活性炭电极的改性及对Co^(2+),Mn^(2+)和Ni^(2+)的电吸附性能

Modification of Activated Carbon Electrode for Efficient Electrosorption of Co^(2+),Mn^(2+)and Ni^(2+)

以商用活性炭(AC)为原料,分别采用磷酸和氢氧化钠改性的方法制备了两种不同的改性活性炭电极材料.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、Brunauer-Emmett-Teller(BET)测试、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段以及电化学分析方法,对改性前后活性炭材料的表面性质和电化学性能进行了探究.结果表明,H_(3)PO_(4)改性使活性炭的孔隙分布更加密集,NaOH改性使活性炭表面的孔隙结构更加清晰均匀;H_(3)PO_(4)和NaOH改性均使活性炭的比表面积增加.循环伏安测试结果表明,改性前后活性炭电极在低扫描速率下均具备良好的双电层特性,并且两种改性处理均能提高活性炭电极的比电容;当扫描速率为5 mV/s时,未改性、H_(3)PO_(4)以及NaOH改性活性炭电极的比电容分别为36.51,77.25和85.19 F/g.电吸附实验结果证明,两种改性活性炭电极对Co^(2+),Mn^(2+)和Ni^(2+)均有较好的去除效果,电吸附过程均更加符合Langmuir模型,在初始浓度、电压和pH相同的条件下,NaOH改性电极对Co^(2+),Mn^(2+)和Ni^(2+)具有更高的去除率和吸附容量,去除率可分别达到96.84%,94.37%和96.90%,吸附容量分别为140.8,111.4和108.5 mg/g.

Two different modified activated carbon(AC)electrode materials were prepared by modification with H_(3)PO_(4) and NaOH using commercial AC as raw material.The surface properties and electrochemical properties of the AC before and after modification were investigated using scanning electron microscope(SEM),transmission electron microscope(TEM),Brunauer⁃Emmett⁃Teller(BET)test,Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and electrochemical analysis.The results showed that the H_(3)PO_(4) modification made the pore distribution of AC denser,and the NaOH modification made the pore structure on the surface of AC more clearer and uniform.The specific surface area of the original AC was increased after modification with H_(3)PO_(4) and NaOH.Moreover,the content of oxygen-containing functional groups of AC was significantly increased by H_(3)PO_(4) and NaOH modifications.The cyclic voltammetry results showed that both modification treatments improved the specific capacitance of the AC electrode.When the scanning rate was 5 mV/s,the specific capacitances of unmodified,H_(3)PO_(4) and NaOH modified AC electrodes were 36.51,77.25 and 85.19 F/g,respectively.The experimental results of electrosorption experiments demonstrate that both modified AC electrodes had excellent removal effects on Co^(2+),Mn^(2+)and Ni^(2+),and the electrosorption processes were more consistent with the Langmuir model.Under the same experi⁃mental conditions,the NaOH-modified electrode had higher removal rates and adsorption capacities for Co^(2+),Mn^(2+)and Ni^(2+).The removal rates could reach 96.84%,94.37%and 96.90%,respectively,and the adsorption capacities were 140.8,111.4 and 108.5 mg/g,respectively.This work indicates the potential application of modified AC electrodes and electrosorption in the efficient remediation of Co^(2+),Mn^(2+)and Ni^(2+).