Adsorption of arsenic(V) into modified lamellar Kenyaite

Abstract

The synthetic Kenyaite sample was used for organofunctionalization process with N-propyldiethylenetrimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide. The resulted materials were submitted to process of adsorption with arsenic solution at pH 2.0 and 298 ± 1 K. The adsorption isotherms were adjusted using a modified Langmuir equation with regression non-linear; the net thermal effects obtained from calorimetric titration measurements were adjusted to a modified Langmuir equation. The adsorption process was exothermic (Δ int H = −4.08 to −5.94 kJ mol −1) accompanied by increase in entropy (Δ int S = 41.29–62.09 J K −1 mol −1) and Gibbs energy (Δ int G = −22.33 to −24.45 kJ mol −1). The energetic effect caused by metal cation adsorption was determined through calorimetric titration at the solid–liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.