Ali Azari - Department of Environmental Health Engineering, Tehran University of Medical Sciences, Health Faculty, Tehran, Iran
Amir Hossein Mahvi - Department of Environmental Health Engineering, Tehran University of Medical Sciences, Tehran, Iran
Simin Naseri - Department of Environmental Health Engineering, Tehran University of Medical Sciences, Tehran, Iran
Roshanak Rezaei Kalantary - Department of Environmental Health Engineering, Iran University of Medical Sciences, Tehran, Iran

Background & Aims of the Study: Nitrate is one of the most important pollutants that itsreduced form, nitrite, can cause serious problems for human health and environment.Adsorption with cheap sorbents such as Zeolite is the best way for removal of thispollutant. So this study aimed to apply modified Clinoptilolite Zeolite for nitrate removal.Materials & Methods: Firstly, Clinoptilolite zeolite was screened by 1-2 mm sieves formonolithic of it. Then zeolite was boiled in HCL 20% for 3 hours for removal of Carbonateand impurities present in zeolite structure and increase of porosity and purity of zeolite.Finally, the zeolite was dried in temperature of 300°C to evaporate the water present inzeolite structure and increase the absorbability. After the modification of the Zeolite, theeffects of pH, time, strings speed, optimum amount of adsorbent in Nitrate removal wereinvestigated and optimized by one factor at the time method. Also reaction kinetics andisotherms were determined.Results: This study indicated that the optimum condition for Nitrate removal by means ofmodified zeolite as adsorbent is pH=5, contact time of 180 minutes and adsorbent amountof 16 g/l. The investigation of isotherm and kinetic equations indicated that Nitrateadsorption follows Langmuir and pseudo first order, respectively.Conclusions: The zeolite modified by HCL and heat has a higher efficiency in Nitrateremoval compared to simple zeolite, because of losing its hydroscopic water and havinglarger sites, although in total it doesn’t have sufficient efficiency for Nitrate removal.

NitrateAdsorptionModified zeoliteClinoptilolite