Adsorption of methyl parathion pesticide from water using watermelon peels as a low cost adsorbent

In the present studies chemically and thermally treated watermelon peels (TWMP) have been utilized for the removal of methyl parathion (MP) pesticide from water. The effect of process variables such as pH of solution, shaking speed, shaking time, adsorbent dose, concentration of solution and temperature have been optimized. Maximum adsorption (99 +/- 1%) was achieved for (0.38-3.80) x 10(-4) mol dm(-3) of MP solution, using 0.1 g of adsorbent in 20 ml of solution for 60 min agitation time at pH 6. BET and SEM analysis have been carried out for the characterization of TWMP. Adsorption data has been analyzed by Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. Lagergren, Morris-Weber and Reichenberg equations have been used for kinetic studies of adsorption process. Thermodynamic parameters Delta H, Delta S and Delta G have been calculated. Positive value of Delta H and negative value of Delta G show endothermic and spontaneous nature of adsorption respectively. The developed adsorption method has been employed. to surface water samples with percent removal 99% +/- 1. (C) 2007 Elsevier B.V. All rights reserved.