Study On Effect Of Degradation Of BTEX And Hydrochemical Condition By Persulfate Activated With Ferrous Ions

Persulfate favored by researchers as a strong oxidizer.There are effects on BTEX remove rate,hydro-chemical condition,activity of microorganisms,when use persulfate oxidation activated with ferrous ions to remedy groundwater contaminated by BTEX.In this study,batch experiments were conducted to better understand the effects of BTEX contaminated groundwater remediation using persulfate oxidation activated with ferrous ions.What's more,the study aimed to determine appropriate mole ratio of PS:BTEX and PS:Fe²⁺.BTEX formed petrol saturated solution was selected as pollutants,and the initial concentration of BTEX was set up as 20 mg/L.Persulfate was selected as strong oxidant,and the molar ratio of PS:BTEX is set up as 9,5,3,18,44,88,respectively.What's more,FeSO₄·7H₂O was selected as activator of persulfate,and the molar ratio of PS:Fe²⁺was set up as 8,4,1.Under the condition of sterilization and non-sterilization,contrast experiments,including blank microcosms,inactivated microcosms,activated microcosms,were carried out.The results show that when the initial concentration of BTEX is 20 mg/L:?1?The degradation rate of BTEX in the group without chemical oxidation was faster than that in the group with chemical oxidation,and the degradation rate of BTEX in the unactivated group was faster than that in the activated group;Increasing the dosage of persulfate can't always help to increase the remove rate of BTEX.Adding a large amount of PS at one time will result in inadequate utilization and residual;When molar ratio of PS:BTEX is set up as 9,5,the smaller molar ratio of PS:Fe²⁺is,the higher remove rate of BTEX becomes in initial stage of reaction.But BTEX degradation will be blocked in the long run;When molar ratio of PS:BTEX is set up as 3,the smaller molar ratio of PS:Fe²⁺is,the higher remove rate of BTEX becomes in the whole process;When molar ratio of PS:Fe²⁺is set up as 8,4 with molar ratio of PS:BTEX being set up as 18,the remove rate of BTEX of blank microcosms is faster than the group of activated,and the remove rate of BTEX of inactivated microcosms is faster than the group of activated;When molar ratio of PS:BTEX is set up as 44,88,the degradation of BTEX rely on chemical oxidation of persulfate,only taking four days to degrade completely.?2?There are effects on water chemistry condition when uses persulfate oxidation activated with ferrous in the process of BTEX contaminated groundwater remediation.In the situation of activated,when molar ratio of PS:BTEX is constant,the smaller molar ratio of PS:Fe²⁺is,the lower pH of system becomes.What's more,the greater oxidation-reduction potential and conductivity of system becomes.?3?The degradation rate of BTEX in sterilization group is much lower than that of non-sterilization group.There are inhibitory effects on activity of aerobic microorganisms and denitrifying bacteria when uses persulfate oxidation activated with ferrous in the process of BTEX contaminated groundwater remediation.When molar ratio of PS:BTEX is constant,the smaller molar ratio of PS:Fe²⁺is,the fewer dissolved oxygen can be used;When molar ratio of PS:BTEX is set up as 9,5,3,the smaller molar ratio of PS:Fe²⁺is,the weaker activity of denitrifying bacteria is.It can draw a conclusion from the phenomenon that the smaller molar ratio of PS:Fe²⁺is,the smaller variation trend of NO₃^-concentration the and the smaller accumulation of NO₂^-become;When molar ratio of PS:BTEX is set up as 18,the activity of denitrifying bacteria is very weak,whether it is activated or not.?4?When all of these indexes are considered together,including the degradation time of BTEX,remove rate of BTEX,the size of the attenuation constant of BTEX,the effects on water chemistry condition and the influence on activity of aerobic microorganisms and denitrifying bacteria,it can find a best way in treatment of BTEX pollution far away from source area.Persulfate has good processing ability on groundwater of BTEX pollution,when molar ratio of PS:BTEX and PS:Fe²⁺is set up as 3,8,respectively.After a 37-day reaction,BTEX degrade completely and the size of the attenuation constant of BTEX reach up to 0.113d^-1.In that situation,the range of pH of system is 7.2⁶.5,the range of Eh of system is 28.7mv²8.7 mv,the range of EC of system is 648.3?s/cm⁶82.7?s/cm,the concentration of SO₄^2-range from 37.0mg/L to 75.2 mg/L,the removal rate of NO₃^-23.5%.