核桃壳生物炭制备及其碘捕获性能  

Preparation of biochar from walnut shells and iodine capture

作　　者：李兴发 潘寒风 安小伟 马旭莉[1,2] 李永国 LI Xing-fa;PAN Han-feng;AN Xiao-wei;MA Xu-li;LI Yong-guo(College of Environment and Ecology,Taiyuan University of Technology,Jinzhong 030600,China;Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,Taiyuan 030000,China;China Institute for Radiation Protection,Taiyuan 030006,China)

机构地区：[1]太原理工大学环境与生态学院,山西晋中030600 [2]山西浙大新材料与化工研究院,山西太原030000 [3]中国辐射防护研究院,山西太原030000

出　　处：《中国环境科学》2024年第10期5406-5414,共9页China Environmental Science

基　　金：山西省科技合作专项项目(202204041101046);山西浙大新材料与化工研究院科研项目(2022SX-TD013)。

摘　　要：将农业废弃物制备成生物炭用于碘捕获具有以废治废的生态功能.废弃核桃壳制备的生物炭具有丰富的孔隙结构和良好的热稳定性,孔径分布以微孔为主,介孔和大孔为辅.静态吸附实验表明,生物炭对气态碘捕获量可达2027mg/g.水溶液中碘捕获实验表明0.1g/L的生物炭在pH=5时对20mg/L和100mg/L的单质碘在90min内均达到97%以上的碘去除.0.4g/L的生物炭对环己烷中20mg/L的单质碘在90min内达到99%以上的碘去除,上述性能均优于同条件下商业核级活性炭的性能.机理研究表明核桃壳生物炭对碘的捕获机制主要为物理吸附作用,吸附后的碘通过电荷转移形成多碘离子.良好的孔结构是核桃壳生物炭具有高碘捕获性能的重要原因,微孔对于碘捕获具有主导作用,分级多孔有助于碘在生物炭结构内外的迁移传递.密度泛函理论(DFT)计算结果支持实验结论,对于单分子层吸附,碘分子更易吸附在与自身动力学大小相匹配的孔径内.Using agricultural waste to prepare biochar for iodine capture possess the ecological function of treating waste with waste.The biochar prepared from waste walnut shell has rich pore structure and good thermal stability in this study,and the pore size distribution was dominated by micropores,supplemented by mesopores and macropores.Static adsorption experiments showed that the amount of gaseous iodine captured by biochar could reached 2027mg/g.In aqueous solution,iodine capture experiments showed that 0.1g/L biochar could remove more than 97%of iodine from 20mg/L and 100mg/L elemental iodine within 90minutes at pH=5.0.4g/L biochar could remove more than 99%of iodine from 20mg/L in cyclohexane within 90minutes.The above properties were better than those of commercial nuclear grade activated carbon under the same conditions.The mechanism study showed that the iodine capture by walnut shell biochar was physical adsorption,and the adsorbed iodine formed polyiodide ions through charge transfer.Pore structure was proved to be an important factor for the high iodine capture performance of walnut shell biochar.Micropores played a leading role in iodine capture.Hierarchical pores contributed to the migration and transfer of iodine inside and outside the biochar structure.The calculation results of density functional theory supported the experimental conclusion that iodine molecules are more easily adsorbed in the pore size matching their own kinetic size for monolayer adsorption.

关 键 词：核桃壳 生物炭 碘捕获 环己烷 密度泛函理论 

分 类 号：X703.1[环境科学与工程—环境工程]