Formation of hypochlorite, chlorate and oxygen during NaCl electrolysis from alkaline solutions at an RuO2/TiO2 anode

Czarnetzki, LR; Janssen, Ljj Jos

doi:10.1007/bf01092683

Cited by 139 publications

(98 citation statements)

References 19 publications

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“…Based on their observations, they proposed that hypochlorite ion is the active chlorine species that is converted electrochemically to chlorate, whereas hypochlorous acid would rather be converted chemically to chlorate, but in a less efficient reaction. The electrochemical conversion of active chlorine to chlorate under alkaline and neutral conditions has also been proposed by several studies [38,44]. In our experiments, the strong buffering effect of carbonate could have enhanced the electrochemical (in alkaline solutions) and chemical (in slightly acidic solutions) conversion of active chlorine to chlorate (Eqs.…”

Section: Hypochlorite Consumptionsupporting

confidence: 76%

Effects of carbonate on the electrolytic removal of ammonia and urea from urine with thermally prepared IrO2 electrodes

et al. 2012

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Recent studies have shown that electrolysis can be an efficient process for nitrogen removal from urine. These studies have been conducted with urea solutions or fresh urine, but urine collected in NoMix toilets and urinals has a substantially different composition, because bacteria hydrolyse urea quickly to ammonia and carbonate. In this study, we compared electrochemical removal of nitrogen from synthetic solutions of fresh and stored urine using IrO 2 anodes. We could show that in fresh urine both ammonia and urea are efficiently eliminated, mainly through chlorine-mediated oxidation. However, in stored urine the presence of carbonate, arising from urea hydrolysis, leads to an inhibition of ammonia oxidation. We suggest two parallel mechanisms to explain this effect: the competition between chloride and carbonate oxidation at the anode and the competition between chlorate formation, enhanced by the buffering effect of carbonate, and ammonia oxidation for the consumption of active chlorine in the bulk. However, further experiments are needed to support the latter mechanism. In conclusion, this study highlights the negative consequences of the presence of carbonate in urine solutions, but also in other wastewaters, when subjected to an electrolytic treatment on IrO 2 in alkaline media.

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Section: Hypochlorite Consumptionsupporting

confidence: 76%

Effects of carbonate on the electrolytic removal of ammonia and urea from urine with thermally prepared IrO2 electrodes

et al. 2012

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“…1. The electrolysis cell has been described previously [6,7]. The anodic and cathodic compartment of the cell were separated by a cation-exchange membrane (Nation ® 117 In some cases, a shorter electrode was used in order to obtain a high current density when the potentialcurrent measurements were carried out.…”

Section: Equipmentmentioning

confidence: 99%

Mechanism of anodic oxidation of chlorate to perchlorate on platinum electrodes

Janssen

Heyden

1995

J Appl Electrochem

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The kinetics and mechanism of the anodic oxidation of chlorate to perchlorate on platinum electrodes have been investigated. The current efficiency for perchlorate formation and the electrode potential have been determined as a function of current density for various solution compositions, flow rates and pHs at 50 ° C. The results have been compared with theoretical relations between the ratio of the current efficiencies for perchlorate and oxygen formation, the electrode potential, the concentration of chlorate at the electrode surface and the current density for various possible mechanisms. It is concluded that the formation of an adsorbed hydroxyl radical is the first step in the overall electrode reaction. The mechanism proposed for the C104 perchlorate and oxygen formation is:The ratio between the current efficiency for perchlorate and that for oxygen formation is determined by the rate of the electrode reaction involving C103 and that for the combination reaction of (OH)a d. List of symbols

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“…In the case without Cl À , the degradation of MCs is derived from direct oxidation of anode. But in the presence of Cl À , the concentration of C1 À became the key factor to influence the MCs removal, because of its effect on the production of active chlorine (Czarnetzki and Janssen, 1992;Yang et al, 2000). Therefore, the oxidation of active chlorine in bulk with Cl À played a more important role in the removal of MCs than direct one.…”

Section: Effect Of Initial Concentration Of CL à In Electrolytementioning

confidence: 99%

Degradation of microcystins in aqueous solution with in situ electrogenerated active chlorine

Shi

Wang

et al. 2005

Chemosphere

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A new and efficient method for the degradation of microcystins (one family of blue algal toxins) was developed and studied. Microcystins (MCs) in water were directly and effectively removed by active chlorine transformed in situ from the naturally existing Cl À in water resource using electrochemical method. , 20°C and pH 7.00. The qualitative analysis showed that the heptapetide ring and the Adda group of both treated MCs were changed. The results also indicated that the removal rates of both MCs increased with the increasing of chloride concentration and applied current density, but decreased with the increasing of initial concentration of MCs and initial pH of electrolyte. In the absence of Cl À , only a small fraction of both MCs were decomposed by direct anodic oxidation, while their almost complete removals could be obtained in the case of indirect electrooxidation with in situ electrogenerated active chlorine from Cl À in water.

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Formation of hypochlorite, chlorate and oxygen during NaCl electrolysis from alkaline solutions at an RuO2/TiO2 anode

Cited by 139 publications

References 19 publications

Effects of carbonate on the electrolytic removal of ammonia and urea from urine with thermally prepared IrO2 electrodes

Effects of carbonate on the electrolytic removal of ammonia and urea from urine with thermally prepared IrO2 electrodes

Mechanism of anodic oxidation of chlorate to perchlorate on platinum electrodes

Degradation of microcystins in aqueous solution with in situ electrogenerated active chlorine

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