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Effect of struvite and organic acids on immobilization of copper and zinc in contaminated bio-retention filter media

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journal of Environmental Sciences 2020年第11期32卷 35-44页

作者： Chathurani Moragaspitiya jay Rajapakse graeme j.millar Science and Engineering Faculty Queensland University of Technology(QUT)Queensland 4000Australia

Few studies have been carried out to connect nutrient recovery as struvite from wastewater and sustainable utilization of the recovered struvite for copper and zinc immobilization in contaminated *** study revealed the effect of struvite on Cu and Zn immobilization in contaminated bio-retention soil in the presence of commonly exuded plant organic *** research hypothesis was that the presence of both struvite and organic acids may influence the immobilization of Cu and Zn in *** outcome of this research confirmed that more than 99%of Cu and Zn was immobilized in bio-retention filter media by struvite ***-soluble Cu and Zn concentrations of struvite treated soil were less than 1.83 and 0.86 mg/kg respectively,and these concentrations were significantly lower compared to the total Cu and Zn content of 747.05 mg/kg in the contaminated *** of struvite to Cu-and Zn-contaminated soil resulted in formation of compounds similar to zinc phosphate tetrahydrate(Zn3(PO4)2·4H2O)and amorphous Cu and Zn *** was effective in heavy metal remediation in acidic soil regardless of the presence of Ca impurities in struvite and the presence of plant organic acids in ***,this study revealed that struvite recovered from wastewater treatment plants has potential for use as an amendment for heavy metal remediation in contaminated bio-retention soil.

关键词： Immobilization Struvite Organic acids Heavy metal Contaminated soil Bio-retention

Effect of Ca:Mg ratio and high ammoniacal nitrogen on characteristics of struvite precipitated from waste activated sludge digester effluent

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journal of Environmental Sciences 2019年第12期31卷 65-77页

作者： Chathurani Moragaspitiya jay Rajapakse graeme j.millar Science and Engineering Faculty Queensland University of Technology (QUT)

This study revealed the relationship between the presence of calcium impurities and ammoniacal nitrogen concentration upon crystallization of *** research hypothesis was that the presence of both calcium and high concentrations of ammoniacal nitrogen(328–1000 mg/L)in waste activated sludge may influence the struvite quality and acid ***,we studied the impact of Ca:Mg ratio upon morphology,particle size,purity and dissolution of struvite,in the presence of varying levels of excess ammoniacal nitrogen.X-ray diffraction revealed that up to 31.4%amorphous material was made which was assigned to *** the ammoniacal nitrogen concentration and elevation of the Mg:Ca ratio maximized the presence of *** particle size was also increased by ammoniacal nitrogen as was twinning of the *** with dilute solutions of organic acid revealed the sensitivity of struvite dissolution to the physical characteristics of the *** particles(21.2μm)dissolved at higher rates than larger particles(35.86μm).However,struvite dissolved rapidly as the p H was further reduced irrespective of the physical ***,addition of struvite to low p H soils was not viewed as beneficial in terms of controlled nutrient ***,this study revealed that waste activated sludge effluent with high ammoniacal nitrogen was prospective for synthesis of high quality struvite material.

关键词： Struvite Purity Calcium Ammoniacal nitrogen Waste activated sludge

Phosphogypsum stabilization of bauxite residue:Conversion of its alkaline characteristics

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journal of Environmental Sciences 2019年第3期31卷 1-10页

作者： Shengguo Xue Meng Li jun jiang graeme j.millar Chuxuan Li Xiangfeng Kong School of Metallurgy and Environment Central South University Institute for Future Environments Science and Engineering Faculty Queensland University of Technology

Reduction of the high alkalinity of bauxite residue is a key problem to solve to make it suitable for plant growth and comprehensive utilization. In this study, phosphogypsum, a waste product from the phosphate fertilizer industry, was used to drive the alkaline transformation of the bauxite residue. Under optimal water washing conditions(liquid/solid ratio of 2 mL/g, 30°C, 24 hr), the impact of quantity added, reaction time and reaction mechanism during phosphogypsum application were investigated. Phosphogypsum addition effectively lowered p H levels and reduced the soluble alkalinity by 92.2%. It was found that the concentration of soluble Na and Ca ions in the supernatant increased gradually, whilst the exchangeable Na+and Ca^(2+)in solid phase changed 112 mg/kg and 259 mg/kg, respectively. Ca^(2+)became the dominant element in the solid phase(phosphogypsum addition of 2%, liquid/solid ratio of 2 mL/g, 30°C, 12 hr). X-ray diffraction data indicated that cancrinite and hydrogarnet were the primary alkaline minerals. SEM images suggested that phosphogypsum could promote the formation of stable macroaggregates, whilst the content of Ca^(2+)increased from 5.6% to 18.2% and Na reduced from 6.8% to 2.4%. Treatment with phosphogypsum could significantly promote the transformation of alkalinity cations by neutralization, precipitation and replacement *** research provided a feasible method to promote soil formation of bauxite residue by phosphogypsum amendment.

关键词： Bauxite residue Phosphogypsum Alkaline ions Alkaline transformation Soil formation

Enhanced dealkalization of bauxite residue through calcium-activated desulfurization gypsum

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Transactions of Nonferrous Metals Society of China 2024年第10期34卷 3412-3424页

作者： Yu-jun WU Sheng-guo XUE Li-ping LIU Feng LI graeme j.millar Fei GE jiang TIAN College of Environment and Resources Xiangtan UniversityXiangtan 411105China School of Metallurgy and Environment Central South UniversityChangsha 410083China School of Mechanical Medical and Process EngineeringFaculty of EngineeringQueensland University of TechnologyBrisbaneQueensland 4000Australia

A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was *** combination of recycled FeCl_(3)solution and EDTA activated desulfurization gypsum lowered the bauxite residue pH to ***,it also improved the residual Ca state,with its contribution to the total exchangeable cations increased(68%-92%).Notably,the slow release of exchangeable Ca introduced through modified desulfurization gypsum induced a phase transition of the alkaline *** treatment stabilized the dealkalization effect of bauxite residue via reducing its overall acid neutralization capacity in abating pH ***,this approach can provide guidance for effectively utilizing desulfurization gypsum to achieve stable regulation of alkalinity in bauxite residue.

关键词： bauxite residue desulfurization gypsum EDTA activation alkalinity regulation recycled FeCl_(3)

Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue

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Transactions of Nonferrous Metals Society of China 2018年第10期28卷 2125-2134页

作者： Yi-wei LI jun jIANG Sheng-guo XUE graeme j.millar Xiang-feng KONG Xiao-fei LI Meng LI Chu-xuan LI School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution Central South UniversityChangsha 410083China Institute for Future Environments Science and Engineering FacultyQueensland University of Technology(QUT)Brisbane Qld 4000Australia

This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride *** results showed that the pH of bauxite residue decreased from 10.49 to 8.93,total alkaline anion(HCO3^-,CO3^2-,OH^-,AlO2^-)concentration reduced from 38.89 to 25.50 mmol/L,leaching rate of soluble sodium was 80.86%with ammonium chloride addition of 0.75%,liquid/solid(L/S)ratio of 3(mL/g),temperature of 30°C and reaction time of 18 h;L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of ***,ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive *** findings of this work will contribute to achieve soil-formation of bauxite residue.

关键词： bauxite residue ammonium chloride leaching behavior alkaline regulation soil formation

Variation of alkaline characteristics in bauxite residue under phosphogypsum amendment

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journal of Central South University 2019年第2期26卷 361-372页

作者： LI Yi-wei LUO Xing-hua LI Chu-xuan jIANG jun XUE Sheng-guo School of Metallurgy and Environment Central South University Hunan Rare Earth Metal Material Research Institute Institute for Future Environments Science and Engineering Faculty Queensland University of Technology (QUT)

Aiming at alkaline problem of bauxite residue,this work focused variation of alkaline characteristics in bauxite residue through phosphogypsum *** results demonstrated that the pH of bauxite residue reduced from initial 10.83 to 8.70 when 1.50 wt%phosphogypsum was added for 91 *** removal rates of free alkali and exchangeable sodium were 97.94%and 75.87%,***,significant positive correlations(POH^–>AlO2^–>HCO3^–.In addition,alkaline phase decreased from 52.81%to 48.58%and gypsum stably presented in bauxite residue which continuously provided Ca^2+to inhibit dissolution of combined ***,phosphogypsum promoted formation of macroaggregate structure,increased Ca^2+,decreased Na+and Al^3+on the surface of bauxite residue significantly,ultimately promoting soil formation in bauxite residue.

关键词： bauxite residue alkaline regulation free alkali phosphogypsum amendment soil formation in bauxite residue

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钙活化脱硫石膏强化赤泥脱碱（英文）

Transactions of Nonferrous Metals Society of China 2024年第10期 3412-3424页

作者：吴玉俊薛生国刘丽坪李峰 graeme j.millar 葛飞田江湘潭大学环境与资源学院中南大学冶金与环境学院 School of Mechanical Medical and Process Engineering Faculty of EngineeringQueensland University of Technology

提出一种通过控制脱硫石膏中钙的释放行为来去除赤泥游离碱和稳定结合碱的新方法。结果表明，利用FeCl3结合EDTA活化脱硫石膏（钙离子活化剂）能够有效降低赤泥碱性（pH值稳定在7.20），显著提高钙离子交换容量饱和度，进而增加Ca对可... 详细信息

提出一种通过控制脱硫石膏中钙的释放行为来去除赤泥游离碱和稳定结合碱的新方法。结果表明，利用FeCl3结合EDTA活化脱硫石膏（钙离子活化剂）能够有效降低赤泥碱性（pH值稳定在7.20），显著提高钙离子交换容量饱和度，进而增加Ca对可交换阳离子总量的贡献（68%～92%）。交换性钙从改性脱硫石膏中缓慢释放后，使碱性矿物发生相转变。该方法通过降低赤泥整体酸中和能力抑制pH回升，最终稳定赤泥碱性调控效果，为脱硫石膏在赤泥碱性调控中的高效应用提供科学指导。

关键词：赤泥脱硫石膏 EDTA活化碱性调控 FeCl3回收液

B vitamins for stroke prevention

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Stroke & Vascular Neurology 2018年第2期3卷 51-58页

作者： graeme j Hankey UWA Medical School Faculty of Health and Medical SciencesThe University of Western AustraliaPerthWestern AustraliaAustralia Department of Neurology Sir Charles Gairdner HospitalNedlandsWestern AustraliaAustralia

Supplementation with B vitamins(vitamin B9(folic acid),vitamin B_(12) and vitamin B_(6))lowers blood total homocysteine(tHcy)concentrations by about 25%and reduces the relative risk of stroke overall by about 10%(risk ratio(RR)0.90,95%CI 0.82 to 0.99)compared with ***-lowering interventions have no significant effect on myocardial infarction,death from any cause or adverse *** that appear to modify the effect of B vitamins on stroke risk include low folic acid status,high tHcy,high cyanocobalamin dose in patients with impaired renal function and concurrent antiplatelet *** regions with increasing levels or established policies of population folate supplementation,evidence from observational genetic epidemiological studies and randomised controlled clinical trials is concordant in suggesting an absence of benefit from lowering of homocysteine with folic acid for prevention of *** trials indicate that in countries which mandate folic acid fortification of food,folic acid supplementation has no significant effect on reducing stroke risk(RR 1.05,95%CI 0.90 to 1.23).However,in countries without mandatory folic acid food fortification,folic acid supplementation reduces the risk of stroke by about 15%(RR 0.85,95%CI 0.77 to 0.94).Folic acid alone or in combination with minimal cyanocobalamin(≤0.05 mg/day)is associated with an even greater reduction in risk of future stroke by 25%(RR 0.75,95%CI 0.66 to 0.86),whereas the combination of folic acid and a higher dose of cyanocobalamin(≥0.4 mg/day)is not associated with a reduced risk of future stroke(RR 0.95,95%CI 0.86 to 1.05).The lack of benefit of folic acid plus higher doses of cyanocobalamin(≥0.4 mg/day)was observed in trials which all included participants with chronic kidney *** metabolic B_(12)deficiency is very common and usually not diagnosed,future randomised trials of homocysteine-lowering interventions for stroke prevention should probably test a combinati

关键词： vitamin prevention impaired

Developing an interatomic potential for martensitic phase transformations in zirconium by machine learning

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npj Computational Materials 2018年第1期4卷 254-261页

作者： Hongxiang Zong Ghanshyam Pilania Xiangdong Ding graeme j.Ackland Turab Lookman State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Theoretical Division&Materials Science and Technology Division Los Alamos National LaboratoryLos AlamosNM 87545USA Centre for Science at Extreme Conditions(CSEC) School of Physics and AstronomyUniversity of EdinburghEdinburgh EH93FDUK

Atomic simulations provide an effective means to understand the underlying physics of structural phase ***,this remains a challenge for certain allotropic metals due to the failure of classical interatomic potentials to represent the multitude of *** on machine-learning(ML)techniques,we develop a hybrid method in which interatomic potentials describing martensitic transformations can be learned with a high degree of fidelity from ab initio molecular dynamics simulations(AIMD).Using zirconium as a model system,for which an adequate semiempirical potential describing the phase transformation process is lacking,we demonstrate the feasibility and effectiveness of our ***,the ML-AIMD interatomic potential correctly captures the energetics and structural transformation properties of zirconium as compared to experimental and density-functional data for phonons,elastic constants,as well as stacking fault *** dynamics simulations successfully reproduce the transformation mechanisms and reasonably map out the pressure–temperature phase diagram of zirconium.

关键词： martensitic transformation zirconium