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

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, H 2 O 2 concentration and nZVI dose. Chlorpheniramine (⩽15   mg/L) was completely removed after 60   min oxidation under the following optimal conditions: initial pH   =   3.0, H 2 O 2 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 ( k obs $k_{\mathit{obs}}$ ) were obtained ( R 2   >   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/H 2 O 2 system was proposed. After nZVI/H 2 O 2 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.