Chlorate reduction by dithionite/UV advanced reduction process

Jung, Byungjo; Sivasubramanian, Raghavendran; Batchelor, Bill; Abdel‐Wahab, Ahmed

doi:10.1007/s13762-016-1132-y

Cited by 38 publications

(6 citation statements)

References 40 publications

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“…In acid medium with sulfuric acid, sodium sul te reacts with H + to form H 2 SO 3 , as presented in Equation (4), in which k 1 1.54 × 10 −2 and k 2 1.02 × 10 −7 . Besides, sodium dithionite and sodium sul te are di erent, and both dissociate to form sodium bisul te, which is the main responsible for the reducing process in solution, but sodium dithionite also dissociates to form sodium thiosulfate [27,[34][35][36][37].…”

Section: Ion Exchange Experiments Ion Exchange Experimentsmentioning

confidence: 99%

Pre-Reducing Process Kinetics to Recover Metals from Nickel Leach Waste Using Chelating Resins

Botelho

Dreisinger

Espinosa

et al. 2018

International Journal of Chemical Engineering

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The main problem of the separation process from nickel mining using the ion exchange technique is the presence of iron, which precipitates in pH above 2.00 and causes coprecipitation of copper and cobalt. Chelating resins have the main advantage of being selected for a specific metal present in solution. Studies have been developed to increase the efficiency of metals recovery using chemical reduction and the ion exchange process to recover metals. The aim of this work was to use sodium sulfite as a reducing agent to convert Fe(III) to Fe(II). Chelating resins Lewatit® TP 207, selective for copper, and Lewatit® TP 220, selective for nickel and cobalt, were studied. Batch experiments were performed to study the effect of pH with and without sodium sulfite. Results indicated that the industrial process has increased efficiency when the reducing process is applied.

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Section: Ion Exchange Experiments Ion Exchange Experimentsmentioning

confidence: 99%

Pre-Reducing Process Kinetics to Recover Metals from Nickel Leach Waste Using Chelating Resins

Botelho

Dreisinger

Espinosa

et al. 2018

International Journal of Chemical Engineering

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“…In spite of this, sulfite has recently been attractively selected as a common reductant (E SOd 3 2− /SOd 4 2− 0 = −0.93 V NHE ) for removing some oxidative inorganic ions. 27,28 Considering the analogous oxidation ability of all the ClO x − constituents, it was reasonably expected that the utilization of sulfite would be able to effectively remove ClO x − from the EO-treated water samples. Based on our previous study, 29 a sulfite-based reduction countermeasure was developed and successfully applied in the removal of ClO 3 − with a concentration below 5 mM in the wastewaters.…”

Section: Introductionmentioning

confidence: 99%

“…Although the transformation of ClO 4 – , ClO 3 – , and ClO 2 – into Cl – by catalytic reduction or enzymatic catalysis has been proven effective, − their obvious drawbacks including cumbersome operating steps and highly demanding reaction conditions made these methods inapplicable in the elimination of ClO x – interference on the COD test. In spite of this, sulfite has recently been attractively selected as a common reductant ( E SO 3 2– /SO 4 2– 0 = −0.93 V NHE ) for removing some oxidative inorganic ions. , Considering the analogous oxidation ability of all the ClO x – constituents, it was reasonably expected that the utilization of sulfite would be able to effectively remove ClO x – from the EO-treated water samples. Based on our previous study, a sulfite-based reduction countermeasure was developed and successfully applied in the removal of ClO 3 – with a concentration below 5 mM in the wastewaters.…”

Section: Introductionmentioning

confidence: 99%

Overevaluation of Electro-oxidation for Chemical Oxygen Demand Removal Using a Boron-Doped Diamond Anode: The Roles of Various Electrogenerated Oxychlorides and Countermeasure

et al. 2023

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Electrochemical oxidation using a boron-doped diamond (BDD) anode has been extensively investigated in various wastewater treatments, where the electrogenerated oxychlorides (ClO x –, x = 1 to 4) from Cl– oxidation have been well illustrated. However, the false chemical oxygen demand (COD) reduction induced by ClO x – adulteration has been almost completely overlooked when evaluating the electrochemical wastewater treatment performance. In this study, it was revealed that all the ClO x – species except ClO4 – served as strong oxidants in lieu of dichromate to degrade organic matter under digestion conditions during the COD test procedure. To eliminate the interference of ClO x – mixtures on the assessment of electrochemical COD removal performance, the modified sulfite-based reduction method was developed for the electrochemical case to remove ClO x – mixtures from the BDD-treated water samples before the COD test. It was demonstrated that the unadulterated COD removal performance of the BDD-based electrochemical system used for both synthetic and real wastewater treatments could be obtained after sulfite-based reduction of the electrogenerated ClO x – mixtures within 30 min in a sealed reaction chamber with the molar [sulfite]ini/[ClO x –]ini ratio of 1–3, where the reactants were isochronously depleted without producing oxidative radicals (SO4 •– and •OH). Due to extreme lack of oxygen in the sealed ClO x –-sulfite system, radical propagation reactions were terminated and ClO x – constituents (ClO3 –, ClO2 –, and ClO–) were reduced by sulfite stoichiometrically via the oxygen transfer process with Cl– and SO4 2– as the final products. This new sulfite-based protocol could be regarded as a robust and adulteration-proof countermeasure for evaluating the real COD removal performance of an electrochemical system.

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“…Ultraviolet-based advanced reduction processes (UV-ARP) have received significant attention in recent years for the treatment of several classes of recalcitrant chemical contaminants in water. − Advanced reduction processes are based on production of highly reducing hydrated electrons (e aq – , Figure ), which exhibit fast bimolecular reaction rate constants with inorganic and organic compounds . In UV-ARP, e aq – are produced by the illumination of e aq – sensitizers with UV lamps.…”

Section: Introductionmentioning

confidence: 99%

“…A patent by Bolton and Cater in 1993 detailing the treatment of wastewater or groundwater containing chloroform as a model halogenated organic with UV/iodide, UV/thiosulfate, UV/sulfite, and UV/iodide/thiosulfate as the e aq – source was one of the first reports of this technology . Subsequent UV-ARP studies have focused on substrates that can undergo reduction by e aq – reaction such as oxyanions, ,− highly oxidized elements (e.g., Cr(VI)), , halogenated disinfection byproducts, ,, and per- and polyfluoroalkyl substances (PFAS). − Several bench-scale studies − and a recent pilot-scale demonstration suggest that UV-ARP is one of the more promising technologies for degrading PFAS, which are resistant to direct photolysis and UV-AOP. ,, …”

Section: Introductionmentioning

confidence: 99%

Critical Review of UV-Advanced Reduction Processes for the Treatment of Chemical Contaminants in Water

2022

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UV-advanced reduction processes (UV-ARP) are an advanced water treatment technology characterized by the reductive transformation of chemical contaminants. Contaminant abatement in UV-ARP is most often accomplished through reaction with hydrated electrons (e aq − ) produced from UV photolysis of chemical sensitizers (e.g., sulfite). In this Review, we evaluate the photochemical kinetics, substrate scope, and optimization of UV-ARP. We find that quantities typically reported in photochemical studies of natural and engineered systems are under-reported in the UV-ARP literature, especially the formation rates, scavenging capacities, and concentrations of key reactive species like e aq − . The absence of these quantities has made it difficult to fully evaluate the impact of operating conditions and the role of water matrix components on the efficiencies of UV-ARP. The UV-ARP substrate scope is weighted heavily toward contaminant classes that are resistant to degradation by advanced oxidation processes, like oxyanions and per-and polyfluoroalkyl substances. Some studies have sought to optimize the UV-ARP treatment of these contaminants; however, a thorough evaluation of the impact of water matrix components like dissolved organic matter on these optimization strategies is needed. Overall, the data compilation, analysis, and research recommendations provided in this Review will assist the UV-ARP research community in future efforts toward optimizing UV-ARP systems, modeling the e aq − -based chemical transformation kinetics, and developing new UV-ARP systems.

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Chlorate reduction by dithionite/UV advanced reduction process

Cited by 38 publications

References 40 publications

Pre-Reducing Process Kinetics to Recover Metals from Nickel Leach Waste Using Chelating Resins

Pre-Reducing Process Kinetics to Recover Metals from Nickel Leach Waste Using Chelating Resins

Overevaluation of Electro-oxidation for Chemical Oxygen Demand Removal Using a Boron-Doped Diamond Anode: The Roles of Various Electrogenerated Oxychlorides and Countermeasure

Critical Review of UV-Advanced Reduction Processes for the Treatment of Chemical Contaminants in Water

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