Electrochemical degradation of crystal violet with BDD electrodes: effect of electrochemical parameters and identification of organic by-products.
This paper explores the applicability of electrochemical oxidation on a triphenylmethane dye compound model, hexamethylpararosaniline chloride (or crystal violet, CV), using BDD anodes. The effect of the important electrochemical parameters: current density (2.5-15 m A cm(-2)), dye concentration (33-600 mg L(-1)), sodium sulphate concentration (7.1-50.0 g L(-1)) and initial pH (3-11) on the efficiency of the electrochemical process was evaluated. The results indicated that while the current density was lower than the limiting current density, no side products (hydrogen peroxide, peroxodisulphate, ozone and chlorinated oxidizing compounds) were generated and the degradation, through OH radical attack, occurred with high efficiency. Analysis of intermediates using GC-MS investigation identified several products: N-methylaniline, N,N-dimethylaniline, 4-methyl-N,N-dimethylaniline, 4-methyl-N-methylaniline, 4-dimethylaminophenol, 4-dimethylaminobenzoic acid, 4-(N,N-dimethylamino)-4'-(N',N'-dimethylamino) diphenylmethane, 4-(4-dimethylaminophenyl)-N,N-dimethylaniline, 4-(N,N-dimethylamino)-4'-(N',N'-dimethylamino) benzophenone. The presence of these aromatic structures showed that the main CV degradation pathway is related to the reaction of CV with the OH radical. Under optimal conditions, practically 100% of the initial substrate and COD were eliminated in approximately 35 min of electrolysis; indicating that the early CV by-products were completely degraded by the electrochemical system.
Palma-Goyes
Ricardo E
RE
Grupo de electroquímica, Instituto de química, Facultad de ciencias exactas y naturales, Universidad de Antioquia, A.A. 1226, Medellín, Colombia.
Guzmán-Duque
Fernando L
FL
Peñuela
Gustavo
G
González
Ignacio
I
Nava
Jose L
JL
Torres-Palma
Ricardo A
RA
D001895:Boron / Q000737:chemistry; D004396:Coloring Agents / Q000737:chemistry*; D018130:Diamond / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005840:Gentian Violet / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis / Q000737:chemistry; D010084:Oxidation-Reduction
D004396:Coloring Agents; D004785:Environmental Pollutants; D009930:Organic Chemicals; D018130:Diamond; D005840:Gentian Violet; D001895:Boron