Study On The Degradation Of Tbbps By Microbubble Conbined With Dielectric Barrier Discharge And Its Degradation Mechanism

Brominated flame retardants（BFRs）are fast developing flame retardants in recent years.A study in 2017 showed that the annual consumption of BFRs in China was about 400000 tons.Tetrabromobisphenol A（TBBPA）is one of the most commonly used brominated flame retardants.Due to its cumulative effect in the environment,it has strong toxicity and carcinogenic effect on human body.In order to reduce the use of TBBPA,tetrabromobisphenol S（TBBPS）appears as a substitute of tetrabromobisphenol in public view.TBBPS,as a new pollutant,has no relevant laws and regulations.At present,the research on TBBPS only stays in the qualitative and quantitative detection of TBBPS in the environment,and there is no related research on the treatment of TBBPS.At present,the existence of TBBPS has been detected in the environment and animals,so it is very necessary to analyze the efficient,energy-saving,easy to operate treatment methods of TBBPS and the degradation pathway of TBBPS.Dielectric barrier discharge plasma technology is an advanced oxidation technology,which can be used to treat refractory pollutants.However,the current technical difficulty of dielectric barrier discharge water treatment technology is the low efficiency of gas-liquid mass transfer.Microbubbles in water can promote the gas-liquid disturbance,expand the gas-liquid contact area,and effectively enhance the gas-liquid mass transfer efficiency.The gas-liquid two-phase uses microporous aeration disk（pore diameter 10μm）as the partition.Plasma is formed in the gas discharge gap,and then enters into the water through the aeration disk to form plasma microbubbles.In this paper,the feasibility of this method was discussed,and the degradation pathway of TBBPS was analyzed.The conclusions are as follows:（1）The results show that the oxidation degradation of TBBPS is feasible by using self-made microbubble and DBD device,and the degradation rate of TBBPS can reach100%in 15 minutes.（2）The results of single factor experiments show that the higher the discharge voltage,the higher the air flow rate and the lower the initial concentration of TBBPS,the faster the degradation rate of TBBPS,but the initial p H of the solution has no effect on the degradation rate.（3）After TBBPS was completely degraded,the mineralization rate was only about 70%,and the solution still had strong biological toxicity.The p H value decreased gradually during the reaction.（4）Through the inhibition of benzoquinone,tert butyl alcohol and DABCO on-O₂^-、?OH^-、¹O2,it is proved that the three substances all participated in the oxidative degradation of TBBPS in the microbubble assisted DBD water treatment system,in which-O₂^-and?OH^-played the main role,and 1O2 played a smaller role.（5）The analysis of ion chromatography data showed that debromination would occur in the process of TBBPS degradation,and a small amount of bromine could be formed in the early stage of the reaction.Through LC/MS analysis and quantitative detection of characteristic products,the main degradation process and pathway of TBBPS were inferred.The main reactions in the degradation process are debromination,sulfone cracking and hydrolysis,followed by carboxylation and benzene ring opening.This is consistent with the degradation mechanism of bisphenol s,which also proves the feasibility of treating TBBPS by microbubble synergistic dielectric barrier discharge.