Optimizing NaCl-modified zeolite for ammonia nitrogen removal from polluted rural surface water

ABSTRACT Adsorption capacity for NH4+-N of NaCl-modified J20 zeolite increased 23.41-fold compared to unmodified J20, suitable for polluted rural surface water treatment. Ammonia–nitrogen (NH4+ -N) contamination in rural water sources poses risks to drinking water safety if not properly treated. Developing economic potential, sustainable, and efficient treatment methods is crucial for safeguarding rural water supplies. This study developed a cost-effective strategy to remove NH4+ -N from polluted rural surface water sources using modified zeolite. Commercial zeolite J20 was modified by soaking in the NaCl solution. The NaCl soaking method significantly improved the adsorption capacity of zeolites, and modification conditions were optimized using response surface methodology without further optimization of adsorption parameters, yielding 6.25% NaCl with an incubation time of about 10.4 h. Under these conditions, the modified J20 zeolite achieved a maximum adsorption capacity of 31.6 mg/g for NH4+-N, representing a 23.41-fold increase compared to the unmodified zeolite. When applied to real rural water samples with an NH4+-N concentration of 0.85 mg/L, the modified zeolite achieved nearly 100% removal after 4 h adsorption, and no additional ions or toxic compounds were detected. This study indicated that NaCl-modified zeolite offers a sustainable, cost-efficient solution for NH4+ -N removal from polluted rural surface water sources, providing an effective pretreatment option for decentralized rural water supplies.