A comprehensive study on pomegranate (Punicagranatum) peels as a low-cost biosorbent: adsorption mechanisms,...

This study investigates the potential of utilizing pomegranate peel, a waste material, as an environmentally friendly adsorbent for the removal of methylene blue (MB) from wastewater. The novelty of this study lies in producing a competitive adsorbent (96% removal in a reasonably short contact time), very low cost, from a biowaste material and in providing cost analysis, regeneration method, application, and a mechanism based on a set of results that are in harmony with each other. Characterization of the purified pomegranate (Punicagranatum) peels (PP) inferred remarkable acidic sites. The MB removal was observed to increase with increasing dosages of adsorbent, contact time (93-94% removal took place in the first 30-40 min), agitation speed (the amount of MB removed increased with increasing agitation speed up to 160 rpm), pH (increasing solution pH up to pH 8.0, the removal efficiency of MB by PP increased), and MB initial concentrations. The experimental results of MB adsorption on PP were best fitted to the Temkin isotherm model and the kinetic studies showed that the adsorption rate was best fitted to the pseudo-second-order (PSO) model showing a correlation coefficient R² of 0.969-0.991. Thermodynamic investigations demonstrated that the removal of MB dye utilizing PP may be due to a spontaneous, electrostatic, chemical, and exothermic interaction with a heterogeneous adsorption mechanism. Adsorption is anticipated to begin with attraction between cationic MB and negatively charged active functional groups on adsorbent's surface, soon to be followed by multisite chemical interaction. The results (up to 96% removal) show that pomegranate peels could be used as a potential eco-friendly, cost-effective, and efficient biosorbent for dye removal from wastewaters. With an average removal effectiveness of 86.8%, PP were successfully utilized to remove MB from MB-spiked actual river water samples.