氢氧化钠改性生物炭/凹凸棒石复合材料对铅、镉的吸附机理研究  

Study on the Adsorption Mechanism of Sodium Hydroxide Modified Biochar/Attapulgite Composites for Lead and Cadmium

作　　者：郭淼[1,2] 李贝贝 许琳玥 张亚平 何跃 GUO Miao;LI Bei-bei;XU Lin-yue;ZHANG Ya-ping;HE Yue(Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210042,China;Sichuan Institute of Geological Engineering Investigation Group Co.Ltd.,Chengdu 610000,China;Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education,School of Energy and Environment,Southeast University,Nanjing 210096,China;Nanjing Institute of Environmental Sciences,Ministry of Ecology and Environment,Nanjing 210042,China)

机构地区：[1]中国科学院南京土壤研究所,江苏南京210042 [2]四川省地质工程勘察院集团有限公司,四川成都610000 [3]东南大学能源与环境学院能源热转换及其过程测控教育部重点实验室,江苏南京210096 [4]生态环境部南京环境科学研究所,江苏南京210042

出　　处：《生态与农村环境学报》2024年第1期119-129,共11页Journal of Ecology and Rural Environment

基　　金：国家重点研发计划(2020YFF0218300);江苏省地质矿产勘查局科研项目(2021KY15)。

摘　　要：利用水稻秸秆与凹凸棒石在缺氧条件下热解制备稻秆生物炭/凹凸棒石复合材料(BA),并通过氢氧化钠改性提升其吸附性能。通过吸附动力学、等温吸附及改变初始pH等吸附试验研究复合材料在Cd、Pb一元及二元污染体系中的吸附行为,并结合扫描电镜能谱(SEM-EDS)、比表面积及孔径分析(BET)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)及X射线光电子能谱分析(XPS)等表征手段深入分析改性后复合材料对溶液中重金属Cd、Pb的吸附机理。试验结果表明氢氧化钠改性复合材料(NBA)对Cd^(2+)和Pb^(2+)的吸附容量分别为117.05和274.65 mg·g^(-1),其去除效率比BA分别增加31.2%和51.7%。在二元金属体系中NBA吸附能力也明显优于BA,准二级动力学模型和Langmuir等温模型能更好地用于模拟吸附结果,表明该吸附主要为单分子化学吸附过程。此外,竞争吸附分析表明在Cd、Pb共存溶液中,与Cd^(2+)相比,Pb^(2+)更易被复合材料吸附。通过SEM-EDS、FTIR、XRD和XPS等表征方法确定了NBA对Cd^(2+)和Pb^(2+)的吸附机制,主要包括其与表面含氧官能团的络合作用、与矿物质的沉淀作用及π-电子作用。综上,改性复合材料NBA在实际废水处理中是一种极具潜力的吸附剂。A novel rice straw biochar/attapulgite composite(BA)was prepared by pyrolysis under anoxic conditions with rice straw and attapulgite,which was modified with sodium hydroxide to improve its adsorption performance.Batch adsorption experiments,including adsorption kinetics,isothermal adsorption and change of initial pH,were conducted to investigate the adsorption behavior of composite materials in single and binary pollution systems of Cd and Pb.SEM-EDS,BET,FTIR,XRD,and XPS were used to analyze the adsorption mechanisms of modified composites of Cd and Pb.The results show that the adsorption capacity of sodium hydroxide modified composite(NBA)for Cd^(2+)and Pb^(2+)was 117.05 and 274.65 mg·g^(-1),respectively,and the removal efficiency of NBA was increased by 31.2%and 51.7%,respectively,compared with BA.In the binary metal system,the adsorption capacity of NBA was also significantly better than that of BA.The pseudo-second-order kinetics model and the Langmuir isotherm model could describe the Cd^(2+)and Pb^(2+)adsorption processes of the composites better,which proves that the adsorption is mainly a single molecule chemical adsorption process.In addition,competitive adsorption analysis showed that Pb^(2+)was more easily adsorbed by composite materials than Cd^(2+)in coexisting solutions.The characterization method determined the adsorption mechanism of NBA for Cd^(2+)and Pb^(2+),mainly including the complexation with surface functional groups,precipitation with minerals andπ-electron interaction.In conclusion,NBA is a highly potential adsorption material for the treatment of heavy metal pollution in wastewater.

关 键 词：生物炭 凹凸棒石 重金属 改性 机理 

分 类 号：X5[环境科学与工程—环境工程]