Effect of Chemical and Thermal Treatment Priority on Physicochemical Properties and Removal of Crystal Violet Dye From Aqueous Solution

Abstract

The release of pollutants, especially dyes, has been a significant concern as it affects the stability of ecosystems due to poor implementation of waste protocols. In this study, the diatomite samples were characterized by pH(pzc), ICP, pore size distribution, XRD, TG-DTA, BET, SEM and FTIR (before-after). The adsorption properties of a cationically charged dye, crystal violet (CV), on the diatomite samples were investigated by varying the adsorption parameters with the aim of evaluating the adsorption mechanism. Nonlinear Langmuir, Freundlich, Dubinin-Radushkevich and Redlich-Peterson isotherm models, pseudo-first and pseudo-second order kinetic models, intraparticle diffusion and Boyd models were evaluated. The adsorption mechanism was explained by the Langmuir isotherm model and the maximum adsorption capacities for CV (at pH 7.0) of D-HCl, D800 degrees C+HCl and DHCl+800 degrees C were 5.07 mg g(-1) and 4.93 mg g(-1) and 65.78. mg g(-1) at 298 K, respectively. It was also shown that the CV adsorption was reasonable according to the second-order kinetic model (R-2=1). Adsorption occurred via two mechanisms: hydrophobic interactions and the combination of surface hydrogen bonding between the hydroxyl groups on the diatomite surface and the nitrogen atoms of the CV. The results indicated that using DHCl+800 degrees C would provide a simple, energy-saving, and cost-effective approach to removing cationic dyes from an aqueous solution.