Effects of water characteristics on nitrate reduction by the Fe0/CO2 process

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.

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“…-reduction (42). The results of our study indicated that by increase in the ionic strength, the nitrates removal decreases.…”

Section: Association Between Removal Efficacy and Ionic Strength And mentioning

confidence: 49%

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

2014

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“…entering the water, blocking of the reaction by Fe(OH) 3 precipitation and low standard potential (E 0 ) (Eqs. 1-3) [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 98%

Experimental investigation of the chemical reduction of nitrate ion in aqueous solution by Mg/Cu bimetallic particles

Ramavandi

Mortazavi

Moussavi

et al. 2011

Reac Kinet Mech Cat

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Bimetallic particles have recently been used as a new means of contaminant reduction from water. Comparing with Fe 0 and Mg 0 alone, synthesized magnesium/copper (Mg/Cu) bimetallic particles have been determined to be potential and efficient agents for nitrate reduction from aqueous solutions. This study suggests that the reductive denitrification of nitrate by Mg/Cu bimetallic particles was dependent on a number of parameters including reductant dose, solution temperature, initial nitrate concentration and contact time. The 1% Mg/Cu (Cu loading of 1 wt.%) bimetallic particles removed the majority of the various nitrate concentrations tested (50, 100, 150, 200 and 300 mg/L) within a short period. The time required for the removal of 90.6% of the NO 3 -from a 100-mg/L solution was about 20 min using 2 g/L bimetallic Mg/Cu at an initial solution pH of 6. The activation energy (E a ) for the nitrate reduction by 1% Mg/Cu over the temperature range of 5-60°C was 12.77 kJ/mol. The experimental results of the kinetic analysis from batch studies indicated that a higher initial nitrate concentration yielded a greater reaction rate constant and the denitrification rate increased with increasing 1% Mg/Cu dosage. The effects of mixing rate on the denitrification rate suggested that the reaction rate increases linearly at mixing rate \100 rpm and remained almost constant at rates over that.

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“…Thus, the process requires acidic conditions to achieve the best performances. Several compounds, such as H2SO4, HCl, acetic acid and buffered agents, were used to speed up the rate of nitrate removal [3]. However, these methods are not convenient in practical applications, because the costs are significantly increased and because the release into waters of undesired compounds, such as sulfate, chloride etc., occurs.…”

Section: Introductionmentioning

confidence: 99%

Use of Nanoscale Zero-Valent Iron (NZVI) Particles for Chemical Denitrification under Different Operating Conditions

Siciliano

2015

Metals

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Abstract:The nitrate pollution of waters and groundwaters is an important environmental and health concern. An interesting method to remove the oxidized forms of nitrogen from waters and wastewaters is chemical denitrification by means of metallic iron (Fe 0 ).Particularly advantageous is the use of nanoscopic zero-valent iron particles due to the elevated surface area, which allows reaching extremely high reaction rates. In the present paper, the efficiency of nitrate reduction by means of nanoscopic Fe 0 has been investigated under several operating conditions. The iron nanoparticles were synthesized by the chemical reduction of ferric ions with sodium borohydride. The effects of Fe 0 dosage, initial N-NO3 − concentration and pH on chemical denitrification were identified. In particular, the results of the tests carried out showed that it is possible to reach an almost complete nitrate reduction in treating solutions with a nitrate nitrogen concentration higher than 50 mg/L. Moreover, the process performance was satisfactory also under uncontrolled pH. By means of the trends detected during the experiments, the kinetic-type reaction was identified. Furthermore, a relation between the kinetic constant and the process parameters was defined.

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Effects of water characteristics on nitrate reduction by the Fe0/CO2 process

Cited by 53 publications

References 15 publications

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

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

Experimental investigation of the chemical reduction of nitrate ion in aqueous solution by Mg/Cu bimetallic particles

Use of Nanoscale Zero-Valent Iron (NZVI) Particles for Chemical Denitrification under Different Operating Conditions

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