Nature, Mechanisms and Reactivity of Electrogenerated Reactive Species at Thin‐Film Boron‐Doped Diamond (BDD) Electrodes During Electrochemical Wastewater Treatment

Abstract

Electrooxidation of hazardous organic pollutants contaminating wastewater using thin-film boron-doped diamond (BDD) electrodes is an efficient and well-studied treatment technique. In this review, the three main reactive species, namely: reactive oxygen, chlorine and sulfate species, which can be electrogenerated and then participate in the oxidation processes during electrooxidative wastewater treatment using BDD electrodes, are discussed. The main factors affecting the nature and quantity of the electrogenerated reactive species, specifically the composition of the BDD electrode (doping level and sp 3 /sp 2 ratio) and the operating parameters (working current density and composition of water matrix been electrolyzed) were explained with relative examples. Extensive discussion on mode and reactivity of the three reactive species with organic pollutants during electrooxidation was provided and the future perspectives and direction of research on reactive species generated on BDD electrodes were also discussed.[a] Dr.

Interrogating the Surface Intermediates and Water Oxidation Products of Boron‐Doped Diamond Electrodes with Scanning Electrochemical Microscopy

“…Boron-doped diamond (BDD) is a unique electrode material due to its ability to be tailored for a variety of applications. [1,2] Since the hydrophobic surface, low density of states, and low availability of binding sites limit inner sphere reactions, the overpotential for the oxidation of water is high, facilitating the production of free hydroxyl radicals, [3,4] the indirect and direct oxidation of electrolyte to form reactive oxygen species (ROS) or other oxidants (such as persulfate and active chlorine), [5][6][7][8][9] and electrochemical combustion of organic molecules and biofilms. [10][11][12][13][14] However, the adsorbate chemistries that influence these reactions have not been studied in depth, as many studies have focused on bulk, galvanostatic measurements.…”

Coupling of Anodic Oxidation and Soil Remediation Processes: A Review

“…Anodic oxidation (AO) also known as electrooxidation is one of the most widely applied electrochemical advanced oxidation processes (EAOPs) due to its excellent efficiency, limited chemical requirement, ease of operation, as well as being environmentally friendly. This process has been extensively applied for the remediation of different classes of organic pollutants from wastewater, landfill leachate, ground water, contaminated soils, reverse osmosis concentrate, and others [ 20 , 22 , 84 ]. The main reactive species in AO is either chemisorbed oxygen/superoxide or physisorbed hydroxyl radicals depending on the electrocatalyst material used as electrode.…”

“…During electrolysis in the region of water discharge potential, the BDD anode promotes production of weakly adsorbed • OH radicals, which are very reactive and can unselectively and completely mineralize different classes of organic pollutants with a high current efficiency. The BDD anode is also an excellent electrocatalyst for the formation of secondary reactive species such as sulfate radicals, persulfate, and free active chlorine, all of which are relatively strong oxidants that can degrade different classes of organic pollutants [ 84 , 86 , 96 ].…”

Cathodic hydrogen production by simultaneous oxidation of methyl red and 2,4-dichlorophenoxyacetate aqueous solutions using Pb/PbO2, Ti/Sb-doped SnO2and Si/BDD anodes. Part 1: electrochemical oxidation

“…Production of hydroxyl radicals and byproducts was kinetically explored as well as the mineralization and current efficiencies were also estimated. Non-active anodes were chosen because these electrocatalytic materials promote a complete mineralization of organic matter in anodic compartment, 12,16 and because no attempts have been published in the literature to produce hydrogen gas coupled with electrochemical oxidation by using these anodic materials in divided cell. purication.…”