application of granular ferric hydroxide in removal of nitrate from aqueous solutions

the aim of this study is to investigate the nitrate adsorption on granular ferric hydroxide (gfh). the effect of factors such as initial concentration of nitrate, ph, contact time, and adsorbent mass were determined. the study was done in laboratory–scale in which synthetic nitrate solutions in a batch reactor were placed in contact with the adsorbent to model adsorption kinetics. it was found that with increasing initial concentration of nitrate, sorption capacity reaches the maximum level within two to three minutes. increasing the amount of adsorbent and decreasing the adsorbent particle size could reduce the adsorption capacity. at alkaline ph (9.5), the highest sorption of nitrate on gfh occurred but it was found that the ph does not have a great impact on nitrate adsorption on gfh. also, it was revealed that the adsorption kinetics followed pseudo–degree reaction model. this method could decrease the nitrate concentrations to less than the standard level (45 mg/l based on nitrate).