High-quality mesoporous adsorbent derived from pomegranate pomace for efficient removal of azo dye from textile wastewater: Influencing factors, reusability, and mechanism studies

Abstract

The solid waste from the processing of pomegranate (Punica granatum L.) juice, known as pomegranate pomace, was utilized as an economical and readily available precursor to produce high-quality activated carbon (AC). The AC was synthesized using a low-cost method at a carbonization temperature of 600 °C, employing a 1:1 impregnation ratio (precursor/H3PO4), and activating for 1 h. Various characterization techniques, including SEM imaging, XRD analysis, FT-IR analysis, BET surface area analysis with pore size determination, and other physicochemical assessments, were conducted on the produced AC. To assess its efficacy in treating textile wastewater, Basic Yellow 28 (BY 28) dye was selected as a representative pollutant. The results displayed a mesoporous structure in the produced AC with a mesopore content of 78.82 %. Notably, it exhibited a high BET surface area of 1089.08 m2/g and a total pore volume of 1 cm3/g. The Langmuir non-linear isotherm model emerged as the most fitting for explaining the adsorption equilibrium data, revealing a substantial monolayer adsorption capacity of 659.13 mg/g at 20 °C. The experimental data fit into a pseudo-second-order kinetic model, where the rate-determining step was found to be intra-particle diffusion. Thermodynamic analysis revealed that the adsorption of BY 28 dye onto the produced AC was an exothermic process. The produced AC exhibited high stability, as demonstrated in desorption studies, maintaining effectiveness through multiple uses. These results signify the potential of using pomegranate pomace, an environmentally problematic waste, as a novel precursor for producing sustainable and cost-effective AC.