Kinetics of reductive denitrification by nanoscale zero-valent iron

Choe, Sangmin; Chang, Yoon Young; Hwang, Kyung Yub; Khim, Jong Seong

doi:10.1016/s0045-6535(99)00506-8

Cited by 339 publications

(196 citation statements)

References 5 publications

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“…This profile reflects the fact that the reactive site concentration increases proportionally with RWZVIP concentration. 28 The pH effect on the degradation of RBB by Fe 0 is presented in Figure 5. In acid solutions the RBB removal efficiency varies from 80.1% to 98.2%.…”

Section: Resultsmentioning

confidence: 99%

Azo dye degradation by recycled waste zero-valent iron powder

Pereira¹,

Freire²

2006

J. Braz. Chem. Soc.

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Neste trabalho é apresentado um método eficiente para a degradação de corantes, usando uma fonte de pó de ferro zero ambientalmente amigável (resíduo de um processo industrial). A influência de vários fatores experimentais (tais como: pH, massa de ferro, tamanho de partícula, concentração do substrato, atmosfera inerte ou oxidante) sobre a eficiência do ferro zero em reduzir o grupo cromóforo e o teor de carbono orgânico total de um azocorante (Preto Remazol B) foi avaliada. O processo de degradação do corante apresentou uma cinética de primeira ordem com uma constante de 0,153 min -1 . Nas condições otimizadas (pH=3, [Fe] = 5 g L -1 , tamanho de partícula ≤ 250 μm), este processo promoveu uma descoloração de 95% e redução de 70% na concentração de carbono orgânico total de uma solução 100 mg L -1 do corante. Este processo também foi empregado na degradação de um efluente industrial têxtil apresentando bons resultados e demonstrando capacidade para ser uma alternativa para a remediação de sistemas aquáticos poluídos.In this paper an efficient method for azo dye degradation using an environmentally friendly zero-valent iron powder source is presented (iron particles discarded from a manufacturing process). The influence of several experimental parameters (such as pH, iron mass, particle size, substrate concentration, oxidizing and inert atmospheres) on the ability of zero-valent iron to reduce the chromophoric groups and total organic carbon content of the azo dye Remazol Black B was evaluated. Kinetic studies revealed that the azo degradation by Fe 0 appeared to be first-order with respect to substrate, with an observed rate constant (k obs ) of 0.153 min -1 . Under the optimized operational conditions (pH 3, [Fe] = 5 g L -1 , iron particle size ≤ 250 μm), the iron-based process produced net a reduction in color and total organic carbon of about 95% and 70%, respectively. The process was also evaluated for the degradation of textile effluent. The studied process showed good characteristics, which can make it an effective alternative for polluted aquatic system remediation.Keywords: reductive degradation process, dye degradation, effluent treatment, Fenton´s reagent IntroductionOver the last decades, the increasing demand for dyes by the textile industry has shown a high pollutant potential. It is estimated that around 10 -15% of the dyes are lost in the effluent during the dyeing processes. 1,2 The discharge of highly colored synthetic dye effluents can be very damaging to the receiving water bodies, since these dyes in the water strongly absorb sunlight, which decreases the intensity of light absorbed by water plants and phytoplankton, reducing photosynthesis and the oxygenation of water reservoirs. 3 Also, public perception of water quality is greatly influenced by its color. The presence of unnatural colors is esthetically unpleasant and tends to be associated with contamination. 4 In addition, dyes used in the textile industry may be toxic to aquatic organisms and can be resistant to natural biological deg...

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Section: Resultsmentioning

confidence: 99%

Azo dye degradation by recycled waste zero-valent iron powder

Pereira¹,

Freire²

2006

J. Braz. Chem. Soc.

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“…However, complete reduction of nitrate was never observed. Most of the previous studies achieved 100% removal of nitrate using freshly prepared ZVI particles that were used immediately after the synthesis because these particles are unstable in air [18,19], which was limited by purging inert gas into the reaction medium and ZVI storage containers [20][21][22][23]. Only few studies [24,25] were carried out using ZVI supported composites.…”

Section: Effect Of Initial Ph Value On the Reduction Of Nitratementioning

confidence: 99%

Chemical reduction of nitrate by zerovalent iron nanoparticles adsorbed radiation-grafted copolymer matrix

Ratnayake¹,

Ratnayake²,

Schild

et al. 2017

Nukleonika

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Abstract. This research specifi cally focused on the development of a novel methodology to reduce excess nitrate in drinking water utilizing zerovalent iron nanoparticles (nZVI)-stabilized radiation-grafted copolymer matrix. nZVI was synthesized by borohydrate reduction of FeCl 3 and stabilized on acrylic acid (AAc)-grafted non-woven polyethylene/polypropylene (NWPE/PP-g-AAc) copolymer matrix, which was grafted using gamma radiation. The use of nZVI for environmental applications is challenging because of the formation of an oxide layer rapidly in the presence of oxygen. Therefore, radiation-grafted NWPE/PP synthetic fabric was used as the functional carrier to anchor nZVI and enhance its spreading and stability. The chemical reduction of nitrate by nZVI-adsorbed NWPE/PP-g-AAc (nZVI-Ads-NWP) fabric was examined in batch experiments at different pH values. At low pH values, the protective layers on nZVI particles can be readily dissolved, exposing the pure iron particles for effi cient chemical reduction of nitrate. After about 24 h, at pH 3, almost 96% of nitrate was degraded, suggesting that this reduction process is an acid-driven, surface-mediated process. The nZVI-water interface has been characterized by the 1-pK Basic Stern Model (BSM). An Eley-Rideal like mechanism well described the nitrate reduction kinetics. In accordance with green technology, the newly synthesized nZVI-Ads--NWP has great potential for improving nitrate reduction processes required for the drinking water industry.

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“…In this respect, different stoichiometric reactions have been suggested for describing the nZVI enhanced NO 3 − reduction [13][14][15]. Apparently, only one study [16] concluded that nitrate was reduced predominantly to N 2(g) as the end product. All other studies reported that between 85% and 90% of the nitrate was reduced to TAN and only the rest of the nitrate (i.e., less than 15%) was reduced to N 2(g) (e.g., [17][18][19]).…”

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confidence: 99%

“…Other studies (e.g., [13,14]) reported that almost 100% of the NO 3 − was reduced to TAN. The reports on the portion of N 2(g) vs. TAN formation have been thus far based mainly on nitrogen species mass balance calculations [16,17]. Accordingly, the following reaction is considered by many (e.g., [17,20]) to represent the predominant reaction between nZVI and NO 3 − at the acidic to neutral pH range:…”

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confidence: 99%

“…To sum up the kinetics part: the results of most of the works reviewed by us show that the time required for complete nitrate removal from an initial nitrate concentrations lower than 120 mg N/L was typically 30 min or more [13,16,19,24]. On the other hand, working with a very high initial nitrate concentration of 10,000 mg N/L, Ryu et al [14] reported a very rapid removal rate (reduction of 5000 mg N/L in one minute).…”

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confidence: 99%

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Removal of Nitrate from Drinking Water by Ion-Exchange Followed by nZVI-Based Reduction and Electrooxidation of the Ammonia Product to N2(g)

et al. 2017

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Ion-exchange (IX) is common for separating NO 3− from drinking water. From both cost and environmental perspectives, the IX regeneration brine must be recycled, via nitrate reduction to N 2(g) . Nano zero-valent iron (nZVI) reduces nitrate efficiently to ammonia, under brine conditions. However, to be sustainable, the formed ammonia should be oxidized. Accordingly, a new process was developed, comprising IX separation, nZVI-based nitrate removal from the IX regeneration brine, followed by indirect ammonia electro-oxidation. The aim was to convert nitrate to N 2(g) while allowing repeated usage of the NaCl brine for multiple IX cycles. All process steps were experimentally examined and shown to be feasible: nitrate was efficiently separated using IX, which was subsequently regenerated with the treated/recovered NaCl brine. The nitrate released to the brine reacted with nZVI, generating ammonia and Fe(II). Fresh nZVI particles were reproduced from the resulting brine, which contained Fe(II), Na + , Cl − and ammonia. The ammonia in the nZVI production procedure filtrate was indirectly electro-oxidized to N 2(g) at the inherent high Cl − concentration, which prepared the brine for the next IX regeneration cycle. The dominant reaction between nZVI and NO 3 − was described best (Wilcoxon test) by 4Fe (s) + 10H + + NO 3 − → 4Fe 2+ + NH 4 + + 3H 2 O, and proceeded at >5 mmol·L −1 ·min −1 at room temperature and 3 < pH < 5.

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Kinetics of reductive denitrification by nanoscale zero-valent iron

Cited by 339 publications

References 5 publications

Azo dye degradation by recycled waste zero-valent iron powder

Azo dye degradation by recycled waste zero-valent iron powder

Chemical reduction of nitrate by zerovalent iron nanoparticles adsorbed radiation-grafted copolymer matrix

Removal of Nitrate from Drinking Water by Ion-Exchange Followed by nZVI-Based Reduction and Electrooxidation of the Ammonia Product to N2(g)

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