The Preparation And Research On Dechlorination Performance Of Electrically Switched Bismuth Oxychloride Ion Exchange Material

Water is the resource that human beings rely on for survival.According to statistics,as many as one billion people worldwide live water-scarce areas.With the continuous economic development and the gradual growth of the population,the shortage and pollution problems of water resources are becoming increasingly serious.The discharge of industrial wastewater is a great hazard to water resources,and chloride ion is the most common anion in wastewater.High concentration of chloride ions not only pose a great threat to the growth of crops,but also causes certain corrosion to industrial equipment and metal pipes.The traditional dechlorination technologies generally require the addition of a large number of chemical reagents,which can easily cause secondary environmental pollution.Therefore,it is urgent to develop a new type of water treatment and purification technology which is environment-benign and energy-efficient.Electrochemically switched ion exchange（ESIX）technology,as an emerging water treatment technology,has attracted the attention of many researchers.In this process,the intercalation and deintercalation of target ions can be easily achieved by adjusting the redox state of the electroactive materials,and the release of the ions is accompanied by the regeneration of the electroactive films.The whole process does not need to add additional chemical regeneration agent,applying an opposite electrode potential,the target ions can be released into the regeneration solution under the action of electrostatic repulsion.The selection of appropriate electroactive ion exchange materials（EIXMs）is the key to ESIX technology.The materials need to possess high capacity and super recognition ability for target ions.Based on the unique layered structure of bismuth oxychloride（Bi OCl）,it can be developed as a new type of EIXMs to extract chloride ions in the solution.In this paper,a hybrid film（Bi OCl/PPy-Cl）formed by bismuth oxychloride doped with chloride ion-imprinted polypyrrole was fabricated by the chemical oxidation method.The microscopic morphology,crystal structure and functional group information of the hybrid film were analyzed by SEM,TEM,XRD,FT-IR and other characterization methods,and the electrochemical performance of the materials were tested by CV and EIS.The adsorption performance of the hybrid film for chloride ions was investigated under different electrode voltages and initial chloride ion concentrations.The results show that the doping of polypyrrole significantly improves the conductivity of the hybrid film.Under the optimal voltage of 0.6 V,the uptake capacity of the hybrid membrane reached 80.81 mg·g^-1.The hybrid film exhibited a stable adsorption capacity during 10 cycles,and its desorption rate remains above 80%.In addition,the hybrid film can effectively extract chloride ions in the presence of other interfering ions.Secondly,the influence of the main exposed crystal faces of bismuth oxychloride on its electrochemical dechlorination performance was studied.Bi OCl with mainly exposed（001）facet（BOC-001）and Bi OCl with mainly exposed（010）facet（BOC-010）were prepared by controlling the p H conditions during the synthesis of Bi OCl.SEM,XRD,FT-IR,CV,EIS and other characterization methods were used to analyze the morphological structure and electrochemical properties of BOC-001 and BOC-010.At the same time,the ion intercalation and deintercalation experiments of BOC-001 and BOC-010 were carried out.The results show that the nanosheet structure of BOC-010 is smaller,and the electrical activity of BOC-001 is better.The uptake capacity of BOC-010 for chloride ions(62.75 mg·g^-1)is higher than BOC-001(49.62 mg·g^-1).Moreover,BOC-010 possesses better hydrophilicity and larger BET specific surface area(4.60 m²·g^-1).