Evaluation of the efficiency of nanomagnetic chitosan in the removal of nitrate and phosphate from aqueous solutions

Background & Objective: The presence of nitrate and phosphate in concentrations above the allowable level in surface and groundwater resources leads to disease and problems. The aim of this study was to investigate the adsorption efficiency of magnetic-metallic chitosan nanocomposite in the adsorption of nitrate and phosphate from aqueous solutions. Materials and methods: The adsorbent was synthesized by co-precipitation method. Different concentrations of nitrate (50-300 mg/L) and phosphate (100-400 mg/L) were prepared and their removal was evaluated by different concentrations of synthesized adsorbent (0.1-0.5 g/L). Various parameters such as temperature (20-40 ° C), pH (5-8), contact time (0-90 minutes) and the presence of interfering ions (chloride, phosphate, hardness 1.5 mM) were investigated. SEM, XRD, FTIR and XRF tests were used to determine the synthesized adsorbent characteristics. Results: Magnetic-metallic chitosan nanocomposite adsorbent is able to effectively remove nitrate and phosphate from aqueous solutions. Nitrate and phosphate removal efficiencies under conditions of  pH=5, nitrate concentration (100 mg/L), phosphate concentration (200 mg/L), 60 min contact time and 0.3 g/L adsorbent concentration were 87.2% and 74.9%, respectively. The adsorption process of both pollutants followed the langmuir model and pseudo second kinetic order. Interfering ions reduced the removal efficiency of contaminants by 73.1% for nitrate and 65.9% for phosphate. Conclusion: Since the presence of nitrate and phosphate anions, as common contaminants and indicators of water resources, the use of magnetic-metallic chitosan nanocomposite adsorbent is very effective in the removal of these contaminants.