国外信息

本研究成功地用电化学法对未漂白蔗渣浆进行了漂白。漂白试验在一个单段中使用氯化钠溶液和直流电进行的,电化学反应器是由一个水平石墨阳极和一个平行的不锈钢网状阴极组成的,化学蔗渣浆、化学机械蔗渣浆和机械蔗渣浆均能被漂白到相当高的白     

催化剂对电化学漂白的影响

以二氧化铅为阳极、不锈钢为阴极,以铁氰化钾为催化剂对硫酸盐苇浆进行了电化学漂白研究。通过对铁氰化钾用量与纸浆粘度、卡伯值和白度的关系的研究,得出了铁氰化钾的最佳用量是12.50 mmol/L,并对铁氰化钾在电化学漂白中存在最佳用量的机理进行了探讨。     

电化学法制备氯漂液在纺织染整中的应用研究

采用电化学法制备了次氯酸钠漂液，考察了该法制备的漂液对织物的漂白能力，结果发现电化学法氯漂液的漂白明显高于普通的次氯酸钠漂液，并且其漂白后的织物的各项指标也优于使用普通的次氯酸钠漂白液。     

电化学漂白木浆的方法

美国专利US 4617099(1986)介绍了一种木浆电化学漂白法,这是采用氯化钠溶液进行二段电化学漂白纸浆的方法。第一段pH为0～2.0;第二段pH大于8。第一段处理后分散的纸浆经过滤,再将添加氯化钠溶液     

纸浆含氯漂白废水的处理

综述了纸浆含氯漂白废水中有机物处理方法。着重介绍了各种方法的优缺点和进展。同时对电化学作为一种无污染、洁净的废水处理的方法的应用前景进行了展望。     

氧气含量对管线钢在饱含O_2+N_2气体地层水中腐蚀影响

利用TaFel曲线、线性极化曲线、电化学阻抗谱等电化学技术研究氧气浓度对管线钢的电化学腐蚀机理。随着氧气在O_2+N_2伴生气体中含量的增加,腐蚀电位负向移动,阴阳极腐蚀电流呈增大趋势,管线钢的腐蚀速率呈现增加趋势,说明氧气含量增加,管线钢腐蚀程度加剧。     

创新型漂白活化体系提升漂白性能

漂白简史 织物漂白技术从古至今的发展历程可以大致分为4个阶段:第一阶段就是利用阳光进行漂白的古代;第二阶段是约在1850年问世的NaOCl氯漂;第三阶段的标志性产品是1907年推出的过硼酸氧漂;第四阶段是自1980年推出并发展至今的漂白活化剂. 在古代,阳光漂白(水、氧气和光照)需要作用很长时间,同时要受到天气条件等因素的制约.采用NaOCl进行氯漂的效果很好,而且消毒作用很好.     

氧化水处理与电化学催化技术

臭氧具有较强的氧化性,能够广泛应用在污水处理中。电化学催化臭氧系统中,使用臭氧发生器将氧气转化为臭氧,并将所得臭氧和氧气的混合气体通过电化学废水处理反应器中,通过电化学反应将氧气还原为过氧化氢,产生氧化能力极强的羟基自由基,使有机废水中的污染物降解并完全矿化。电催化臭氧技术是一种经济、高效而且对环境友好的水处理技术。     

漂白过程的电化学研究Ⅲ．利用旋转圆盘电极模拟照相漂白过程

将银旋转圆盘电极在给定时间内浸在漂白液中进行氧化。在氧化过程中，来自漂白液中的卤化物在银电极表面与氧化生成的银离子形成卤化银。氧化反应生成的卤化银量可以用电化学还原方法进行定量测定。利用这种简单的方法可以研究漂白动力学，研究漂白液的组份、浓度和ｐＨ对漂白速度的影响。通过记录在银电极上氧化还原对的电流。电位曲线可以定量描述漂白过程。     

漂白过程的电化学研究：Ⅲ.利用旋转圆盘电极模拟照相漂白…

将银旋转圆盘电极在给定时间内浸在漂白液中进行氧化。在氧化过程中，来自漂白液中的卤化物在银电极表面与氧化生成的银离子形成卤化银。氧化反应生成的卤化银量可以用电化学还原方法进行定量测定。利用这种简单的方法可以研究漂白动力学，研究漂白液的组份、浓度和ｐＨ对漂白速度的影响。通过记录的银电极上氧化还原对的电流－电位曲线可以定量描述漂白过程。     

A new electrochemical technique for bleaching cellulose pulp

A study of electrochemical bleaching of cellulose pulp was carried out in an electrolyte cell composed of a horizontal graphite anode and a parallel stainless screen steel cathode, using NaCl as electrolyte. Variables studied were: current density, sodium chloride concentration, pulp concentration, pH and temperature. The rate of bleaching was found to increase with increasing current density, salt concentration and temperature. The rate of bleaching was found to decrease with increasing pH and pulp concentration. Energy consumption ranged from 0.1 kWh kg^?1 (pulp) to 1.75 kWh kg^?1 (pulp), depending on current density and degree of bleaching. The quality of electrochemically bleached pulp was found to compare favourably with that of chemically bleached pulp.     

Voltammetric, EQCM, and in situ conductivity studies of 3,6-bis(2-thienyl)-N-ethyl carbazole

3,6-Bis(2-thienyl)-N-ethylcarbazole (Th-ECz-Th) was obtained by using organometallic polycondensation mediated by organotransition metal complexes. The properties of electrochemically obtained polymer films from this monomer were characterized by simultaneous voltametric and in situ conductivity and electrochemical quartz microbalance techniques.     

Treatment of Fenton‐refractory olive oil mill wastes by electrochemical oxidation with boron‐doped diamond anodes

In this work, the electrochemical oxidation of an actual industrial waste with conductive diamond anodes has been studied. The wastewater is the effluent of a wastewater treatment plant consisting of a Fenton reactor followed by a settler and a sand filter, in which the wastes generated in an olive oil mill are treated. These wastes contain a residual chemical oxygen demand of nearly 700 mg dm^?3 which cannot be further oxidized with the Fenton process. The electrolyses were carried out under galvanostatic conditions, using a bench‐scale plant equipped with a single‐compartment electrochemical flow cell. Boron‐doped diamond (BDD) and stainless steel (AISI 304) were use as anode and cathode of the cell, respectively. The complete mineralization of the waste was obtained with high current efficiencies limited only by mass transport processes. This confirms that besides the hydroxyl radical‐mediated oxidation that occurs in the Fenton process, the electrochemical oxidation with conductive diamond electrodes combines other important oxidation processes such as direct electro‐oxidation on the BDD surface and oxidation mediated by other electrochemically formed compounds generated in this electrode. Copyright © 2006 Society of Chemical Industry     

The effect of the surface state on the electrochemical behaviour of copper electrodes

All investigated treatments of copper electrodes, which include mechanical (grinding and polishing with abrasives of different grain size: 210, 85, 75 and 42 μm), chemical (polishing, etching and shine-etching) and electrochemical (polishing), lead to an increase both of the anodic (copper dissolution) and of the cathodic (hydrogen evolution and oxygen reduction) polarization. This effect may be explained by the combined action of several types of factors.(1) Change in the real surface area of the examined electrode. This is the only factor in the case of mechanical treatment and an important factor for all other cases.(2) Formation of oxygen layers on the surface, an important factor in all types of chemical and electrochemical treatment.(3) Removal of the deformed layer composed upon mechanical polishing. This factor fully affects the electrochemically polished samples, partially the chemically polished one and does not affect the other types of chemical treatment.(4) These data correlate well with, and confirm, the concept about the higher electrochemical homogeneity of the electrochemically polished surface in comparison to the mechanically polished one.Our investigations show that a correct choice of the nature and sequence of the preliminary treatment of copper electrode surface makes it possible to impart on it the desired surface and electrochemical properties.     

Electrochemically oxidized carbon anode in direct l-ascorbic acid fuel cells

The activity of electrochemically oxidized carbon electrode was investigated in the operation of a direct l-ascorbic acid fuel cell anode. The surface oxygen species placed on electrochemically oxidized carbon electrode were analyzed by X-ray photoelectron spectroscopy and cyclic voltammetry. The electrochemical oxidation process of carbon electrode can facilitate the pore-filling process (i.e., wetting) of the electrolyte into the microstructure of the carbon electrode by increasing the number of more polar functional groups on the electrode surface. The electrochemically oxidized carbon electrode exhibited significantly enhanced electro-catalytic oxidation activity of l-ascorbic acid compared to an unmodified carbon electrode. Moreover, the simplified electrode structure using carbon paper without an additional powder-based precious catalyst layer is very favorable in creating percolation network and generates power density of 18 mW/cm² at 60 °C.     

Continuous Determination of the Oxidation State in a Soda-Lime-Silica Glassmelt During Refining

Influences on the oxidation state of glassmelts can be studied by using an electrochemical oxygen sensor which allows in-situ measurements at melting temperatures. The action of fining agents such as arsenic and sodium sulfate was investigated. The behavior of arsenic (i.e. release and uptake of oxygen) and the decomposition of sodium sulfate with and without carbon additions can be seen electrochemically.     

Evaluation of the electrochemical activity of a Ti-RuO2-TiO2 permanent anode

Most of the hydrometallurgical processes use sulphuric acid solutions. The main anodic reaction is oxygen evolution by decomposition of water. Traditional anode materials have been lead alloys that have high overpotential towards oxygen evolution. Oxide type anodes are more active but they are also more expensive. In this work, the activities of binary RuO₂-TiO₂ anodes were measured using different electrochemical techniques. The activity measurements were based on the measurement of the redox reaction between Ru(III) and Ru(IV) in cyclic voltammetry and on the oxygen evolution reaction in potentiostatic tests and galvanostatic electrochemical impedance spectroscopy. Factors related to intrinsic electrocatalytic properties and electrochemically active surface area could be separated. Above 30 mol% no significant increase in activity towards oxygen evolution is gained by increasing the concentration of active oxide. With low amount of active oxide most of the active sites are inside the pores and cracks. This will cause anode failure by bubble formation inside the anode.     

Voltammetric, EQCM, and in situ conductance studies of p- and n-dopable polymers based on ethylenedioxythiophene and bithiazole

New co-oligomers based on 4,4′-dialkyl-2,2′-bithiazole and 3,4-ethylene-dioxythiophene (EDOT) in a donor-acceptor type molecule were obtained using organometallic polycondensation mediated by organotransition metal complexes. The properties of electrochemically obtained polymer films from these monomers were characterized by cyclic voltammetry combined with in situ conductivity, UV-vis spectra, and electrochemical quartz microbalance (EQCM) method.     

Oxidation of methane on a Au + SrFeO3−δ//YSZ electrode characterised by mass spectroscopy and 18O2 pulses

A solid state electrochemical reactor is described in which reactants can be oxidised at high temperatures over an anode/catalyst using co-fed oxygen gas as well as electrochemically supplied oxygen. The setup permits injection of isotopic pulses in the reactant streams. The composition and isotopic distribution in the products are recorded with a quadrupole mass spectrometer. The use of the system is exemplified by oxidation of methane over a Au + SrFeO_3?δ//YSZ anode at 800–850°C. Pulses of ¹⁸O₂ in the stream of co-fed O₂ were used to study the reactivity and products of gaseous oxygen as distinguished from the electrochemically supplied oxygen. The results indicate that the anode used supports oxygen pumping, but is only moderately active for methane oxidation. The products are mainly CO and CO₂. The content of ¹⁸O in the products is low, indicating that methane oxidation takes place by ¹⁶O-rich lattice oxygen. In comparison, a reference Au//YSZ electrode was found to be a slower anode for oxygen pumping, but a better catalyst for the reaction between CH₄ and gaseous O₂, seemingly involving adsorbed oxygen.