Effect of common inorganic ions on aniline degradation in groundwater by activated persulfate with ferrous iron

Aniline is widespread in groundwater and of great toxicity. Advanced oxidation processes, such as the ferrous iron (Fe²⁺)-activated persulfate process, have been proven to be effective for organic pollutants. However, few studies have focused on the effects of coexisting ions on the degradation of aniline. In this study, the degradation efficiency of aniline and the effects of common inorganic ions (CO₃²⁻, PO₄³⁻, HCO₃⁻, SO₄²⁻, NO₃⁻, Na⁺, K⁺, Mg²⁺, and Ca²⁺) on aniline degradation were examined. Under the optimum operating conditions, 86.33% aniline degradation (C₀ = 11 mmol/L) was observed within 60 min. The effects of cations on aniline degradation were negligible. Anions decreased the removal efficiency of aniline because of the radicals generated by the reaction between sulfate radical or hydroxyl radical and these anions. As the concentrations of PO₄³⁻, CO₃²⁻, SO₄²⁻, HCO₃⁻, and NO₃⁻ increased from 0 mmol/L to 5 mmol/L, the removal efficiency of aniline decreased to 19.72%, 24.56%, 66.76%, 68.76%, and 82.42%, respectively. The order of inhibitory effects was PO₄³⁻ > CO₃²⁻ > >SO₄²⁻ > HCO₃⁻ > >NO₃⁻.