Study On Efficiency And Mechanism Of Thermal Coupling Sodium Persulfate In Remediation Of Phthalate Contaminated Soil

Phthalates（PAEs）are mainly used as plasticizers in the manufacture and processing of plastic products.They are one of the emerging pollutants of global concern.There is no chemical bond between PAEs and plastic molecules,which are only connected by van der Waals force（intermolecular force）,and the interaction is weak.Therefore,PAEs is easy to leak into the environment from plastic products.Moreover,PAEs is very harmful.It not only has reproductive toxicity similar to estrogen,but also has teratogenic,carcinogenic and mutagenic triple toxicity,which can enter the human body through breathing,diet and skin contact,Harmful to human health.Therefore,it is urgent to find an efficient and fast governance technology to remove PAEs from the environment.Based on this,this paper studied the effect of indirect heating activated sodium persulfate degradation on the removal of phthalates in water under the factors of different initial concentration of pollutants,activation temperature and concentration of sodium persulfate and the amount of cosolvent,and identified and analyzed the degradation mechanism of PAEs in water by GC/MS;The effect of indirect heating activated sodium persulfate on the oxidative degradation of phthalates in soil under different temperature,different PS concentration,different water-soil ratio and different heating methods;Using resistance heating activated sodium persulfate to remove PAEs from soil,the regression model between various factors and soil DBP degradation rate was established by box Behnken response surface method,and the effect of resistance heating activated sodium persulfate on soil microbial diversity was investigated.The main results are as follows:（1）In the experiment of degradation of PAEs in water by thermally activated PS,the initial concentration of phthalate is inversely proportional to the removal rate,and the reaction temperature,sodium persulfate concentration and p H are directly proportional to the removal rate of phthalate.When the concentration of sodium persulfate was 84 mmol/L at 80℃ and the amount of cosolvent was 30%,the degradation rate of DBP and DEHP reached 100% and 92.8%.The degradation mechanism of DBP / o-phthalic acid is mainly dealkylation of DBP and ophthalic acid under the condition of high temperature activation.（2）In the experiment of thermally activated PS degrading PAEs in soil,higher temperature,PS concentration and water-soil ratio will increase the degradation rate of PAEs.The degradation effect of heating every 30 min for 1 min is the best,and the degradation rate of PAEs in soil is significantly lower than that in water.（3）In the PAEs experiment in ERH activated PS degraded soil,the higher the electric field intensity and PS concentration,the faster the soil temperature rise rate,the higher the moisture content,and the slower the soil temperature rise rate.With the increase of degradation time,the higher the electric field intensity,moisture content and PS concentration,the degradation efficiency first increased and then decreased.Under the experimental conditions,the influence degree of three influencing factors on DBP degradation rate is as follows: electric field intensity >soil moisture content > PS concentration;There is a strong synergistic effect between electric field intensity and water content,water content and PS concentration,while there is a weak antagonistic effect between electric field intensity and PS concentration.The optimum process parameters of ERH were as follows: electric field intensity 6.44 V/cm,soil moisture content129.5%,PS concentration 80.22 mmol/kg,and the degradation rate of DBP was 91.42%.（4）ERH and the method of ERH coupling PS have significantly changed the community structure of microorganisms and significantly reduced the number and richness of bacteria.Proteobacteria and Firmicutes have become the main bacteria of ERH coupling PS and soil microorganisms after restoration,Sphingobium and bacillus are the main genera after treatment and recovery.Therefore,these bacteria can be considered as the main bacteria for the treatment of PAEs.