Adsorptive Removal of Methylene Blue from Water Using High-Performance Alginate-Based Beads

Abstract

In this study, composite ACCF-A was synthesized using activated carbon (AC), copper ferrite (CF), and alginate (A) and used as adsorbent to remove methylene blue dye from aqueous solution. The beads were prepared by incorporating AC/CF nanocomposites into alginate by an ionic gelation method. The synthesized ACCF-A composite was characterized using FTIR, SEM, EDX, BET, TGA, and zeta-potential. The adsorptive capacities of ACCF-A composite toward methylene blue (MB) as a model dye in aqueous solution were studied through batch adsorption experiments in which the effects of initial dye concentration, adsorbent dosage, pH, temperature, ionic strength, and contact time on MB removal efficiency were examined. Results revealed that ACCF-A had a maximum adsorption capacity of 400.0 mg/g for MB, suggesting the potential of ACCF-A as a promising adsorbent for the removal of dyes from water. The adsorbent demonstrated fast adsorption kinetics and high adsorption capacity over a wide pH range (6–12). The adsorption data were fitted using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. Thermodynamic results indicated that the adsorption of MB on ACCF-A was spontaneous and exothermic. The pseudo-first-order kinetic model described the MB adsorption process with good fitting. Intra-particle diffusion model indicated that diffusion is not the only rate-limiting step in the adsorption process. The developed adsorbent was successfully regenerated for up to eight consecutive cycles, with only 2% loss in adsorption capacity.