A comprehensive review of methylene blue dye adsorption on activated carbon from edible fruit seeds: A case study on kinetics and adsorption models

Abstract

In recent years, several industries have discharged wastewater containing high quantities of dyes directly into the ecosystem, creating a significant environmental hazard due to the contamination of soil, groundwater, and surface water. The rapid growth of the textile industry has exacerbated this issue, as residual materials, particularly dyes, in treated wastewater contribute to environmental degradation. Recent studies have demonstrated that activated carbon is highly effective in removing cationic dye, specifically methylene blue (MB), from wastewater. Adsorption has become the most widely used separation technique due to its efficiency in contaminant adsorption. This study focuses on the use of both treated and untreated adsorbents derived from discarded fruit seeds. Given the global demand for food and fruits, the use of fruit seeds to produce adsorbents has gained popularity due to their low cost, biocellulose content, and availability. The adsorbents were analyzed using FTIR, BET, SEM, and thermogravimetric (TG) methods. The relationship between the pH of the methylene blue solution and the pHpzc (point of zero charge) of the adsorbent surface was thoroughly characterized. This study provides a comprehensive examination of isothermal models, kinetic models, and thermodynamic functions. The phenomenon of adsorption, along with its relationship to surface area and pH, is also investigated. Finally, it was found that biowaste fruit seeds can serve as a low-cost alternative to commercial activated carbon for the effective removal of various pollutants from the aquatic environment on a large scale.