Vivi Yessi, Nazriati
Industrial dye waste is difficult to decompose naturally and poses a significant environmental problem. Methylene blue (MB) is one of the most common dye pollutants, requiring effective removal methods such as adsorption. Adsorption is widely recognized as a simple and cost-effective approach for wastewater treatment. In this study, natural zeolite, a non-metallic mineral, was utilized as an adsorbent. However, due to its relatively low specific surface area, natural zeolite requires modification to increase its adsorption capacity. This research investigates the performance of alkali-activated natural zeolite obtained from Sumbermanjing Wetan, Malang, as a low-cost adsorbent for MB removal. The zeolite was chemically activated using a 2 M NaOH solution, and structural changes were analyzed using X-ray diffraction (XRD). Batch adsorption experiments were carried out to examine the effects of contact time, adsorbent dosage, initial dye concentration, and temperature on the adsorption process. The results show that MB adsorption onto the modified zeolite follows the Freundlich isotherm model and exhibits pseudo-second-order kinetic behavior. Thermodynamic analysis reveals that the adsorption process is spontaneous and exothermic, accompanied by a decrease in system entropy. © 2026 The Authors, published by EDP Sciences.
Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jl. Semarang 5, Malang, 65145, Indonesia
