Hydroxylamine promoted degradation of organic contaminants using peroxydisulfate activated by Fe-alginate.

Abstract

To overcome the shortcomings of Fe(Ⅱ)/peroxydisulfate (PDS) system including the limited working pH range and large iron sludge production, a Fe-doped alginate (Fe-Alg) catalyst was prepared and combined with hydroxylamine (HA) to continuously activate PDS for the removal of organic pollutants in neutral condition. Due to the strong reductive capability of HA, it could significantly enhance the catalytic capability of Fe-Alg for PDS. The results of characterization suggested that Fe(Ⅲ)/Fe(Ⅱ) was evenly distributed in Alg through its complexation with carboxyl groups, and the reduction of Fe(Ⅲ) to Fe(Ⅱ) initiated by HA enabled Orange G (OG) to be continuously degraded in the Fe-Alg/HA/PDS system. The results of quenching experiments suggested that $S{O}_4^{\bullet -}$ and HO^• played a dominant role for OG removal in the Fe-Alg/HA/PDS process. The effect of influence factors (e.g. initial pH, HA concentration, Fe-Alg dose and PDS concentration) and water matrix components (i.e. $S{O}_4^{2-}$, $N{O}_3^{-}$, Cl^-, $\mathrm{HC}{O}_3^{-}$ and dissolved organic matters (DOM)) on the performance of Fe-Alg/HA/PDS system was systematically investigated. Other refractory organic contaminants, including diclofenac (DCF), sulfamethoxazole (SMX), oxytetracycline (OTC) and bisphenol AF (BPAF) were also efficiently eliminated in Fe-Alg/HA/PDS system, suggesting the feasibility of this system for the treatment of organic pollutants. This work provides a method to optimize Fe(Ⅱ)/PDS system and a novel process applied to degrade refractory pollutants.