Valorization of peanut shells into recyclable carbon adsorbent for the separation of eosin yellow dye from aqueous solutions

There is growing interest in the development of economically and environmentally sustainable adsorbents derived from biomass for water treatment applications. This study investigates the effectiveness of peanut shells as a natural precursor for the removal of eosin yellow (EY) dye from aqueous solutions. The prepared peanut shell-based activated carbon (PSAC) was characterized using SEM, EDS, XRD, and FTIR techniques. Batch experiments were conducted to evaluate the effects of initial EY concentration (2–150 mg L⁻¹), pH (2.0–8.0), adsorbent dosage (10–40 mg), and temperature (298, 313, and 333 K). The results showed that PSAC exhibited high adsorption efficiency, achieving a removal rate of 99.2% under optimal conditions (10 mg L⁻¹, 120 min, 10 mg, 298 K), with a maximum adsorption capacity of 344 mg g⁻¹. The adsorption behavior was best described by the Freundlich isotherm and pseudo-second-order kinetic models. Thermodynamic analysis indicated that the adsorption process was spontaneous and exothermic. Overall, the findings demonstrate that PSAC is a promising and eco-friendly adsorbent for the removal of EY dye from wastewater.