Utilizing Jackfruit Peel as a Sustainable Adsorbent for Methylene Blue Dye: Adsorption Efficiency and Isotherm Analysis

This study investigates the potential of jackfruit peel, an agricultural waste, as a sustainable and low-cost adsorbent for removing methylene blue (MB) dye from wastewater. Adsorption parameters, including adsorbent dosage (0.15–0.45 g), initial dye concentration (5–300 mg/L), pH (3–9), temperature (30–55 °C), and contact time (3–90 minutes), were systematically optimized. The highest adsorption capacity (36.48 mg/g) was achieved within 5 minutes, indicating rapid kinetics and strong dye affinity. The process was most effective at pH 9, consistent with the pHpzc value of 4.92, which enhances electrostatic attraction between the negatively charged adsorbent surface and the cationic dye. Isotherm fitting revealed multilayer adsorption on a heterogeneous surface, as described by the Freundlich and Temkin models. Surface characterization showed an irregular morphology and a BET surface area of 4.006 m²/g. Thermodynamic analysis confirmed that the process is spontaneous and endothermic. The substantial annual availability of jackfruit peel, along with its sustainable processing and high adsorption efficiency, makes it an excellent eco-friendly adsorbent for wastewater treatment. This abundant by-product offers a cost-effective alternative to traditional adsorbents and demonstrates its practical utility in removing pollutants like methylene blue dye. Additionally, its chemical-free preparation process ensures that jackfruit peel is safe, scalable, and environmentally friendly, making it a viable solution for both community-level and industrial-scale applications.