trivalent metal ions,Al^(3+) and Fe^(3+),are found to considerably affect the precipitation efficiency of REEs.When Al^(3+) and Fe^(3+)concentrations are increased by 1×10^(−4) mol/L,in order to achieve an acceptable cerium recovery of 93%from solutions containing 1×10^(−4) mol/L Ce^(3+),oxalate dosage needs to increase by 1.2×10^(−4) and 1.68×10^(−4) mol/L,respectively.Such great impacts on the required oxalate dosage are also observed for Nd^(3+) and Y^(3+),which indicates that oxalic acid consumption and cost will be largely increased when the trivalent metal ions exist in REE-concentrated solutions.Effects of the divalent metal ions on the oxalate dosage are minimal.Furthermore,solution equilibrium calculation results show that the precipitation of Fe^(3+) and Ca^(2+)(e.g.,hematite and Ca(C_(2)O_(4))∙H_(2)O(s))likely occurs during the oxalate precipitation of REEs at relatively high pH(e.g.,pH 2.5),which will reduce rare earth oxalate product purity.In addition to the metal ions,anionic species,especially SO_(4)^(2-),are also found to negatively affect the precipitation recovery of REEs.For example,when 0.1 mol/L SO_(4)^(2-) occurs in a solution containing 1×10^(−4) mol/L Ce^(3+) and 4×10^(−4) mol/L oxalate,the pH needs to be elevated from 2.0 to 3.3 to achieve the acceptable recovery.Overall,findings from this study provide guidance for the obtainment of high-purity rare earth products from solutions containing a considerable amount of contaminant metal ions by means of oxalic acid precipitation.
基金National Natural Science Foundation of China(Nos.41967019 and 41661077)the National Key Technologies Research and Development Program of China(No.2017YFD0801500)+1 种基金the Guangxi Science and Technology Development Project of Major Projects of Guangxi(Guike AA17204047-3)Scientific Research and Technology Development Program of Guilin(Nos.20190205 and 20180107-3).
文摘The current study evaluated the effects of oxalic acid(OA)application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese(Mn)-contaminated soils sampled from an unexplored area(US),an explored area(ES)and a tailing area(TS)of the Ertang Mn mine,South China.The supplied levels of OA were 0(control),1(low level),3(medium level),and 9(high level)mmol/kg,referred to as CK,OA1,OA3 and OA9,respectively.The results revealed that the average water-extractable Mn concentrations US,ES and TS amended with OA increased by 214.13,363.77 and 266.85%,respectively.All OA supply levels increased plant growth and Mn concentrations in US.The low OA supply level increased plant growth in ES and TS;however,contrasting results were found for the medium and high OA supply levels.Plant Mn concentrations and total Mn increased in ES and TS in response to all OA supply levels.Total Mn in the aerial parts increased by 81.18,44.17 and 83.17%in US,ES and TS,respectively;the corresponding percentages for the whole plants were 81.53,108.98 and 77.91%,respectively.The rate of·O_(2)^(−)production and malondialdehyde(MDA)concentrations increased in response to OA amendment,especially the medium and high OA supply levels in ES and TS.In general,antioxidant enzymes might play a vital role in alleviating Mn stress in plants cultivated in US,while non-enzymatic antioxidants might be the main factor for plants cultivated in ES and TS.
基金supported by the National Natural Science Foundation of China (Nos. 51708407 and 51803150)the Science and Technology Plans of Tianjin (Nos. 19JCQNJC02900, 18ZXJMTG00120,20JCYBJC00120)。
文摘Dye desalination is a challenge in the treatment of textile wastewater with high salt concentration. It is imperative to develop salt resistance membrane that is from sustainable materials to effectively treat dye/salt mixtures. And most polymer membrane materials are non-renewable petrochemical resources.In this paper, a green hydrogel membrane(CMCS-OA-Na Alg) was prepared by non-metallic ions of oxalic acid(OA) cross-linking of two natural macromolecules of sodium alginate(Na Alg) and carboxymethyl chitosan(CMCS). The membrane showed excellent anti-swelling at high salt concentration(swelling rate less than 8.0% in 10.0 wt% Na Cl solution) and good anti-fouling performance. The membrane exhibited a rejection higher than 95.0% for dyes(bright blue, direct black, direct red, and Congo red) and lower than7.0% for Na Cl, which can achieve better dye/Na Cl separation performance. This study provides a promising membrane material for high salt textile wastewater treatment only using water and carbohydrates as raw materials without any organic solvents.
基金supported by Central Public-interest Scientific Institution Basal Research Fund (1610172021003)Supported by the earmarked fund for CARS-13Key Area Research and Development Program of Hubei Province (2021BBA077)
文摘In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.
基金financially supported by the National Natural Science Foundation of China(Nos.41825021,42007020,and 21876097)the National Natural Science Foundation Project of International Cooperation and Exchange,China(No.41961144010)。
文摘The use of trichlorphon in large quantities causes a large number of organic pollutants to enter water, sediments, and soils. Phyllosilicate minerals are considered effective adsorbents for organic pollutants. However, the adsorption behavior of organic pollutants on soil minerals affected by low-molecular-weight organic acids(LMWOAs) is not fully understood. In this study, the effect of LMWOAs on the adsorption behavior of trichlorphon on phyllosilicate minerals was investigated using a combination of adsorption measurements and molecular spectroscopic techniques(attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR) and X-ray photoelectron spectroscopy(XPS)). The adsorption of trichlorphon onto kaolinite(KAO) and montmorillonite(MON) was suppressed by increasing pH, indicating that electrostatic interaction played a key role in adsorption, especially at low pH. In the presence of citric acid(CA), there was an obvious promotion of trichlorphon adsorption on KAO and MON. In the presence of oxalic acid(OA), the adsorption of trichlorphon on KAO was promoted, whereas the adsorption on MON was inhibited, especially at pH 4.0. The presence of CA and OA increased the adsorption by increasing the exposure of hydrophobic sites of KAO and MON. The results from ATR-FTIR and XPS also indicated that the hydrophobic Si–O sites of phyllosilicate minerals were the preferred adsorption sites for trichlorphon in the presence of CA and OA, probably driven by the hydrophobic effect. However, the weak effect of OA on MON caused an increase in the electrostatic repulsion between MON and trichlorphon molecules, thus inhibiting adsorption. This study is significant for a deeper understanding of self-purification of soil and sediment systems in the presence of organic pollutants.
基金financially supported by the National Natural Science Foundation of China (No.52025103)。
文摘An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas.The desorption effect of As,Cd,Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques.It was found that the heavy metals concentration increased with decreasing particle size.The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides,while the maximum proportion of As,Sb and Pb were in the residual.The optimal solid-liquid ratio of the hydrocyclone was 1:20,and the corresponding separation efficiency and flow rate were 84.7%and 1.76 m^(3)/hr,respectively.The grade efficiency of soil particle separation increases with particle size and exceeds 99%for particles above 1,000μm.Leaching experiments have revealed that oxalic acid(OA)and a combination of oxalic acid and EDTA(OAPE)were more efficient than citric acid(CA)and a combination of citric acid and EDTA(CAPE)for the desorption of heavy metals,respectively.The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%,7.5%,7.2%and 7.8%for As,Cd,Sb and Pb compared to the former,respectively.The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals.It is expected to provide technical support for soil remediation with reduced usage of leaching agents.
基金Project supported by the Key Research and Development of Gansu Province,China(17JR7GA014)the National Natural Science Foundation of China(52075234)。
文摘The recovery of rare earth elements(REEs)from NdFeB slurry by traditional hydrometallurgy has been limited becuase a large number of REEs are lost during separation together with iron.In this paper,a simple and sustainable method is proposed to efficiently separate and recover REEs and iron from NdFeB slurry.REEs were recovered by one-step selective precipitation in phosphoric acid,and the dissolved iron was recovered by oxalic acid.Phosphoric acid leaching results show that under the conditions of 4 mol/L phosphoric acid,80℃,L/S of 30:1 and 90 min,the leaching efficiencies of Fe and REEs reach 98.76%and1.09%,respectively.While the rest of REEs remained in the leaching residue in the form of REEPO_(4)·nH_(2)O precipitation.Subsequently.the mixed rare earth oxide(rare earth oxalate roasted at 800℃)and FeC_(2)O_(4)·2 H_(2)O are obtained by oxalic acid precipitation with purities of 99.49%and 97.17%from the REEPO4·nH_(2)O dissolving solution and the phosphoric acid leaching solution.Moreover,the phosphoric acid is regenerated while recovering iron,and it can be reused in the phosphoric acid leaching step after removing the impurity C_(2)O_(4)^(2-).In summary,this work provides an efficient and environmentally friendly method for recovering REEs and iron from NdFeB slurry waste.
基金financed by the research grant programs of the Lebanese University (le projet est soutenu par le programme de subvention de la recherche scientifique à l’Université Libanaise)。
文摘This study focused on metal release from technosols induced by synthetic root exudate(SRE).The effect of SRE composition on metal release was studied using six technosols.This was done by treating the technosols with SRE solutions having varying concentrations of low molecular weight organic acids (LMWOAs),namely oxalic,citric,and malic acids.Consequently,the physico-chemical parameters (p H and electric conductivity),Ca,Mg,Fe,Zn,and Cu release (by atomic absorption spectroscopy,AAS),chemical changes (by Fourier transform infrared,FT-IR),and organic parameters (by fluorescence) were investigated.Metal release showed to be dependent on the SRE composition and technosol characteristics.Citric acid selectively released Ca,Mg,Zn,and Cu from technosols in a concentration-dependent manner;oxalic acid showed a significant role in the release of Mg and Fe.Under relatively high LMWOA concentrations,particulate organo-mineral complexes precipitated.Additionally,technosol weathering was seen by the dissolution of humic substances and ferriallophanes,which in turn caused metal release.However,re-precipitation of these phases showed to re-sorb metals,thus underestimating the role of LMWOAs in metal release.Therefore,the selective metal leaching was highly dependent on the SRE composition and LMWOA concentrations on one hand,and on the mineral,organic,and organo-mineral components of the technosols on the other.The understanding of such processes is crucial for proposing and implementing environmental management strategies to reduce metal leaching or for the beneficial re-usage of metals (e.g.,for agromining) from technosols.
