Effects of Natural Water Ions and Humic Acid on Catalytic Nitrate Reduction Kinetics Using an Alumina Supported Pd−Cu Catalyst

Chaplin, Brian P.; Roundy, Eric; Guy, Kathryn A.; Shapley, John R.; Werth, Charles J.

doi:10.1021/es0525298

Cited by 155 publications

(137 citation statements)

References 35 publications

(78 reference statements)

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“…accumulation, in a reaction system with Pd-based bimetallic catalysts at high pH conditions, was attributed to electrostatic repulsion between nitrite and the negatively charged surface of particles (Chaplin et al, 2006;Prusse and Vorlop, 2001). In our experiment, while nitrite accumulation was detected at pH 9, we did not observe nitrite accumulation at pH 8.5 despite the IEP of nZVI being pH 8.1.…”

Section: Effect Of Low Levels Of Cd(ii) On Nitrate Reductionmentioning

confidence: 99%

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

et al. 2014

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a b s t r a c tNanoscale zerovalent iron (nZVI) has demonstrated high efficacy for treating nitrate or cadmium (Cd) contamination, but its efficiency for simultaneous removal of nitrate and Cd has not been investigated. This study evaluated the reactivity of nZVI to the cocontaminants and by-product formation, employed different catalysts to reduce nitrite yield from nitrate, and examined the transformation of nZVI after reaction. Nitrate reduction resulted in high solution pH, negatively charged surface of nZVI, formation of Fe 3 O 4 (a stable transformation of nZVI), and no release of ionic iron. Increased pH and negative charge contributed to significant increase in Cd(II) removal capacity (from 40 mg/g to 188 mg/g) with nitrate present. In addition, nitrate reduction by nZVI could be catalyzed by Cd(II): while 30% of nitrate was reduced by nZVI within 2 h in the absence of Cd(II), complete nitrate reduction was observed in the presence of 40 mg-Cd/L due to the formation of Cd islands (Cd(0) and CdO) on the nZVI particles. While nitrate was reduced mostly to ammonium when Cd(II) was not present or at Cd(II) concentrations ! 40 mg/L, up to 20% of the initial nitrate was reduced to nitrite at Cd(II) concentrations < 40 mg/L. Among nZVI particles doped with 1 wt. % Cu, Ag, or Au, nZVI deposited with 1 wt. % Au reduced nitrite yield to less than 3% of the initial nitrate, while maintaining a high Cd(II) removal capacity.© 2014 Elsevier Ltd. All rights reserved. Available online at www.sciencedirect.com ScienceDirect journal homepage: www.else vier.com/locate /wa tres w a t e r r e s e a r c h 6 3 ( 2 0 1 4 ) 1 0 2 e1 1 1http://dx

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Section: Effect Of Low Levels Of Cd(ii) On Nitrate Reductionmentioning

confidence: 99%

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

et al. 2014

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“…These studies are mainly carried out in batch reactors and with distilled water containing only nitrates [4,[22][23][24][25]. Nevertheless, the presence of other ions in the reaction media could influence the activity and selectivity of the catalyst [26][27][28], for this reason it is important to study the activity of the bimetallic catalysts supported on different materials, but using polluted natural water that contains other ions together with the nitrates and preferably with a continuous reactor.…”

Section: Introductionmentioning

confidence: 99%

A study of different supports for the catalytic reduction of nitrates from natural water with a continuous reactor

2011

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The aim of this work is to study the activity for the nitrate catalytic reduction in natural water, using a continuous stirred tank reactor, of Pd/Cu and Pd/Sn catalysts supported on different materials. The studied supports are: -Al 2 O 3 (commercial), active carbon, graphite, hydrotalcite and alumina synthesized in our laboratory with a high surface area. The activity and selectivity of the catalysts supported on these materials have been compared. The best results have been obtained with the Pd/Sn catalysts supported on alumina. These results show that the surface area of the support is not the only important characteristic for an active catalyst in this reaction, being also very significant its acid-base properties, its electrical conductivity and its interaction with the metallic active sites. The adequate combination of these characteristics is necessary to obtain an active catalyst. The influence of the Pd/Sn content on the activity of the alumina supported catalysts was studied, observing that the best activity was obtained when the Pd/Sn ratio was higher than 1. This result clearly indicates that it is necessary to have both Pd and Pd-Sn centers in order to obtain an active catalyst.

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“…Reports have shown the influence of ions in water on the reduction of NO [25,26]. Reports have shown that the presence of SO 4 2-in water slightly affects the catalytic performance [6,15].…”

Section: Introductionmentioning

confidence: 99%

“…Studies have shown that HCO 3 -lowers the reaction rate for the reduction of NO 3 - [11,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Remediation of actual groundwater polluted with nitrate by the catalytic reduction over copper–palladium supported on active carbon

Wang

Sakamoto

Kamiya

2009

Applied Catalysis A: General

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Catalytic reduction of nitrate (NO 3 -) in groundwater over a Cu-Pd catalyst supported on active carbon was investigated in a gas-liquid co-current flow system at 298 K. Although CuPd/active carbon, in which the Cu/Pd molar ratio was more than 0.66, showed high activity, high selectivity for the formation of N 2 and N 2 O (98%), and high durability for the reduction of 100 ppm NO 3 -in distilled water, the catalytic performance decreased during the reduction of NO 3 -in groundwater. The catalyst also irreversibly deactivated during the reaction in groundwater. The organic species in the groundwater caused the decrease in the catalytic performance and the irreversible catalyst deactivation. Ozone-treatment of the groundwater to remove the organic species substantially helped to maintain the catalytic activity and to halt the irreversible deactivation of the catalyst. Chloride ion (Cl -) in the groundwater also caused the decrease in the activity and selectivity, but the effects of Cl -were reversible. Sulfate ion (SO 4 2-) and cations, including Mg 2+ , Ca 2+ and K + , had little or no effect on the catalytic performance of Cu-Pd/active carbon, though they were present in the groundwater sample.More than an allowable level of NH 3 (NH 4 + ) was formed during the catalytic reduction of NO 3 -in the groundwater, but was completely removed by the cation-exchange process using Namordenite.3

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Effects of Natural Water Ions and Humic Acid on Catalytic Nitrate Reduction Kinetics Using an Alumina Supported Pd−Cu Catalyst

Cited by 155 publications

References 35 publications

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles

A study of different supports for the catalytic reduction of nitrates from natural water with a continuous reactor

Remediation of actual groundwater polluted with nitrate by the catalytic reduction over copper–palladium supported on active carbon

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