Changes in the Structure of Wool Fiber in Dyeing in a Redox Medium

The suitability of redox systems for wool dyeing with acid and active dyes at temperatures below the boiling point of the dyeing solutions was studied. The influence of the hydrogen peroxide-reductant (glucose, ethylene glycol, 1,2,3-propanetriol, polyoxymethylene, and hexamethylenetetramine) systems on the surface of wool roving was elucidated.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 616-618.Original Russian Text Copyright © 2005 by Petrova, Grebennikov, Burinskaya.     

Kinetics of the Formation of Solketal in the Presence of Sulfuric Acid

The kinetics of reversible solketal synthesis in the presence of sulfuric acid as a catalyst is studied. The parameters of kinetic equations describing direct and reverse reactions are found.     

Dual Reactive Domain Model for Sorption of Aqueous Organics by Wood Fiber

An experimental study of 2,4,5-trichlorophenol (2,4,5-TCP) sorption to kraft papermaking fiber demonstrates that the dual reactive domain model (DRDM) effectively characterizes the process over a broad concentration region. Isotherm data were deconvoluted into linear partitioning and nonlinear adsorption contributions in accordance with the model demonstrating the importance of both mechanisms to the overall process. DRDM accurately fit concentration-dependent distribution coefficient, K(d)(C), data that could not be characterized with the Freundlich or Langmuir equations, and the model predicts the asymptotic movement toward a limiting K(d)(C) value at high solute or cosolute concentrations observed in experiments. Competitive effects were accounted for by modifying the adsorption portion of the model. With its limitations understood, the extended Langmuir equation was utilized and provided an effective fit of data. Langmuir fitting parameters for competitive data with five different n-alcohol homologs allowed estimates of free energy values per methylene linkage, which were in agreement with previously reported values. Also obtained from competitive data were relative sorption values for various benzene analogs, indicating that interactions in addition to those stemming from solute hydrophobicity often contribute in driving the overall sorption process. These results have implications for papermaking given the ubiquitous nature and importance of sorption in the process. Copyright 2001 Academic Press.     

Graft Copolymerization of Poly(ethyl Acrylate) onto Wool in the Presence of Ceric Ammonium Nitrate as Redox Initiator

Poly(ethyl acrylate) has been grafted onto Himachali wool in an aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Copolymerization was studied at five different temperatures: 40, 45, 50, 55, and 60°C. Maximum grafting occurred at 45°C. Nitric acid was found to catalyze the graft copolymerization reactions. Percentage and efficiency of grafting were found to be dependent upon concentrations of CAN (initiator) and of monomer. Percentage of grafting has been determined as function of time, and from the slope of percent grafting versus time plot, the initial rate of graft copolymerization (R) has been determined.     

Sorption Studies in DMSO-NITRIC Acid and DMSO-Acetic Acid Systems and Separation of Metal Ions on TIN(IV)-Iodophosphate

Abstract

Some new samples of tin(IV)-iodophosphate have been synthesized and their ion exchange properties have been studied. Adsorption behaviour of different metal ions on tin(IV)-iodophosphate (TIP₅), in H⁺ form, in different solvent systems have been examined. Kd values of few metal ions, in 4M DMSO medium, have also been determined on the same ion-exchanger in NH⁺ ₄ form. Effect of particle size of tin(IV)-iodophosphate (TIP₅), in H⁺ form, on the Kd values of metal ions has been studied. Separations of a number of metal ions have been achieved on tin(IV)-iodophosphate (TIP₅) columns.     

高效液相色谱研究丝素亲核基团与一氯均三嗪型活性染料反应动力学

以异丙胺、对甲酚和甲醇分别模拟蚕丝丝素的氨基、酚羟基和醇羟基,应用高效液相色谱分析一氯均三嗪型活性染料与蚕丝丝素的不同亲核基团的反应速率.结果表明:在pH=8～10、70～95 ℃的条件下,染料的酚解总反应速率远大于染料的氨解总反应速率和醇解总反应速率.其中C.I.活性红24 和C.I.活性橙2在pH=9,95 ℃条件下的酚解总速率分别约为其氨解总反应速率的8.5倍和12.5倍,为其醇解总反应速率的23倍和50倍;该两染料的酚解效率分别为47.4和96.3,氨解效率分别为4.6和6.9,醇解效率仅为1左右.通过异丙胺-对甲酚-甲醇混合溶液(1∶ 10∶ 100,V/V)模拟蚕丝与染料的反应,研究一氯均三嗪型活性染料与丝素上亲核基团的反应选择性,推断出一氯均三嗪型活性染料染蚕丝的最适宜条件为pH=8～9,温度85 ℃左右.在此条件下,酚羟基在蚕丝的一氯均三嗪型活性染料染色中起主要作用,氨基起次要作用,而醇羟基的作用甚微.     

苯胺氧化还原选择测定大量抗坏血酸存在下的多巴胺

铂电极;伏安法;苯胺氧化还原选择测定大量抗坏血酸存在下的多巴胺     

Acrylonitrile Polymerization by Ceric lon-Primary Alcohol Redox Systems in Aqueous Nitric Acid

The polymerization of acrylonitrile (AN) initiated by Ce^IV-primary alcohol redox systems has been studied in aqueous nitric acid under nitrogen in the temperature range 0 to 45° C. Taft's correlation can be applied to fit the kinetic results relative to a series of differently substituted primary alcohols. The polymerization is initiated by primary radicals formed in water from the dismutation of the Ce^IV -alcohol complex, This process has a high activation energy (21 kcal/mol) and gives rise to an induction period at temperatures lower than 40° C. PAN chains containing the alcohol residue are terminated predominantly on metal ions. The alcohol enhances the AN solubility in water and accordingly influences the polymerization kinetics. Variations in temperature and concentration of both components of the redox system allow control of the polymerization rate and of the molecular weight of the resulting PAN.     

Photograft Copolymerization of Methyl Methacrylate on Wool Using Ce4+ -Oxalic Acid Redox Initiator in a Limited Aqueous System

Abstract

Photograft copolymerization of methyl methacrylate on reduced wool (reduction done by treatment with thioglycollic acid, TGA) was studied at nearly 30°C using a Ce⁴⁺ -oxalic acid redox initiator system in a limited aqueous system (2.7 mL water for 0.15 g wool). Reduction of wool for 16 h with 15% TGA solution produced optimum grafting effects. Percent grafting and grafting efficiency under different sets of conditions were studied and compared, and the mechanism of grafting discussed. Generation of grafting sites (radical centers) on reduced wool was more effective in the presence of light than in the dark. Percent grafting of 250–350% and grafting efficiency of 65-80% over a conversion range of 60–90% in 3–5 h were easily obtained.     

Effect of pH on the Redox and Sorption Properties of Native and Phosphorylated Starches

Starch is a common biopolymer that can be used for removing heavy metal ions from aqueous solutions. A valuable property of starch is its functional diversity, which can be enhanced by chemical modification. Hydroxyl groups enclosed in the starch and formed during hydrolysis act as reducing agents of Cr(VI). The sorption properties of native starch depend mainly on the presence of carboxyl groups formed during redox processes and basic centers created during acid hydrolysis, while the superiority of phosphorylated starch is related to the presence of phosphate groups binding Cr(III) ions. The effectiveness of starch depends on a series of equilibria established in its aqueous suspension and chromate ions solution, where the pH is the driving force for these processes. In this article, a systematic discussion of pH changes being the consequence of chemical reactions unraveling the extraordinary functionalities of starch was given. It also explained the influence of establishing equilibria and chemical modifications of starch on the efficiency of chromium ion removal. This allowed for the development of a comprehensive mechanism for the interaction of Cr(VI) and Cr(III) ions with native and phosphorylated starch.     

Sorption and Abiotic Redox Transformation of Nitrobenzene at the Smectite-Water Interface

The effect of the redox state of structural Fe on the surface reactivity of iron-bearing phyllosilicates in aqueous suspension was investigated using a molecular probe. For this purpose the structural Fe in montmorillonite and ferruginous smectite was chemically reduced by sodium dithionite in citrate-bicarbonate (CB) buffer solution under N(2) at 70 degrees C, with the excess reactants removed by washing and centrifugation. Nitrobenzene was chosen as an electron acceptor probe to react with unaltered and chemically reduced smectites. Nitrobenzene was transformed into aniline only in the presence of the reduced smectites. This abiotic reductive transformation depended on the concentration of the electron acceptor in solution and the total accessible structural Fe(II) in smectites. As much as 40% of the crystal layer structural Fe(II) of the reduced smectites was oxidized to Fe(III); these electrons migrated to the surfaces/edges and then were transported into the adjacent aqueous layer. No significant effect of the oxidation state of structural Fe on the sorption of nitrobenzene on smectites was observed, but the reduced smectites sorbed less aniline than the unaltered smectites. The electronic structure and molecular geometry of the probe were modified within the smectite-water interface. Reducing structural Fe in smectites perturbed the surface reactivity. Copyright 2001 Academic Press.     

Voltammetric Determination of Dopamine in the Presence of Ascorbic Acid Using Polycarminic Acid Film Coated Carbon Fiber Cylinder Microelectrode

Dopamine ((3,4-dihydroxyphenyl) ethylamine, DA) is an important neurotransmitter in the mammalian central nervous system (CNS). Recently, investigations on the measurement of DA have attracted much attention. Ascorbic acid (AA), however, usually coexists together with DA in mammalian body and their oxidative potential are very close. Therefore, the measurement of DA in vivo is always interfered with AA. In this paper, we reported the polycarminic acid (PCA) film coated carbon fiber cylinder microelectrodes. This film tends to exclude the interference of big anions such as AA but selectively responds to big cations such as DA.     

偶氮染料吸附和光催化氧化动力学

以甲基橙和酸性大红两种偶氮染料为模拟污染有机物,对它们的暗吸附和光催化氧化行为进行研究.实验结果表明,两种偶氮染料的吸附受溶液酸碱度影响很大,酸性（pH=3）条件下,两种染料吸附量都很大,酸性大红吸附量更大；近中性（pH≈6）时两种染料的吸附显著减少；碱性（pH=9）条件下两种染料不发生吸附.光催化反应结果显示,碱性条件或酸性条件下两种染料降解速度都很快.说明在不同酸碱度条件下,光催化反应按不同机理进行.酸性条件下,反应在催化剂表面进行,在碱性介质中,光催化氧化在溶液中进行.提出了一个碱性条件下的动力学方程,经过进一步简化,可以得到表观一级方程,形式上和准一级L-H方程十分相似,但其含义不同.     

Study of Kinetics of Isoprene Polymerization in the Presence of Neodymium-Containing Catalytic Systems Modified in Turbulent Flows

Russian Journal of Applied Chemistry - The results of studying the kinetics of the polyisoprene synthesis in the presence of neodymium-containing catalytic systems under conditions of preliminary...     

Electropolymerization of Preadsorbed Layers of Some Azine Redox Dyes on Graphite

The redox-active azine dyes Nile blue A (NB) and Toluidine blue O (TB) were electropolymerized after preadsorption onto the surface of graphite electrodes by potential cycling, using an anodic scan limit of 0.9 or 1.0 V vs SCE, where irreversible electrooxidation of the dye proceeds, yielding polymerizable species. Electropolymerization of both dyes is followed by the progressive disappearance of the characteristic current peaks in the cyclic voltammograms, and formation of new ones, shifted by ca. 0.21 V to the positive direction. Also, a decrease and gradual disappearance of the characteristic luminescence at a maximum of 671 nm was observed during the electropolymerization of NB. The resulting electrodes, modified by electropolymerized derivatives of NB and TB, were shown to be able to catalyze the electrooxidation of the coenzyme NADH. Thus, the modified electrodes prepared can be used for amperometric detection of the reduced form of the coenzyme. Copyright 2000 Academic Press.     

Decolorization of Reactive Black 5 and Reactive Blue 4 Dyes in Microbial Fuel Cells

Microbial fuel cells (MFCs) have potential to treat industrial wastewater containing organic compounds and simultaneously generate power. Organic compounds include textile dyes with various chromophore groups, which can be decolorized reductively by microorganisms under anaerobic conditions. In the present study, we examined the decolorization of Reactive Black 5 (RB5) azo dye and Reactive Blue 4 (RBL4) anthraquinone dye under open circuit potential in MFCs with graphite plate and graphite felt electrodes and a microbial consortium originally derived from bovine rumen fluid. RB5 dye was more than 90% decolorized in 120, 165, and 225 min at 50, 100, and 200 mg L^?1 concentrations, respectively. RBL4 dye at 50 and 100 mg L^?1 took 225 and 300 min to decolorize, while 200 mg L^?1 RBL4 dye was not decolorized at all. Under closed circuit conditions, decolorization increased with decrease in external load, whereas current generation increased with external resistance. The results demonstrate that the reductive cleavage of the chromophore was more rapid with RB5 than with RBL4.     

Photo-electrochemically Synergetic Effect in the Catalytic Degradation of Reactive Dyes

The dye wastewater has a high potential environmental impact principally due to the wastewater containing high organic charge and strong coloration. As far as back the 1980s, the totals of synthesized dyes have been more than 800 thousand tons every year in the whole would. However, in the all of dyes, reactive dyes represent an important fraction of the commercialized synthetic pigments used. The major environmental problem associated with the use of the reactive dyes is their loss in the dyeing processes with general low fixation efficiency, large mount of dye-containing wastewater was inevitably discharged into water supply. So, the treatment of wastewater containing reactive dyes is very urgent for our health.     

Ion-Exchange Sorption of Palladium(II) from Hydrochloric Acid Solutions in the Presence of Silver(I)

Russian Journal of Physical Chemistry A - The sorptive extraction of palladium(II) chloride complexes in the presence of silver(I) chloride complexes from 2 and 4 M aqueous solutions of HCl with a...