Experimental Study On Degradation Of Typical Phthalates By Zero-valent Iron-Sodium Persulfate System

Phthalates(Phthalates,PAEs)are an environmental endocrine disruptor.China National Environmental Monitoring Center,the European Union,and the US Environmental Protection Agency have listed dimethyl Phthalate(DMP)and diethyl Phthalate(DEP)as priority pollutants.Under the traditional wastewater treatment process conditions,PAEs are difficult to remove completely,and residual PAEs enter the surface water and groundwater environment along with the drainage.In this study,three PAEs of dimethyl Phthalate(DMP),dibutyl Phthalate(DBP),and dioctyl Phthalate(DEHP)were selected as target pollutants,with zero-valent iron(ZVI)-Sodium persulfate(Persulfate)as the activation system(ZVI-PS),carried out the degradation experiment of PAEs under different temperature conditions,to explore the kinetic process of PAEs degradation under ZVI-PS.Experimental results show that:The removal rate of the three PAEs degraded by the ZVI-PS system increases with the reaction temperature.The removal rate of DEHP has the strongest response to temperature,and the maximum removal rate reaches more than 70%;the three PAEs show up with the reaction time.With different degradation trends,the removal rate of DEHP increases rapidly with time and then gradually stabilizes.DBP is rapidly degraded before 30 minutes of reaction,and then the reaction rate is significantly reduced.However,DMP degrades slowly before 150 minutes of reaction,and then the removal rate increasing rapidly.Under the condition of 25 ?-30 ?,the degradation effect is proportional to the length of the carbon chain,that is,DEHP> DBP> DMP;further using differential and integral methods for kinetic and thermodynamic analysis,respectively obtained the reaction rate constant,compared The difference between the two methods is that the integral method fits well,and the reaction rate constant increases with increasing temperature.The column experiment further explored the degradation behavior of ZVI-PS system in porous media for PAEs,and compared the use of pyrite(Pyrite)-sodium persulfate(Persulfate)as the activation system(Pyrite-PS)in porous media for PAEs.Degradation behavior.By comparison,it was found that the two activated materials can degrade PAEs well.The Pyrite-PS system degrades DMP significantly better than the ZVI-PS system.Excess persulfate ions in the ZVI-PS system consume sulfate radicals.According to the experimental conditions of the column,a mathematical model of one-dimensional convection-dispersion and reaction process was established.Through fitting with the experimental data of the column experiment,the reaction rate constants of DBP degradation by ZVI-PS and Pyrite-PS system in porous media were investigated.Optimal solution.It was found that the fitted reaction rate constant was not much different from the result obtained by the batch experiment quasi-first order reaction kinetics integration method,indicating that the model and the column experiment data fit well.