Adsorption Of Arsenic From Groundwater By Cationic Surfactant Modified Activated Carbon Electrode

In this paper,the effect of cationic surfactant modified activated carbon electrode on arsenic adsorption in groundwater was studied by capacitance deionization technique.By comparing the adsorption performance of arsenic of different kinds of activated carbons combined with electrochemical analysis,this paper finds out the electrode prepared by activated carbon(PAC)with high specific surface area was superior to the electrode prepared by coconut shell activated carbon(YK-AC),ligno activated carbon(MZ-AC)and mineral activated carbon(KWZ-AC),which indicate that powder activated carbon(PAC)is more suitable for used as CDI electrode materials.According to the experimental comparison results,it can be seen that the electrode properties prepared by PAC are better than those of YK-AC,MZ-AC and KWZ-AC electrodes.On this basis,the effects of KOH,CPC and CTAC on the electrochemical properties of PAC electrodes were studied.The experimental results showed that the specific capacitance of the KOH-PAC-3M/3h electrode was the highest in the KOH modified PAC electrode,which was 37% higher than that of the unmodified PAC electrode(46 F/g).CTAC-PAC electrode has the highest specific capacitance in CTAC modified PAC electrode,which is 45% higher than that of unmodified PAC electrode(46 F/g).The CPC-PAC electrode had the highest specific capacitance in the CPC modified PAC electrode,which was 38% higher than that of unmodified PAC electrode(46 F/g).In order to further improve the electrochemical properties of the modified activated carbon electrode,conductive carbon black(CB)and polyvinylidene fluoride(PVDF)with different contents were added to the electrode preparation process,and the electrochemical properties of the electrodes with different preparation ratios(CB/PVDF/AC)were studied on the KOH-PAC-3M/3h,CPC/PAC-1mm/5h,and CTAC-PAC-1mm/12 h electrode.The experimental results show that the modified activated carbon electrode prepared according to the proportion of CB/PVDF/KOH-PAC=15/10/75,CB/PVDF/CPC-PAC=15/5/80 and CB/PVDF/CTAC-PAC=15/5/80 has the best electrochemical performance.Compared with the unmodified PAC electrode(46 F/g),the specific capacitance of the modified activated carbon electrode which are prepared accordingto the proportion of CB/PVDF/KOH-PAC=15/10/75,CB/PVDF/CPC-PAC=15/5/80 and CB/PVDF/CTAC-PAC=15/5/80,increased by 143%,169% and 143%,respectively.The electrochemical performance of the electrode was significantly higher than that before the preparation ratio was not adjusted.In the arsenic adsorption experiment,the removal rates of arsenic ions with CB/PVDF/CTAC-PAC-15/5/80 and CB/PVDF/CPC-PAC-15/5/80 electrodes were both increased by 29% compared with PAC electrodes,indicating that the removal rates of arsenic ions and the specific capacitance of electrode were improved after the modification of cationic surfactant and the adjustment of electrode preparation proportion.The removal rate of CB/PVDF/ KOH-PAC-15/10/75 electrode to arsenic ion was lower than that of PAC electrode,indicating that the specific capacitance of electrode increased significantly after the modification of KOH and the proportional adjustment of electrode preparation,but the removal rate of arsenic by CB/PVDF/KOH-PAC-15/10/75 electrode decreased.By comprehensive comparison of its electrode performance,it can be seen that the adsorption of arsenic ions and electrochemical performance of CB/PVDF/CPC-PAC-15/5/80 electrode are better than that of CB/PVDF/KOH-PAC-15/10/75 electrode and CB/PVDF/CTAC-PAC-15/5/80 electrode,and the CB/PVDF/CPC-PAC-15/5/80 electrode stability is good,which is suitable for the CDI electrode.According to the experimental comparison results,it can be seen that CB/PVDF/CPC-PAC-15/5/80 electrode has the best performance.The CB/PVDF/CPC-PAC-15/5/80 electrode is assembled into a CDI component and the optimum operating conditions of CDI were studied by selecting four factors,operation flow rate,electrode spacing,operation voltage and treatment concentration of arsenic.The experimental results show that the most optimal processing parameters of CDI in this study are charging voltage of 1.5V,flow rate of 5mL/min,space between polar plates of 2 mm.Under that condition,the removal rate of arsenic by CDI is 93%,and the arsenic concentration in the effluent can be controlled below 10 ?g/L,meeting the limit of arsenic concentration in the standard of drinking water(GB5749-2006).