Abstract
The capacity of natural adsorbents to remove anionic contaminants from water is limited. This limitation can be overcome by modifying the surface of the minerals with organic cations. In this research, zeolite (clinoptolite) and naturally occurring deposits of aluminum silicate collected from Saudi Arabia was modified using Hexadecyltrimethyl ammonium bromide (HDTMABr) to be used for removing the nitrate (NO3) from aqueous solutions. The batch method has been employed, using metal concentrations of 5-100 mg L-1 and adsorbent mass of 2-16 g L-1. The results showed that surfactant modification of clinoptolite or naturally occurrence deposits using HDTMABr resulted in a significant increase in the adsorption capacity of the adsorbent. The present data of surfactant modified zeolite (SM zeolite) and surfactant modified deposit (SM deposit) fit the Langmuir (Type 1 and 2), Freundlich and Temkin models well with a correlation coefficient, r(2) = 0.914-985. The both modified adsorbents of SM deposit at initial NO3 <= 25 mg L-1 and especially SM zeolite at initial NO3 of 5-100 mg L-1 showed higher affinity for NO3 compared to the natural unmodified samples. Results suggest that surfactant modified naturally occurrence deposits and especially zeolite might be a potential material for nitrate removal from water.