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-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 (ΔintH=−4.15–5.98 kJ mol−1) accompanied by increase in entropy (ΔintS=41.32–62.20 J k−1 mol−1) and Gibbs energy (ΔintG=−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.

Grapical AbstractThe results suggest that the adsorption capacities increased with an increase of reactive basic centers in the pendant organic chains of the intercalated agent.Figure optionsDownload full-size imageDownload as PowerPoint slide