Remediation of γ-Hexachlorocyclohexane Contaminated Soil Using Nanoscale Zero-Valent Iron

γ-Hexachlorocyclohexane (γ-HCH), an organochlorine pesticide is of immense concern for human health and the environment because of its low aqueous solubility, high stability, lipophilicity and recalcitrant nature. Nanoscale zero-valent iron (nZVI) has been shown to effectively transform chlorinated organic compounds. In view of this an attempt has been made to explore the potential of nZVI for the remediation of γ-HCH spiked soil. For this batch experiments were conducted to test the degradation potential of γ-HCH using various concentration of nZVI ranging from 0.20 g L^–1 to 2.0 g L^–1. Analysis of the data showed complete disappearance of 10 μg g^–1 of γ-HCH within 24 hours at nZVI concentration of 1.6 g L^–1, indicating its possible use in environmental cleanup. Kinetic studies revealed that nZVI mediated γ-HCH degradation follows pseudo first order kinetic model with a degradation rate constant of 7.02 × 10^–1 h^–1 at nZVI concentration of 1.6 g L^–1 and 7.2 pH. Gas chromatographic analysis showed the formation of benzene as the final degradation product of γ-HCH. Factors such as pH and reaction time likely to affect the degradation efficacy of nZVI have also been studied. It was found that lower pH and increase in reaction time assist nZVI in the degradation of γ-HCH. The role of nZVI in the remediation of γ-HCH contaminated soil has been discussed.