摘要
利用尿素、三聚氰胺、硝酸铵、氨气等氮化合物改性水稻秸秆和桉树叶、蚕茧、鸡粪、墨鱼汁等富氮生物质制备氮(自)掺杂生物炭用于去除水中六价铬(Cr(VI)),通过准/伪一级动力学模型考察了氮掺杂生物炭还原和吸附六价铬的动力学过程,并利用BET、FTIR、XPS等表征分析手段,探讨了氮掺杂改性对生物炭去除水中六价铬的影响及其作用机理.结果表明,氮掺杂能显著提高生物炭对Cr(VI)的去除能力,如尿素改性使得秸秆生物炭的Cr(VI)去除速率提高了5.9倍,达到0.102 h^(-1),而利用墨鱼汁制备的氮自掺杂生物炭对Cr(VI)的去除速率为0.412 h^(-1),较其他富氮生物质高约4~8倍.氮掺杂强化了生物炭对Cr(VI)的吸附和还原作用,通过增加生物炭表面氨基官能团作为活性吸附位点,在酸性条件下质子化形成带正电的—NH_(3)^(+),通过静电作用吸附Cr O_(4)^(2-),或直接通过络合作用吸附Cr^(3+);氨基具有还原性,能作为电子供体将Cr(VI)直接还原为Cr(III);氮掺杂还增强了生物炭的氧化还原介导能力,使生物炭能利用低分子有机酸作为电子供体介导还原Cr(VI),从而实现氮掺杂生物炭对水中六价铬的高效去除.本研究为改性生物炭在废水重金属治理中的应用提供了理论基础.
In this study,nitrogen-doped biochar was prepared by pyrolyzing rice straw with various nitrogen sources,including urea,melamine,ammonium nitrate,and ammonia,as well as nitrogen-rich biomasses,such as eucalyptus leaves,silk cocoons,chicken manure,and squid ink.The as-synthesized nitrogen-doped biochar was used for the removal of Cr(VI)from wastewater.The kinetics of Cr(VI)reduction and adsorption by nitrogen-doped biochar were investigated using quasi/pseudo first-order kinetic models.The mechanism of Cr(VI)removal from water by nitrogendoped biochar were explored by BET,FTIR and XPS analysis.The results demonstrated that nitrogen doping significantly enhanced the performance of biochar in Cr(VI)removal.For instance,urea-modified biochar exhibited a high removal rate of Cr(VI)(0.102 h^(-1)),which was 5.9-times higher than that of unmodified-biochar.Moreover,the nitrogen self-doped biochar derived from squid ink achieved a remarkable removal rate of 0.412 h^(-1),which was 4~8 times higher than that of others.Nitrogen-doping enhanced the of Cr(VI)by synergistic adsorption and reduction and the underlying mechanism was proposed.Nitrogen doping increased the amino groups,which served as active adsorption sites on the biochar surface.Nitrogen-doping biochar effectively absorbed Cr(VI)in the form of CrO_(4)^(2-)through electrostatic attraction with protonated amine groups(—NH_(3)^(+))and Cr^(3+)through complexation with amine groups under acidic conditions.The reductive amino group also serve as electron donor,facilitating the reduction of Cr(VI)to Cr(III).Additionally,nitrogen-doping enhanced the redox-mediated ability of biochar to mediated Cr(VI)reduction with low-molecular-weight organic acids as electron donors,thereby achieving high-performance Cr(VI)removal.In summary,this study offers a theoretical foundation for the utilization of modified biochar for high-performance Cr(VI)remediation in wastewater.
作者
代祥
罗婴棋
张文俊
邓大禄
袁勇
王逸
DAI Xiang;LUO Yingqi;ZHANG Wenjun;DENG Dalu;YUAN Yong;WANG Yi(School of Environmental Science and Engineering,Guangdong University of Technology,Guangzhou 510006;Guangdong Provincial Key Laboratory of Environmental Catalysis and Health Risk Control,Institute of Environmental Health and Pollution Control,Guangzhou 510006)
出处
《环境科学学报》
CAS
CSCD
北大核心
2023年第11期84-93,共10页
Acta Scientiae Circumstantiae
基金
国家自然科学基金青年基金项目(No.42377242,41907122)
广东省自然科学基金卓越青年团队项目(No.2023B1515040022)
广州市科技计划基础与应用基础研究项目(No.202102020788)。
关键词
氮掺杂
生物炭
六价铬
吸附还原
电子传递
nitrogen doping
biochar
hexavalent chromium
reduction and absorption
electron transfer
