The removal efficiency of chestnut shells for selected pesticides from aqueous solutions

The removal of selected pesticides such as carbofuran(CF) and methyl parathion (MP) using low-cost abundant sorbent chestnut shells from aqueous solutions has been investigated in the present study. The sorption parameters, i.e., contact time, pH, initial pesticide solution concentration and temperature have been studied. Maximum percent sorption (99 +/- 1 %) was achieved for (0.38-3.80) x 10(-4) and (0.45-4.5) x 10(-4) mol dm(-3) of MP and CF pesticide solutions respectively, using 0.4 g of sorbent in 100 nil of solution for 30 min agitation time at pH 6. The Freundlich, Langmuir and Dubinin-Radushkevich (D-R) models have been applied, and their constants for methyl parathion and carbofuran, sorption intensity I In (0.55 +/- 0.02 and 0.54 +/- 0.04), multilayer sorption capacity Cm (28.3 +/- 0.5 and 16.4 +/- 0.7) x 10(-3) mol l(l-1/n) dm(3/n) g(-1), monolayer sorption capacity Q (22.5 +/- 0.5 and 10.8 +/- 0.3) x 10(-6) mol g(-1), binding energy, b (2.9 +/- 0.2 and 5.2 +/- 0.5) x 10(4) dm(3) mol(-1), and sorption energy E (11.2 +/- 0.1 and 11.5 +/- 0.2 kJ mol(-1)) have been evaluated respectively. Lagergren, Morris-Weber and Reichenberg equations were employed to study kinetics of sorption process. Thermodynamic parameters Delta H (-5.09 +/- 0. 1 and 22.8 +/- 0.4 kJ mol(-1)), Delta S (-4.33 +/- 0.0003 and 0.09 +/- 0.001 kJ mol(-1) K-1) and Delta G((303K)) (-2.9 and -3.8 kJ mol(-1)) have been calculated for methyl parathion and carbofuran, respectively. The developed sorption procedure has been employed to environmental samples. (c) 2007 Elsevier Inc. All rights reserved.