指示剂用染料

商业上对传统染料(或着色剂)的要求是颜色坚牢,然而作为指示剂,尤其是分析化学中使用的指示剂,却希望它们的颜色能随环境的变化而变化。根据引起结构变化的原因,本文介绍了pH指示剂、氧化还原指示剂和金属离子指示剂等三种指示剂,给出了各类pH指示剂的变色范围、颜色变化等性质,还简要介绍了氧化还原指示剂和滴定金属离子的指示剂的典型品种和作用原理。     

活性炭纤维的制备及其液相吸附研究-对水溶液中有机物和银的吸附特性

活性炭纤维(ACF)是1种高效而又用途广泛的吸附材料，在环保、食品、化工等领域得到广泛的应用。目前，提高ACF的制备得率，阐明吸附与ACF结构的本质关系，开拓ACF的应用新领域，仍然是人们致力研究而又未能很好解决的问题。本论文围绕ACF的制备及其液相吸附性能，特别是对水中有机物的吸附性能和对银离子的还原吸附特征及其吸附机理，开展了一些基础性研究工作。论文主要包括如下3部分内容 1 ACF的制备及其结构表征 主要采用水蒸汽活化法，并通过前处理及后期氧化改性制备了一系列ACF。系统地研究了碳化-活化温度或时间对ACF的孔结构和化学结构的影响，并用多种方法，包括基于低温氮吸附的DR-法、α,-法、t-法等孔结构的评价方法，X-射线衍射、红外光谱以及X-射线光电子能谱等分析技术系统地表征和比较了这些ACF的结构。揭示了ACF制备的动力学规律，并提出相应的机理。碳化-活化反应是一个对碳为一级反应的过程，该反应需要克服一定的活化能。纤维在碳化过程中形成类石墨微晶的同时，也形成了孔的雏形；而活化过程则使石墨微晶被不断蚀刻和破坏，并在已形成的孔结构的基础上使孔不断扩大。因此，控制碳化反应的最后温度，对于控制ACF的孔发育，具有与控制其它活化条件同等重要的作用。 同时，还归纳了碳化-活化温度可用于控制孔的发育 的一些规律。对于水蒸汽活化制备ACF，低温条件下(800-820)碳化活化，可使得到的ACF含有均一的极微孔；而较高的活化温度(>840℃)，使所得的ACF含有较大比例的超微孔及中孔。 此外，还阐述了用无机氧化剂对剑麻基ACF(SACF)进行后期改性，虽然降低了所得改性ACF(OACF2)的比表面积，但可以改变OACF5的表面化学 结构，有利于改善ACF的化学吸附性能。纤维在碳化前用金属氯化物预处理，可提高了ACF的得率，但该类ACF的比表面积较低。 2 ACF对水溶液中染料的吸附 较深入地研究了ACF对亚甲基蓝、结晶紫、铬蓝黑R、铬黑T、二甲酚橙、溴酚蓝、荧光素等几种染料的静态和动态吸附特征及影响因素，探讨了吸附的热力学和动力学规律。初步阐明了染料在ACF上的吸附机理。染料在ACF上的吸附与吸附剂和吸附质的结构密切相关。由于染料分子的几何尺寸较大，染料分子在ACF上的吸附受孔屏蔽效应的强烈影响。ACF的孔径大小及分布成为决定染料吸附速度和吸附量大小的主导因素。孔径越大，染料的吸附速度越快；而比表面积越高，染料的吸附量也越高。另一方面，ACF表面含氧量的增加，有利于对染料的吸附。碱性阳离子染料比酸性偶氮染料更易于在ACF上吸附。 热力学研究表明，ACF自溶液吸附染料是1个自发过程， G为负值。ACF对亚甲基蓝和结晶紫的吸附为一吸热过程和熵增加的过程。这是由于染料的吸附首先经历了二聚体或多聚体离解的吸热过程所致。提高温度，有利于吸附的进行，其原因是温度升高，使染料的二聚乃至多聚发生离解，减低了ACF的孔屏蔽；同时，也提高了染料的内能，可以克服染料在微孔中扩散所需的能量。至于熵增加的原因，是由于染料的离解和染料替换了ACF表面的水分子的结果。 染料在ACF上的吸附速度随表面覆盖度的升高而降低，并可用简单的Langmuir动力学方程描述。染料的吸附速度决定于染料及ACF的性质，而与染料的初始浓度无关。 3 ACF对有机物和银离子的共吸附 研究了溶液中有机物的存在和ACF表面氧化改性后对活性碳纤维还原吸附银离子的能力的影响。揭示了某些有机物如亚甲基蓝、苯胺等对ACF还原吸附能力的显著促进作用，并初步探讨了其还原吸附机理。溶液中有机物的吸附强烈影响ACF还原吸附Ag(NH3)+2 的能力。溶液中亚甲基蓝的存在可使SACF对Ag(NH3)+2的还原吸附容量提高数倍；溶液中苯胺的存在更显著地提高SACF或OACFs对Ag(NH3)+2的还原吸附容量及还原效率。其它有机物如对硝基苯酚和苯甲酸对ACF还原吸附Ag(NH3)+2的影响，依ACF的不同而不同，但影响程度不大。SACF的氧化改性，提高了产物OACFs对Ag(NH3)+2的还原能力，显示ACF表面化学性质对其氧化还原吸附能力的重要性。 对Ag(NH)+2 在ACF上还原吸附机理的初步分析，显示有机物吸附对ACF还原吸附能力的影响，可能是改变了ACF表面的酸碱环境，或改变了ACF表面的Zeta电位，影响ACF表面的阴极极化程度，从而促进或阻碍了Ag(NH3)+2 在ACF上的还原。 上述研究的结果，为ACF的制备及其结构控制提供了指导依据；为利用染料作为“分子探针”确切评价ACF的液相吸附性能提供了理论基础；为利用ACF的还原能力回收贵金属提供了更有效的方法。这些结果对于环境治理和资源再生，也具有现实和理论上的意义。     

从氧化还原电位的角度看菁染料的光谱增感与结构的相关性

本文用循环伏安法测定了一些菁染料的氧化还原电位,估算了一些未测得的数值,并与收集到的相同条件下的文献值进行了系统的比较。详尽地分析了菁染料的各种结构因素对氧化还原电位,进而对光谱增感作用的影响。从氧化还原电位的角度为选择性能优良的增感染料提供了一个重要的途径。     

光助Fenton氧化处理染料废水的实验研究

采用光助Fenton高级氧化技术对模拟染料废水进行氧化处理，考察了光助Fenton对染料废水的处理效果。实验在1L环流式光化学氧化反应器进行。结果表明在反应温度为30℃，pH=4，双氧水加入量为彻底矿化4BS染料所需的理论量Qth，Fe^2 和H2O2的摩尔比为1：10时，经30min的光助Fenton处理，4BS去除率可达90％。在低双氧水投加量下(1／4Qth)，经光助Fenton氧化预处理30min后的4BS废水，其生化性(BOD，／CODcr)可从初始的0提高到0．3，为后续废水的生化处理创造了条件。     

高级氧化技术处理染料废水的研究进展

由于染料废水中含有高浓度难降解有机污染物,对其有效处理一直是个难题.综述了近几年国内外采用湿式氧化法、Fenton法、光化学与光催化氧化法、电化学法、臭氧氧化法、微波辅助氧化法和超声氧化法等高级氧化技术处理染料废水的进展情况,并指出了高级氧化技术在染料废水处理中的发展趋势.     

TiO_2形状对染料敏化太阳能电池性能的影响

第三代太阳能电池,即染料敏化太阳能电池(DSSCs)是由纳米多孔半导体薄膜(如TiO2)、有机染料敏化剂、氧化还原电解质(如I3-/I-)、对电极和导电基底等几部分构成。不同的TiO2的形状及构造对电池性能有着很大的影响。     

元素周期表解说(下)

五、还原与氧化 (还原电位,氧化电位,电极电位;还原剂,氧化剂;还原价,氧化价) 还原是物质获得电子的作用,氧化是物质失去电子的作用。用离子—电子方程式表示: 还原作用:Cl_2+2e~-→2Cl~- (1) Cu~(2+)+2e~-→Cu (2) 氧化作用:Na→Na~++e~- (3)     

Fe（Ⅲ）-5-Br-PADAP络合物光化学还原反应的研究

研究了溶液酸度、光强度、有机酸及其浓度对Fe(Ⅲ)-5-Br-PADAP络合物光化学还原反应的影响,并对该光化学还原反应的机理作了初步探讨.结果表明,在pH为5.5的HAc-NaAc缓冲溶液中,Fe(Ⅲ)-5-Br-PADAP络合物的光化学还原反应速度较快;光强度增加,该光化学还原反应速度加快;甲酸等有机酸能加速该光化学还原反应;乙二酸、丙二酸能明显抑制该光化学还原反应;能促进反应的有机酸浓度增加,该光化学还原反应的速度加快.     

用于染料敏化太阳能电池的苊并吡嗪类染料的设计与合成，

以吡嗪环作为吸电子基团,单羧基为连接基团,选用不同的芳环供电基团设计合成了3个苊并吡嗪类染料敏化太阳能电池(DSSC)染料。其中,以二苯胺为供电基的染料Va性能最好,主要吸光范围是400~500 nm,ELUMO为-1.10 eV,远负于TiO2的导带能级-0.5 eV,说明染料的激发态电子注入到纳米TiO2的导带在热力学上是可行的;EHOMO为1.31 eV,远正于I-/I3-的氧化还原电位0.4 eV,说明处于氧化态的染料分子从氧化还原电对得到电子再生。光电转换效率最高为3.06%,达到经典染料N719效率的43%。     

粘胶纺液着色用还原染料的颜料化研究

本文以隐色体研磨氧化法对还原蓝RSN进行了颜料化处理,研究讨论分散剂种类、分散剂浓度以及研磨氧化时间等因素对还原蓝RSN颜料化后的粒径和分散性能的影响,同时还比较了不同染料浓度颜料化效果的差异.另外还对还原蓝RSN等染料以"超细颜料化"方式应用于粘胶纺液着色加工的可行性进行了探讨.     

Analysis of the photofading of phenylazo-aniline and phenylazo-pyridone disperse dyes on poly(ethylene terephthalate) substrate using the semiempirical molecular orbital PM5 method

The photofading characteristics of six monoazo disperse dyes on polyester fabric upon exposure to a carbon arc in air were analyzed in terms of the reactivity (k₀) towards ¹O₂ and the photosensitivity (f). The photochemical properties of the dyes were estimated by catalytic fading in mixture dyeings of two yellow (pyridone-azo and quinolone-azo) dyes. The k₀ ratios for the componential dyes in the 1:1 mixture dyeings varied with the partner yellow dye, implying that they depend upon the f values and the concentrations of the component dyes as well as the superposition of absorption spectra, and the changes in their concentration, even in the initial stages of fading. The relative k₀ values, as estimated by the sum of the electrophilic frontier densities using the PM5 method were demonstrated experimentally, while taking the influencing factors into consideration. The assumption that the rates of oxidative fading on PET were proportional to the product of two factors of k₀ and f was confirmed as reasonable based on the fading behavior upon exposure to a carbon arc in air of eight disperse azo dyes with a wide range of two factors.     

环境因素对染料日晒牢度的影响

本文综述了光、染料聚集态、染色深度、汗液及纤维种类等环境因素对染料日晒牢度的影响.并对各个因素所起作用的机理和方式作了详尽的阐述.指出染料的日晒牢度是受其化学结构和所处的外部环境及形态共同作用的,要根据不同的服用环境和需要来设计染料结构,以提高染料的日晒牢度.     

Graft copolymerization of hydrophilic monomers onto irradiated polypropylene fibers

A method of graft copolymerization of hydrophilic monomers, such as 1-vinyl-2-pyrrolidone, acrylonitrile, acrylic acid, and acrylamide, onto irradiated polypropylene fibers has been studied. γ ray as well as electron beam were employed for the irradiation processes. Graft-copolymerization kinetics and the properties of grafted fibers have been investigated. Moisture regain, dyes absorption, and melting point of the grafted fibers were found to increase with the increasing of the degree of grafting. Polypropylene for 1-vinyl-2-pyrrolidone grafted fibers showed excellent dye absorption for almost all kinds of dyes such as direct, basic, acid, reactive, disper, and naphthol dyes. However, for polypropylene acrylic acid grafted fibers, the colorfastness to washing was found to be unsatisfactory. The colorfastness to washing for polypropylene 1-vinyl-2-pyrrolidone grafted fibers was found to be fairly good for certain types of dyes such as vat and naphthol dyes.     

The effect of perspiration on photo-induced chemical reaction of azo dyes and the determination of aromatic amine products

In order to investigate the impact of perspiration on photo-induced chemical reaction of azo dyes and the carcinogenic aromatic amine products produced from the reaction, we have carried out experimental studies on the photochemical reaction of C.I. Reactive Red 2 mixed with American Association of Textile Chemists and Colorists（AATCC）standard artificial perspiration. UV-vis spectroscopic technique was employed to monitor the reaction processes, and the reaction products were analyzed by hollow fiber protected liquid-liquid-liquid phase micro-extraction with capillary electrophoresis（HF-LLLME-CE). The results showed that perspiration had remarkable influence on the photochemical reaction of azo dyes. Aromtic amines formed during the photochemical process as a result of reduction of azo dyes by organic components in perspiration. The HF-LLLME-CE methodology was validated in analyzing aromatic amines produced from the photochemical degradation of azo dye C.I. Reactive Red 2 and C.I. Acid Red 35 mixed with artificial perspiration.     

Photochemical Tendering Activity of Sulphur Dyes

The photochemical tendering activity of a series of sulphur dyes on cotton cloth has been assessed in terms of (I) the changes in the physical and chemical properties of the fibre and (2) the extent of fading of the dyes and the formation of hydrogen peroxide during exposure.     

Kinetics of graft copolymerization of acrylamide and 2-hydroxyethylmethacrylate monomer mixture onto poly(ethylene terephthalate) fibers

Poly(ethylene terephthalate) (PET) fibers were grafted with acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of AAm/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 10 mmol/L. The maximum graft yield was obtained (prep.) 273%. The optimum temperature and polymerization time were found to be 85 °C and 120 min, respectively. The rate of grafting was found to be proportional of the 1.39 and 0.37 powers of AAm/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by FTIR spectroscopy and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity and diameter were determined. The dyeability of the PET fibers increased with an increase in grafting with acidic and basic dyes.     

Screening Xanthene Dyes for Visible Light‐Driven Nicotinamide Adenine Dinucleotide Regeneration and Photoenzymatic Synthesis

Regeneration of the nicotinamide cofactor is a critical issue in biocatalysis. Herein we have screened xanthene dyes for a highly efficient, visible light‐driven photochemical regeneration of cofactors and enzymatic synthesis. Superior catalytic performance was observed with several xanthene dyes such as phloxine B, erythrosine B, eosin Y, and rose bengal. We found that the photo‐ and electrochemical properties of the xanthene dyes were affected by the halogen atom substitution, which is a key factor in the efficient light‐induced electron transfer from the donor molecule to the catalytic mediator.     

Optimization of high performance m‐aramid fiber with disperse dye containing high color strength

This study focuses on the optimization of parameters involved in the process of dyeing such as temperature, concentration of dye, and swelling agent for m‐aramid fibers with disperse dyes and these parameters were used to investigate the shade depth and fastness properties of m‐aramid fibers. Experiments were carried out in batch system to study the effect of factors and their levels mainly on shade depth of the fibers. The shade depth, that is, K/S value of m‐aramid fibers was improved proportionally with the increasing concentration of swelling agent and dye concentration.     

Photoinitiated surface grafting of synthetic fibers,IV. Applications of textile dyes onto surface-photografted synthetic fibers

High-strength polyethylene (HSPE), polypropylene (PP), poly(ethylene terephthalate) (PET), and poly(vinyl alcohol) (PVA) textile yarns have been surface-photografted with various functional monomers, such as acrylic acid (AA), acrylamide (AM), glycidyl acrylate (GA) and 4-vinyl pyridine (VP), by means of the continuous presoaking process developed. The dyeing of these surface-modified yarns with various textile dyes has been investigated. In general, considerable improvements of dyeability have been observed. The dye adsorption of the surface-photografted fibers is influenced by many factors, such as type of fiber, amount and properties of the functional monomer grafted on the surface of the fibers, type of textile dye, etc. The fibers surface-grafted with a monomer containing basic groups, such as acrylamide and 4-vinyl pyridine, are efficiently dyed with an acid dye. Conversely, a fiber surface-grafted with acidic functional monomer is easily dyed to deep shades with basic dyes. The dye adsorption increases monotonically with increasing grafting measured in ESCA spectra as relative intensities of relevant lines. The ungrafted HSPE, PP and PET fibers can be dyed to some extent with certain dyes. In the present work, the dye adsorption increased by 3.4 times for HSPE fiber grafted with GA and dyed with the metal complex dye IO, by 7.9 times for PP fiber grafted with AA and dyed with the basic dye MB, by 6.1 times for PET with AM and with the direct dye SL, and by about 15.3 times for PVA with VP and with the acid dye TE.     

Photostability of Anthraquinone and Azo Dyes in N-Ethylacetamide (Nylon Model)

Measurements of the quantum yields of photodegradation of anthraquinone and azo dyes in N-ethylacetamide (nylon model) and triplet sensitisation of dye fading showed that the photochemical reactions are initiated by an upper excited n-π* triplet state. The primary photochemical reaction with both anthraquinone and azo dyes involves hydrogen abstraction from the amide so/vent. In some cases oxygen retards dye fading by reoxidation of the reduced structures. In other cases oxygen accelerates the photochemical reaction via free-radical initiated oxidation reactions. The quantum yields of dye fading are strongly wavelength dependent. On exposure to a simulated sunlight spectrum photodegradation is mostly caused by radiation in the region 300–400 nm. While unsubstituted anthraquinone is very photoreactive, amino-substituted anthraquinones are much more photostable in N-ethylacetam/de. Photostability of mono- and di-substituted anthraquinone derivatives increases with the electron-donating power of substituent groups. Azo dyes with increased conjugation such as diazo and naphthazo structures are more photostable than simple azobenzene derivatives. Certain electron-withdrawing substituents, which do not affect dye colour, improve the ‘oxidative’ photostability of both anthraquinone and azo dyes. A cobalt premetallised azo dye (C.I. Acid Red 182) is very photostable in N-ethylacetamide, showing the effect of metal chelates on photostability. The low values of quantum yields for the dye solutions are comparable with those of acid and disperse dyes in nylon films, indicating that N-ethylacetamide is a suitable nylon model for mechanistic studies of dye fading.