Performance Evaluation of Hexadecyltrimethyl Ammonium Chloride (HDTMA-CL) and Cetylpyridinium Bromide (CPB) Modified Zeolite Clinopitolite inRemoval of Nitrates from Aqueous Solutions

Toxic contaminants such as inorganic anions cause water pollution and create some potential risks to human health and the environment. Nitrate as an inorganic anion is one of the most important sources of pollutants for surface and underground waters. Regarding adsorptive properties of zeolite, it is widely used to absorb water and wastewater pollutants. The aim of this study was to investigate the nitrate removal from the aqueous solutions by using zeolite clinoptilolite modified by surfactants.
In this laboratory study, the zeolites granulated and modified by surfactant Hexadecyltrimethyl Ammonium Chloride and cetylpyridinium bromide were investigated through the impact of the parameters such as pH (3 to12), time (30 to 300 min), initial concentration of nitrate (20 to 250 mg/L), and adsorbent dose (5 to 20 grams per liter) in a batch laboratory scale. For better understanding of the adsorption process, the experimental data were analyzed with Langmuir and Freundlich isotherm models and kinetic adsorption studies.
The results showed that nitrate removal efficiency had a reversed relationship with adsorbent dose and direct contact time,The results also showed that the removal of nitrate from solution is inversely related to the initial nitrate concentration. The maximum nitrate removal efficiency for both absorbents was in pH=7. Time of nitrate removal was obtained by 180 min in equilibrium. The data for both absorbents follow Freundlich adsorption isotherm and pseudo-second degree kinetics.
The results of the study showed that the Iranian surfactant-modified zeolites could be used effectively for removal of nitrate. Considering its low cost, easily availability and modification, the zeolites can be used to remove nitrate from underground waters.