Abstract
The life-threatening nature of high nitrate concentrations in various water resources motivated the present study to investigate the nitrate adsorption by ZSM-5 nanozeolite and the feasibility of increasing nitrate removal efficiency using iron-doped ZSM-5 (ZSM-5/Fe) nanosorbent. Energy dispersive X-ray diffraction analysis was employed to determine the physical properties of the adsorbent and the presence of iron particles in the nanosorbent structure and BET analysis to measure the specific surface area of the nanosorbent. The optimal adsorption conditions were determined first by modeling the central composite design (CCD) using Design Expert.7 software based on four influential factors . Then, the isotherms of nitrate adsorption under optimized conditions were investigated using the degree of fit of experimental data with Langmuir and Freundlich models for mathematical modeling of the nitrate adsorption process. Based on the test design results, the highest nitrate removal efficiency (%93.1) was reported at the contact time of 150 min, pH value of 3, adsorbent dosage of 4 g/l and initial concentration of 40 mg/l. Analysis of adsorption isotherms also confirmed the greater fit of the experimental data with the Freundlich equation, so that the correction factor of the Freundlich equation was greater than the Langmuir equation.
Highlights
Nitrate is known to be one of the most serious threats to human health in the world, which enters the human body through the penetration into groundwater and surface water resources following the excessive use of chemical fertilizers and uncontrolled discharge without nitrification of municipal and industrial wastewater in the environment [1,2,3]
Optimization and experimental design In this research, the experimental design using response surface methodology (RSM) in combination with central composite design (CCD) method was performed to investigate the effects of influential variables of pH (A), contact time (30-180 minutes) (B) and adsorbent dosage (1-5 g L-1) (C) on nitrate removal efficiency
The highest nitrate removal efficiency was reported at the contact time of 150 min, pH value of 3, adsorbent dosage of 4 g L-1 and initial concentration of 40 mg L-1
Summary
Nitrate is known to be one of the most serious threats to human health in the world, which enters the human body through the penetration into groundwater and surface water resources following the excessive use of chemical fertilizers and uncontrolled discharge without nitrification of municipal and industrial wastewater in the environment [1,2,3]. Hafeshjani et al used sugarcane residues to remove nitrate from aqueous solutions, and investigated the physicochemical properties of the adsorbent such as morphology, element composition, ion exchange capacity and specific surface area They measured parameters such as pH, adsorbent dosage, contact time, initial nitrate concentration and temperature using different adsorption kinetic models such as Freundlich, Langmuir and others. Sepehri et al presented a natural zeolite-supported zero-valent iron nanoparticles (ze-Nzvi adsorbent) using the sodium borohydride reduction method with the aim of removing nitrate from aqueous solution They measured the parameters of contact time, adsorbent dosage, initial nitrate concentration, initial pH, the results of which showed that the nitrate removal efficiency was decreased with increasing the initial solution pH and the adsorbent dosage but elevated with increasing the initial nitrate concentration [32]. They tested the effect of pH, sand and iron particles parameters on nitrate removal efficiency
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
