Modification of clinoptilolite zeolite adsorbent from Miyaneh mines to remove ammonia from the water environment

Zeolite is well known for its excellent adsorption properties, making it a popular choice for water and wastewater treatment. However, clinoptilolite, the most common type of natural zeolite, has a relatively low capacity for ammonium adsorption. This study aimed to improve its performance by treating natural clinoptilolite with 1 M NaOH and KOH solutions. Batch experiments were conducted to examine how solution pH, contact time, initial ammonium concentration, adsorbent amount, and type of chemical modifier affect adsorption efficiency. The highest adsorption capacity was achieved with NaOH-treated clinoptilolite under optimal conditions: pH 8, 120 minutes contact time, 100 mg/L initial ammonium, and 4 g/L adsorbent, reaching a capacity of 17.03 mg/g. Desorption tests using 0.1 M NaCl over five cycles confirmed the reusability of the modified material with minimal performance loss. Isotherm modeling closely matched both Langmuir and Freundlich models, suggesting the coexistence of monolayer and multilayer adsorption processes. Overall, the modified clinoptilolite shows strong potential as an efficient and economical adsorbent for ammonium removal in wastewater treatment.