Study of the Effect of Iron Nanoparticles on the Efficiency of Zeolite in the Removal of Effluent Nitrate

Abstract

Introduction: Iron nanoparticles, due to their high absorption level, have a great ability to increase the efficiency of adsorbents such as zeolite in removing pollutants. The purpose of this research in the form of a laboratory design is to investigate the performance of zeolite and compare it with zeolite modified by Iron nanoparticles.
Materials & Methods: At first, zeolite A was prepared using sodium clinoptilolite, sodium chloride, and sodium hydroxide and sodium aluminate. Then composite of revised Zeolite and Iron nanoparticles) Fe3O4/A Zeolite (was prepared with different ratios of zeolite and nano Fe3O4. First, the best pH with maximum absorption was obtained. Then the effect of contact time, amount of adsorbent, temperature and initial concentration of nitrate was investigated. In the next step, pseudo-first-order kinetic model and pseudo-second-order kinetic model were used to evaluate the absorption process speed. X-ray diffraction analysis was used to check the characteristics of the sample such as lattice geometry and determine the size of the crystals.
Results: The results of XRD analysis confirmed the presence of iron oxide on zeolite and indicated that the desired composite has been produced. The experiments of this study showed that the composite with 30% nano Fe3O4 has the highest efficiency (70%) for
nitrate absorption. The results of investigating the effect of effective parameters on the absorption process showed that the effect of temperature on the amount of absorption can be ignored. Examining the effect of pH on nitrate removal shows that the highest percentage of nitrate removal is 81% at pH=5. Investigating the effect of contact time showed that the maximum amount of nitrate removal by zeolite was equal to 60% in contact time of 120 minutes and by composite was equal to 82% in contact time of 60 minutes. The results of determining the optimum adsorbent concentration stated that by increasing the amount of adsorbent five times, the removal percentage has only increased by 5%. Also, increasing nitrate concentration did not have much effect on removal percentage. Examining the absorption models showed that the Freundlich model showed a better fit and can describe the nitrate ion absorption behavior well, which indicates the inhomogeneity of the absorbent surface. Based on the results of this study the 2nd-order quasi-kinetic has a better match with the experimental data and has a high correlation coefficient and a lower mean error (MAE).
Conclusion: The prepared composite has a high ability to absorb nitrates from urban wastewater. It has been shown with the conducted studies that this composite has a high ability to remove nitrate (more than 80%) in concentrations of 5 to 400 mg/liter of nitrate.