摘要
以小麦秸秆为原料在500℃N2气氛下制备生物炭(WB),该文进一步用FeCl3·6H2O和FeSO4·7H2O进行改性制备磁性生物炭(MWB),用于溶液中Cr(Ⅵ)的吸附,研究MWB对Cr(Ⅵ)的吸附性能和吸附机理。实验结果表明,与WB相比,MWB对初始浓度为100 mg/L时水中Cr(Ⅵ)去除率由36.86%提高到93.90%。Langmuir模型更适合描述MWB对Cr(Ⅵ)的吸附等温过程,吸附动力学符合准二级动力学模型,活化能为44.81 k J/mol。热力学参数ΔG<0、ΔH>0、ΔS>0,表明吸附是自发进行的吸热过程。XPS和FTIR分析结果表明铁元素负载到生物炭上,产生的磁性有利于固液分离,还可为化学吸附作用提供更多活性位点。Cr(Ⅵ)在磁性生物炭表面的吸附主要是通过表面络合反应或氧化还原反应进行,且MWB表面的Fe-O基团强化了其对铬离子的化学吸附作用,提高了MWB对Cr(Ⅵ)的吸附性能。
Biochar(WB)derived from wheat straw via pyrolysis at 500℃under N2 atmosphere was further modified with FeCl3·6 H2 O and FeSO4·7 H2 O to prepare the magnetic biochar(MWB).MWB was used as the adsorbent for Cr(Ⅵ)in aqueous solutions.The adsorption performance and adsorption mechanism of Cr(Ⅵ)on MWB were investigated.The results showed that the ability of MWB to remove Cr(Ⅵ)was significantly improved compared with WB,and the removal rate of Cr(Ⅵ)at an initial concentration of 100 mg/L was increased from 36.86%to 93.90%.Langmuir model was more suitable for describing the adsorption process of Cr(Ⅵ)on MWB.The pseudo-second-order model could be applied to describe the adsorption kinetics of Cr(Ⅵ)and the activated energy was 44.81 kJ/mol.The values of thermodynamic parameters free energy change(ΔG)was negative,enthalpy change(ΔH)was positive,and entropy change(ΔS)was positive,which indicated that the adsorption of Cr(Ⅵ)on MWB was a spontaneous endothermic process.XPS and FTIR analysis showed that the iron element was successfully loaded onto the biochar.The resulted magnetic property benefited the solid-liquid separation.Moreover,the loaded Fe provided more active sites for the chemisorption of Cr(Ⅵ).The adsorption mechanism of Cr(Ⅵ)on the magnetic biochar was revealed as following the complexation reaction and the redox reaction.Fe-O groups on the surface of the MWB enhanced the chemisorption of chromium ions and improved the adsorption performance of Cr(Ⅵ)by MWB.
作者
康宁
毛磊
童仕唐
张宇
KANG Ning;MAO Lei;TONG Shitang;ZHANG Yu(School of Chemistry and Chemical Engineering,Wuhan 430081,China;Hubei Province Key Laboratory of Coal Conversion and New Carbon Materials,Wuhan University of Science and Technology,Wuhan 430081,China)
出处
《环境科学与技术》
CAS
CSCD
北大核心
2020年第3期116-122,共7页
Environmental Science & Technology
基金
国家自然科学基金(51204125)
关键词
六价铬
生物炭
磁性
化学吸附
hexavalent chromium
biochar
magnetism
chemisorption
作者简介
康宁(1994-),女,硕士研究生,主要研究方向为功能生物炭,(电子信箱)374647842@qq.com;通迅作者:毛磊,教授,硕士生导师,(电子信箱)maolei@wust.edu.cn。
