Organically modified micron-sized vermiculite and silica for efficient removal of Alizarin Red S dye pollutant from aqueous solution

Micron-sized vermiculite (VMT) clay was modified with 3-aminopropyltriethoxysilane (APTES) through sonication. The surface modification was proficient within 30 min of sonication relatively than long reflux times reported prior. A grafted mesoporous silica (GSIL) was synthesized through demineralization of the micron-sized VMT and further functionalized with APTES. The adsorbents were characterized by FTIR, TGA, XRD, and FE-SEM. The pore size distribution and surface area were determined using N-2 adsorption-desorption isotherms. The performance of the synthesized substances as adsorbents was evaluated by the removal of an Alizarin Red S (ARS), organic dye from aqueous solutions. The maximum sorption capacity was 18.2 mg/g for APTES grafted vermiculite and 59.8 mg/g for APTES grafted silica. The adsorbent dose, pH, temperature, dye concentration, and influence of contact time on the removal of ARS were investigated. The ARS adsorption increased with adsorbent dosage and reached a maximum of 0.8 mgmL(-1) for both adsorbents. The experimental data were best fitted by the Langmuir isotherm model. The Kinetics of adsorption modeling confirmed that the ARS adsorption pursued a second-order model. The thermodynamic parameters evaluated from van't Hoff's model revealed a spontaneous endothermic adsorption process. (c) 2020 Elsevier B.V. All rights reserved.