Gaseous trichloroethylene removal using an electrochemically generated homogeneous low-valent ligand-free Co(I) electrocatalyst by electro-scrubbing

• Published in: Journal of hazardous materials 2016-07, Vol.311, p.210-217
• Main Authors: G., Muthuraman, A.G., Ramu, Moon, I.S.
• Format: Article
• Language: English
• Subjects: Anodizing; Degradation; Divided electrolytic cell; Electro-scrubbing; Electrocatalysts; Electrodes; Formations; Gaseous TCE; Homogeneous [Co(II)(OH)4]2; MER; Reduction (electrolytic); Titanium; Trichloroethylene
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.03.011

[Display omitted] •Ligand-free homogeneous electro-catalyst Co(I) generated electrolytically.•Oxide electrode and 10M NaOH favors formation of the low-valent Co(I).•Degradation of TCE achieved 100% with competitive amount 42.3mg/day.•Electrochemical regeneration of Co(I) makes this process sustainable. The interest in heterogeneous Co(OH)2 electrocatalysts for energy applications has increased steadily. This study focused on a ligand-free homogeneous electrocatalyst for the degradation of gaseous trichloroethylene (TCE) in NaOH in a divided electrolytic cell. The initial electrolysis results revealed a change in the oxidation reduction potential (ORP) of [Co(II)(OH)4]2− (Co(II)) from −267mV to −800mV on anodized Ti during electrolytic reduction identifies low-valent homogeneous [Co(I)(OH)4]3−(Co(I)) formation in 10M NaOH. Cyclic voltammetry analysis of Co(II) at different anodized electrodes, Ag, carbon and Ti, in a 10M NaOH solution, showed no stripping like peak in the reverse scan only the Ti electrode, supporting the formation of low-valent Co(I). UV–vis spectral analysis of the electrolyzed solution showed an enhanced peak corresponding to metal-to-ligand transition, demonstrates Co(I) formation. Co(II) reduction reached a maximum yield of 18% at 30mAcm−2 on an anodized Ti cathode. For gaseous TCE removal, continuous mode electro-scrubbing was adopted and degradation was monitored using an online FTIR gas analyzer that showed 99.75% degradation of TCE in the presence of homogeneous Co(I). Three consecutive regenerations of Co(I) and degradation steps of TCE confirmed the possibility of industrial applications in a sustainable manner.