Modification of magadiite surface by organofunctionalization for application in removing As(V) from aqueous media: Kinetic and thermodynamic

Abstract: A synthetic Na-magadiite sample has been modified by organofunctionalization process using synthetic route involved the reaction of 2-mercaptopyrimidine with 3-chloropropyltriethoxysilane. The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms adjusted to the Langmuir equation at room temperature and pH 2.0. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second-order reaction with k 2 in the 4.9–14.0mmol−1 min−1 range for MMPY. The adsorption process was exothermic (Δint H =−4.09 to −5.79kJmol−1) accompanied by increase in entropy (Δint S =41.29–61.80JK−1 mol−1) and Gibbs energy (Δint G =−22.34 to −24.19kJmol−1). The energetic effect caused by arsenic(V) 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. [Copyright &y& Elsevier]