MgO-mediated activation of active carbon as an affordable strategy to "in situ" degradation of lindane in contaminated soils

Abstract

The accumulation in soil landfills of toxic and persistent lindane, widely used as an insecticide, triggers the risk of leaching with the concomitant contamination of surrounding rivers. Thus, viable remediation to eliminate in situ high concentrations of lindane in soil and water becomes an urgent demand. In this line, a simple and cost-effective composite is proposed, including the use of industrial wastes. It includes reductive and non-reductive base-catalyzed strategies to remove lindane in the media. A mixture of magnesium oxide (MgO) and activated carbon (AC) was selected for that purpose. The use of MgO provides a basic pH. In addition, the specific selected MgO forms double-layered hydroxides in water which permits the total adsorption of the main heavy metals in contaminated soils. AC provides adsorption microsites to hold the lindane and a reductive atmosphere that was increased when combined with the MgO. These properties trigger highly efficient remediation of the composite. It permits a complete elimination of lindane in the solution. In soils doped with lindane and heavy metals, it produces a rapid, complete, and stable elimination of lindane and immobilization of the metals. Finally, the composite tested in lindane-highly contaminated soils permits the "in situ" degradation of nearly 70% of the initial lindane. The proposed strategy opens a promising way to face this environmental issue with a simple, cost-effective composite to degrade lindane and fix heavy metals in contaminated soils.

Keywords: Adsorption; Dehydrohalogenation; Dihaloelimination; Heavy metals; Soil remediation.