Adsorptive removal of cationic and anionic dyes on a novel mesoporous adsorbent prepared from diatomite and anionic cellulose nanofibrils: Experimental and theoretical investigations

Abstract

A new nanocomposite, named A-CNF/DT, is prepared based on anionic cellulose nanofibrils (CNFs) treated with the (2, 2, 6, 6-tetramethyl piperidine-1-yl) oxyl (TEMPO) and diatomite (DT) via hydrothermal alkaline synthesis. The A-CNT/DT adsorbant was characterized by N2 adsorption at 77 K, FTIR, XRD, TGA, SEM and TEM analysis and used to removal of methylene blue (MB) and indigo carmine (IC) dyes from water. The effects of solution pH, temperature, initial concentration, and contact time were investigated. The corrected Akaike Information Criterion (AICc) was found to rank adsorption isotherm and kinetic models better than error functions (R2). Based on the AICc values, the adsorption isotherm data of IC and MB onto A-CNT/DT were well fitted by Langmuir and Sips isotherms, respectively. The maximum monolayer adsorption capacity (qmax) of A-CNT/DT for the adsorption of IC and MB was 375.6 and 175.2 mg/g, respectively. The experimental kinetic data fitted very well to pseudo-first order model for adsorption of IC and pseudo-second order model for adsorption of MB onto A-CNT/DT. Thermodynamic parameters indicate endothermic (MB) and exothermic nature (IC) of dyes adsorption onto A-CNT/DT. In addition, the interaction between the dyes molecules and A-CNT/DT surface has been investigated by using Monte-Carlo calculation method (MC). The results have shown that the interaction of the dyes onto A-CNT/DT occurred through both polar and nonpolar interactions. The overall study shows that the synthesized A-CNT/DT was proved to act as a promising adsorbent to remove the dyes from the aqueous solutions proficiently.