Enhanced degradation of 2,4-dinitrotoluene in groundwater by persulfate activated using iron-carbon micro-electrolysis

The reactivity of potassium persulfate (PP) in the degradation of 2,4-dinitrotoluene (2,4-DNT), with when iron and carbon as activators, is investigated. Effects of pH, persulfate concentration, and ionic strength on the degradation efficiency of 2,4-DNT by persulfate are studied in batch experiments, with simulated groundwater environmental conditions of no light, neutral pH and low temperatures (15 degrees C). The degradation of 2,4-DNT heightens and follows the pseudo-first-order kinetic model in the system comprising Fe/AC and S2O82-. Addition of activated carbon (AC) increases the release of Fe2+ to activate PP. When the concentration of persulfate is 100 mg/L, the 2,4-DNT degradation is the best at an initial pH of 2. The 2,4-DNT removal efficiency increases in the order of pH 2 > pH 9 > pH 3 > pH 5 > pH 11 > pH 7 in the Fe/AC +PP system. 2,4-DNT degradation in the presence of Cl- is slower in the first 100 min, but there is no obvious difference in degradation efficiency further on. This is most likely due to persulfate activation and Fe/AC reduction in this system. Meanwhile, the presence of bicarbonate ions inhibits the degradation of 2,4-DNT. A possible mechanism is proposed based on the reasons for the degradation of 2,4-DNT in the Fe/AC + PP system. Iron-carbon micro-electrolysis promotes micronmeter-sized iron to generate Fe2+. This study provides the design for an advanced, refractory organic matter-based oxidation technique for improved groundwater pollution remediation. (C) 2016 Elsevier B.V. All rights reserved.