Synergistic effects of activated carbon and MgZnAl layered triples hydroxides for removing anionic and cationic dyes: Experimental and theoretical insights

Abstract

This study introduces a novel approach using MgZnAl-layered triple hydroxide (LTH) and activated carbon (AC) derived from argan nutshells, designed to enhance MO and MB adsorption from aqueous solutions. Synthesized via coprecipitation, carbonization, and H₃PO₄ activation processes, the LTH_AC composites were thoroughly characterized using XRD, FTIR, Raman, BET, SEM, and TEM. The LTH_AC500 composite showed good adsorption capacities, achieving 154.219 mg/g for MO and 112.989 mg/g for MB. The adsorption kinetics followed a pseudo-second-order model, indicating predominant chemisorption, while the Freundlich isotherm model suggested multilayer adsorption on heterogeneous surfaces. Thermodynamic analysis confirmed the process’s spontaneity, with MO adsorption being endothermic and MB adsorption exothermic. DFT theoretical studies revealed mechanisms such as π-π stacking, coordination interactions, anion exchange, and charge transfer between the dyes and the composite. Additionally, the composite demonstrated stability, recyclability over five cycles, and interference resistance, proving its potential for dye wastewater treatment.