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

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Synthetic Na-magadiite sample was used for organofunctionalization process with N-propyldiethylenetrimethoxysilane 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±1 K. 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 (Δ int H=−4.15–5.98 kJ mol −1) accompanied by increase in entropy (Δ int S=41.32–62.20 J k −1 mol −1) and Gibbs energy (Δ 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.