Adsorption of arsenic(III) into modified lamellar Na-magadiite in aqueous medium-Thermodynamic of adsorption process

Synthetic Na-magadiite sample was used for organofunctionalization process with N-propyldiethylene-trimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide, after expanding the interlayer distance with polar organic solvents Such as dimethylsulfoxide (DMSO). The resulted materials were submitted to process of adsorption with arsenic solution at pH 2.0 and 298 +/- 1K. The adsorption isotherms were adjusted using a modified Langmuir equation with regression nonlinear: the net thermal effects obtained from calorimetric titration measurements were adjusted to a modified Langmuir equation. The adsorption process was exothermic (Delta H-int = -4.15-5.98 kJ mol(-1)) accompanied by increase in entropy (Delta S-int = 41.32-62.20Jk(-1) mol(-1)) and Gibbs energy (Delta(int)G = -22.44-24.56 kJ mol(-1)). The favorable values corroborate with the arsenic (III)/basic reactive centers interaction at the solid-liquid interface in the spontaneous process. (C) 2008 Published by Elsevier Inc.