Development of experimental design models to predict Photo-Fenton oxidation of a commercially important naphthalene sulfonate and its organic carbon content

In the present study, Photo-Fenton oxidation of the commercially important K-acid (2-naphthylamine-3,6,8-trisulfonic acid) was optimized and modeled by employing response surface methodology and central composite design. The experimental design tool was used to assess the influence of treatment time ( t r), initial COD of aqueous K-acid solutions (COD o) as well as H 2O 2 and Fe 2+ concentrations on K-acid, COD and TOC removal efficiencies. According to the established second-order polynomial regression models, K-acid removal efficiency was affected by the process variables in the following decreasing order; t r > COD o (negative impact) > Fe 2+ > H 2O 2, while the effect on COD and TOC removals was COD o (negative impact) > H 2O 2 > t r > Fe 2+. Analysis of variance indicated that the experimental design models obtained for the Photo-Fenton oxidation of aqueous K-acid and its organic carbon content (expressed as COD and TOC) were statistically significant and satisfactorily described the treatment process for the entire Photo-Fenton treatment period (up to 125 min) as well as different treatment targets (partial and full oxidation) and initial COD values (150–750 mg/L). Complete K-acid removal accompanied with high COD (70–100%) and TOC (55–100%) abatements were achieved under relatively mild Photo-Fenton treatment conditions.