Sodium citrate(SC)is a widely-used food and industrial additive with the properties of com-plexation and microbial degradation.In the present study,nano-zero-valent iron reaction system(SC-nZVI@BC)was successfully established by modifying nanoscale zero-valent iron(nZVI)with SC and biochar(BC),and was employed to remove Cr(Ⅵ)from aqueous solu-tions.The nZVI,SC-nZVI and SC-nZVI@BC were characterized and compared using X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analy-ses(TGA),vibrating sample magnetometer(VSM),scanning electron microscope(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The results showed that nZVI was successfully loaded on the biochar,and both the agglomeration and surface pas-sivation problems of nanoparticles were well resolved.The dosage of SC,C∶Fe,initial pH and Cr(Ⅵ)concentration demonstrated direct effects on the removal efficiency.The maximum Cr(Ⅵ)removal rate and the removal capacity within 60 min were 99.7％and 199.46 mg/g,respectively(C∶Fe was 1∶1,SC dosage was 1.12 mol.％,temperature was 25℃,pH=7,and the original concentration of Cr(Ⅵ)was 20 mg/L).The reaction confirmed to follow the pseudo-second-order reaction kinetics,and the order of the reaction rate constant k was as follows:SC-nZVI@BC＞nZVI@BC＞SC-nZVI＞nZVI.In addition,the mechanism of Cr(Ⅵ)removal by SC-nZVI@BC mainly involved adsorption,reduction and co-precipitation,and the reduction of Cr(Ⅵ)to Cr(Ⅲ)by nano Fe0 played a vital role.Findings from the present study demon-strated that the SC-nZVI@BC exhibited excellent removal efficiency toward Cr(Ⅵ)with an improved synergistic characteristic by SC and BC.

Hongyi Zhou;Mengyao Ye;Yongkang Zhao;Shams Ali Baig;Ning Huang;Mengyan Ma

College of Environment,Zhejiang University of Technology,Hangzhou 310014,China;Department of Environmental Sciences,Abdul Wali Khan University Mardan,Mardan 23200,Pakistan

环境科学学报（英文版）

[1]Hongyi Zhou;Mengyao Ye;Yongkang Zhao;Shams Ali Baig;Ning Huang;Mengyan Ma-.Sodium citrate and biochar synergistic improvement of nanoscale zero-valent iron composite for the removal of chromium(Ⅵ)in aqueous solutions)[J].环境科学学报（英文版）,2022(05):227-239

plexation

Sodium,citrate,biochar,synergistic,improvement,nanoscale,zero,valent,iron,composite,removal,chromium,aqueous,solutions,SC,widely,used,food,industrial,additive,properties,microbial,degradation,In,present,study,reaction,system,nZVI,BC,was,successfully,established,by,modifying,employed,remove,from,were,characterized,compared,using,ray,diffraction,Fourier,transform,infrared,spectroscopy,FTIR,thermogravimetric,analy,ses,TGA,vibrating,sample,magnetometer,VSM,scanning,microscope,photoelectron,XPS,results,showed,that,loaded,both,agglomeration,surface,pas,sivation,problems,nanoparticles,well,resolved,dosage,initial,concentration,demonstrated,direct,effects,efficiency,maximum,capacity,within,respectively,temperature,original,confirmed,pseudo,second,order,kinetics,constant,follows,addition,mechanism,mainly,involved,adsorption,reduction,precipitation,Fe0,played,vital,role,Findings,exhibited,excellent,toward,improved,characteristic

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