Transforming agro-waste into Bio-activated carbon: a sustainable solution for efficient R590 dye removal from wastewater

A bio-based adsorbent, H₃PO₄-treated activated carbon derived from pomegranate peels (ACPP), was developed to remove Rhodamine 6G (R590) dye from wastewater. ACPP achieved a maximum removal efficiency of 91.3% (154 mg/g) under optimal conditions: pH 6, contact time of 40 min, 25 °C temperature, ACPP dose of 30 mg, 30 ppm R 590 concentration, and a solution volume of 30 mL. Kinetic studies showed that the nonlinear pseudo second-order model best described the adsorption process, indicating chemisorption. Similarly, isothermal studies demonstrated that the Langmuir model provided the best fit, suggesting monolayer adsorption. Thermodynamic parameters revealed the adsorption to be spontaneous and endothermic, with negative ΔG°, and positive ΔH° and ΔS° values. Regeneration experiments demonstrated ACPP’s reusability, with only a 7.3% decrease in adsorption capacity after five cycles, confirming its long-term efficiency. These findings highlight ACPP as a promising, cost-effective, and sustainable solution for addressing the global challenge of wastewater treatment, particularly for the removal of toxic dyes like R 590.