Electrochemical Treatment of 4-Nitrophenol-Containing Aqueous Wastes Using Boron-Doped Diamond Anodes

Abstract

The electrochemical oxidation of aqueous wastes containing 4-nitrophenol (4-NP) using a borondoped diamond thin-film electrode has been studied. Within the parameter ranges used (150-4000 mg of 4-NP dm -3 , pH 2-12, 30-60 mA cm -2 , 25-60 °C), the complete treatment of the organic waste was achieved. The maximum current efficiencies were obtained under kinetic control. On the basis of the results of voltammetric and galvanostatic electrolysis studies, a simple mechanistic model was proposed. The first stage in the treatment of 4-NP-containing aqueous wastes is the release of the nitro group from the aromatic ring. As a consequence, phenol or quinones are formed. These organic compounds are oxidized first to carboxylic acids (maleic and oxalic) and later to carbon dioxide. On the cathode, the reduction of the 4-NP to 4-aminophenol takes place. In alkaline media, this compound can be polymerized and transformed into a dark brown solid.

Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: Aplicação em águas de chuva de regiões de Santa Catarina

“…Entretanto, nos últimos anos, poucos artigos descreveram o tratamento eletroquímico destes compostos. E os poucos descritos, focam-se apenas por vias de oxidação e seus mecanismos de atuação são complexos [14]. A detecção de nitrofenóis é geralmente realizada por técnicas cromatográficas e espectroscópicas [15,16].…”

Decontamination of Wastewaters Containing Organics by Electrochemical Methods

“…However, for mono-and di-nitro substituted phenol derivates, the cathodic current increased at the potential value of about -0.4 V Ag/AgCl, which was ascribed to the reduction of -NO2 [40,41]. In addition, in the cathodic potential range a polymer of aminophenol formed cathodically could occur.…”

Electrolytic Treatment Characteristics of Boron-doped Nanocrystalline Diamond/Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition

“…In cases where such electrodes are used for electrochemical treatment, electrolysis of water preferentially occurs because of the electrodes' narrow potential window, which is much narrower than that of BDD electrodes. Aqueous waste containing various persistent substances is reported to be decomposed by BDD films used as anode electrodes (3) . BDD electrodes have also been used as electrodes for electrosynthesis (4) and electrochemical sensors (5) ; thus, BDD is an electrode material with numerous potential electrochemical applications.…”