The Photoelectrocatalytic Degradation Of Benzoisothiazolinone By CeZn/TiO₂ Nanotube Array

Seawater desalination is an important method to solve the solution of the shortage of water resources.Reverse osmosis is an efficient and stable desalination method,which is the most widely used seawater desalination technology up to now.Isothiazolinone was usually used as the bactericide in reverse osmosis process.Therefore,a large amount of isothiazolinone exists in concentrated reverse osmosis water.Benzisothiazolinone is a typical kind of isothiazolinone and is very stable in the water environment and has biological genotoxicity.TiO₂ nanotube array（TNTA）is one of the most widely used photoactive materials in photocatalytic and photoelectrocatalytic degradation technologies,which has the characteristics of high efficiency and no pollution,as well as a broad development prospect in the field of efficient and green pollutant treatment.The disadvantages limited its application with the wide band gap of TiO₂and fast electron-hole recombination.Doping metal elements is a relatively common and effective modification method.In this study,anodic oxidation method was used to prepare TNTA.The anodization time will affect the morphology of TNTA.The TNTA with the oxidation time of 2 h is more uniform and highly ordered as well as has good photocatalytic performance than that of 1 h and 4 h.A simple microsolvent combustion synthesis method was proposed and applied to doping metal elements-cerium（Ce）and zinc（Zn）onto TNTA to successfully prepare CeZn/TNTA composite catalyst in this study.After co-doping Ce and Zn,CeZn/TNTA can improve the utilization rate of visible light and the separation efficiency of photogenerated electron-hole,reduce the charge transfer resistance,improve the carrier transfer rate,and show a high photocatalytic activity.Its catalytic degradation rate of methylene blue light can reach 85.27%in 1 h.The experimentally prepared CeZn/TNTA was used for the use of photocatalytic and photocatalytic degradation of benzisothiazolinone.The factors affecting the degradation of benzisothiazolinone,such as CeZn doping amount,initial benzisothiazolinone concentration,initial pH of concentration,and applied bias voltage,were investigated.Benzisothiazolinone with a concentration of less than 20 mg/L has excellent photocatalytic degradation performance,and the removal rate exceeds 93.79%.The lower the concentration,the higher the degradation rate,which proves that it is suitable for low concentration degradation of benzisothiazolinone.Photoelectrocatalytic was used to degrade benzisothiazolinone exceeded30 mg/L.The removal rate can achieve more than 90%by applying a bias voltage of 1-3.5V at the concentration of 30 mg/L.In neutral and basic solutions,the PEC degradation rate of benzisothiazolinone was much higher than those in acidic solutions.1 V was chosen as the optimal voltage.In neutral and basic solutions,the photoelectrocatalytic degradation rate of benzisothiazolinone was much higher than those in acidic solutions.Phosphate in simulated reverse osmosis concentrated water partially quenches active free radicals,so it can inhibit the degradation of benzisothiazolinone.The stability of CeZn/TNTA has also been verified.After four cycles of recycling,it still has a removal rate of more than 90%.To clarify the degradation mechanism of CeZn/TNTA,quenching experiments were used to analyze the active radicals.The experimental results show that in the photocatalytic degradation of BIT,the main active radicals causing benzisothiazolinone degradation are hydroxyl radicals,superoxide free radicals and holes;under the same experimental conditions,photocatalysis can significantly improve the degradation efficiency of benzisothiazolinone.Hydroxyl and superoxide free radicals showed important roles during the photoelectrocatalytic system.The degradation products of benzisothiazolinone are analyzed,and the proposed degradation pathways of benzisothiazolinone by photocatalysis and photoelectrocatalysis are proposed.The CeZn/TNTA composite catalyst prepared in this experiment has stable performance,low cost and easy availability.It has good photocatalytic and photoelectriccatalytic degradation efficiency of benzisothiazolinone,and excellent practical application potential for the removal of benzisothiazolinone.