改性水热炭同时吸附溶液中Cr(Ⅵ)和Cd(Ⅱ)

Simultaneous adsorption of Cr(Ⅵ) and Cd(Ⅱ) from aqueous solution by modified hydrochar

以竹屑为基质制备了水热炭(HC),通过NaOH溶液和ZnCl_(2)溶液改性分别制备了改性水热炭OHHC和ZHC,并将两种改性水热炭耦合制成复合水热炭MHC。考察了水热炭投加量和初始溶液pH对溶液中Cr(Ⅵ)和Cd(Ⅱ)去除率的影响。并通过吸附动力学和等温吸附曲线,探究吸附机理。实验结果表明:ZHC的芳香性增高,比表面积增大;OHHC的含氧官能团数量增多,孔径增大。在初始溶液pH=4、MHC投加量为16 g/L的最佳条件下,Cr(Ⅵ)和Cd(Ⅱ)去除率分别达98.98%和81.38%。水热炭对Cr(Ⅵ)和Cd(Ⅱ)的吸附数据拟合结果更符合准二级动力学模型和Langmuir等温吸附模型,表明吸附过程中主要为化学吸附和单层均匀吸附。

Hydrochar(HC)was prepared using waste bamboo debris as raw materials and modified using NaOH solution and ZnCl_(2) solution to prepare the modified hydrochar OHHC and ZHC.The two kinds of modified hydrochar were coupled into composite hydrochar MHC.The effects of hydrochar amount and initial solution pH on the simultaneous removal of Cr(Ⅵ)and Cd(Ⅱ)were investigated.In addition,the adsorption mechanism was explored through adsorption kinetics and isothermal adsorption.The results indicate that the aromaricity and specific surface area of the ZHC is increased,and the functional group number and pore diameter of OHHC is increased.The largest removal rate of Cr(Ⅵ)and Cd(Ⅱ)are 98.98%and 81.38%respectively under the optimum conditions of initial solution pH 4 and MHC amount 16 g/L.Pseudo-second-order kinetic model and Langmuir isothermal adsorption model can accurately describe the adsorption of Cr(Ⅵ)and Cd(Ⅱ)on the hydrochar,which demonstrates that the adsorption process is chemisorption on homogeneous monolayers.