羧甲基纤维素-十二烷基醇聚氧乙烯醚丙烯酸酯共聚物表面活性剂在水溶液中的胶束形态

采用动态激光光散射及环境扫描电镜研究了羧甲基纤维素型高分子表面活性剂在水溶液中的胶束形态 .结果表明 ,共聚物在水溶液中的形态完全不同于羧甲基纤维素分子 ,亲水疏水链段的引入 ,使共聚物分子聚集形成了以疏水链段为核心的棍状胶束结构 .高分子表面活性剂水溶液体系的归一化一级相关函数不符合单指数衰减 ,表明胶束形态的多分散性 .在 0 .0 0 5%～ 1 %浓度范围内 ,胶束粒子大小均分布在两个区域 ,随共聚物浓度增大 ,低粒径区保持在 3 0～ 1 0 0nm范围 ,为单分子区 ;而高粒径区随浓度增大移向更高值 ,表明多分子胶束不断长大 .     

THE PHOTOOXIDATION OF DIETHYLHYDROXYLAMINE BY ROSE BENGAL IN MICELLAR AND NONMICELLAR AQUEOUS SOLUTIONS

The photooxidation of N,N -diethylhydroxylamine (DEHA) by Rose Bengal (RB) has been investigated in micellar and nonmicellar aqueous solutions. We measured the quantum yield of oxygen consumption forming H₂O₂ and monitored two intermediates, the superoxide and diethylnitroxide radicals. When the pH was vaned, the quantum yield of oxidation remained constant for 6 < pH < 10.5, decreased in acidic pH, and increased considerably in NaOH solution; these changes could be attributed to the protonation and dissociation processes of the >N-OH moiety of DEHA. The formation of diethylnitroxide radical was enhanced by superoxide dismutase or strong alkaline solution. Around neutral pH, the oxidation proceeded mainly via electron transfer from DEHA to the RB triplet ( k _q = 10⁷ M ^-1 s^-1) with little ¹O₂ participation ( k_q < 10⁵ M ^-1 s^-1). However, when RB was incorporated into micelles in alkaline solution, the contribution of the singlet oxygen pathway increased at the expense of electron transfer, which was inhibited by the less polar micellar environment. Dark autoxidation of DEHA was accelerated by heavy metal impurities and increased very strongly in NaOH solution.     

脂肪酸钠盐对于苯甲酸在水中溶度的影响

在25°脂肪酸钠盐对正戊酸在水中溶度的影响是不规则的盐溶和盐析作用,其原因是排代出的新酸分布于正戊酸相和盐溶液相间^[1]。黄子卿等^[2]曾在25°研究脂肪酸盐(甲酸钠至戊酸钠)对正己酸在水中溶度的影响,除甲酸钠外,盐溶随盐的碳原子数目的增加而下降。Philip等^[3]曾在25°测定苯甲酸在甲酸钠和乙酸钠水溶液中的溶度。在本文中,作者测定在25°苯甲酸在五种脂肪酸钠(甲酸钠至戊酸钠)水溶液中的溶度。     

A NEW METHOD FOR THE DETECTION OF SINGLET OXYGEN IN AQUEOUS SOLUTIONS

Abstract— In experiments on the interception of reactive intermediates of strongly oxidizing character in dye (S) sensitized photooxidations using p -nitrosodimethylaniline (RNO) as a selective scavenger, it has been observed that some substrates (A) or ¹O₂ acceptors (like imidazole derivatives) induce the bleaching of RNO as followed spectrophotometrically at 440 nm. Since singlet oxygen (¹O₂) does not react chemically with RNO, this bleaching is a consequence of ¹O₂ capture by the imidazole ring which results in the formation of a trans-annular peroxide intermediate [¹O₂] capable of inducing the bleaching of RNO (-RNO). In the absence of RNO, [¹O₂] decomposes or rearranges into the final oxygenation product ¹O₂: ¹Δ_g Thus, the system imidazole plus RNO can be used as a sensitive and selective test for the presence of ¹O₂ in aqueous solutions. The method can also be applied in the presence of sensitizing dyes which, under visible irradiation, can partially bleach RNO even in the absence of imidazole derivatives. In such a case, the bleaching of RNO is strongly increased by the presence of imidazoles with a characteristic dependence on their concentration. The separation of the product of RNO bleaching by thin layer chromatography can serve as additional proof of the presence of ¹O₂ in the system. The imidazole plus RNO method has been applied to a number of sensitizing and non-sensitizing dyes.     

黄原胶溶致液晶行为的研究

以小角激光光散射法、偏光显微镜法及旋转粘度计法研究了黄原胶水溶液在不同浓度和温度下的光学性质。结构区域及粘性行为。发现当溶液浓度达到3％(临界浓度值)时,呈现胆甾型液晶特征,液晶的形成对温度有显著的依赖性。     

壳聚糖在水溶液中的辐射降解反应

研究了壳聚糖在CH3COOH/NaCl缓冲溶液均相体系下的辐射降解反应,给出了H2O2、异丙醇、pH、样品初始分子量等因素对壳聚糖降解的影响,探讨了实验条件下溶液中不同自由基对壳聚糖降解的作用,并对辐照前后壳聚糖的结构进行了表征.结果表明,酸性条件下,壳聚糖的降解主要由.H和.OH自由基共同作用引起,加入H2O2或者通入N2O都能够略微提高.OH自由基浓度,对壳聚糖的降解有促进作用.加入异丙醇后,由于同时降低了.H和.OH自由基浓度,导致壳聚糖降解缓慢.当溶液的pH接近中性后,对壳聚糖的降解起主要作用的为.OH自由基,加入H2O2或者通入N2O都会增加.OH自由基的浓度,从而明显提高壳聚糖的降解速率.此外,研究发现低分子量的壳聚糖具有较快的降解速率.样品的UV、FTIR分析表明,辐照后除在壳聚糖分子链端生成羰基外,壳聚糖主链结构未见变化,脱乙酰度也没有显著改变,显示出辐射降解是一种有效的控制壳聚糖分子量方法.     

FLASH PHOTOLYTIC INVESTIGATIONS OF THE ELECTRON TRANSFER BETWEEN AROMATIC HYDROCARBON RADICALS AND TRYPTOPHAN IN MICELLAR SOLUTIONS

Abstract— Electron transfer reactions between tryptophan and cation radicals of various polycyclic hydrocarbons which are known to differ with respect to their carcinogenic and photodynamic activity have been investigated by flash spectroscopy. The hydrocarbons were solubilized in sodium dodecyl sulfate micelles. Their cation radicals were produced by photoionization probably via the excited singlet states. In the case of benz[a]anthracene, benzo[ghi]perylene, pyrene, benzo[rst]pentaphene, dibenz[a, h]-anthracene and anthracene, the electron transfer takes place in the Stern layer of the micelles and leads to neutral tryptophan radicals. It is assumed that tryptophan forms charge transfer complexes with the cation radicals of 3-methylcholanthrene and 7,12-dimethylbenz[a]anthracene. With perylene tryptophan only reduces the radical yield. New species could not be detected in this case. No correlation exists between the carcinogenic or the photodynamic activity of the hydrocarbons and the electron transfer behaviour of their cation radicals.     

COMPETITION BETWEEN THE SINGLET OXYGEN AND ELECTRON TRANSFER MECHANISMS IN THE PORPHYRIN-SENSITIZED PHOTOOXIDATION OF l-TRYPTOPHAN AND TRYPTAMINE IN AQUEOUS MICELLAR DISPERSIONS

Abstract— Kinetic studies of the hematoporphyrin–sensitized photooxidation of l -tryptophan and tryptamine at pH 10 in either homogeneous aqueous solutions or in aqueous dispersions of Triton X–100 and cetyltrimethylammonium bromide micelles indicate that the indole substrates are attacked via a mixed type I (electron transfer from triplet dye)/type II (¹O₂-involving) mechanism. Both reactive intermediates, generated by micelle-solubilized hematoporphyrin, can diffuse to attack substrate molecules located in either the bulk aqueous phase or a different micelle. In particular, incorporation of the substrate into a micelle has only minor effects on its reactivity toward¹O₂, although the ¹O₂—indole interaction appears to be more efficient in cationic micelles owing to a favourable orientation of the target with respect to the attacking species. On the other hand, the electron transfer from triplet porphyrin to a micellized substrate is virtually non-operative when the latter is located in an anionic micelle, whereas in neutral or cationic micelles, the efficiency of the process is again controlled by the substrate orientation. Studies of tryptamine photooxidation sensitized by meso-tetra-(4-sulfonato-phenyl) porphine in the presence of sodium dodecylsulphate micelles lend further support to the abovementioned conclusions.     

光催化乙醇水溶液脱氢的EPR研究

本文报道,在含有Pt/CdS的乙醇水溶液中分别加入不同俘获剂: POBN (α-(4-pyridyl N-oxide)-N-tert-butyl nitrone), MV²⁺(methylviologen), NB(nitrosobenzene)或 TCNQ(7,7,8,8-tetracyano-p-quinodimethane),在可见光(λ≥450nm)照射下,光催化产氢及其光催化脱氢机理的EPR(电子顺磁共振)研究。结果表明,在Pt/CdS-CH₃CH₂OH/H₂O体系中进行可见光反应3小时,其产氢量相当高(0.0136 mmol);在加入POBN的体系中,由于其俘获了CH₃HOH自由基而使产氢量降低了三分之二,这说明由CH₃HOH经H⁺产氢比水分解经H⁺产氢更容易。在加入TCNQ或NB的体系中,由于其俘获了电子(e^-)或自由基,因而都未检测到氢气;这说明在可见光照射下,Pt/CdS催化乙醇水溶液脱氢的机理是经由: H⁺+e^-→Ñ→1/2H₂.     

L型沸石液相成核的研究

在大量实验基础上发现了L型沸石液相成核区,考察了各种因素对L型沸石液相成核速度的影响。发现了L型沸石导向剂并对其作用进行了研究。     

氯苯类化合物在盐水溶液中的活度系数

在25.00±0.01 ℃下用紫外、可见分光光度法分别测定了氯苯(CB)、m-二氯苯(mDCB)、p-二氯苯(pDCB)、1,2,4-三氯苯(TCB)在NaCl、KCl、Na_2CO_3、K_2SO_4、CaCl_2盐水溶液及氯苯在Et_4NBr水溶液中的话度系数, 得出盐效应常数. 除Et_4NBr对氯苯呈盐溶作用, 其余均为盐析作用. 盐析次序大致为K_2SO_4>Na_2CO_3>CaCl_2>NaCl>KCl. 计算了盐效应常数的各种理论值, 与实验值进行比较, 进一步证实了改进后的内压力理论值更接近实际. 同时也讨论了这些数据在环保中的应用.     

胆绿素在碱性水溶液中稳定性的极谱研究

胆绿素是人体内存在的重要胆色素之一，为线型叶啉结构，热敏性及光敏性较强，很不稳定，升温及光照均加速其氧化，使测定结果偏低。作者对胆绿素在碱性水溶液中的极谱行为进行了深入研究，试验了支持电解质、溶液酸度、溶液中溶解氧、光照及微量金属离子的存在等多种因素对胆绿素稳定性的影响，并研究了部分影响的作用机理。本文提出的极谱法测定胆绿素的最佳操作条件为：０．０４ｍｏｌ／ＬＮａ＿２ＨＰＯ＿４缓冲溶液为底液，ＰＨ值为１１，底液中加入４×１１￣（－４）／ＬＥＤＴＡ或通氮气１Ｏｍｉｎ，避光操作，测定在０．５ｈ内完成。     

四氯化碳液相催化加氢反应动力学的研究

氯氟烃的生产工艺中 ,甲烷氯化生产甲烷氯化物是其中重要的一步 ,因此必然伴有大量的四氯化碳生成。由于氯氟烃和四氯化碳的臭氧破坏系数(ＯＤＰ)值比较高[1] ,为了保护人类赖以生存的环境 ,根据“蒙特利尔公约”规定 ,我国目前已经禁止出口四氯化碳 ,对氯氟烃的出口也采取了许可证制度 ,并进行限制生产 ,准备逐步淘汰 ,因此对于大量四氯化碳和氯氟烃的处理成了人们普遍关注的一个重要问题。目前把大量的四氯化碳和氯氟烃转化为相应消耗臭氧指数较低的化合物则是比较现实的途径 ,选择性催化加氢脱氯就是其中一种有效的方法。四氯化碳催化加…     

SURFACE ACTIVITY AND ENERGETICS OF AGGREGATE FORMATION IN AQUEOUS SODIUM BENZOATE AND SALICYLATE SOLUTIONS

Aqueous solutions of the two hydrotropic agents sodium benzoate and sodium salicylate exhibit moderate surface activity as surface tension measurements indicated. The surface cross sectional area of the salicylate ion is reasonably higher than that of benzoate. The area occupied per ion increases with the rise in temperature for both hydrotropes. The critical aggregate concentration (CAC) obtained from viscosity and conductivity measurements substantiates those obtained from surface tension measurements. Analysis of the temperature dependence of CAC showed that aggregation of benzoate and salicylate ions in aqueous solution is driven by enthalpy and entropy factors. The entropy contribution is larger especially for salicylate ion. This indicates that the entropy gain associated with freeing water molecules structured around salicylate ions is the primary driving force for aggregation. The enthalpy contribution to aggregate formation of benzoate ion is relatively larger than that of salicylate, and this agrees well with more hydrophobic nature of the former species.     

STABILITY MEASUREMENT AND DISPERSION PROCESS OF CaC03 SUSPENSIONS IN SODIUM POLYACRYLATE AQUEOUS SOLUTIONS

To use an automatic sedimentometer for suspension stability measurement, we compared the results given by this technique to other, more conventional, measurements of suspension properties: sediment volume, sedimentation rate, viscosity. The study was conducted with aqueous dispersions of synthetic calcium carbonate in the presence of sodium polyacrylate as a dispersing agent. Besides a very good correlation between all techniques, the combination of measurements gives an analysis of the polymer action process. There is first a step where bulky floes are disintegrated into dense aggregates, then the breaking up of aggregates into fine particles. The limit between both steps is sharply defined at a polymer concentration 830 mg/1.     

TIME-RESOLVED SPECTROSCOPIC STUDIES ON PHOTOPHYSICAL PROPERTIES OF BENOXAPROFEN IN MICELLAR SOLUTIONS: AN INTRAMICELLAR FLUORESCENCE QUENCHING

The micellar dependencies of the photophysical properties of benoxaprofen (BXP), a 2-phenyl benzoxazole derivative, have been investigated using fluorescence spectroscopy and laser flash photolysis techniques. The fluorescence of BXP in aqueous solution has been observed to be remarkably quenched upon addition of a surfactant, cetyltrimethyl ammonium bromide (CTAB) or Triton X-100, in contrast to its enhancement in sodium dodecyl sulfate (SDS) micellar solution. Time-resolved fluorescence measurements show that the fluorescence decays biexponentially in the micellar solution, indicating the relaxation of micellar environments surrounding the excited BXP. The major component of fluorescence lifetimes in CTAB or Triton X-100 micellar phase is even shorter (330–427ps) than in SDS micellar phase (731 ps). The nonradiative decay constants are significantly larger (ca 3.0 times 10⁹ s^?1) in the CTAB or Triton X-100 micellar phase than in SDS micelles by a factor of ca 10. The major nonradiative decay is interpreted to be the internal conversion due to nuclear geometric change of BXP in the first excited singlet state. This is consistent with the observation that the quantum yields of intersystem crossing are very low (less than 0.01) in the micellar solutions as determined by the laser flash photolysis technique. The laser-induced transient absorption spectrum of BXP in CTAB or Triton X-100 micellar solution shows that the decay kinetics of the transients in CTAB or Triton X-100 are significantly different from first order kinetics in SDS.     

RADICAL GENERATION DURING THE ILLUMINATION OF AQUEOUS SUSPENSIONS OF TUNGSTEN OXIDE IN THE PRESENCE OF METHANOL, SODIUM FORMATE and SODIUM BICARBONATE. DETECTION BY SPIN TRAPPING

Abstract— Free radical intermediates appearing during illumination of aqueous suspensions of tungsten oxide were detected by electron spin resonance using the technique of spin trapping. Solutions irradiated contained methanol, formaldehyde, sodium formate and sodium hydrogen carbonate. Signals assigned to the spin adducts of the •H, •OH, •CO₂^- and •CH₂OH radicals were found.     

ADSORPTION PROPERTIES OF THE STEARIC ACID-OCTADECANE PARTICLES IN AQUEOUS SOLUTIONS

The adsorption properties and surface charge creation for the stearic acid and octadecane/aqueous electrolyte solutions are considered. The hairy structure of surface charge for these systems was confirmed on the basis of potentiometric titration, ion adsorption and electrophoretic measurement data. For the system with stearic acid the reaction of ionization and complexation of carboxyl groups of stearic acid molecules from subsurface layer are responsible for the creation of surface charge and adsorption properties. The surface charge at octadecane particle is probably the results in adsorption and orientation of water molecules at the interface.     

钯系高分子载体催化剂对硝基苯液相加氢催化活性的研究

制备了以弱碱性（ＡＨ－１、ＡＨ－２ХＨ）、中等碱性（ＡＨ－３１、ЭⅡЭ－１０∏）以及强碱性（ＡＢ－１７－８、ＡＢ－１６ΓＣ）等阴离子交换树脂为载体的钯系催化剂,测定了它们硝基苯催化加氢的活性,其中Ｐｄ－ＡＨ－１、Ｐｄ－ＡＢ－１６ГＣ和Ｐｄ－ＡＢ－１７－８的活性较好。本文还分析了树脂结构对催化活性的影响。