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.     

Preparation of Sb2O3‐loaded Activated Carbon Particle Electrode and Its Electrocatalytic Degradation of Methyl Orange in a Three‐dimensional Electrode Cell

Electrocatalysis on the degradation of methyl orange is investigated using Sb₂O₃‐loaded activated carbon (Sb₂O₃/AC), a new particle electrode. The electrode was prepared by an impregnation method. An orthogonal array with four factors and three levels was selected to carry out the experiment. Electrocatalysis on the degradation of methyl orange through Sb₂O₃/AC was characterized by a series of parameters, including the amount of the particle electrode, the concentration of Na₂SO₄, the cell voltage, and the electrolysis time, and the results were compared with those of a conventional AC particle electrode. The results indicate that calcination temperature has the greatest impact on the catalytic activity of the particle electrode. The optimal conditions for preparing the Sb₂O₃/AC electrode include an 8 mL SbCl₃ solution, 90 min hydrolysis time, 400 °C calcination temperature, and 180 min calcination time. As well, the degradation efficiency of the Sb₂O₃/AC electrode is consistently higher than that of the AC electrode under the same electrolysis conditions. The electrochemical oxidation of methyl orange of both electrodes conformed to pseudo first‐order kinetics, but the rate constant of the Sb₂O₃/AC electrode was 2.29 times that of the AC electrode; this is likely due to the high electrocatalytic activity of the experimental electrode. The electrocatalysis results exhibited the synergetic effects of AC and Sb₂O₃ in the new particle electrode.     

二氧化碳在P+/P-Si半导体电极上光电化学还原的研究

1870年,Royer使用Zn电极将CO₂还原为HCOOH。近年来,人们对CO₂在几十种金属电极上的电化学还原进行了深入的研究。但普遍存在的问题是CO₂在金属电极上还原的过电位较大,导致耗电较多。     

新型Ti/TiOxHy/Sb-SnO2电极上苯胺电化学氧化反应

苯胺是一种重要的化工原料,广泛应用于印染、制药、造纸、橡胶等领域.随着化工行业的迅速发展,苯胺的需求量越来越大.然而,苯胺毒性高,大量使用势必造成水体中苯胺浓度的升高,给人类健康及生态环境造成危害.因此,急需一种高效、洁净、经济的方法处理含苯胺废水.电化学氧化法比较新颖,相比传统废水处理方法,它具有高效、简单、清洁等优点,因此被应用于很多废水处理当中,但过多的能耗限制了其进一步广泛应用.阳极作为电化学氧化技术的核心部件,直接影响到电化学氧化反应性能.因此开发出一种高效、经济的阳极材料很有必要.此外,对苯胺降解条件的优化也同样重要.关于苯胺电化学氧化,已有的研究包括Pt电极、PbO2电极和石墨电极等阳极材料.比较而言, Ti/Sb-SnO2电极具有制备工艺简单,析氧过电位较高,材料廉价和电催化性能较强等优点.然而,它的稳定性仍有待提高.因此本文制备了一种高稳定性的Ti/TiOxHy/Sb-SnO2电极,并用于处理苯胺废水.较为系统地研究了电流密度、苯胺初始浓度、pH、NaCl投加量及反应器类型对苯胺电催化氧化性能的影响,同时采用扫描电镜(SEM)、X射线衍射(XRD)和电化学测试对该电极进行了表征,并应用紫外-可见光谱、化学需氧量、电流效率及能耗对不同参数进行评定和优化. SEM及XRD结果表明, Ti/TiOxHy/Sb-SnO2电极涂层覆盖比较完全、紧实,未出现裂缝的发生,因而有利于提高电极稳定性.循环伏安测试结果表明,此电极具备较高的析氧过电位(2.0 V vs Ag/AgCl)及电化学孔隙度(76.31%),因此有利于电极催化性能的提高.苯胺电化学氧化实验结果发现,该反应符合准一级动力学模型,且高电流密度、酸性环境、适当NaCl投加量(0.2 wt%)更有利于苯胺的降解.另外, Ti/TiOxHy/Sb-SnO2电极在三维反应器中对苯胺的处理效果要远远好于在二维反应器中.可以看出, Ti/TiOxHy/Sb-SnO2电极具有较好的处理苯胺性能,可为苯胺废水处理的应用提供了一定的理论指导.     

三相流化床电极反应器深度处理制浆废水

应用三相流化床电极反应器(新型电化学反应器)处理制浆废水.研究了曝气量、槽电压、溶液pH值及FeSO4浓度等因素对电解效果的影响.结果表明,该反应器深度处理制浆废水的最佳工艺条件为:槽电压20 V,曝气量为0.3 m3.h-1,FeSO4浓度为1000 mg.L-1,pH值≈2.5,反应时间为90 m in时COD去除率为70.1%.     

高碳铬铁在氢氧化钠水溶液中电化学氧化过程

铬铁电化学氧化法是一种新的制备铬酸钠的方法,然而高碳铬铁在NaOH水溶液中的电化学氧化过程尚不明确。 采用循环伏安法(CV)、稳态极化法(LSV)等电化学测试方法对金属铬、高碳铬铁在NaOH水溶液中的电化学氧化过程进行研究,通过扫描电子显微镜(SEM)、能量散射谱(EDS)和X射线光电子能谱(XPS)对高碳铬铁电解后固相产物表征,判断固相产物的组成。 结果表明,高碳铬铁不同于金属铬的电氧化过程,它在NaOH溶液中通过Cr(0)→Cr(Ⅵ)的电氧化方式生成铬酸钠,中间产物Cr(OH)₃和Fe(0)发生电化学反应生成稳定的FeCr₂O₄。 随着NaOH浓度的增加,电势较低时,受高碳铬铁中Fe(0)的影响,高碳铬铁容易在NaOH水溶液中发生钝化;当电势足够正时,钝化膜溶解,生成铬酸钠、氢氧化铁和亚铬酸亚铁,同时,阳极表面有氧气析出。 高碳铬铁电化学氧化制备铬酸钠的适宜条件:碱浓度≥2 mol/L,阳极电势≥1.6 V(vs.SCE)。     

Sorbic Acid and Its Degradation Products: Electrochemical Characterization

The electrochemical redox behavior of sorbic acid (SA), an important food preservative, was investigated at a glassy carbon electrode using cyclic, differential pulse, and squarewave voltammetry over a wide pH range. The oxidation of SA is an irreversible, diffusion-controlled, and pH-independent process that occurs with the transfer of only one electron and does not involve the formation of any electroactive oxidation product. Adsorption of SA at GCE electrodes was also observed. Following incubation in different pH electrolytes, the degradation of SA was electrochemically detected by the appearance of a new oxidation peak at lower potential value. The degradation products, formed homogenously in solution, undergo irreversible oxidation and lead to the formation of two oxidation products that strongly adsorb on the electrode surface and are reversibly oxidized. SA degradation was also confirmed using HPLC and UV-Vis spectrophotometry. A mechanism for oxidation of SA and its degradation products in aqueous solutions was proposed.     

活性炭/LiNi0.5Mn1.5O4电容器性能及活性炭负极的劣化分析

为提高电化学电容器的工作电压,采用电池材料LiNi_0.5Mn_1.5O₄(LNMO)为正极,活性炭为负极,组装成混合型电容器并探索了提高其性能的最佳条件。 负/正极质量比增加、充放电截止电压的升高均能显著提高电容器的放电容量和能量密度,在负/正质量比为4,电压0~3 V, 电流密度1×10^-3 A/cm²的条件,700次循环后容量保持率达97.5%。 运用三电极体系、电化学阻抗谱等测试手段对此负极活性炭的劣化及其对电容器性能的影响进行了深入探索。     

Efficient electrochemical incineration of phenol on activated carbon fiber as a new type of particulates

The feasibility of activated carbon fibers (ACFs) used as a new type of particle electrodes in 3-dimensional (3D) electrode for the electrochemical degradation of phenol wastewater was investigated for the first time. The surface morphology, textual properties and electrochemical behaviors of ACF were studied by scanning electron microscopy (SEM), N₂-BET sorption and cyclic voltammograms (CVs), respectively. Compared with the commercialized granular activated carbon (GAC), ACF particle electrodes exhibited higher electrochemical oxidation performance on the mineralization of target pollutant. The identification of intermediates indicated most of oxidation products were adsorbed onto the ACFs. The detection of hydrogen peroxide and hydroxyl radicals in the reaction system suggested that the reaction mechanism was direct anodic oxidation of pollutant on ACFs if the cathode did not contact the ACFs. The operative parameters including initial concentration of substrate, applied current density and the initial aqueous pH have been scientifically studied in search of the optimum condition. Based upon the obtained results, the ACFs longevity was tested in solution at pH 2.0, revealing relatively high electrooxidation capacity and long catalyst lifetime of ACFs in acid solution.     

Direct electrocatalytic reduction of p-nitrophenol at room temperature ionic liquid modified electrode

Direct electrochemical reduction ofp-nitrophenol （PNP） was investigated on a room temperature ionic liquid N-butylpyridinium hexafluorophosphate （BPPF6） modified carbon paste electrode （CILE）. The cathodic peak potential was positively shifted and the peak currents were increased compared to that obtained on traditional carbon paste electrode （CPE）. The results indicated that the presence of ionic liquid BPPF6 on the electrode surface showed excellent catalytic ability to the electrochemical reduction of PNP. The electrochemical behaviors of PNP on the CILE were investigated by cyclic voltammetry and the conditions such as the scan rate, the buffer pH, the substrate concentration were optimized. The electrochemical parameters were further calculated with the results of the electron transfer number （n）, the charge-transfer coefficient （α） and the surface concentration （Гr） as 1.76, 0.37 and 2.47 × 10^-9 mol/cm^2, respectively, for the selected reductive peak. The results indicated that PNP showed an irreversible adsorption-controlled electrode process on the CILE.     

Enhanced three-dimensional electrochemical process using magnetic recoverable of Fe3O4@GAC towards furfural degradation and mineralization

Furfural is as one of the major environmental pollutants in different industrial effluents such as refinery and petrochemical, paper, cardboard and oil refining. This toxic chemical is irritant and causes allergy for skin, eyes and mucous membranes. This study was developed to investigate the efficiency of a three-dimensional electrochemical process in the presence of granular activated carbon magnetized with Fe₃O₄ (Fe₃O₄@GAC) particle electrodes for removal of furfural from aqueous solution. The particle electrodes structural and morphological featured were determined via BET, VSM, XRD, FE-SEM and FTIR techniques. The experiments were performed based on central composite design (CCD) and the role of influencing factors including reaction time, pH, voltage and initial furfural concentrations at five levels were evaluated. The Quadratic model with high correlation coefficient = 0.9872 (R² and (R²_Adj = 0.9724)) was suggested for experimental data analysis. The performance of electrochemical oxidation towards furfural degradation was enhanced substantially after adding Fe₃O₄@GAC. The highest furfural removal efficiency (98.2%) was achieved under optimal conditions (furfural: 201 mg/L, electrolysis time: 69 min, voltage: 19 V, and pH: 5.0). Besides, over 78 and 74 % of COD and TOC were removed by Fe₃O₄@GAC-based three-dimensional process, respectively. Based on the COD/TOC ratio and average oxidation state (AOS) index, a significant increase was observed in the biodegradability of intermediates of furfural after treatment. Results showed that three-dimensional electrochemical process with particle electrodes is a promising technology for efficient removal of furfural, even at high concentrations. Results of Liquid chromatography–mass spectrometry (LC-MS) analysis and degradation pathway showed that furfural could be oxidized to compounds with smaller molecular masses, which eventually converted to carbon dioxide and water.     

Redox properties of isradipine and its electrochemical detection in the HPLC determination of the compound in human serum

The electrochemical behaviour of isradipine in a mixed solution of Britton-Robinson buffer (pH 11.8):acetonitrile:methanol (6:3:1, v/v) was studied by cyclic voltammetry and spectroelectrochemistry using an optically transparent thin layer electrode of carbon cloth. The cyclic voltammogram showed several peaks whose shape and potentials depended on the pH. The peak at 330 nm, corresponding to the absorbance of the dihydropyridine ring, disappeared after electrolysis at a potential that was more positive than the oxidation peak. The oxidation peak corresponds to the oxidation of the dihydropyridine ring. Peak height at pH 11.8 was proportional to isradipine concentration. On the basis of the redox properties of isradipine, HPLC was conducted applying electrochemical detection on a polybutadiene coated alumina column using an alkaline mobile phase. The method was applied for the determination of isradipine content in human serum. A good linear relationship between isradipine concentration and peak height was found in the concentration range of 2-200 ng/mL with a correlation coefficient of 0.9924. The detection limit was 0.5 ng/mL. The within-day and day-to-day variation were examined for control human serum and percentage relative standard deviation ranged from 0.5 to 6.7. Interference from many other coadministered drugs was studied in the specified experimental conditions. Photo and heat stabilities of the compound were also studied.     

Metal complex effect on the hydrogenation of o-chloronitrobenzene over polymer-stabilized colloidal ruthenium clusters

Effect of metal complex on hydrogenation of o-chloronitrobenzene (o-CNB) over poly-vinylpyrrolidone stabilized ruthenium colloid (PVP-Ru) has been studied in methanol media under 320 K and 4.0 MPa. The addition of Zn(II) complexes of diamines to PVP-Ru catalyst system leads to significant increase in the activity of PVP-Ru, while the selectivity for o-chloroaniline (o-CAN) maintained 100%. Especially, rate enhancement more than 30 times that over neat PVP-Ru has been achieved in the presence of Zn(trien)Cl₂. It was verified that the incorporation of Zn(II) complexes of multi-amines changed the reaction kinetics.     

Electrochemical degradation of 2,4-Dinitrotoluene (DNT) from aqueous solutions using three-dimensional electrocatalytic reactor (3DER): Degradation pathway,evaluation of toxicity and optimization using RSM-CCD

2,4-Dinitrotoluene (2,4-DNT) has been found to be an important petrochemical compound, which is primarily employed for the synthesis of tolylene diisocyanate and the production of dyes, rubber, and explosives. Since this compound has high toxicity and carcinogenicity, the cautions should be considered when wastewater contaminated with DNTs and their derivatives is released into the environment. Thus, the object of the present study was the investigation of the 2,4-DNT degradation efficiency using the three-dimensional electrocatalytic reactor (3DER) with two different types of particle electrodes (granular activated carbon (GAC) and magnetized clinoptilolite zeolite (MCZ)@Fe₃O₄ nanoparticles)). Preparation of the graphite (G)/β-PbO₂ anode was done by electrochemically depositing PbO₂ layers on graphite sheets. The prepared graphite sheet and a stainless-steel 316 sheet (with the same dimensions) were employed as the anode and the cathode, respectively. Field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), and energy-dispersive X-ray spectroscopy mapping (EDS-mapping) confirmed the successful preparation of G/β-PbO₂ anode. The surface morphology, chemical composition of MCZ@Fe₃O₄ nanoparticles as a particle electrode were determined by scanning electron microscope (SEM) and XRD pattern. To determine the optimal conditions, we employed the response surface methodology-based central composite design (RSM-CCD) method. According to observed results, higher efficiency of 3DER was obtained by increasing the reaction time and current density and decreasing pH and the pollutant concentration. Studies highlighted the initial 2,4-DNT concentration of 23.5 mg/L, current density 4.8 mA/cm², pH of 4.1, electrolysis time of 50 min, particle electrodes dose = 6 g/250 cc as optimum values of parameters. The 2,4-DNT degradation efficiencies using GAC and MCZ@Fe₃O₄ nanoparticles as particle electrodes under mentioned optimal conditions were 98.6% and 96.5%, respectively. Moreover, the chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies were 88.5% and 80.9% at the end of 50 min, respectively. Furthermore, results were indicative of an enhancement in average oxidation state (AOS) (from 1.27 to 2.36) and carbon oxidation state (COS) (from 1.27 to 3.68) in the 3DER process and a reduction in the COD/TOC ratio (from 1.81 to 1.09); these signposts the effectiveness of 3DER system for providing the biodegradability of 2,4-DNT. Considering the results, the 3DER could lead to suitable results for the degradation of wastewater containing DNT and resistant contaminants as pretreatment and has remarkable applicability for enhancing the biodegradability of wastewater.     

Electrochemical Degradation of the Pesticide Dimethenamid‐P at Gold,DSA Platinum and Ruthenium Oxide Electrodes in Different Electrolytes

For the first time the electrochemical degradation of the pesticide dimethenamid‐P was studied. Its direct electrochemical degradation, using potential cycling at a gold electrode, was performed by cyclic voltammetry and HPLC analysis of electrolyte after 72 h showed 56.8 % of degradation. HPLC‐MS indicates the formation of degradation products through the elimination of chlorine atom and C? N bond cleavage. By indirect electrolysis using DSA Ti/PtOx and DSA Ti/RuO₂ electrodes during 30 minutes 87.2 % and 88.3 % of dimethenamid‐P was degradated, respectively. The high percentage of degradation of dimethenamid‐P was achieved with non time consuming, simple and cheap electrochemical processes.     

Degradation of p-aminophenol wastewater using Ti-Si-Sn-Sb/GAC particle electrodes in a three-dimensional electrochemical oxidation reactor

In this study, Ti-Si-Sn-Sb/GAC particle electrodes were prepared by sol–gel method. The particle electrodes were characterized by SEM, XRD, EDX, and BET then used to carry out three-dimensional (3D) electrocatalytic oxidation degradation on simulated refractory p-aminophenol (PAP) wastewater. The effects of initial pH, cell voltage, aeration flow rate and initial PAP concentration on degradation experiments were investigated. Under the optimal conditions, the PAP and COD removal rates were 89.45% and 75.17% respectively. In addition, the possible degradation mechanism of PAP was further investigated by UV–Vis and HPLC. Finally, it was found that the Ti-Si-Sn-Sb/GAC particle electrodes with high catalytic activity and excellent stability could significantly improve the PAP wastewater removal efficiency.     

阴极溶出催化极谱法测定微量硒

本文提出将溶出伏安法和极谱催化法结合起来,用溶出催化波来测定微量硒;考察了各种试验条件及其它离子对分析结果的影响,并对实样进行了分析测定。用国产883型笔录式极谱仪,配用旋转玻碳电极测定硒,电解富集3-5分钟,可定量测定浓度在4×10^-9-1×10^-7M 范围内的硒;富集20-30分钟,硒的检出下限为7×10^-10M。测定时不必除氧。在测定硒的基础上,用玻碳电极和大汞电极相配合,对硒的溶出催化电极过程进行了研究,探讨了此过程中各步反应的机理。     

氢氧化钠水溶液体系中金属铬的电化学氧化过程

铬铁电氧化溶出技术是一种全新的制备铬酸钠的方法,具有反应条件温和、过程可控、工艺环保等优点,然而金属铬在NaOH水溶液中的电化学氧化过程尚不明确. 本文采用循环伏安法（CV）和阳极极化法（LSV）对金属铬在NaOH水溶液中的电化学氧化过程进行研究. 使用EDS、SEM、XRD和XPS对电解前后的金属铬表征,判断中间物的产生,使用紫外可见分光光度计验证电解液中生成了铬酸钠. 结果表明,金属铬和中间产物Cr(OH)₃可能依次发生电化学氧化直接生成Na₂CrO₄,阳极极化为金属铬的活化. 随着NaOH溶液浓度的增加,Cr(OH)₃和Na₂CrO₄的生成量在增加,金属铬电化学氧化制备铬酸钠的适宜条件为碱浓度≥ 2 mol·L^-1,阳极电势≥ 1.6 V（vs. SCE）.     

CO_2熔盐电化学转化碳材料的电化学特性

基于对熔融碳酸盐体系中电化学还原CO_2所得碳材料(electrolytic-carbon,EC)的形貌、结构、组成的认识,以粉末微电极循环伏安法测试为基础,在稀溶液中对EC的本征电化学行为进行了考察,以揭示这类碳材料的界面电化学特性。实验发现,在典型条件(450°C、4.5 V槽压)下制备的电解碳(450°C-4.5 V-EC)的伏安行为有别于多壁碳纳米管、石墨烯、石墨、乙炔黑等常见碳材料,在负电位区表现出显著的"双电层充放电响应迟滞"现象。通过考察溶液pH值、电位扫描速率、阴阳离子种类对这一现象的影响,发现pH和电解液组成都不影响这一现象的出现;电解液浓度提高和低扫描速率时滞后现象减弱,表明迟滞充放电是这类碳材料的本征特性,与其表面含氧官能团及其对阳离子的特性吸附密切相关。实验进一步研究了不同电解条件下制备的EC所展现的电化学特性吸附及电容性质,发现随着熔盐温度的升高,EC对电解液中阳离子的特性吸附能力降低,而相同温度不同槽压下制备的EC特性吸附能力相近,表现出相似的电容特性,这与EC的含氧量和比表面积有关。电解碳所展现的独特电容特性对其潜在的应用或可提供有价值的线索和指导。     

超细氢氧化亚镍的溶胶凝胶法制备及其准电容特性

以聚乙二醇为抑制剂,采用溶胶凝胶法制备了粒径小于200 nm且具有链珠状特殊形态的超细氢氧化亚镍电极材料.伏安特性测试和电化学阻抗测试表明在氢氧化亚镍中掺加适量碳纳米管可以显著改善电极材料的容量特性和阻抗特性,其中碳纳米管质量分数为20％的复合电极其比电容量可以达到320 F&;#8226;g^－1.采用复合电极作为正极,活性炭电极作为负极组成的复合型电化学电容器最大工作电压可以达到1.6 V,具有良好的容量特性和大电流放电特性.恒流充放电测试证明复合型电化学电容器具有高能量密度及高功率放电特性,电容器的峰值功率密度为8.6 W&;#8226;g^－1.当以0.88 W&;#8226;g^－1功率放电时,电容器能量密度可达20.11 W&;#8226;h&;#8226;kg^－1, 当采用3.46 W&;#8226;g^－1的高功率进行放电时,复合型电容器的能量密度仍然能够达到11.11 W&;#8226;h&;#8226;kg^－1.