Removal of nitrate ion from aqueous solution by modified ethiopian bentonite clay

Abstract

The use of nitrogen fertilizers in agricultural areas, animals manure and wastewaters are the major reasons for surface and ground water pollution with nitrate ions. World Health Organization (WHO) and US Environmental Protection Agency (USEPA) set maximum acceptable concentration of nitrate ions in drinking water to be 50 mg/L and 45mg/L respectively. Drinking waters having nitrate ions concentration exceeding this value is considered as polluted water and causes diseases such as methemoglobinemia and stomach cancer. Under this study, the ability of Ethiopian acid activated bentonite clay adsorbent media for nitrate ions removal from aqueous solutions has been investigated. The clay was taken from Gewane area, Afar region, Northeastern Ethiopia, activated with 2M HCl and characterized by FT-IR Spectroscopy. The adsorption properties of activated clay were then studied in terms of adsorbent dose, pH, temperature, contact time, and contaminant concentration via batch experiment method. The percentage of nitrate ion removal from aqueous solution using this clay was determined to be 80% at an optimium condition of initial concentration, adsorbent dose (acid activated bentonite clay), contact time and pH determined. Experimental data has been analyzed using the Freundlich and Langmuir isotherms that the data best fits with Langmuir model.