Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

Abstract

Background: Contamination of water resources with nitrate is a serious environmental problem in many regions of the world. In addition, this problem has been observed in some regions of Iran. As Nitrate is threatening for human health and environment, it must be decreased to standard levels in drinking water. Objectives: The purpose of this research was to model the nitrate removal from water by nano-scaled zero-valent iron (nZVI) using response surface methodology and to investigate the effects of the nZVI dose, nitrate concentration, contact time, and ionic strength on removal efficiency. Materials and Methods: Box-Behnken design was used. Response surface methodology was used for modeling nitrate removal. All experiments were conducted according to standard methods. Important assessed parameters included nZVI dose (0.5-2 g/L), nitrate concentration (50-150 mg/L), contact time (15-60 minutes), and ionic strength (1000-5000 μmho/cm). Results: Results indicated that there was a direct association between nitrate removal efficiency and time and nZVI dosage. Therefore, increasing of the contact time or nZVI dose would increase nitrate removal. On the other hand, the nitrate removal was decreased when ionic strength and initial concentration were increased. The analysis of variance revealed that the proposed regression model could be appropriately used to design experiments. The model correlation coefficient was 0.9992 and the adjusted value was 0.9982. Conclusions: Response surface methodology and Box-Behnken design were powerful statistical tools for navigating nitrate reduction process. The results showed that a high percentage of nitrate were reduced by nZVI and this method might be efficiently used for nitrate removal from water.

Synthesis of TiO2/nZVI nanocomposite for nitrate removal from aqueous solution

“…This removal decrease may be because of the competitive adsorption among NO 3 − and interfering Cl − ions toward the adsorbent. Similar findings were reported by Kim and Zazouli in their works on nitrate adsorption by nZVI [22,64]. Ali et al [33] also reported the same result for atrazine herbicide adsorption onto the iron nanocomposite.…”

A System Dynamics Model to Analyze Nitrate and Ammonia in Reservoirs and Lakes

“…Therefore by increasing the contact time and level of NZVI, nitrate removal rate increases as well. In other words, by increase of ionic strength and initial concentration, nitrate removal is reduced (18).…”

Development of a predictive model of the limiting current density of an electrodialysis process using response surface methodology

“…Response surface methodology (RSM) is such one. RSM is an effective technique for analyzing the interactions among factors, exploring the relationships between the response and the independent variables, and optimizing the processes or products where multiple variables may influence the outputs (Wang et al 2010, Zazouli et al 2014, Fouladitajar et al 2014, Mourabet et al 2012.…”

“…The main advantage of RSM is the small number of experimental trials needed to evaluate multiple parameters and their interactions (Wang et al 2010, Zazouli et al 2014, Fouladitajar et al 2014, Boubakri et al 2014a, and this makes the optimization process more efficient and costeffective in terms of both manpower and resources.…”