Removal of chlorpheniramine in a nanoscale zero-valent iron induced heterogeneous Fenton system: Influencing factors and degradation intermediates

•Removal of chlorpheniramine by nZVI/H2O2 was studied for the first time.•The optimal reaction conditions were determined for chlorpheniramine degradation.•Degradation pathway of chlorpheniramine in the nZVI/H2O2 system was proposed.•NDMA was formed during the decomposition of chlorpheniramine by nZVI/H2O2.•NDMA FP was significantly reduced by nZVI/H2O2 reaction.

Removal of chlorpheniramine in a nanoscale zero-valent iron (nZVI) induced heterogeneous Fenton system was investigated. The removal efficiency of chlorpheniramine depended on its initial concentration, initial pH, H2O2 concentration and nZVI dose. Chlorpheniramine (⩽15 mg/L) was completely removed after 60 min oxidation under the following optimal conditions: initial pH = 3.0, H2O2 concentration = 0.1 mM and nZVI dose = 22.4 mg/L. The degradation of chlorpheniramine fitted well with the pseudo first-order kinetics model, and the rate constants (kobskobs) were obtained (R2 > 0.9). Several degradation intermediates of chlorpheniramine were detected and confirmed, including 4-hydroxy-4-methyl-2-pentanone, 2-methylaminopyridine, 4-chlorophenol, 2-propionylpyridine, 2-acetylpyridine, 4-chlorophenyl-2-pyridyl ketone, dimethylamine (DMA) and N-nitrosodimethylamine (NDMA). Based on the identified intermediates, a tentative degradation pathway of chlorpheniramine in the nZVI/H2O2 system was proposed. After nZVI/H2O2 reaction, 52.2% of NDMA formation potential (FP) from chlorpheniramine was reduced. Therefore, nZVI as the catalyst used in the heterogeneous Fenton system is not only an alternative to remove chlorpheniramine, but also effective in reducing NDMA FP.

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