Toxicología ambiental y analítica

Synthesis, Characterization and Evaluation of Peanut Shells-Derived Activated Carbons for Removal of Methomyl from Aqueous Solutions

Abstract

Magda A Akl, Abdel Fatah M Youssef, Asaad H Hassan and Heba Maher

Peanut shells-derived activated carbons (ACPNS) with different chemical characteristics, appropriate for the removal of methomyl pesticide in aqueous solutions are prepared. The steam activated carbon is obtained from the carbonized peanut shells in the presence of nitrogen in the temperature range from 973 to 1173K. The carbonized peanut shells are, further, chemically activated using NaOH and ZnCl2. The structure of the ACPNS was characterized by N2 adsorption at 77K, scan electron microscopy and FTIR. B.E.T methods are used to deduce the effective surface areas. The parameters (such as initial pH, temperature, etc) affecting the adsorption capacity of peanut shells-derived activated carbons toward methomyl removal from aqueous solutions are investigated using batch experiments. The study of kinetic models including pseudo first order and pseudo second-order are carried out. Adsorption isotherms are investigated. Equilibrium adsorption data fitted the Langmuir adsorption isotherm well with R2> 0.9980. The maximum adsorption capacities of peanut shells-derived activated carbons for the removal of methomyl, are calculated. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for the adsorption processes of methomyl on the ACPNS were calculated, and the negative value of ΔG° indicated the spontaneous nature of adsorption. The prepared peanut shells derived activated carbons are successfully applied to the removal of methomyl pesticide from different water samples with a recovery % > 95 and a RSD< 3%. The mechanism of adsorption is proposed.