Polish Journal of Chemical Technology (v.12, #1)
New arylhydrazonothiazolidin-5-one disperse dyes for dyeing polyester fibers
by Mohamed A. Metwally; Mohamed E. Khalifa; Ehab A. Attia; Fathy A. Amer; (pp. 1-6).
A series of new thiazolidin-5-one disperse dyes was synthesized from the reactions of 2-substituted 3-phenylthiazolidinones with various aryldiazonium chlorides. The synthesized dyes were characterized by UV-visible absorption, IR, NMR and MS spectroscopy. The dyes gave orange to reddish-violet shades with very good depth on polyester fibers. The dyed fabrics show moderate to good fastness to light and very good to excellent fastness to washing and perspiration. Also, the assessment of color coordinates was discussed.
Keywords: Thiazolidin-5-one; Diazonium salts; Azo coupling; Disperse dyes; Polyester fibers; Fastness properties; Color properties
4-amine-2-mercaptopyrimidine modified silica gel applied in Cd(II) and Pb(II) extraction from an aqueous medium
by Adriano S. Pereira; Guilherme Ferreira; Laercio Caetano; Renata S. D. Castro; Ademir dos Santos; Pedro M. Padilha; Gustavo R. Castro; (pp. 7-11).
This paper discusses silica surface modification by a process involving a two-step reaction: anchoring of a silylating agent, followed by an attachment of a 4-amino-2-mercaptopyrimidine molecule. The modified material (Si-BP) was successfully characterized by the FTIR spectra, which revealed amine absorption bands, and through 13C and 29Si NMR spectra, which confirm the proposed structure of the modified silica (Si-BP). Si-BP was used to extract cadmium and lead from an aqueous medium at 298 K. The Si-BP kinetics towards metal ions was very fast, i.e., about 10 minutes, although extraction was significantly impaired at pH 3. The series of adsorption isotherms were adjusted to a modified Langmuir equation and the maximum extraction capacity was 0.193 and 0.387 mmol g-1 for Cd(II) and Pb(II), respectively. An analysis of the Ø values lead to the inference that the resulting metal ligand complex was type 1:1.
Keywords: 4-amine-2-mercaptopyrimidine; silica; metal extraction; aqueous medium
Improvement of enzyme stability via non-covalent complex formation with dextran against temperature and storage lifetime
by Melda Altikatoglu; Huriye Kuzu; (pp. 12-16).
The optimal methodology to prepare the novel modified enzyme, polymer-enzyme complex, was developed to give a high catalytic activity in aqueous solution. The non-covalent complexes of two different enzymes (horseradish peroxidase and glucose oxidase) were prepared with various molar ratios (nD/nE 0,05; 0,1; 1; 5; 10; 15; 20) by using 75kDa dextran. The thermal stabilities of the obtained complexes were evaluated with the activities determined at different temperatures (25, 30, 35, 40, 50, 60, 70, 80°C) applying 60 minutes incubation time for pH 7. The complexes with the molar ratio nD/nHRP: 10 and nD/nGOD: 5 showed the highest thermal stability. Its activity was very high (ca. 1,5-fold higher activity than pure enzyme for HRP-dextran complexes) and almost the same between applying one hour incubation time and without incubation, and could also be measured at high temperatures (70, 80 °C). We finally succeeded in preparing dextran-enzyme complexes which showed higher activity than pure enzyme in aqueos solution at all temperatures for pH 7. In addition, the mentioned complexes at pH 7 had very long storage lifetime compared to purified enzyme at +4 °C; which is considered as a good feature for the usage in practice.
Keywords: Thermal stabilization; Complex; Enzyme; Dextran; storage lifetime
A new method for the preparation of solvatochromic 5-(5-X-6-hydroxynaphthyl-2)-7H-indolo[1,2-a]quinolinium merocyanines
by Marta J. Sawicka; Jacek A. Soroka; Monika Gąsiorowska; (pp. 17-22).
A new method for the preparation of 7H-indolo[1,2-a]quinolinium solvatochromic dye precursors has been investigated. 5-(6-Hydroxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium perchlorate, 5-(5-bromo-6-hydroxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium perchlorate and 5-(5-nitro-6-hydroxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium perchlorate were obtained via demethylation of the corresponding 5-(5-X-6-methoxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium salts. The application of pyridinium hydrochloride in the demethylation of the methoxy perchlorates allowed to obtain the products with the almost quantitative yield in a very short time, especially when the reaction was carried out using microwave irradiation.
Keywords: 7H-indolo[1,2-a]quinolinium perchlorate; solvatochromic dye; pyridinium hydrochloride; microwave synthesis; demethylation
Extraction of vanadium compounds from the used vanadium catalyst with the potassium hydroxide solution
by Krzysztof Mazurek; Katarzyna Białowicz; Mieczysław Trypuć; (pp. 23-28).
The paper presents the results of the research on the degree of the recovery of vanadium(V) from the used vanadium catalyst with the use of KOH solution. The extraction was performed at 293 - 323 K, for 0.5 to 4 h and the catalysts of the variable grain diameter. The concentration of the extracting solution was varied in the range 5 - 20%. The optimal ratio of solid to liquid phase S/L was determined. Additionally the degree of the recovery of total iron ions was presented.
Keywords: vanadium catalyst; leaching; recovery; vanadium; iron; sulfuric acid; potassium hydroxide
The Ti-MWW catalyst - its characteristic and catalytic properties in the epoxidation of allyl alcohol by hydrogen peroxide
by Agnieszka Wróblewska; Anna Fajdek; Eugeniusz Milchert; Barbara Grzmil; (pp. 29-34).
Ti-MWW, one of the latest titanium-silicalite catalysts, has been prepared by direct hydrothermal synthesis using hexamethyleneimine as a structure-directing agent. The characteristic of the catalyst was performed by means of the following methods: XRD, SEM, IR, UV-vis and X'Ray microanalysis. The catalytic properties of Ti-MWW have been compared with those of the conventional titanium-silicalites TS-1 and TS-2 in the epoxidation of allyl alcohol with hydrogen peroxide. The process has been described by the following main functions: the selectivity of the transformation to glycidol in relation to allyl alcohol consumed, the conversions of the substrates (allyl alcohol and hydrogen peroxide) and the selectivity of the transformation to organic compounds in relation to hydrogen peroxide consumed.
Keywords: Ti-MWW; titanium-silicalites; glycidol; liquid phase epoxidation; hydrogen peroxide
The effect of cathode materials on the electrochemical reduction of nitric acid
by D. Vasudevan; (pp. 35-37).
Electrochemical or chemical reduction of nitric acid is a well studied area in literature due to the importance of the products formed. The present work focuses on the effect of conventional cathode materials including PbO2, amalgamated Cu, graphite, Pb, Pt and a modified electrode material Ti/TiO2 on the reduction of nitric acid. Ammonia and hydroxylamine are the main products which are estimated by conventional titration methods. Other conditions being similar, the product distribution varies quite drastically as a function of the electrode material and Ti/TiO2 is found to favor a higher ratio of hydroxylamine to ammonia formation compared to other electrodes. The conditions have also been optimized based on the maximum yield of the product.
Keywords: Electroreduction; Nitric acid; Hydroxylamine; Ammonia; Conventional and modified cathodes; Mechanism
Kinetics of nanocrystalline iron nitriding
by Walerian Arabczyk; Jacek Zamłynny; Dariusz Moszyński; (pp. 38-43).
Nitriding of nanocrystalline iron was studied under the atmosphere of pure ammonia and in the mixtures of ammonia - hydrogen - nitrogen at temperatures between 350°C and 500°C using thermogravimetry and x-ray diffraction. Three stages of nitriding were observed and have been ascribed to the following schematic reactions: (1) α-Fe → γ'-Fe4N, (2) γ'- Fe4N → ε - Fe3N and (3) ε - Fe3N → ε - Fe2N. The products of these reactions appeared in the nitrided nanocrystalline iron not sequentially but co-existed at certain reaction ranges. The dependence of a reaction rate for each nitriding stage on partial pressure of ammonia is linear. Moreover, a minimal ammonia partial pressure is required to initiate the nitriding at each stage.
Keywords: iron nitrides; microporous materials; chemical synthesis; thermogravimetric analysis; X-ray diffraction