Influencing factors and degradation behavior of propyphenazone and aminopyrine by free chlorine oxidation.

Highlights: [•] Free chlorine can effectively remove PRP and AMP in the order: PRP>AMP. [•] Chlorine dosage was favorable to the removal of two pharmaceuticals by free chlorine. [•] Higher removal efficiencies of PRP and AMP were observed with neutral and slightly acidic pH, respectively. [•] PRP and AMP were not mineralized by free chlorine, but were transformed to other byproducts. [•] The substitution of Cl, dealkylation and ring-opening were the main transformation pathways. [Copyright &y& Elsevier]