Electrochemical Oxidation of 4-Chlorophenol for Wastewater Treatment: Definition of Normalized Current Efficiency (φ)

Abstract

The electrochemical behavior of lead dioxide and synthetic boron-doped diamond thin film electrodes ͑BDDs͒ has been studied in acid media containing 4-chlorophenol ͑4-CP͒ by bulk electrolysis under different experimental conditions. In order to quantify the electrochemical activity of a given electrode, for the electrochemical oxidation of organic compounds ͑4-CP͒, the current efficiency of the anodic oxidation has been normalized taking into consideration mass-transport limitations. The normalized current efficiency ͑͒ has been defined as the ratio between the current efficiency of the investigated anode to the current efficiency of an ideal anode which has a very fast oxidation rate, resulting in a complete combustion of organics to carbon dioxide. The results have shown that even if the complete combustion of 4-chlorophenol has been achieved at both lead dioxide and boron-doped diamond anodes, the latter give higher . The difference in reactivity of the electrogenerated hydroxyl radicals on the anode surface, has been proposed to explain the high values obtained using boron-doped diamond anodes.

Trends in Research on Electrochemical Oxidation

“…Pt, BDD, PbO 2 , TiO 2 , and SnO 2 had been the objects of recent investigations, due to the reason that they had shown better characteristics in the electrochemical oxidation system. 22,29,32 High activity and stability of Pt made it a suitable electrode material and electrocatalyst for electro-oxidation. The top cited publication related to Pt electrode was in 2009.…”

“…In this paper, boron-doped diamond was compared with Ti/SnO 2 /PbO 2 in para-chlorophenol degradation and a new parameter not influenced by mass-transfer limitation was introduced. 32 After the review by Panizza and Cerisola 6 about the application of boron-doped diamond electrodes in 2005, BDD began to attract more and more attention. PbO 2 , TiO 2 , SnO 2 were all dimensional stable anodes (DSA) -type electrode materials, showing high surface area, with excellent mechanical and chemical resistance even at high current density and in strongly acid media.…”

Anodic Materials with High Energy Efficiency for Electrochemical Oxidation of Toxic Organics in Waste Water

“…BDD film was found to be the most active anodic material for degradation of refractory or priority pollutants such as isopropanol and acetic acid (Foti et al, 1999), different carboxylic acids (Gandini et al, 2000), 4-chlorophenol (Rodrigo et al, 2001;Gherardini et al, 2001), phenol (Iniesta et al, 2001b), 3-methylpyridine (Iniesta et al, 2001a), benzoic acid (Montilla et al, 2002), polyacrylates (Bellagamba et al, 2002), 4-chlorophenoxyacetic acid (Boye et al, 2002) and an amaranth dyestuff (Hattori et al, 2003). All these investigations could confirm very high current efficiencies for COD removal, usually higher than 90%.…”

Degradação eletroquímica da vinhaça usando eletrodo de diamante dopado com boro

“…Foi estudada a oxidação eletroquímica do 4-clorofenol em meio ácido sobre o DDB, utilizando as técnicas de voltametria cíclica, cronoamperometria e eletrólises exaustivas a altos potenciais anódicos. 23,24 Os autores observaram a incineração completa do 4-clorofenol sobre o DDB por meio dos radicais hidroxilas eletrogerados na superfície. Inesta et al 21 reportaram a oxidação destrutiva de fenol sobre um eletrodo de DDB realizada em diferentes regiões de potenciais e observaram que para a região de potencial antes do desprendimento de oxigênio ocorre a transferência direta de elétrons, formando um filme polimérico na superfície do eletrodo.…”