Application Of Electrochemically Switched Ion Exchange Technology In Dechlorination

With the rapid development of industrialization,the discharge of wastewater has continuously increased in China.Majoriety of the wastewater contains high concentrations of chloride ions,which causes great damage to not only the equipment,but also plants,animals and human bodies.At present,the techniques for removing chloride ions in wastewater mainly include ion exchange method,distillation method,membrane separation method and precipitation method.Although the above technology has been applied,it still has some cons such as high cost,easy to generate secondary pollution,and small amount of wastewater treatment.Electrochemical controlled ion exchange technology(ESIX)is a highly efficient,green and environmentally friendly wastewater treatment technology that combines electrochemical and ion exchange technologies.The main driving force of the technology is the electrode potential,which can easily control the operating conditions.In addition,the process consumes less energy,and the secondary pollution from the chemical regenerant and associated rinse water of conventional ion exchange technology can be avoided.The main aim of the current technology is to find ion exchange materials with high ion exchange capacity and excellent electrical activity.In this study,PPy was prepared by in-situ polymerization to selectively remove chloride ions(Cl-)from wastewater.It has excellent affinity with chloride ion.Removal chloride ions was undertaken from industrial wastewater by electrochemically switched ion exchange.The effects of removal chloride ions of PPy ion exchange film was investigated with different initial concentration,current density and coexisting anions.The effects of dynamic chloride ion removal experiments on the removal of chloride ions indicate that the PPy film electrode removes chloride ions quickly to less than 1 ppm within 20 min and can be well described by a pseudo-second-order model;when the flow rate is 4 mL·min-1,it removes chloride ions from 3 BV(reaction cell volume)waste to less than 1 ppm.Therefore,this is a promising material for removing chloride ions from wastewater.Based on the first part of the study,BiOCl was successfully synthesized by hydrothermal method.After doping with polypyrrole,a novel nano-hybrid material PPy/BiOCl was synthesized and applied for dechlorination.In this experiment,the effect of BiOCl on the dechlorination effect of the hybrid material was investigated.The effects of initial concentrations of chloride ions,current density of electrode and co-existing anion on the removal performance were investigated.In addition,the stability of PPy/BiOCl was also investigated.The results show that the rate of chloride ion implantation on the PPy/BiOCl membrane electrode is prompt,the high concentration of Cl-gradually reaches equilibrium in about 40 minutes,and the low concentration of Cl-gradually reaches equilibrium in 10 minutes;the ion exchange capacity average out 150.1 mg·g-1.By adjusting the oxidation-reduction potential of the film electrode,the chloride ion can be placed and disposed,thereby achieving the reusability of the film electrode.