锰电解过程关键因素研究及技术经济性分析

从槽液Mn²⁺浓度、电解时间和过电位关键因素研究电解初期过程,在三电极体系采用计时电量法探讨和优化工艺参数. 研究表明,在不锈钢表面,锰的初期电解析氢显著. 随时间延长,锰逐渐覆盖于不锈钢表面,析氢更困难,其电流效率随之提升,在高过电位区出现极限电流,反应受扩散控制. 在含0.02 g·L^-1 SeO₂溶液体系中,在40 g·L^-1 Mn²⁺ + 120 g·L^-1 (NH₄)₂SO₄、过电位为0.151 V、槽液温度为40 ^oC、PH为6.6、时间为0.5 h的电解条件下,电流效率可达95.3%;在实用矿粉制液体系,效率也可达81.4%,较企业相同电解体系提高了15%.     

Electroreductive polymerization of phenylmethyldichlorosilane in a divided cell using a neutral membrane

Electrochemical formation of poly(phenylmethylsilane) in a divided cell containing a Teflon® neutral membrane was studied. The electrolysis of dichlorosilanes was carried out in a solution containing tetrahydrofuran + hexamethylphosphoramide as the solvent, tetrabutylammonium perchlorate as the support electrolyte and stainless steel as the cathode, with Pt and graphite as the resistant anodes or stainless steel as the sacrificial anode. Polysilanes with a number-average molecular weight in the range from 2,600 to 130,000 g/mol were obtained, depending on the conditions used.     

Electrolytic Preparation of Vanadium(V) Oxide from Saturated Solutions of Ammonium Metavanadate

A study was made of the voltammetric characteristics and dependences of the deposition rate and current efficiency on the electrolysis conditions in anodic deposition of vanadium(V) oxide on a stainless steel support from saturated solutions of ammonium vanadate, including those containing active and supporting additives.     

Reaction kinetics and mechanism for hydrothermal degradation and electrolysis of glucose for producing carboxylic acids

Electrolysis in subcritical water can convert biomass-derived saccharides into value-added chemicals and fuels without any additives. In this work, we aim to understand reaction behaviours of glucose under subcritical water degradation or electrochemical conditions for the purpose of developing a new method for producing useful carboxylic acids. Degradation of glucose was carried out using a continuous flow-type reactor in subcritical water at various operating conditions, and electrochemical reactions of their product solutions were conducted at identical conditions with a 500-mL batch autoclave. Gaseous products obtained were analyzed by gas chromatography-thermal conductivity detection (GC-TCD), and liquid products were analyzed by high-performance liquid chromatography (HPLC) and gas chromatography-flame ionization detection (GC-FID). The total organic carbon (TOC) in the aqueous product solution was determined by using a TOC analyzer. Based on the experimental results, a reaction pathway for glucose is proposed for subcritical water degradation and electrolysis.     

Hydrothermal decomposition of brominated epoxy resin in waste printed circuit boards

Brominated flame retardant (BFR), which containing in printed circuit boards (WPCBs), brings a series of environmental and health problems. Hydrothermal technology was applied to decompose brominated epoxy resin in WPCBs at subcritical or supercritical water conditions. The brominated epoxy resin was decomposed into oil and the environmental influence of BFR was eliminated. The experiment was carried out in a 5.7 ml tube reactor and heated by a salt-bath. The variation of degradation rate of brominated epoxy resin with reaction temperature, time and additives were studied. The compositions of liquid products were analyzed by gas chromatography-mass spectrometry (GC-MS). When reaction temperature exceeded 300 °C, retention time stayed over 30 min and alkaline additive existed, more than 80% brominated epoxy resin could be mainly decomposed into phenol, which can be used as chemical material. Two different hydrothermal decomposition pathways were discussed according to the characterization of products. The results indicated that brominated epoxy resin in WPCBs could be handled effectively by hydrothermal decomposition.     

Electrochemical synthesis of diacetone-2-keto-L-gulonic

The electrochemical oxidation of technological-grade diacetone-L-sorbose to diacetone-2-keto-L-gulonic acid by the preparative electrolysis in alkaline media is studied. The effect of various technological parameters, namely, the cathode material, the temperature, the sodium hydroxide concentration, the current density, and the cell design, on the yield of discetone-2-keto-L-gulonic acid is considered. For the electrosynthesis of diacetone-2-keto-L-gulonic acid on the anode made of Kh18N10T stainless steel, the conditions are found that provide its total substance yield and current efficiency over all stages of oxidation and isolation from solution at the level of 88.5 and 37.5–38.0%, respectively.     

Electrochemical Degradation of o-Chloronitrobenzene by Three-dimensional Electrodes

Degradation of o-chloronitrobenzene wastewater was experimentally investigated at a three-dimensional electrode(TDE) with granular activated carbon as the particle electrode, graphite as the anode, and stainless steel plate as the cathode. The kinetic model of o-chloronitrobenzene degradation was studied, and the effects of pH, electrolysis time, particle electrode, electrolyte concentration, and initial concentration of the solution on degradation efficiency were investigated to determine the optimal operating conditions. The degradation of o-chloronitrobenzene by oxidation at the TDE was monitored by chemical oxygen demand(COD) measurements, UV-Vis absorption, and high performance liquid chromatography(HPLC). COD degradation by electrochemical degradation followed pseudo-first order kinetics with respect to the concentration of o-chloronitrobenzene solutions. Optimal reaction conditions included 15 g of activated carbon as the particle electrode, 400 mg/L o-chloronitrobenzene solution containing 0.10 mol/L Na₂SO₄, pH=3, and 60 min of electrolysis. The UV-Vis absorption spectra and HPLC results illustrate that the benzene ring in o-chloronitrobenzene was rapidly broken down to form aliphatic substances through electrochemical degradation. COD degradation was approximately 98.5% at optimal conditions.     

Electrochemical chlorine-free AC disinfection of water contaminated with <Emphasis Type="Italic">Salmonella typhimurium</Emphasis> bacteria

Deionized (DI) water contaminated with Salmonella typhimurium (S. typhimurium) bacteria was disinfected by alternating current. Ammonium sulfate was used as electrolyte. Disinfection was carried out in the circulation system including an electrochemical cell with stainless steel electrodes. The process efficiency was estimated and the number of killed bacteria was directly proportional to the water treatment time and concentration of hydroxyl radicals generated by electrolysis. The presence of OH radicals was detected with N,N-dimethyl-p-nitrosoaniline (RNO) used as a spin trap. Similar experiments were carried out with water remaining after poultry washing at poultry farms and additionally contaminated with S. typhimurium bacteria. Measures were recommended to increase the process efficiency and decrease the water treatment time.     

Observation of gas-phase molecular dications formed from neutral organics in solution via the controlled-current electrolytic process inherent to electrospray

This article reports the first electrospray (ES) mass spectrometry observation of molecular dications that were formed in solution by sequential one-electron oxidation of the neutral molecules [viz., nickel(II) and cobalt(II) octaethylporphyrin] via the controlled-current electrolytic (CCE) process inherent to electrospray. Dication formation was found to require (1) the addition of electrolyte to the sample solution, which increased the magnitude of the ES current and, therefore, increased the extent of analyte electrolysis in the ES capillary, (2) a relatively low solution flow rate, which increased the electrolysis time (i.e., the time the analyte remained in the capillary), thereby providing more time for the analytes to diffuse to the metal-solution interface and react, and (3) the use of a platinum ES capillary, which, because it is difficult to oxidize, increased the proportion of the faradaic current that might be provided by electrolysis of solution species compared to that proportion available when the typical stainless steel capillary is used. These interpretations of the data are made on the basis of the known characteristics of the CCE process inherent to ES, supplementary data obtained from direct solution-phase observation of the metalloporphyrin redox products formed within the different metal ES capillaries by means of a novel ES ion source, and off-line cyclic voltammetry studies of the metalloporphyrins performed by using platinum and stainless steel working electrodes.     

Determination of silicon in high-silicon electrical steel by ICP-AES with on-line sample electrolytic dissolution.

A flow-injection procedure combining electrolytic sample decomposition and inductively coupled plasma atomic emission spectrometry (ICP-AES) is proposed in order to rapidly determine the content of silicon in high-silicon electrical steel. This system is characterized by sample decomposition through electrolysis directly coupled to ICP-AES. A steel sample is dissolved by electrolysis using a 6 mol L(-1) HCl solution as an electrolyte with a flow rate of 5 mL min(-1); the electrolyte containing a dissolved sample is subsequently introduced into ICP-AES via a nebulizer. The effects of the electrolysis current and the temperature on the decomposition of the sample were studied. Samples were electrolyzed under the condition of a 1.5 A constant current, at room temperature (25 degrees C) to avoid the hydrolysis of silicon to precipitate. Comparing the analytical results of steel samples obtained by this analytical system with those obtained by the gravimetric method, determined values agreed well quantitatively. The RSD of silicon at approximately 3% was 0.3% (n = 6).     

阴极冷却反应器电合成乙醛酸

以过饱和草酸水深液为阴极液 ,盐酸溶液为阳极液 ,在阴极冷却电化学反应器内草酸电解合成乙醛酸 .考察了电极温度、电解液温度、电流密度和电极材料对合成乙醛酸的时空产率和电流效率的影响 .结果表明 ,阴极冷却反应器既节省能耗 ,又可使电解过程在较高草酸浓度下进行 ,提高电流效率和时空产率 .用石墨板做阳极 ,铅做阴极 ,电流密度为 4 0 9.4 6A·m-2 ,阴极液流速 μ=1 .0 8m·s-1,电解温度为 2 0℃左右时 ,电解 3 .70h ,可得到质量分数为 3 .52 %的乙醛酸溶液 ,平均时空产率为 0 .0 3 2kg·dm-3·h     

In Situ Activating Ubiquitous Rust towards Low‐Cost,Efficient, Free‐Standing,and Recoverable Oxygen Evolution Electrodes

Developing effective ways to recycle rusted stainless steel and to promote the sluggish oxygen evolution reaction (OER), associated with water splitting and metal–air batteries, is important for a resource‐sustainable and environment‐friendly society. Herein, we propose a strategy to enable rusted stainless steel plate to be used as an abundant and low‐cost OER catalyst, wherein a hydrothermal combined in situ electrochemical oxidation–reduction cycle (EORC) method is developed to mimic and expedite the corrosion process, and thus activate stainless steel into free‐standing OER electrodes. Benefiting from the plentiful electrolyte‐accessible Fe/(Ni) oxyhydroxides, high conductivity and mechanical stability, this electrode exhibits remarkable OER performances including low overpotential, fast kinetics, and long‐term durability. The slight degradation in current after long‐term use can be repaired immediately in situ by an EORC.     

In Situ Activating Ubiquitous Rust towards Low‐Cost,Efficient, Free‐Standing,and Recoverable Oxygen Evolution Electrodes

Developing effective ways to recycle rusted stainless steel and to promote the sluggish oxygen evolution reaction (OER), associated with water splitting and metal–air batteries, is important for a resource‐sustainable and environment‐friendly society. Herein, we propose a strategy to enable rusted stainless steel plate to be used as an abundant and low‐cost OER catalyst, wherein a hydrothermal combined in situ electrochemical oxidation–reduction cycle (EORC) method is developed to mimic and expedite the corrosion process, and thus activate stainless steel into free‐standing OER electrodes. Benefiting from the plentiful electrolyte‐accessible Fe/(Ni) oxyhydroxides, high conductivity and mechanical stability, this electrode exhibits remarkable OER performances including low overpotential, fast kinetics, and long‐term durability. The slight degradation in current after long‐term use can be repaired immediately in situ by an EORC.     

Ta/BDD薄膜电极电化学催化氧化硝基酚

研究了热丝化学气相沉积法(HFCVD)制备得到钽衬底掺硼金刚石膜电极(Ta/BDD)的物理性质和电势窗口, 并考察了其用于电化学催化氧化硝基酚过程中的性能及各种影响因素. 扫描电镜和拉曼光谱表明, Ta/BDD电极具有良好的物理性能, 通过测试Ta/BDD电势窗口发现, 该电极具有较高的析氧过电位. 在Ta/BDD电化学催化氧化硝基酚过程中, 化学需氧量(COD)和高效液相色谱测试表明, 硝基酚能够有效降解, 电流密度、支持电解液及浓度对降解过程影响较大, 温度影响不明显. 强化寿命实验表明, Ta/BDD电极具有较好的稳定性. 实验结果表明, Ta/BDD电极是一种适于硝基酚降解和COD去除的优良电极.     

Solar-powered electrochemical oxidation of organic compounds coupled with the cathodic production of molecular hydrogen

A Bi-doped TiO2 anode, which is prepared from a mixed metal oxide coating deposited on Ti metal, is shown to be efficient for conventional water splitting. In this hybrid photovoltaic-electrochemical system, a photovoltaic (PV) cell is used to convert solar light to electricity, which is then used to oxidize a series of phenolic compounds at the semiconductor anode to carbon dioxide with the simultaneous production of molecular hydrogen from water/proton reduction at the stainless steel cathode. Degradation of phenol in the presence of a background NaCl electrolyte produces chlorinated phenols as reaction intermediates, which are subsequently oxidized completely to carbon dioxide and low-molecular weight carboxylic acids. The anodic current efficiency for the complete oxidation of phenolic compounds ranges from 3% to 17%, while the cathodic current efficiency and the energy efficiency for hydrogen gas generation range from 68% to 95% and 30% to 70%, respectively.     

Removal of proteinaceous soils using hydroxyl radicals generated by the electrolysis of hydrogen peroxide

We have developed here for the first time a novel method to generate hydroxyl radicals, *OH, by applying slightly negative electric potentials (-0.2--0.8 V vs Ag/AgCl) to the surface of a metal (or metal oxide) that is in contact with hydrogen peroxide solution containing a supporting electrolyte. Namely, *OH radicals were generated at the surface by the electrolysis of hydrogen peroxide according to the equation, H2O2+e- --> *OH+OH-. This method was used to clean a stainless steel fouled with a model protein, beta-lactoglobulin. The *OHs generated at the surface were effective in removing beta-lactoglobulin that had been irreversibly adsorbed, by several minutes of treatment at room temperature (22+/-2 degrees C). The removal rates measured for various concentrations of H2O2 and supporting electrolyte and different potentials were determined exclusively by the electric current.     

Electrochemical synthesis of 1,3-dimethyl-4-amino-5-formyluracyl in the presence of ammonium chloride

The synthesis of 1,3-dimethyl-4-amino-5-formyluracyl, an intermediate of theophylline synthesis, was studied in an ammonium chloride medium using the electroreduction of 1,3-dimethyl-4-amino-5-nitrosouracyl to a diamino derivative with its further formylation. The electrolysis and formylation conditions were optimized. The reduction of 1,3-dimethyl-4-amino-5-nitrosouracyl was performed under the following conditions: its concentration was 12.0–13.5 %, the cathode was a Kh18N10T stainless steel gauze, the electrolysis was performed in the presence of ammonium chloride, the current density was 7.5–8.0 A/dm², the electrolysis temperature was 40–45°C, and the formylation temperature was 71–72°C. The substance yield of overall formylaminouracyl was 81.2–83.3% and the current efficiency was 62.0–64.5%. The developed process of 1,3-dymethyl-4-amino-5-formyluracyl synthesis was evaluated at a scaled-up laboratory setup with a filter-press cell.     

间接电氧化2-丁酮制备α-羟基缩酮的研究

在板框式循环电解槽中,以KOH为电解质,KI为催化剂,石墨电极分别为阳极和阴极,研究电化学间接氧化2-丁酮合成乙偶姻中间体α-羟基缩酮,讨论电流密度、极板间电解液流速、电解液中2-丁酮浓度、电解温度以及通电量等电解条件对中间体收率和电流效率的影响,经优选工艺条件为：电流密度40 mA·cm^-2,流速6.4 cm·s^-1,2-丁酮浓度1.75 mol·L^-1,电解温度30℃,通电量为1.5 F·moL^-1时,中间体收率可达78.9%,电流效率40.1%. 循环伏安测试结果表明,电解时碘离子在阳极氧化生成碘单质,甲醇在阴极还原生成甲氧基负离子,原料2-丁酮与电解产物反应,并最终生成乙偶姻中间体.     

印染废水的电化学深度处理及回用研究

针对印染废水水质特性,在PbO₂/Ti阳极、不锈钢板阴极的电解反应器中研究了电化学氧化对印染废水生化出水的处理效果. 试验结果表明,电氧化工艺可以实现化学需氧量（Chemical Oxygen Demand,COD）、氨氮和色度的同步去除. 在电流密度10 mA·cm^-2时电解60 min,废水中COD、氨氮、色度、氯离子浓度以及pH值等指标均可达到GB/T 19923-2005《城市污水再生利用工业用水水质》中工艺与产品用水标准,电流效率达45.6%,吨水能耗4.1 kW·h.