Study on Benzo[a]Pyrene degradation in soil by different oxidants based on Fe(Ⅱ)catalyst
To remove the typical polycyclic aromatic hydrocarbons of Benzo[a]Pyrene(BaP)in a contaminated site,the performance of BaP degradation by Persulfate(PS),Calcium Peroxide(CP),and Sodium Percarbonate(SPC)three oxidants based on Fe(Ⅱ)catalyst were explored and compared.Citric Acid(CA)as a Fe(Ⅱ)chelating agent and ferrous sulfide(FeS)asaFe(Ⅱ)enhancing agent were used to modify BaP removal in different oxidation systems.The effect of dosage addition and water/soil mass ratio were further evaluated.The results show that 56.3％BaP removal performance can be observed in PS/Fe(Ⅱ)system under the experiment condition of 0.2 mmol/g PS and 0.002 mmol/g Fe(Ⅱ).Both CA and FeS can promote BaP removal in PS/Fe(Ⅱ)system,and CA performs better promoting effect than FeS.Nearly 40％BaP removal can be found in CP/Fe(Ⅱ)and SPC/Fe(Ⅱ)systems,however,there is no obvious acceleration for BaP removal in CP/Fe(Ⅱ)and SPC/Fe(Ⅱ)systems by the addition of CA or FeS.The comparison of PS,CP and SPC three different oxidants present that PS performs better than CP and SPC,and PS/Fe(Ⅱ)/CA system performs the best BaP removal with an 80.2％degradation efficiency in 5 h under the experiment condition of 0.2 mmol/g PS and 0.002 mmol/g Fe(Ⅱ)-CA.The increasing of PS oxidant addition can enhance BaP removal in PS/Fe(Ⅱ)/CA system,nevertheless,the excess addition of PS not only can competitively consume ROSs with target contaminant but also promoting the mutual consumption reaction of ROSs,thus inhibiting the target contaminants removal.BaP degradation can be inhibited by the high or low n[Fe(Ⅱ)]∶n(CA)in PS/Fe(Ⅱ)/CA system and the best n[Fe(Ⅱ)]∶n(CA)for BaP removal is 1∶1.The BaP removal in PS/Fe(Ⅱ)/CA system is decreased with the increasing water:soil mass ratio from 1∶1 to 10∶1 and the BaP degradation can attach over 90.5％in the best condition of water/soil mass ratio of 1∶1.
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