Mechanistic proposal for the electrochemical and sonoelectrochemical oxidation of thiram on a boron-doped diamond anode

A comparative study was carried out of sonochemical (SCh), electrochemical (ECh) and sonoelectrochemical (SECh) strategies for the degradation of the fungicide thiram in dilute aqueous solution. The SCh and SECh studies were performed using a sonicator equipped with an 11 mm titanium-alloy probe and operated at 20 kHz with a power intensity of 523 W cm⁻². In the ECh and SECh investigations, galvanostatic electrolyses were implemented using a single compartment electrochemical cell with a boron-doped diamond electrode as anode and applied current densities in the range 10–50 mA cm⁻². For these processes, the decrease in concentration of thiram was monitored by high performance liquid chromatographic (HPLC) analysis and values of current efficiency and energy consumption were determined. The results showed that the rate of degradation of thiram and the amount of energy consumed were directly proportional to the applied current density, while current efficiency was inversely related to current density. The kinetics of thiram degradation followed a pseudo first order model with apparent rate constants in the region of 10⁻³ min⁻¹. Thiram in aqueous solution was subjected to “exhaustive” degradation by ECh and SECh processes for 5 h at applied current densities of 35 mA cm⁻² and the intermediates/byproducts so-formed were identified by HPLC–mass spectrometry. Mechanisms of the degradation reactions have been proposed on the basis of the results obtained.     

Review on the electrochemical oxidation of endocrine-disrupting chemicals using BDD anodes

The application of synthetic diamond-based electrodes in water treatment has been shown to be promising, especially for boron-doped diamond (BDD). With a wide potential window and high overpotential for oxygen evolution among many more excellent qualities, BDD anodes surpass the capabilities of conventional electrodes. Currently, the synthesis and fabrication of low-cost BDD anodes are still in the primary stages of development. Electrochemical oxidation of EDCs on BDD anodes in water samples have been shown to be effective with very high removal efficiencies. The presence of this group of pollutants in wastewater effluents and various water matrices causes environmental concerns and requires an immediate solution due to their persistence and threat for both humas and wildlife. Extensive research on BDD continues to be carried out with various EDCs, such as parabens and pesticides, to determine the most suitable parameters, possible mechanisms of the degradation process, and its viability in large-scale applications. These efforts remain imperative as the presence of EDCs could severely affect human health and the surrounding environment. Although significant progress has been achieved, the advanced technology is unable to achieve feasible application in a large scale due to major hindrances. In this mini review, the focus was on the recent applications of electrochemical oxidation using BDD thin-film anodes (2019 to present) for the removal of a range of EDCs. The main factors that affect the performance of BDD anodes in the electrochemical oxidation of EDCs were discussed and evaluated, highlighting some ways to overcome the issues that prevent the technology from moving onto the next stage of development.     

Electrochemical technologies for the treatment of pesticides

Pesticides are used worldwide in large quantities to increase yield in agriculture. On the other hand, they are in general toxic/persistent organic pollutants presenting strong adverse effects to the environment and human health, including acute and chronic toxicity. Consequently, water polluted by pesticides should be treated efficiently before its release into receiving water bodies to protect the natural aquatic environment. Different methods have been used for the treatment of water contaminated by pesticides. Among them, electrochemical technology seems to be very efficient in removing pesticides from water. Therefore this review aims to provide an overview of the recent works on the treatment of pesticide wastewater using electrochemical technology with a special focus on electrochemical advanced oxidation processes that demonstrated high efficiency in the removal of various types of pesticides from contaminated water.     

Electro-oxidation of certain naphthalene derivatives

Naphthalene and alkylnaphthalenes are electro-oxidized to give many products, of which 1,4-naphthoquinones and binaphthyls are the most stable, especially in the case of substrates, which are not substituted in α-positions. On the other hand, α-substituted naphthalenes give the respective naphthoquinols as the main products. Interestingly, 1,2-naphthoquinones are not separated as products, instead, a fragmentation of one of the rings leads to oxidation products, in which the 1,2-bond in naphthalene is broken to form dialdehydes or diketones. An anodic formation of binaphthyls is described, starting from alkyl-substituted naphthalenes, dissolved in acetone-water (1:1 v/v) and using 0.1 M (CH₃)₄N(BF₄) supporting electrolyte. Several isomeric binaphthyls were obtained depending on the substrates. The structure of the binaphthyls formed is discussed based on molecular orbital calculations using the AM1 program. Cyclic voltammetric oxidation curves are shown for naphthalene and three methyl derivatives. Correspondence: Roman Edmund Sioda, Department of Analytical Chemistry and Electrochemistry, Institute of Chemistry of University of Podlasie, ul. 3 Maja 54, 08-110 Siedlce, Poland.     

石墨电极直接电氧化合成D-阿拉伯糖

本文报道采用石墨电极直接电氧化Ｄ＿葡萄糖酸钠（ＮａＧＬ）合成Ｄ＿阿拉伯糖研究结果．研究了葡萄糖酸钠浓度、电解电压、温度及电解液组成对电流效率和合成产率的影响。同时指出采用液体电解池进行恒电位电解,其效果比恒电流电解法更好     

乙醇在Pt/nanoTiO2-CNT复合催化剂上的电催化氧化

通过前驱体Ti(OEt)4直接水解和电化学扫描电沉积法制备在Ti基体上的纳米TiO2-碳纳米管复合膜载Pt(Pt/nanoTiO2-CNT)复合催化剂. 透射电镜 (TEM) 和X射线衍射 (XRD) 结果表明, 锐钛矿型纳米TiO2粒子和Pt纳米粒子(粒径均为5~10 nm)均匀地分散在碳纳米管表面. 通过循环伏安和计时电流法研究表明, Pt/nanoTiO2-CNT 复合催化剂(Pt载量为0.32 mg•cm−2) 具有高达51.8 m2•g−1的电化学活性比表面积, 常温常压下对乙醇的电化学氧化具有高催化活性和稳定性, 乙醇氧化峰电位分别为0.59、0.96和0.24 V, 氧化峰电流密度分别达到−115、−113和−75 mA•cm−2. 复合催化剂对乙醇电氧化的高催化活性可归因于nanoTiO2、CNT和Pt纳米粒子的协同催化作用.     

聚四氨基钴酞菁膜修饰电极对甲巯咪唑的电催化氧化

用循环伏安法(CV)研究了聚四氨基钴酞菁(CoTAPc)膜修饰电极(p-CoTAPc CME)对甲巯咪唑的电催化氧化行为.在pH=2的缓冲溶液中,与未修饰玻碳电极(GC)相比,甲巯咪唑在p-CoTAPc CME(GC基体)上的氧化峰电位(Vpa)负移220 mV左右,峰电流(Ipa)变为原来的3倍多;还原峰电位(Vpc)正移大约223 mV,峰电流(Ipc)几乎变为裸电极时的6倍.同时,p-CoTAPc CME对甲巯咪唑的电催化氧化活性有很高的稳定性.     

Electro-oxidation of Ascorbic Acid on PVP-stabilized Graphene Electrode

Polyvinylpyrrolidone-stabilized graphene(PVP-graphene) was synthesized and investigated as a modifier for the determination of ascorbic acid(AA).With PVP acting as stabilizer and dispersant,the resulting PVP-graphene material could disperse well into water.And the PVP-graphene modified glassy carbon electrode(PVP-graphene-GCE) showed an obvious electrocatalytical activity toward the oxidation of AA in a phosphate buffer solution(PBS,pH=7.0) with an oxidation potential of AA at 0.052 V vs.Ag|AgCl(sat.KCl).The calibration curve for AA was linear in a concentration range from 1.0×10-5 to 5.0×10-4 mol/L with a correlation coefficient of 0.9998.And the detection limit was found to be 1μmol/L.During the oxidation of AA,the π-π interaction of graphene plane with conjugated hexenoic acid-lactone in AA molecules might play a key role.As a result,an obvious decrease of overpotential was achieved at such a PVP-graphene electrode through a possible adsorption/enrichment process,which will probably trigger potential applications for the electroanalysis of some aromatic and heterocyclic compounds.     

Graphene Oxide as a Platform for Copper Pentacyanonitrosylferrate Nanoparticles and their Behavior in the Electro‐oxidation of N‐Acetylcysteine

This work describes the preparation of graphene oxide by the Modified Hummers Method and the chemical modification of its surface with nanoparticles of copper pentacyanonitrosylferrate(III) (GOCuNP). The materials obtained were characterized by Raman spectroscopy, x‐ray photoelectron spectroscopy and transmission electron microscopy. The GOCuNP was characterized by cyclic voltammetry using a graphite paste electrode that presented electrocatalytic response for N‐acetylcysteine with detection limit of 2.97×10^?5 mol L^?1 at concentration range of 3.00×10^?5 to 6.00×10^?3 mol L^?1 of N‐acetylcysteine. By this way, the bimetallic complex formed is included in the list of materials obtained as potential candidates for the construction of electrochemical sensors for N‐acetylcysteine detection.     

Electroanalysis of Carbendazim using MWCNT/Ca‐ZnO Modified Electrode

The present research involves the report on electrochemical deportment of Carbendazim (MBC) at multiwalled carbon nanotubes and calcium‐doped zinc oxide nanoparticles altered nanocomposite based carbon paste electrode (MWCNTs/Ca‐ZnO‐CPE). The modified carbon paste evidenced manifest electrocatalytic behavior for MBC in 0.2 M phosphate buffer (PB) solutions. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and square wave voltammetry (SWV) techniques were used for the analysis. The working electrode assembly exhibits faster electron transfer of MBC with increase in the peak current. At bare CPE, MBC showed maximum peak current of 1.098 μA at potential 0.7568 V whereas at MWCNT/Ca‐ZnO/CPE peak current of 5.203 μA was observed at potential 0.7541 V in 0.2 M PBS of pH 7.0 at the sweep rate of 50 mV s^?1. The synthesized 5 % Ca‐ZnO nanoparticles (NPs) were characterized by X‐ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X‐ray analysis (EDX), and Transmission electron microscopy (TEM) analysis. Various factors influencing the voltammetry of MBC such as pre‐concentration time, pH, sweep rate, and amount of MBC were studied and from the studies we observed that the response was found to be diffusion‐controlled. The concentration variation studies for MBC was watched in the linear working range of 0.01 μM to 0.45 μM and the detection limit was found by SWV technique.