Investigation on haloacetic acid (HAA) degradation by iron powder: Application of response surface methodology

Response surface methodology (RSM) was applied to investigate the degradation of major haloacetic acids (HAAs) in aqueous solutions using iron powder. The individual and combined effects of initial pH, iron dosage, and reaction time were considered as three major controlling factors. For all HAAs, the decrease of initial pH value and the increase of iron dosage improve degradation efficiency. The increase of reaction time was found to be influential on all HAA degradation (except DCAA and TCAA). However, its effect was not as significant as that of the initial pH and iron dosage. Brominated HAAs show higher degradation rates than chlorinated ones in similar experimental conditions. According to the ANOVA (analysis of variance) test outcomes, all the developed regression models to predict HAA degradation presented high R2 values (0.95, 0.92, 0.93, 0.99, 0.97, and 0.97 for TCAA, DCAA, MCAA, TBAA, DBAA, and MBAA, respectively) which confirms the applicability of polynomial regression models for HAA removal estimation.