Enhanced chlordecone (Kepone) removal by FeO-nanoparticles loaded on activated carbon

Chlordecone (CLD) is a chlorinated pesticide that was spread intensively on the French Antilles over two decades to control the proliferation of the banana root borer. This leads to massive contamination of soils, rivers and consequently of the food chain in the surrounding of the banana-producing areas. Therefore, drinking water plants were equipped with filters filled with commercial activated carbon (AC). However, due to the limited effectiveness of the existing systems, it remains an urgent challenge to find new and better adsorbents or to improve the existing ones. This article addresses our attempts to improve the adsorption efficiency of AC towards CLD by using, for the first time, in-situ-immobilized-iron oxyhydroxide/iron oxide nanoparticles (FeO-Nps) generated on the surface of AC by means of forced hydrolysis technique. By targeting waste minimization, major improvement of this existing process has been achieved using FeOs filtrates at their maximum efficiency. Modified ACs were obtained without altering their initial textural properties. TEM and XPS analyses allowed detecting the presence and characterizing these FeOs-Nps on the surface of AC in the form of goethite (α-FeOOH) and hematite (α-Fe2O3). Pseudo first and second order kinetic models were used to fit CLD adsorption kinetics on AC and FeO-Nps-ACs. The adsorption isotherms were studied using various isotherm models and among them the best fit was obtained with Langmuir model. The calculated average monolayer capacity obtained for FeO-Nps-ACs is 79.8 μg/mg, which is 64% higher than for AC, demonstrating a dramatic improvement of the CLD adsorption efficiency of the FeO-Nps-AC composites.