One-pot solvothermal synthesis of magnetic biochar from waste biomass: Formation mechanism and efficient adsorption of Cr(VI) in an aqueous solution

TY - JOUR

T1 - One-pot solvothermal synthesis of magnetic biochar from waste biomass

T2 - Formation mechanism and efficient adsorption of Cr(VI) in an aqueous solution

AU - Liang, Sha

AU - Shi, Shunquan

AU - Zhang, Haohao

AU - Qiu, Jingjing

AU - Yu, Wenhao

AU - Li, Mingyang

AU - Gan, Quan

AU - Yu, W.

AU - Xiao, Keke

AU - Liu, Bingchuan

AU - Hu, Jingping

AU - Hou, Huijie

AU - Yang, Jiakuan

N1 - Publisher Copyright: © 2019 Elsevier B.V.

PY - 2019/12/10

Y1 - 2019/12/10

N2 - A facile one-pot solvothermal method was applied to synthesize a magnetic biochar composite (MB) using phoenix tree leaves-derived biochar as the carbon matrix. The structure of MB was optimized by varying the load ratio and particle size of Fe3O4 nanoparticles on biochar. Time-dependent structure and composition evolution of solid and liquid phases during heterogeneous solvothermal process were investigated to understand the formation mechanism of MB. Firstly, Fe2+/Fe3+ ions were coordinated by oxygen-containing groups on biochar and part of them were hydrolyzed to form iron hydroxides. Then, those iron-containing precursors were thermally decomposed and reduced to iron oxides; and finally Fe3O4 nanoparticles were generated. The MB had an adsorption capacity for Cr(VI) of 55.0 mg/g in an aqueous solution, which exceeds those of biochar (39.8 mg/g) and Fe3O4 nanoparticles (26.5 mg/g). The adsorption mechanism study reveals that biochar as a carbon skeleton mainly provided binding sites for Cr(VI) and electron-donor groups for reduction of Cr(VI), while Fe3O4 nanoparticles mainly involved in the immobilization of newly formed Cr(III) through formation of Fe(III)-Cr(III) hydroxide. MB exhibited a stable structure with a lower Fe leakage at pH 2.0 than that of a comparable magnetic biochar sample prepared by conventional co-precipitation method. Recycling experiments suggested that MB could keep 84% of its initial removal capability for Cr(VI) even after seven cycles. The results indicate that solvothermal method is a promising alternative to prepare magnetic biochar for adsorption of heavy metal-containing wastewater.

AB - A facile one-pot solvothermal method was applied to synthesize a magnetic biochar composite (MB) using phoenix tree leaves-derived biochar as the carbon matrix. The structure of MB was optimized by varying the load ratio and particle size of Fe3O4 nanoparticles on biochar. Time-dependent structure and composition evolution of solid and liquid phases during heterogeneous solvothermal process were investigated to understand the formation mechanism of MB. Firstly, Fe2+/Fe3+ ions were coordinated by oxygen-containing groups on biochar and part of them were hydrolyzed to form iron hydroxides. Then, those iron-containing precursors were thermally decomposed and reduced to iron oxides; and finally Fe3O4 nanoparticles were generated. The MB had an adsorption capacity for Cr(VI) of 55.0 mg/g in an aqueous solution, which exceeds those of biochar (39.8 mg/g) and Fe3O4 nanoparticles (26.5 mg/g). The adsorption mechanism study reveals that biochar as a carbon skeleton mainly provided binding sites for Cr(VI) and electron-donor groups for reduction of Cr(VI), while Fe3O4 nanoparticles mainly involved in the immobilization of newly formed Cr(III) through formation of Fe(III)-Cr(III) hydroxide. MB exhibited a stable structure with a lower Fe leakage at pH 2.0 than that of a comparable magnetic biochar sample prepared by conventional co-precipitation method. Recycling experiments suggested that MB could keep 84% of its initial removal capability for Cr(VI) even after seven cycles. The results indicate that solvothermal method is a promising alternative to prepare magnetic biochar for adsorption of heavy metal-containing wastewater.

KW - Adsorption

KW - Cr(VI) removal

KW - Formation mechanism

KW - Magnetic biochar

KW - Solvothermal process

UR - http://www.scopus.com/inward/record.url?scp=85070643585&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2019.133886

DO - 10.1016/j.scitotenv.2019.133886

M3 - 文章

C2 - 31422325

AN - SCOPUS:85070643585

SN - 0048-9697

VL - 695

JO - Science of the Total Environment

JF - Science of the Total Environment

M1 - 133886

ER -