A comparative study of the electrochemical oxidation of the herbicide tebuthiuron using boron-doped diamond electrodes

Abstract

The thiadiazolylurea derivative tebuthiuron (TBH) is commonly used as an herbicide even though it is highly toxic to humans. While various processes have been proposed for the removal of organic contaminants of this type from wastewater, electrochemical degradation has shown particular promise. The aim of the present study was to investigate the electrochemical degradation of TBH using anodes comprising boron-doped (5000 and 30,000 ppm) diamond (BDD) films deposited onto Ti substrates operated at current densities in the range 10-200 mA cm(-2). Both anodes removed TBH following a similar pseudo first-order reaction kinetics with k(app) close to 3.2 × 10(-2) min(-1). The maximum mineralization efficiency obtained was 80%. High-pressure liquid chromatography with UV-VIS detection established that both anodes degraded TBH via similar intermediates. Ion chromatography revealed that increasing concentrations of nitrate ions (up to 0.9 ppm) were formed with increasing current density, while the formation of nitrite ions was observed with both anodes at current densities ≥ 150 mA cm(-2). The BDD film prepared at the lower doping level (5000 ppm) was more efficient in degrading TBH than its more highly doped counterpart. This unexpected finding may be explained in terms of the quantity of impurities incorporated into the diamond lattice during chemical vapor deposition.

Electrochemical Oxidation of Reactive Black 5 and Blue 19 Dyes Using a Non Commercial Boron-Doped Diamond Electrode

“…Mais detalhes sobre a configuração deste reator podem ser obtidos em Alves et al 21 A técnica de deposição química a partir da fase vapor assistida por filamento quente (HFCVD) foi utilizada para obter o filme de diamante dopado com boro, que foram crescidos sobre peça de Titânio com dimensão de 25 mm x 25 mm x 0,5 mm, resultando em um eletrodo de trabalho com área geométrica de 4,15 cm 2 . .…”

“…Tendo em vista que os eletrodos do tipo DDB suportados em silício são frágeis e apresentam baixa condutividade, e o nióbio é um material com elevado custo, os eletrodos do tipo DDB suportados em titânio (Ti/DDB) têm se destacado em aplicações ambientais, mais especificamente na descontaminação de água poluídas com contaminantes orgânicos por processos de oxidação eletroquímica. 15,[20][21][22][23][24] Tal relevância também é devida às propriedades como alta área superficial, baixo custo, alta condutividade, resistência mecânica e resistência à corrosão. 19 No entanto, o eletrodo de Ti/DDB ainda apresenta problemas de delaminação e desprendimento dos filmes, o que motiva o estudo desse eletrodos.…”

Effluent characteristics of advanced treatment for biotreated coking wastewater by electrochemical technology using BDD anodes

“…In particular, electrochemical technology using boron-doped diamond (BDD) anodes appears to be the most suitable technology because it has important properties of an extremely wide potential window, very low background current, and robust oxidation capacity (Panizza and Cerisola 2005;Martinez-Huitle and Brillas 2008;Jeong et al 2009). Meanwhile, electrochemical technology using BDD anodes has been used to treat different organic pollutants and different types of wastewater, such as phenol and its derivatives (Pereira et al 2012;Nejmeddine et al 2013), oxalic and oxamic acids (Garcia-Segura and Brillas 2011), salicylic acid (Nejmeddine and Mohamed 2012), sulfanilic acid (El-Ghenymy et al 2012), herbicide (Alves et al 2012), dyes (Costa et al 2009), reverse osmosis concentrate (Bagastyo et al 2013), coking wastewater (Zhu et al 2009), and landfill leachate (Anglada et al 2011). Research on the above organic degradation by a BDD anode has mainly focused on four aspects: (1) investigating variable effects, (2) identifying the oxidation pathway, (3) exploring degradation kinetics, and (4) comparing the organic removal efficiency between BDD anodes and electrodes made of other materials.…”

Electrochemical oxidation of imazapyr with BDD electrode in titanium substrate

“…The robustness and efficiency of these technologies were mainly achieved through advances in electrodic materials and reactor designs for industrial applications (Marselli et al, 2003;Rodrigo et al, 2010). Among the anodic material available, the electrodes comprising boron-doped diamond film supported on titanium (BDD/Ti) have been extensively studied for the treatment of various refractory organic compounds, e.g., dyes (Migliorini et al, 2011;Sales Solano et al, 2013), pharmaceutical compounds (Vidales et al, 2012;Cavalcanti et al, 2013) and pesticides (Sirés et al, 2008;Alves et al, 2012). The results have shown high efficiency, attributed to the material characteristics such as the high overpotential for water electrolysis, excellent chemical and electrochemical stability, satisfactory conductivity and the ability to generate other oxidants depending on the wastewater composition and the operation conditions (Panizza and Cerisola, 2009).…”