The behavior of dissolution/passivation and the transformation of passive films during electrocoagulation: Influences of initial pH, Cr(VI) concentration, and alternating pulsed current

Yang, Zhen; Xu, Haiyin; Zeng, Guangming; Luo, Yuanling; Yang, Xin; Huang, Jing; Wang, Like; Song, Peipei

doi:10.1016/j.electacta.2014.11.183

Cited by 99 publications

(36 citation statements)

References 45 publications

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“…Visual inspection of the field electrodes used by Amrose et al (2014) showed modifications of the electrode surface consistent with the presence of a macroscopic layer of oxidized Fe. Such macroscopic surface layers on EC electrodes have been suggested to influence the long-term performance of EC field treatment (Holt et al, 2005;Eyvaz et al, 2014;Xu et al, 2015;Yang et al, 2015), presumably by inhibiting the production and transport of electrochemically-produced ions. For example, the accumulation of Fe-bearing minerals on EC electrode surfaces was proposed by Timmes et al (2010) to lead to a reduction in EC treatment efficiency of seawater over several days.…”

Section: Introductionmentioning

confidence: 99%

Formation of macroscopic surface layers on Fe(0) electrocoagulation electrodes during an extended field trial of arsenic treatment

et al. 2016

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Section: Introductionmentioning

confidence: 99%

Formation of macroscopic surface layers on Fe(0) electrocoagulation electrodes during an extended field trial of arsenic treatment

et al. 2016

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“…Oxide layer formation over aluminium electrode surface generates passivation effect and chloride addition in an electrolytic system make the corrosion potential negative, which leads to better surface activation of sacrificial anodes . Higher chloride concentration in the electrolyte results in pitting corrosion of anode surface as explained by Mouedhen et al .…”

Section: Resultsmentioning

confidence: 98%

Importance of Chloride Addition on Arsenite Removal by Aluminium Electrocoagulation

et al. 2020

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Effect of chloride addition on arsenite removal by electrocoagulation process was carried out in this study. Electrocoagulation experiments were executed in a 5 L capacity rectangular tank equipped with 7 anodes and 7 cathodes. Addition of chloride significantly enhanced the arsenite removal efficiency of electrocoagulation process and the removal is purely by the separation process, rather than the oxidation of arsenite to arsenate by electrolytically generated active chlorine. 250 mg L−1 of chloride was found as optimal, and more than 99 % of arsenite were removed from its initial concentration of 1 mg L−1 at pH 6, applied voltage of 5 V, and 60 min of electrolysis. Sludge produced after electrocoagulation treatment was analyzed by scanning electron microscopy (SEM) / energy dispersive X‐ray analysis (EDAX), X‐ray diffraction (XRD), and Fourier transforms infrared (FTIR) techniques.

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“…It is noteworthy that when the initial pH value exceeded 12, less flocs formed and Tl(I) removal efficiency declined. The main reason for flocs' reduction may relate to the anodic passivation at higher pH, which inhibits the dissolution of the sacrificial anode [53]. The superposition factors for the flocs reduction can be attributed to the lower corrosion rate of iron, as can be seen from its corrosion rate-pH chart [30] and the formation of soluble Fe(OH) 4 − in alkaline pH [54].…”

Section: Effect Of Initial Phmentioning

confidence: 99%

Removal of Trace Thallium from Industrial Wastewater by Fe0-Electrocoagulation

Yang

et al. 2020

Water

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As thallium (Tl) is a highly toxic heavy metal, there are compulsory environmental regulations in many countries on minimizing its release. This research investigated the treatment of real industrial wastewater with low Tl(I) concentration by Fe0-electrocoagulation (Fe0-EC) in a batch aeration-forced pump cycle reactor. The effects of pH (7–12), current density (8.3–33.3 mA/cm2), dissolved oxygen (DO) in wastewater, and initial Tl(I) concentration (66–165 µg/L) on Tl(I) removal efficiency were investigated. The removal efficiency of Tl(I) is pH-dependent, to be exact, it increases significantly with pH rising from 8 to 11. Initial pH of influent and DO concentration were the key operation parameters which strongly affect Tl(I) removal. After the water sample with initial Tl(I) concentration of 115 µg/L was treated for 12 min by a single-step process at pH of 11 and current density of 16.7 mA/cm2, the residual Tl(I) concentration was decreased to beneath the emission limit in China (2 µg/L) with a low energy consumption of 0.82 kWh/m3. By prolonging the operation time, the concentration was further reduced to 0.5 µg/L or even lower. The main composition of the flocculent sludges is iron oxyhydroxide, yet its crystal structure varies dependent on pH value which may result in different Tl(I) removal efficiency. Feroxyhyte nanosheets generate in situ by Fe0-EC, which contributes to the rapid and effective removal of Tl(I), while the speedy oxidation under DO-enriched conditions benefits the feroxyhyte formation. The mechanism of Tl(I) removal by Fe0-EC is attributed to the combination of electrostatic attraction and the formation of inner-sphere complexes. As shown in the technical and mechanical studies, Fe0-EC technology is an effective method for low Tl concentration removal from wastewater.

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The behavior of dissolution/passivation and the transformation of passive films during electrocoagulation: Influences of initial pH, Cr(VI) concentration, and alternating pulsed current

Cited by 99 publications

References 45 publications

Formation of macroscopic surface layers on Fe(0) electrocoagulation electrodes during an extended field trial of arsenic treatment

Formation of macroscopic surface layers on Fe(0) electrocoagulation electrodes during an extended field trial of arsenic treatment

Importance of Chloride Addition on Arsenite Removal by Aluminium Electrocoagulation

Removal of Trace Thallium from Industrial Wastewater by Fe0-Electrocoagulation

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