Abstract
The synergy between electrochemical oxidation and adsorption on particle electrodes was investigated in three-dimensional (3D) systems for p-nitrosodimethylaniline (RNO) decolorization and pesticide removal. A comparison was made between granular activated carbon (GAC) and a novel synthesized nitrogen-doped graphene-based particle electrode (NCPE). Experiments on RNO decolorization show that the synergy parameter of the 3D-NCPE system was improved 3000 times compared to the studied 3D-GAC system. This was due to the specific nanostructure and composition of the NCPE material. Nitrogen-doped graphene triggered an oxygen reduction reaction, producing hydrogen peroxide that simultaneously catalyzed on iron sites of the NCPEs to hydroxyl radicals following the electro-Fenton (EF) process. Data showed that in the experimental setup used for the study, the applied cell voltage required for the optimal value of the synergy parameter could be lowered to 5V in the 3D-NCPEs process, which is significantly better than the 15–20 V needed for synergy to be found in the 3D-GAC process. Compared to previous studies with 3D-GAC, the removal of pesticides 2,6 dichlorobenzamide (BAM), 2-methyl-4-chlorophenoxyaceticacid (MCPA), and methylchlorophenoxypropionic acid (MCPP) was also enhanced in the 3D-NCPE system.
Highlights
Electrochemical oxidation is an emerging technology that has been effectively used for the removal of organic pollutants from water and is appropriate to be implemented as part of a decentralized water treatment system [1]
Synergy has only been investigated for activated carbon-based catalysts, so the novelty of the current study is to study the synergy using the nitrogen-doped catalytic particle electrode (NCPE) material
The rate of RNO decolorization newly synthesized particle electrodes compared with activated carbon
Summary
Electrochemical oxidation is an emerging technology that has been effectively used for the removal of organic pollutants from water and is appropriate to be implemented as part of a decentralized water treatment system [1]. The use of a bed material inside the reactor as a third electrode can effectively increase the specific surface area of the electrodes [2,3,4]. Li et al [5] used a ceramic particle electrode for the electrochemical degradation of 2-diethylamino-6-methyl-4-hydroxypyrimidine in a three-dimensional electrode reactor. There are reports showing that the combination of metals and ceramic materials as particle electrodes could be effective in promoting 3D-electrochemical water treatment processes [6,7,8]. The improvement of three-dimensional electrochemical systems (using GACs as the third electrode) was attributed to its extensive specific surface area [13,14,15] and the ability of carbon materials to Granular activated carbon (GAC) is widely studied as a third electrode due to its interesting surface properties such as high surface area, high porosity and active surface chemistry [9,10,11,12].
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