Oxidation of Nitrites in Mine Waters

A major component in the disinfection cost of mine water is the oxidation of microbiologically formed nitrite ion, which can be effectively oxidized by ozone (at close to the stoichiometric ratio of 3.4 mg O₃ per mg nitrite–snitrogen. The injudicious use of oxidizing disinfectants in the mine water may be implicated n i nitrite ion buildup. Laboratory batch reactor experiments show that 3 to 12 mg Cl₂/L and 3 to 11 mg CIO₂/L can inhibit nitrite ion oxidation by Nitrobacter. This inhibitive effect has not been observed for ozone.     

Bromate Formation in Ozone and Advanced Oxidation Processes

Both the direct ozone reaction and the indirect hydroxyl radical reaction are important in ozonation of drinking water. This article investigates the effectiveness of ozone versus the advanced oxidation process of ozone coupled with hydrogen peroxide in the formation of bromate. The investigation was conducted on a pilot scale at various H₂O₂:O₃ dose ratios of 0.1, 0.2, and 0.35 at different times of the year. The results of this study show a reduction in bromate with the addition of hydrogen peroxide to an ozone system versus ozone alone. It was also observed that bromate increased with increased H₂O₂:O₃ ratios; however, concentrations were still lower than those in the ozone only system.     

Identification of Oxidation Intermediates in Humic Acid Oxidation

The effects of using ultraviolet irradiation (UV), ozone (O₃) and the combined O₃-UV advanced oxidation process (AOP) on humic acid (HA), which is regarded as the main disinfection by-products (DBPs) precursor, have been evaluated and compared. In particular, aromatic acids, short-chain aldehydes and carboxylic acids were measured. The purpose of this study was to determine the different classes and yields of oxidation intermediates, compare O₃, UV and O₃-UV for HA removal, as well as investigate the effects of O₃, irradiation time, UV intensity on the mineralization of HA. Based on that, the knowledge gap of DBPs generation was made up. The results showed that by UV irradiation and O₃ oxidation, HA broke down into smaller molecules that were more hydrophilic, namely formaldehyde, acetaldehyde, propaldehyde, butyraldehyde, glyoxal, methyl-glyoxal, formic, acetic, fumaric, benzoic, phthalic, protocatechuic and 3-hydroxybenzoic acids. Meanwhile, unsaturated conjugated double bonds in the structure of HA were destroyed, which lead to UV₂₅₄ a slight decrease. Due to the synergistic effect of O₃-UV, DOC and UV₂₅₄ significantly decreased and remained stable after the reaction of 10 min, indicating that O₃-UV system had stronger potential of mineralization and lower nonselectivity. Besides, the kinds and concentration levels of the intermediates were obviously reduced with light intensity increasing. Hydroxyl radical (^.OH) could mineralize some organics that could not be mineralized by O₃.     

Studies in Radiation Chemistry: Application to Ozonation and Other Advanced Oxidation Processes

Advanced oxidation/reduction processes (AORPs) are an alternative water treatment that is becoming more widely utilized. Our radiation-chemistry based studies are being used to develop a fundamental understanding of AOP treatment options, and are divided into three complementary types of contaminants; disinfection by-products (DBPs), emerging pollutants of concern (EPoCs), and natural organic matter (NOM). More than 600 DBPs have been identified, and one class that appears to have severe potential adverse health effects is the halonitromethanes (HNMs). Of the nine HNMs, trichloronitromethane (chloropicrin) is the most common, with levels up to 180 nM in US drinking waters. EPoCs are of interest because of their biological activity at low concentrations in water and while the initial focus was on endocrine disruptor chemicals (EDCs) this class has now been expanded to include many other recalcitrant chemicals such as hormones, antibiotics, industrial contaminants, and health care products. Natural organic matter is one of the most common radical scavengers in natural waters and therefore may adversely affect AOPs. Our approach is to study NOM both directly and using model compounds thought to be representative of structural components of this complex material.     

阳极氧化制备氧化钛薄膜机理探讨

在钛合金表面采用阳极氧化工艺制备出氧化钛薄膜。通过实验验证了阳极氧化原理,得出在不同的氧化电压下可生成不同厚度的氧化钛薄膜,薄膜越薄呈色越鲜艳;并分析了阳极氧化电解液对形成薄膜的影响;最后模拟分析了氧化薄膜的生长过程。     

高级氧化过程降解废水及其反应机理

探讨了高级氧化过程如：O3／H2O,Fenton试剂均相催化氧化;H2O2／UV,O3／UV兴催化氧化;非均相湿式催化氧化,活性炭纤维电极法,非均相催化和生化氧化等过程处理废水及其反应机理。     

Oxidation Mechanism of C in MgO–C Refractory Bricks

Kinetics of oxidation of MgO–C refractory bricks containing 14.3% graphite, 80.9% magnesia, and 4.8% phenolic resin is investigated comprehensively. Effect of temperature and grain size distribution on the rate of oxidation of graphite is evaluated by application of a mathematical model developed on the basis of shrinking core/progressive conversion regime to the gas–solid processes involved. Incorporation of the experimental data into the mathematical model indicates that a mixed controlling mechanism governs the oxidation rate. Three activation energies were recognized: (a) 68 kJ/mol for chemical adsorption of gas on the surface of the graphite flakes, (b) 22 kJ/mol for pore diffusion of the gases within the decarburized layer, and (c) 140 kJ/mol for internal diffusion of the reactants toward the active reaction sites. The first process was influential at all temperatures, the second was confined to the temperatures above 800°C and the third was attributed to the temperatures lower than 800°C. Empirical data indicated a much lower weight loss rate at temperatures lower than 800°C.     

有机精细化工中间体的发展现状及仿生催化氧化在中间体合成中的研究进展

综述了近年来我国有机精细化工中间体研究开发以及生产的现状,分析了我国有机精细化工中间体在研究开发、生产及应用方面所面临的问题及今后发展的机遇。同时介绍了笔者在仿生催化氧化合成有机精细化工中间体方面的研究进展,展望了仿生催化氧化技术在有机精细化工中间合成体领域的应用前景。     

硼钡复掺对C3S形成机制及影响研究

针对防辐射水泥钡水泥、硼水泥防辐射效果单一化、胶凝性不高的缺点,本文拟从复掺和组分优化设计上入手,将具有防γ、X射线效应Ba元素及防中子射线效应B元素以掺杂的形式固溶至C3S相中,通过f-CaO测定及XRD、SEM测试,研究BaO、B2O3对C3S形成机制的影响.结果表明:掺量较小时,掺BaO或B2O3对C2S有明显的稳定作用,均不利于C3S的形成;掺量较大时,B2O3的助熔作用一定程度上促进C3S形成,BaO的矿化作用不利于C3S形成.采用复掺方法时,较小比例B2O3的促熔作用结合BaO的矿化作用,对C3S形成的阻碍作用影响不大.     

Phosphorus-Containing Surfactants - Sodium Alkylphosphinates with Alkyl Chain C10, C12, C14 and C16

A group of not well known anionic phosphorus-containing surfactants have been obtained. In these surfactants the hydrophobic chain is directly linked to the phosphorus atom through a P-C bond. These products are alkylphosphinates with C10, C12, C14 and C16 alkylic chains. The products have been prepared by direct reaction between sodium hydrophosphite and the corresponding α-olefin, using tert-butyl perbenzoate as reaction initiator. Surfactants properties such as surface tension, foaming power and wetting power of the sodium and ammonium salts of all these alkylphosphinates have been measured.     

Early Events, Kinetic Intermediates and the Mechanism of Protein Folding in Cytochrome c

Kinetic studies of the early events in cytochrome c folding are reviewed with a focus on the evidence for folding intermediates on the submillisecond timescale. Evidence from time-resolved absorption, circular dichroism, magnetic circular dichroism, fluorescence energy and electron transfer, small-angle X-ray scattering and amide hydrogen exchange studies on the t ≤ 1 ms timescale reveals a picture of cytochrome c folding that starts with the ~ 1-μs conformational diffusion dynamics of the unfolded chains. A fractional population of the unfolded chains collapses on the 1 – 100 μs timescale to a compact intermediate I_C containing some native-like secondary structure. Although the existence and nature of I_C as a discrete folding intermediate remains controversial, there is extensive high time-resolution kinetic evidence for the rapid formation of I_C as a true intermediate, i.e., a metastable state separated from the unfolded state by a discrete free energy barrier. Final folding to the native state takes place on millisecond and longer timescales, depending on the presence of kinetic traps such as heme misligation and proline mis-isomerization. The high folding rates observed in equilibrium molten globule models suggest that I_C may be a productive folding intermediate. Whether it is an obligatory step on the pathway to the high free energy barrier associated with millisecond timescale folding to the native state, however, remains to be determined.     

Phase Formation Processes in Formation of Low-Melting Devitrified Glazes

The phase formation processes are studied for all stages of the synthesis of devitrified glaze coatings for ceramics, which are produced by directed crystallization of -spodumene, diopside, and gahnite. The mechanism of simultaneous crystallization of a set of prescribed phases is determined, which makes it possible to produce low-melting glass-ceramic glazes with high service parameters under low-temperature fast firing.     

Radiation Chemistry of Ethylene Glycol,Meso-Erythritol, 2-Deoxy-D-Ribose and Alkyl Phosphates as DNA Model Compounds

The γ-radiolysis of ethylene glycol, meso-erythritol, 2-deoxy-ribose, and alkyl phosphates has been studied in diluted (10^?2 M), N₂ O-saturated, deoxygenated aqueous solutions. Products and their G values have been determined. Reaction schemes were derived from complete material balances. In the polyols the primary attack of the radiolytically formed OH radicals and H atoms leads to α, β-dihydroxyalkyl radicals (A) which eliminate water to give substituted α-carbonyl-methyl radicals: (B) Disproportionation reactions of the radicals A and B yield products having the structural units ? CO? CHOH? and ? CO? CH₂ —. In ethylene glycol a chain reaction is induced, radical B abstracts a hydrogen from ethylene glycol to give acetaldehyde and radical A. In 2-deoxy-ribose the major attack is at C-1. Products from this radical are 2-deoxy-ribonic acid and 2,5-dideoxy-ribonic acid. In the formation of the latter a rearrangement is involved. With trimethyl phosphate, the reaction of the solvated electron is only small (2 × 10^s 1/mole sec), as shown by pulse radiolysis. Dimethyl and methyl phosphates do not react with the solvated electron to a measurable extent. The attack of the OH radical apparently leads to a cleavage of the alkyl phosphate linkage.     

Catalytically Reactive Ruthenium Intermediates in the Homogeneous Oxidation of Alcohols to Esters

Ru(η⁴-tetracyclone)(CO)₃ and [Ru(η⁴-tetracyclone)(CO)₂]₂ were prepared from Ru₃(CO)₁₂ and diphenylacetylene. Their rate of oxidation of PhCH₂OH are, respectively, 1.6 and 4.2 times faster than their precursor Ru₃(CO)₁₂. Both complexes, as well as others, were also found in the oxidation reaction mixture: PhCH₂OH+ Ph₂C₂ + Ru₃(CO)₁₂ which generates benzyl benzoate. Ru(η⁴-tetracyclone)(CO)₂ is most probably the true catalytic species in the catalytic oxidation of alcohols to esters.     

2种C1化工路线制乙二醇技术经济分析

介绍了以煤炭或天然气衍生的合成气为原料,一步法直接合成和经甲醛(或草酸酯)间接法合成乙二醇工艺的历史和进展,并对这2条被认为是有希望在不远的将来实现产业化的技术路线进行了工艺比较和经济性比较。认为CO经草酸酯合成乙二醇技术路线具有反应条件温和、设备投资小、环境友好等优点,并且其产品工厂成本低18.7%,是首选的C1化工合成乙二醇技术路线。     

Kinetics and Mechanism in the Liquid-Phase Hydrogenation of Maleic Anhydride and Intermediates

The influence of zinc oxide on the kinetics and mechanism of the liquid-phase hydrogenation of maleic anhydride (MA) and intermediates was investigated on copper-based catalysts. No influence of zinc oxide on the hydrogenation of maleic anhydride was observed in previous experiments. The discontinuous hydrogenation of succinic anhydride (SA) resulted in the formation of γ-butyrolactone (γ-BL) and 1,4-butanediol (1,4-BD) on a copper/zinc catalyst. On a zinc-free copper catalyst only γ-butyrolactone was formed while the hydrogenation of γ-butyrolactone to 1,4-butanediol was inhibited. It was observed that succinic anhydride which is adsorbed on the copper surface of the catalyst prevents the adsorption of γ-butyrolactone. On copper/zinc catalysts the reversible adsorption of succinic anhydride on the inactive zinc oxide crystallites, which led to a reversible decrease of the carbon balance, is responsible for a decrease of the succinic anhydride coverage of the copper sites. It appears that the decrease of the succinic anhydride coverage of the copper surface is proceeding by surface diffusion of succinic anhydride to the adjacent zinc oxide crystallites. On this basis two different reaction pathways via succinic anhydride adsorbed on the copper surface and via succinic anhydride adsorbed on the zinc oxide crystallites were proposed for the hydrogenation of maleic anhydride and intermediates. Kinetic modeling of the reaction pathway taking into account both reaction pathways led to good agreement of calculated and experimental results.     

烷基酚醛增粘树脂改性方法及增粘机理分析

介绍烷基酚醛增粘树脂的合成工艺、改性方法和作用机理。烷基酚醛增粘树脂由于酚环上有一定支化度且柔顺性好的取代烷烃基团,与橡胶分子具有良好的相容性,酚羟基具有一定的极性,彼此之间能形成氢键,混炼过程中在胶料界面上形成互穿氢键网络结构,使粘合材料达到均一充分的融合。通过改性可进一步提高烷基酚醛增粘树脂的极性,从而提高其增粘效果。     

精细化学品的催化氧化与绿色化学

绿色化学是一门致力于从源头消除污染的科学，自20世纪90年代提出以来受到国际社会的普遍关注，已成为当今的环保趋势，绿色化学在传统的化学工业中引起了一场绿色革命，正在迫使化学工业调整传统的思维方式和研究方向。在这场革命中催化氧化起着关键的作用。是实现绿色合成的一种重要手段。根据这一趋势，综述了在精细有机合成中催化氧化与绿色化学以及原子经济性的关系，对催化氧化反应的发展前景进行了展望。     

光氧化技术在染料废水处理中的应用

概述了光氧化工艺的原理,具体介绍了UV-Fenton体系的原理及应用,并展望了其发展前景,指出光氧化技术是处理难降解染料废水的一种有效的方法。