Effects of peroxide types on the removal of anti-inflammatory medicines in water with rGO/CNTs catalytic membranes
Sulfapyridine(SSZ)and trimethoprim(TMP)were the typical combinations of anti-inflammatory medicines,and it would cause ecological risks when discharged into water bodies.The carbon mats composited with reduced graphene oxide and carbon nanotubes(rGO/CNTs)were loaded onto the microfiltration membranes,which were used to activate various peroxides for the removal of pollutants.Thus,an in-situ catalytic oxidation system could be built up in the continuous flow mode.Results showed that peroxodisulfate(PDS)and permonosulfate(PMS)were the best alternative for effectively removing SSZ and TMP with rGO/CNTs catalytic membranes,respectively.Meanwhile,the performances of hydrogen peroxide(H2O2)-based systems significantly decreased as increasing continuous operation time.According to the quenching experiments of reactive oxygen species,functional group characterization on the surface of carbon mats and density functional theory calculations,the defects structures in carbon mats were considered as the critical sites for the adsorption and activation of PDS and PMS molecules,resulting in non-radical pathways including surface-confined oxidation and singlet oxygen(1O2).In comparison to H2O2-based systems dominated by hydroxyl radical(·OH)reaction,the PDS and PMS catalytic oxidation processes exhibited more significantly target selectivity,more resistant to background substances in real water matrices and more effectively control membrane fouling.These findings could provide the guides in the further optimizing functional design of carbonaceous catalytic membranes and promoting the development of novel in-situ catalytic oxidation processes.
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