摘要
热解炭化是重金属富集植物后处理的一种有效途径.本研究以富集重金属后的植物香根草(Chrysopogon zizanioides)为原料,在不同温度下(300、400、500和700℃)裂解制备生物炭(HBC)用于负载纳米零价铁合成复合材料(HBC/nZVI),并探究其物化特征和去除Cr(Ⅵ)的效果与机理.结果表明:在400℃下热解所得生物炭(HBC400)比热解温度在300、500和700℃时生成的生物炭展现出更好的孔隙度和形态结构,HBC400有效地抑制了纳米Fe0粒子的团聚.修复实验表明,HBC400/nZVI对Cr(Ⅵ)的去除率最高,当初始Cr(Ⅵ)浓度为50 mg·L^(-1)、pH=3和投加量为1.0 g·L^(-1)时,HBC400/nZVI对于Cr(Ⅵ)的去除率达到98.9%,吸附过程高度符合准二级动力学方程.FTIR和XPS等结果表明HBC400/nZVI主要通过吸附、还原和共沉淀过程去除Cr(Ⅵ).含氧官能团将Cr(Ⅵ)吸附在HBC400/nZVI表面后,Cr(Ⅵ)被Fe0粒子还原为Cr(Ⅲ),Cr(Ⅲ)和Fe(Ⅲ)会发生共沉淀以CrxFe1-x(OH)3和Fe(OH)3-Cr(OH)3形式附着于HBC400/nZVI表面.同时,整个反应过程中,生物炭中的Cd和Pb等金属离子未析出.本研究表明HBC/nZVI可安全用于处理Cr(Ⅵ)污染水体.
Pyrolytic carbonization is a promising strategy for the post-treatment of heavy metals accumulated plants.In this study,The Vetiver was pyrolyzed at alternative peak temperatures(300~700℃)to produce biochar(HBC).Meanwhile,the HBC assisted nano zero valent iron(HBC/nZVI)were prepared.The physical characteristics and the potential mechanisms of Cr(Ⅵ)removal by HBC and HBC/nZVI were also investigated.Results showed that HBC pyrolyzed at 400℃(HBC400)showed a superior porosity and morphology structure compared to that pyrolyzed at 300℃,500℃and 700℃.The HBC400 effectively decreased the agglomeration of Fe0 nano-particles.In addition,HBC400/nZVI exhibited the highest Cr(Ⅵ)removal efficiency.When the initial concentration of Cr(Ⅵ)was 50 mg·L^(-1),pH=3 and 1 g·L^(-1) adsorbent dosage of HBC400/nZVI,the removal efficiency of Cr(Ⅵ)achieved 98.9%.In this reaction,the adsorption Kinetic was highly fitted to the pseudo-second-order dynamic equation.The removal mechanisms of Cr(Ⅵ)by HBC400/nZVI was revealed by Fourier transform infrared,X-ray diffraction and X-ray photoelectron spectroscopy.Cr(Ⅵ)that were involved in reduction,adsorption,and coprecipitation.The Cr(Ⅵ)was adsorbed to HBC400/nZVI surface through oxygen-containing functional groups and then Cr(Ⅵ)was reduced to Cr(Ⅲ)by Fe0,and finally co-precipitated with Fe(Ⅲ)in the form of CrxFe1-x(OH)3 and Fe(OH)3-Cr(OH)3 on the surface of HBC400/nZVI.Furthermore,metal ions such as Cd and Pb in biochar were not dissolved during the whole reaction process.These findings provided it is a safe application of HBC/nZVI in the treatment of Cr(Ⅵ)polluted water.
作者
于亚慧
吴斌
郭舒雅
李佳
YU Yahui;WU Bin;GUO Shuya;LI Jia(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,College of Ecology and Environment,Chengdu University of Technology,Chengdu 610059)
出处
《环境科学学报》
CAS
CSCD
北大核心
2024年第7期116-126,共11页
Acta Scientiae Circumstantiae
基金
四川省科技项目(No.2022YFN0066)
凉山州重点研发项目(No.22ZDYF0185)
贵州省科技支撑计划项目(No.黔科合支撑[2023]一般255)。
关键词
生物炭
纳米零价铁
六价铬
去除机制
biochar
nano zero valent iron
hexavalent chromium
removal mechanisms
