A comparison between flow-through cathode and mixed tank cells for the electro-Fenton process with conductive diamond anode

This work focusses on the production of hydrogen peroxide and in the removal of bromacil by the electro-Fenton process using two different electrochemical cells: mixed tank cell (MTC) and flow-through cell (FTC). Both cells use boron doped diamond (BDD) as anode and carbon felt as cathode to promote the formation of hydrogen peroxide. In the case of the MTC, two surface area ratios, Acathode/Aanode, have been used. Results show that the H2O2 produced by MTC and FTCPSC increases with the time until a stabilization state. For the FTCPSC, the average hydrogen peroxide concentration produced increases progressively with the current, while for MTC the maximum values are found in applying very low current densities. In addition, the FTCPSC provides higher concentrations of hydrogen peroxide for the same current density applied. Regarding the MTC, it can be stated that the higher the area of the cathode, the higher is the amount of H2O2 produced and the lower is the cell voltage (because of a more efficient current lines distribution). The initial oxidation of bromacil is very efficiently attained being rapidly depleted from wastewater. However, the higher production of hydrogen peroxide obtained by the FTCPSC cell does not reflect on a better performance of the electro-Fenton process. Thus, bromacil is better mineralized using the MTC cell with the lowest cathode area. This observation has been explained because larger concentrations of produced hydrogen peroxide seems to benefit the oxidation of intermediates and not the mineralization

Experimental Design Methodology Applied to the Oxidation of Quinolines in Aqueous Medium by Electro-Fenton Process

采用碳毡阴极和铂阳极的电芬顿工艺研究了喹啉模型分子8-羟基喹啉硫酸盐（8-HQS）在水溶液介质中的降解行为. 由于电化学诱导芬顿药剂（H2O2，Fe2+）产生大量的羟基活性基（OH），成为与有机物发生反应直到有机物完全矿化的强有力氧化剂，因此，电芬顿工艺具有很强的氧化能力. 采用正交实验设计确定了水溶液介质中8-HQS降解的操作参数. 结果表明，电流密度和8-HQS的初始浓度是影响降解速度的主要因素. 8-HQS浓度随着电解时间而减少，说明8-HQS的氧化遵循准一级反应动力学. 通过竞争动力学方法确定的由OH引起8-HQS氧化的绝对反应速度常数为1.62×109 mol-1·L·s-1. 通过Doehlert 矩阵研究了8-HQS矿化的最佳实验参数，由此确定最佳条件下电芬顿工艺能导致8-HQS在水溶液中的准完全矿化（总有机成分去除率95%）. 对8-HQS水溶液的处理，使得8-HQS矿化前的最终产物为短链羧酸. 同时研究了电芬顿处理中短链羧酸的演变行为. 溶液毒性演变的跟踪研究发现，中间产物的毒性比8-HQS强，但溶液的毒性在中间产物矿化后可以完全消除.The degradation behavior of 8-hydroxyquinoleine sulfate (8-HQS), a model molecule of quinolines, was studied in an aqueous medium by electro-Fenton process using a carbon felt cathode and a platinum anode. The great oxidation ability of this process is due to a large production of hydroxyl radical (OH) by electrochemically induced Fenton’s reagent (H2O2, Fe2+). Hydroxyl radicals are very powerful oxidizing agents which react on organics up to complete mineralization. A factorial experimental design was used for determining the operating parameters on the degradation of 8-HQS in an aqueous medium. The results showed that the current intensity and the initial concentration of 8-HQS were the main factors that influenced the degradation rate. The decay in concentration of 8-HQS with the electrolysis time shows that the oxidation of 8-HQS follows pseudo-first order kinetics. The absolute rate constant for the oxidation of 8-HQS by OH was determined by using competition kinetics method and found to be 1.62×109 mol-1·L·s-1. The optimal experimental parameters for the mineralization of 8-HQS have also been investigated by the use of Doehlert matrix. It has been demonstrated that under the optimal conditions determined by this method, electro-Fenton process can lead to a quasi-complete mineralization (95% of TOC removal) of 8-HQS aqueous solution. The treatment of 8-HQS aqueous solutions leads to the formation of short-chain carboxylic acids as end-products before mineralization. Their evolution during electro-Fenton treatment was studied. The follow-up of the solution toxicity evolution shows the formation of intermediates more toxic than 8-HQS. However, the solution toxicity was totally removed after mineralization of these intermediates.作者联系地址：1. Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), UPEMLV, 77454 Marne-la-Vallée, France; 2. Laboratoire de Chimie Analytique et Electrochimie, Département de Chimie, Faculté des Sciences de Tunis, Campus Universitaire 2092, El Manar Tunis, Tunisia;3. Département de Génie Chimique et Biologique Institut National des Sciences Appliquées et de Technologie 1080 Tunis, TunisiaAuthor's Address: 1. Université Paris-Est, Laboratoire Géomatériaux et Environnement LGE, UPEMLV, 77454 Marne-la-Vallée, France; 2. Laboratoire de Chimie Analytique et Electrochimie, Département de Chimie, Faculté des Sciences de Tunis, Campus Universitaire 2092, El Manar Tunis, Tunisia;3. Département de Génie Chimique et Biologique Institut National des Sciences Appliquées et de Technologie 1080 Tunis, Tunisia通讯作者E-mail：[email protected]

Efficiency of plasma elaborated sub-stoichiometric titanium oxide (Ti4O7) ceramic electrode for advanced electrochemical degradation of paracetamol in different electrolyte media

This paper investigates the behavior of conductive Ti4O7 ceramic anode in different electrolytes during the degradation of the anti-inflammatory drug paracetamol (PCM) by advanced electrochemical oxidation processes mainly anodic oxidation with generation of H2O2 (AO-H2O2) and electro-Fenton (EF). Regardless of the medium, better degradation and mineralization efficiency was always observed with EF compared to AO-H2O2. The degradation of PCM was carried out by hydroxyl radical (OH) produced on the anode surface from water oxidation and mediated oxidation in the solution from oxidant species generated at the anode such as sulfate radicals and active chlorine species depending on the supporting electrolytes used, as well as OH generated homogeneously in the solution by electrochemically assisted Fenton’s reaction. Faster degradation was observed in Cl− compared to other media, but the solution was poorly mineralized. Highest total organic (TOC) removal efficiency with excellent degradation rate was attained in SO42− with either process, thus remain the best medium for advanced electrochemical wastewater treatment. Comparative studies with dimensional stable anode (DSA) and boron-doped diamond anode (BDD) showed similar trend of degradation and TOC removal efficiency with DSA anode achieving low mineralization power compared to Ti4O7 anode, whereas BDD showed slightly better efficiency than Ti4O7 in all electrolytes studied. The analysis of concentration of generated active chlorine species, especially ClO−, during AO-H2O2 decreased in the order: DSA > Ti4O7 > BDD. Therefore, the Ti4O7 electrode was found to be a promising anode material for an efficient treatment of PCM in SO42−, NO3− and ClO4− media but less effective in Cl− medium

Electrochemical abatement of analgesic antipyretic 4‐aminophenazone using conductive boron‐doped diamond and sub‐stoichiometric titanium oxide anodes: kinetics, mineralization and toxicity assessment

The oxidation ability of two prominent eco‐friendly electrochemical advanced oxidation processes (EAOPs), namely anodic oxidation with H2O2 generation (AO‐H2O2) and electro‐Fenton (EF) for complete abatement of acidic solution of 4‐aminophenazone (4‐APZ) has been investigated using conductive boron‐doped diamond (BDD) and sub‐stoichiometric titanium oxide (Ti4O7) anodes and carbon‐felt cathode. The higher performance of EF compared to AO‐H2O2 with either anode was demonstrated. In all trials, 4‐APZ was completely destroyed, following pseudo first‐order kinetics with the rate constant values increasing with applied current and higher values attained with BDD compared to Ti4O7 anode at similar conditions. The absolute rate constant for the reaction between 4‐APZ and hydroxyl radicals was found to be 3.9±0.2×109 L mol−1 s−1. Complete mineralization could be attained with BDD anode, whereas Ti4O7 anode only showed excellent mineralization up to 94 % TOC removal. Therefore, Ti4O7 anode can constitutes a promising anode material thanks to its lower manufacturing cost. Inorganic ions like NO3− and HCO3− at concentration up to 25 mM has no effect on mineralization efficiency during AO‐H2O2, but the presence of Cl− even at lower concentration of 10 mM significantly reduced the TOC removal efficiency. The toxicity of the solution sharply increased at initial stage of treatment, corresponding to the formation of cyclic by‐products but their conversion to carboxylic acids due to longer treatment time involved a sharp toxicity decrease, thus ensuring overall detoxification

Electro-Fenton Process: New Developments and Applications to the Treatment of Toxic/Persistent Organic Pollutants.

Seminar, South-Central University for Nationalities, Wuhan - Chin

Effect of Electrode Materials in process Efficiency in Electrochemical Advanced Oxidation processes.

Seminar, Wuhan University, Wuhan - Chin

New Developments in Electro-Fenton Process: Electrode Materials and Hybrid Processes.

Seminar, Wuhan University, Wuhan - Chin

New Developments in Electrode Materials and Coupling Possibilities with Other Methods.

International audienc

Using the electrochemical advanced oxidation processes for the treatment of landfill leachates.

International audienc

Using the electrochemical advanced oxidation processes for the treatment of landfill leachates.

International audienc