Fe(Ⅵ)@PMS double oxidation system for degradation of methylparaben from wastewater
Ferrate-activated peroxymonosulfate(Fe(Ⅵ)@PMS system)was used to degrade methylparaben(MeP)in wastewater.The degradation performance of MeP with different Fe(Ⅵ)dosage,PMS concentration,initial pH value,reaction temperature,initial MeP concentration and coexisting ions was investigated.Based on the Box-Behnken experimental design,a multifactorial experiment was conducted to fit the relationship between the degradation rate of MeP and Fe(Ⅵ)dosage,PMS concentration and initial pH to optimize the reaction conditions.The results showed that the MeP degradation rate was 99.03％under the conditions of Fe(Ⅵ)dosage of 0.92g/L,PMS concentration of 1.08mmol/L,initial pH of 6.83,and temperature of 25℃,which was similar to the model prediction of the maximum degradation rate of 99.17％for MeP,indicating that the response surface model has a better simulation and prediction ability.Cl-,NO3-,HCO3 and SO42-had no significant effect on the degradation of MeP.The free radical identification experiments proved that the degradation of MeP was accomplished by a combination of free radicals(·OH and SO4·)and non-radical(1O2)oxidation,with 1O2 playing a major role.Liquid chromatography-mass spectrometry(LC-MS)analysis showed that the main pathways of MeP degradation included hydroxylation and decarboxylation reactions.ECOSAR toxicity analysis showed that the toxicity of MeP could be significantly reduced into non-toxic and harmless in Fe(Ⅵ)@PMS system.
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