零价金属对氯代有机物还原脱氯的研究进展

对零价金属及双金属体系在还原氯代有机物中的应用做了综述,展望了零价金属还原脱氯降解氯代有机物研究领域的发展前景.     

氯代有机物结构性质对还原脱氯速率的影响

研究了氯代甲烷系列和氯代乙烷系列的多种氯代烷烃在铁、铜二相金属体系中的还原脱氯反应,分析了氯代有机物结构性质对还原脱氯反应的影响和规律性。结果表明氯代有机物的结构性质对还原脱氯速率有着明显影响,有机物氯化程度越高,脱氯速率越快,四氯化碳经过1h后脱氯率可达50.7%,而二氯甲烷脱氯则很慢,在氯代乙烷系列中脱氯速率最快的是1,1,1-三氯乙烷。电子直接转移是氯代烷烃还原脱氯的主要途径。     

Fe/Cu催化还原法处理氯代有机物的机理分析

研究了多种氯代有机物在铁、铜二金属体系中的还原脱氯处理效果,着重分析了氯代有机物还原脱氯处理中的机理问题,探讨了还原脱氯反应的基本原理、还原脱氯反应中pH值的变化、出水中Fe2 浓度的变化以及有机物结构性质对还原脱氯反应的影响。     

氯代烷烃在Fe/Cu二相金属体系中的催化还原脱氯研究

以氯代甲烷系列为例研究了多种氯代烷烃在Fe／Cu二相金属体系中的还原脱氯反应．分析了氯代有机物结构性质对还原脱氯反应的影响和规律性,以及反应过程中pH的变化．并探讨了氯代烷烃在金属还原作用下的还原脱氯机理。     

催化还原技术处理水溶液中氯代有机物的实验研究

以四氯化碳和四氯乙烷为代表物,研究了水溶液中氯代烷烃的催化还原脱氯技术,使用的还原剂为废铁刨花并添加催化剂和极化材料．结果表明该方法能使氯代有机物在零价铁体系中有效地发生还原反应,能迅速脱氯为氯离子,降低氯代有机物的毒性。探讨了有机物浓度对反应速率的影响,并分析了还原脱氯速率和反应中间产物,四氯化碳的反应产物主要是二氯甲烷,而1,1,2,2-四氯乙烷的主要反应产物是二氯乙烯。氯代有机物直接得到电子而发生还原脱氯是其主要反应机理。     

氯代有机物在铁、铜双金属体系中的还原脱氯研究

本文研究了多种氯代有机物在铁、铜双金属体系中的还原脱氯处理效果,着重分析了氯代有机物在还原脱氯处理中的机理问题,探讨了还原脱氯反应的基本原理、还原脱氯反应中pH值的变化以及有机物结构性质对还原脱氯反应的影响。     

含氯代有机物废液预处理技术研究进展

对于化工行业产生的含氯代有机物废液,现有环保技术处理难度较大,存在设备腐蚀,产生酸性气体与二噁英等二次污染物等问题.为解决含氯代有机物废液的高效清洁处理,可先对其进行预处理脱氯,再进行后续无害化或资源化处置.介绍了含氯代有机物废液预处理脱氯技术的原理、特点、研究进展与适用情况,并提出了含氯代有机物废液预处理脱氯技术发展...     

Ni-Fe双金属对氯代苯酚催化还原脱氯的试验

分别采用Ni-Fe双金属体系和单一零价铁对氯代有机物2,4-二氯苯酚、2-氯苯酚和4-氯苯酚进行了催化还原脱氯的研究。结果表明:单一零价铁能够对氯代苯酚还原脱氯,但效率不高,通常在10%～25%。在镍的催化作用下,零价铁对氯代苯酚的还原脱氯效率大大提高。当零价铁加入量为60 g/L,硫酸镍为0.6 g/L,初始氯代苯酚的质量浓度在25 mg/L左右,反应初始pH值控制在偏酸性的条件下,还原脱氯效率可达到70%以上。氯代苯酚降解的准一级速率常数和降解率满足以下规律:4-氯苯酚大于2-氯苯酚大于2,4-二氯苯酚。     

硫酸盐还原作用对氯代有机物还原脱氯影响的研究进展

脱氯是氯代有机物降解的关键步骤,还原脱氯是其模式之一。硫酸盐还原是典型的还原过程,在有机污染物厌氧降解中扮演重要角色,但其对氯代有机物还原脱氯的影响及机制尚未形成定论。本文综述了硫酸盐还原作用对氯代有机物还原脱氯的影响情况、影响因素及可能的影响机制,提出了今后值得深入研究的方向。     

氯代有机物脱氯时pH值变化影响因素的研究

研究了氯代有机物在Fe/Cu双金属体系中发生还原脱氯反应时pH值的变化与影响因素,结果表明在脱氯过程中pH值会不断发生变化,pH值条件对还原脱氯有很重要的影响,其最佳初始pH值条件为4~5左右,但是该反应体系有较强的pH值缓冲功能,能够适应较广的pH值变化范围。     

Surface-enhanced Raman study of electrochemical and photocatalytic degradation of the azo dye Janus Green B

The photocatalytic degradation of Janus Green B azo dye over silver modified titanium dioxide films was investigated by surface-enhanced Raman spectroscopy (SERS). An optimized SERS-active substrate was employed to study the photodegradation reaction of Janus Green B. Considering that photocatalytic degradation processes of organic molecules adsorbed on TiO₂ might involve either their oxidation or reduction reaction, the vibrational spectroelectrochemical study of the dye was also performed, in order to clarify the transformations involved in initial steps of its photochemical decomposition. In order to understand the changes in Raman spectra of Janus Green B after photodegradation and/or electrochemical processes, a vibrational assignment of the main Raman active modes of the dye was carried out, based on a detailed resonance Raman profile. Products formed by electrochemical and photochemical degradation processes were compared. The obtained results revealed that the first steps of the degradation process of Janus Green B involve a reductive mechanism.     

The role of sulphur in coal hydroliquefaction

The effects on coal hydroliquefaction of organic and pyritic sulphur, and of H₂S formed from the reductive decomposition of these compounds, are reviewed. Under suitable conditions, all are shown to exert beneficial effects on both product yields and quality. The reasons for the effectiveness of each of these sulphur compounds are discussed.     

Productivity of Selective Electroenzymatic Reduction and Oxidation Reactions: Theoretical and Practical Considerations

The volumetric productivities, final product concentration and total process times, of electroenzymatic processes comprising reductive electrochemical cofactor regeneration coupled to dehydrogenase or oxygenase catalyzed redox reactions determine process performance. Exemplified for the production of fine chemicals, operational windows were defined to consider these parameters. This theoretical approach allows the identification of limiting process parameters and promising process developments. Several biocatalytic processes for syntheses of specialty chemicals are already in a performance range of technical relevance. Electroenzymology thus evolved to a strong additional technology in the toolbox of biocatalysis and organic chemistry.     

Electrolysis of V(IV) and free meso-tetraphenyl porphyrin in two immiscible liquids

The electrochemical decomposition of free and vanadyl tetraphenyl porphyrin in xylene solutions, and in the presence of water, using K₂SO₄ as electrolyte, was studied. Electrolysis of the two-phase system was carried out at constant current density and potential. It was observed that the electrochemical decomposition of the porphyrins, using a two-phase liquid system, is possible. An inexpensive organic solvent (xylene instead of THF, acetonitrile, methylene chloride etc.) can be very effectively used in such a system. The decomposition occurs through an oxidation process, with the subsequent formation of cationic and dicationic radicals, and a final breakdown of the macrocycle.     

Electrochemical decomposition of bisphenol A using Pt/Ti and SnO2/Ti anodes

Methodology for the electrochemical decomposition of bisphenol A is described. The electrochemical behaviour of bisphenol A at a Pt electrode was investigated by means of cyclic voltammetric techniques. The electrochemical oxidation of bisphenol A led to the deactivation of the electrode as a result of the deposition of an electropolymerized film. However the electrochemical decomposition of bisphenol A could be achieved by the use of a platinum coated titanium (Pt/Ti) electrode and a tin dioxide coated (SnO₂/Ti) electrode. The electrolysis was carried out galvanostatically at a constant current of 0.3 A. The mineralization of bisphenol A was monitored by determining the amount of total organic carbon. Furthermore, the generation and nature of intermediates produced in the electrochemical reactions was investigated. Although large amounts of aliphatic acids were generated by electrolysis with the Pt/Ti anode, they were produced only to a small extent in at the SnO₂/Ti anode. In the case of the SnO₂/Ti anode, bisphenol A is rapidly oxidized to carbon dioxide and water, compared to the Pt/Ti anode.     

Electrochemical Molecular Conversion of α-Keto Acid to Amino Acid at a Low Overpotential Using a Nanoporous Gold Catalyst

A nanoporous gold (NPG) electrode prepared through a facile anodization technique was employed in the electrochemical reductive amination of biomass-derivable α-keto acids in the presence of a nitrogen source to produce the corresponding amino acids. NPG showed a clear reductive current in the presence of α-keto acid and NH₂OH, and the electrolysis experiments confirmed the production of L-amino acid. A reductive voltammetric signal at the NPG electrode appeared at a more positive potential by 0.18–0.79 V, compared with those at the planar-gold electrode without anodization and other previously reported electrode systems, indicating the high activity of the prepared nanostructure for the electrochemical reaction. Maximum Faradaic efficiencies (FEs) of 74–93% in the reductive molecular conversion to amino acids of Ala, Asp, Glu, Gly, and Leu were obtained under the optimized conditions. The FE values were strongly dependent on the applied potential in the electrolysis, suggesting that the hydrogen evolution reaction at the electrode surface was more significant as the applied potential became more negative. The effect of potential at the NPG was lower than that at the planar-gold electrode. These results indicate that nanostructurization decreases the overpotential for the electrochemical reductive amination, resulting in high FE.     

硫铁矿还原磷石膏反应热力学分析

采用HSC Chemistry热力学软件对硫铁矿还原磷石膏工艺进行了相关计算,探索了反应分解温度、不同温度下物相组成,并与相同条件下的硫铁矿还原磷石膏实验结果进行了比较。XRD分析结果表明,硫铁矿还原分解磷石膏的主要产物为Ca2Fe2O5和CaO,热力学计算结果与实验结果一致,表明采用化学热力学平衡分析方法可作为硫铁矿还原磷石膏反应特性研究的指导性方法。     

In situ FTIR study of the decomposition of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide ionic liquid during cathodic polarization of lithium and graphite electrodes

In this work we analyzed the cathodic reactions of an important ionic liquid (IL) based electrolyte solution, namely lithium bis(trifluoromethylsulfonyl)imide (LiTFSI)/N-methyl-N-methylpyrrolidinium (BMP) TFSI. In situ FTIR spectroscopy was used for the analysis of gaseous products of the electrochemical decomposition of this IL solution during cathodic polarization of lithium metal and graphite electrodes. The main volatile product of the reductive decomposition of the anion in these BMPTFSI solutions is trifluoromethane. BMP cations decompose to mixtures of tertiary amines and hydrocarbons. The composition of the products is influenced by the nature of the anode material. Graphite possesses a catalytic activity in the electroreduction process of BMP cations which occurs along with their intercalation into the graphite structure. The liquid phase after cathodic polarization of graphite electrodes was analyzed by multinuclear NMR spectroscopy coupled with FTIR spectroscopy. ¹⁵N NMR and FTIR spectra revealed an increase in the Li cations content in the electrolyte solution, as a result of BMP cations decomposition during repeated cycling of graphite electrodes.     

六甲基二硅烷的研究进展

综述了近年来国外关于六甲基二硅烷的合成工艺（还原耦合法、格氏试剂法、电解还原法等）；并就其未来的研究方向提出了建议。