Taguchi orthogonal optimization for the oxidative degradation of 2-chlorophenol using zero valent iron-activated persulfate

Abstract

Chlorophenols (CPs) are persistent toxicants and major groundwater pollutants due to their carcinogenic properties. This study focused on optimizing the degradation of 2-chlorophenol (2-CP) in the aqueous phase using zero-valent iron (ZVI)-activated sodium persulfate (SPS). The Taguchi Design of Experiment methodology (L9 orthogonal array) and ANOVA statistical analysis were applied to identify optimal conditions, with key parameters including initial pH, SPS concentration, and ZVI concentration. Results indicated that SPS concentration had the most significant impact on 2-CP degradation. Confirmation tests conducted at the optimal conditions (pH = 6, SPS = 60 mM, ZVI = 60 mM) achieved 100% 2-CP degradation within 10 min, characterized by rapid 2-CP degradation, SPS decomposition, and 2-CP mineralization. Experiments with 2-CP spiked reverse osmosis water and groundwater samples showed total organic carbon removal rates of 75% and 67%, respectively, with discussions highlighting the potential effects of groundwater constituents on degradation efficiency. ZVI surface analysis through SEM-EDS identified iron oxide crystal formation on recovered iron particles, while XRD analysis confirmed the presence of Fe₃O₄ on the particle surface post-reaction. These findings underscore the effectiveness of ZVI-activated SPS as a promising approach for 2-CP degradation in natural groundwater systems, contributing to supportable groundwater remediation efforts.