bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soda—Oxygen bleaching of kraft bagasse pulp
Authors: El‐Ashmawy Ahmed E. , Hiekal Salwa O. , Fadl Mohammed H. 
Published: July 2010

AbstractSoda—oxygen bleaching of commercially available kraft bagasse pulp has been investigated. Alkali charge, temperature and oxygen pressure are important factors in controlling brightness and physical properties of the pulps produced. Pulp yields, lignin and degree of polymerisation of the bleached pulps decreased with increasing alkali charge from 2 to 6%. Strength properties as well as brightness increased by increasing alkali charge at 368 K, whereas optimum strength properties are obtained with 4% alkali at 383 K. In the range of oxygen pressure used, 5–8 kg cm−2, DP as well as strength properties of the bleached pulps increased with increasing oxygen pressure. Brightness up to 61% was reached by soda‐oxygen alone. To obtain higher brightness an afterbleaching step is necessary. The soda—oxygen—hypochlorite and soda—oxygen—chlorite pulps prepared have strength properties comparable with those of conventionally bleached pulps.
Production of solasodine by microbial hydrolysis of glycoalkaloids of Solanum eleagnifolium Cav. and its application to the synthesis of 16‐dehydropregnenolone acetate
Authors: Rodriguez J. , Segovia R. , Guerreiro E. , Ferretti F. , De Sosa G. Zamarbide , Ertola R. 
Published: July 2010

AbstractGlycoalkaloids from Solanum eleagnifolium Cav. were converted into solasodine in high yield by microbial hydrolysis. It was possible to use the mycelium obtained in the fermentation for further enzymic conversion of glycoalkaloids. The crude solasodine obtained by microbial hydrolysis was converted into 16‐DHPA with 48–53% yields.
Recent advances in the analysis of coal‐derived products
Authors: Bartle Keith D. , Collin Gerd , Stadelhofer Jürgen W. , Zander Maximilian 
Published: July 2010

AbstractRecent developments in some of the most important fields of the analytical chemistry of coal and its derivatives are critically reviewed: separation methods; in particular gel‐permeation, high‐pressure liquid and gas chromatography, 13C‐nuclear magnetic resonance spectroscopy, u.v. visible spectrophotometry, fluorimetry and phosphorimetry. Progress in statistical structural analysis, based on both chemical reactions and physical methods, usually n.m.r., is also comprehensively reported.
The reduction of ilmenite with carbon
Authors: Wouterlood Huibert J. 
Published: July 2010

AbstractThe reduction of natural and pre‐oxidised ilmenite with carbon at temperatures between 1173 and 1473 K (900–1200°C) was studied. The reaction was carried out in the atmosphere produced by the gaseous reaction products and the degree of reduction was determined from the CO and CO2 contents of the product gas, as measured by chemical absorption and continuous infrared analysis. Solid reaction products were analysed chemically, by X‐ray diffraction and by magnetic balance. The reaction was found to consist of a fast first stage representing the reduction of ferric to ferrous iron, and a slower second stage in which ferrous iron was reduced to metallic iron. A change in reaction mechanism, leading to retention of iron in solid solution in the reaction product, was shown to be promoted by high temperatures and/or the presence of Mn and Mg solute impurities. The applicability of various reaction models to the experimental data is discussed.
A thermodynamic method based upon the theory of regular solutions for selection of solvents and process conditions for aromatics extraction
Authors: Mukhopadhyay Mamata 
Published: July 2010

AbstractSelectivity and distribution coefficients are two important parameters required for selection of solvents and process conditions for efficient separation of aromatics from a multi‐component hydrocarbon feedstock. A simple thermodynamic method is presented in this paper for the prediction of these parameters from a knowledge of physical properties of the pure components, such as vapour pressure, molar volume and critical temperature. The activity coefficients were calculated using the solubility parameter theory extended to multi‐component mixtures of polar and nonpolar components. The compositions of the extract and raffinate phases were computed using an iterative search technique for simultaneous solution of the thermodynamic criterion equations and the material balance equations for each component. For testing the validity of this method, the predicted values of the selectivity at infinite dilution and the equilibrium phase compositions were compared with the corresponding experimental values from the literature and the agreement is found to be highly satisfactory.
A study of the rate of sedimentation of magnesium hydroxide obtained from sea water
Authors: Petric Bartul , Petric Nedjeljka 
Published: July 2010

AbstractA study has been made of the influence of incomplete precipitation on the rate of sedimentation of magnesium hydroxide obtained from sea water with the use of the following flocculants: Flocculant‐B (polyacrylamide) and slag from Fe—Cr of a high carbon content. Incomplete precipitation of magnesium ions from sea water considerably affected the rate of sedimentation of magnesium hydroxide. The rate of sedimentation increased considerably and thus the capacity of the thickener was also increased. At a precipitation of 80%, the capacity of the thickener increased by 86.5% in relation to complete precipitation. Calculations were made according to Kynch's theory. The above procedure leads to a substantial reduction in the content of calcium salt in the product, which can be explained by the law of adsorption, as set out by Paneth, Fajans and Hahn. For optimal conditions of sedimentation, a mathematical expression of the dependence of the quantity of the flocculant, ‘Flocculant‐B’ on the degree of completeness of precipitation was determined.
The reduction of sulphur dioxide by carbon monoxide on a La0.5Sr0.5CoO3 catalyst
Authors: Hibbert D. Brynn , Tseung Alfred C. C. 
Published: July 2010

AbstractThe semiconducting perovskite oxide, La0.5Sr0.5CoO3, is a catalyst for the reduction of sulphur dioxide by carbon monoxide. Unlike aluminia‐supported metal catalysts, La0.5Sr0.5CoO3 tolerates high levels of oxygen in the gas stream if sufficient carbon monoxide is present to react with all the oxygen. Water vapour (2%) does not adversely affect the reaction; unwanted byproducts H2S and COS are reduced for contact times less than 0.25 s. A computer model is used to predict equilibrium gas compositions for systems containing oxygen and water vapour. During the reaction the catalyst itself reacts with sulphur producing metal sulphides, possibly of simple cubic structure. The perovskite sulphides LaCoS3 and La0.5Sr0.5CoS3 are theoretically unstable.
Origin of porosity in titania gels. I. Microporous and mesoporous gels prepared from titanous chloride and ammonia
Authors: Ragai Jehane , Sing Kenneth S. W. , Mikhail Raouf 
Published: July 2010

AbstractTitania gels were prepared by oxidation of precipitates of hydrous TiIII oxide obtained at different pH values from aqueous titanous chloride by the addition of ammonia. The gels were dried at 110–120°C (383–393 K) and their surface properties were characterised by nitrogen adsorption at 196°C (77 K). The nitrogen isotherms have been analysed by the BET and αs‐methods. Gels prepared at pH values of 3.30, 5.01, 6.20 and 7.10 were all mesoporous; the pore volume increasing with increase of pH, over the range studied. The gel prepared at pH 2.30 had a small micropore volume, whereas the gel prepared at pH 5.01 and aged for 6 months in water had a much larger micropore volume. The formation of the mesopore structure appears to be due to a condensation‐polymerisation process associated with the creation of hydroxo and oxo bridges between neighbouring Ti3+ ions. If stabilising ligands (H2O or NH3) are allowed to remain attached to the cations, the condensation‐polymerisation process is retarded and microporosity results.
The photosynthetic efficiency of Chlorella biomass growth with reference to solar energy utilisation
Authors: Pirt S. John , Lee Yuan‐Kun , Richmond Amos , Pirt Margaret Watts 
Published: July 2010

AbstractThe photosynthetic efficiency (PE) of a growing algal culture was determined from the growth yield (Y), that is, biomass produced/light absorbed and the calorific value of the biomass (k); PE = kY. To obtain the maximum photosynthetic efficiency the algae were grown in light‐limited chemostat cultures in urea‐mineral salts media plus CO2 and steady‐states were obtained at different specific growth rates. With a given light input the biomass output rate was independent of the specific growth rate up to at least 70% of the maximum specific growth rate. The photosynthetic efficiency was independent of the incident light intensity over the range studied, 5.3–21.3 W m−2. The light source had a spectral range of 400–700 nm and its mean wavelength was assumed to be 575 nm. The values of the maximum growth yields (YG, g dry weight kJ−1) were 0.0153 for the Sorokin Chlorella strain 211/8k and 0.0206 for a newly selected mixed culture MA003 which consisted of an alga and three species of heterotrophic bacteria. The maintenance energy (m) of the mixed culture MA003 was in the range 0–0.32 kJ g−1 dry weight h−1 and the specific maintenance rate (mYG) was in the range 0–0.0066 h−1. In Chlorella strain 211/8k the maximum PE was 34.7% which corresponds to a quantum demand (n) of 6.6 per O2 molecule evolved. In the mixed culture MA003 the maximum PE was 46.8% with 95% confidence limits, 42.7–51.5. This PE value corresponds to a quantum demand (n) of 4.8 per O2 molecule evolved. These results call in question the current model of photosynthesis which predicts that the maximum PE with absorbed light of mean wavelength 575 nm should not exceed 29% and the minimum quantum demand, n = 8. From our results with culture MA003 it is deduced that the maximum practicable storage of total solar energy by algal biomass growth in vitro is 18%.
The production of chlorate with a bipolar pump cell
Authors: Ghoroghchian Jamal , Jansson Robert E. W. 
Published: July 2010

AbstractChlorate has been produced in a system consisting of an electrochemical pump cell (space‐time ∼ 150 ms) and a holding volume. The overall current efficiency has been determined as a function of ratio of tank:cell volume, electrolyte concentration and applied voltage, and the interaction of the electrochemical and chemical reactions investigated. At low applied voltages the reduction of dispersed and dissolved oxygen provides an alternative counter reaction to the more normal evolution of hydrogen, although only at low current densities on graphite. Space‐time yields range from 0.52 to 8.76 mol h−1 dm−3 at energy yields of 2.65 to 7.59 kW h kg−1.
Active carbons from almond shells as adsorbents in gas and liquid phases
Authors: Linares‐Solano Angel , De D. López‐González Juan , Molina‐Sabio Miguel , Rodriguez‐Reinoso Francisco 
Published: July 2010

AbstractAlmond shells have been used as raw material to prepare activated carbons. The preparation conditions, by direct activation of the raw material with CO2 or air, or by activation after carbonisation under nitrogen, have been compared in respect to the percentage burn‐off and the adsorptive properties of the resulting carbons. It is shown that direct activation with CO2 in the temperature range 1023–1173 K (750–900°C) gives activated carbons with similar or larger surface areas than those obtained by the conventional method (carbonisation followed by activation). On the other hand, the results show the role played by the particle size of the carbonised products on the adsorptive properties of the activated carbons prepared from them. Activation with air (in the temperature range from 573 to 673 K) does not produce carbons with large surface areas, but the yield is large and this could be of practical interest. The adsorption of methylene blue and phenol, both in aqueous solution, has allowed further comparison of the adsorptive properties of the activated carbons. In all, the direct activation with CO2 seems to be a very good way to prepare activated carbons from almond shells; they can be favourably compared with commercial activated carbons, two of which have been used in this study.
Synthesis of 4,4′‐aryldihydrazono‐3‐(3′‐pyridyl)‐2‐pyrazolin‐4,5‐diones and 1‐aryl‐3‐(3′‐pyridyl)‐4,4′‐arylbisazo‐5‐aryliminopyrazoles and their application as disazo disperse dyes. Part II
Authors: Amer Fathy A. , Afsah El‐Sayed , Soafan Mamdouh 
Published: July 2010

Abstract3‐(3′‐Pyridyl)‐2‐pyrazoline‐4,5‐dione 4,4′(4,4′‐biphenylenedihydrazone and p‐phenylenedihydrazone) and its derivatives (IIa‐e, IIIa‐e) were obtained by the coupling reaction of tetrazotised benzidine and p‐diamonobenzene with 3‐(3′‐pyridyl)‐2‐pyrazolin‐5‐ones (Ia‐e). Similarly, bis‐azo compounds containing pyrazole nucleous as, 1‐aryl‐3‐(3′‐pyridyl)‐4,4′‐arylbisazo‐5‐aryliminopyrazoles (VIa‐i and VIIa‐i) were prepared by the interaction of the corresponding chloro compound (IV and V) with aromatic amines. The compounds so obtained (II, III, VI and VII) are used as disazo disperse dyes for dyeing polyester fibres fast yellow‐orange shades. Their fastness properties towards washing, rubbing, acid‐alkaline perspiration and light were investigated.
Selectivity and reactor analysis for parallel electrochemical reactions
Authors: Sakellaropoulos George P. , Francis Gary A. 
Published: July 2010

AbstractA methodology is outlined for the analysis of multiple parallel electro‐organic reactions of arbitrary, simple electrode kinetics on solid or porous electrodes, in the absence and in the presence of slow mass transport processes. The analysis is further used to predict the selectivity and rate of two model electrochemical reactors under potentiostatic, channel plug‐flow or complete mixing. The product yield of both reactors depends strongly on the electrode potential, with reductions of low transfer coefficients favoured by positive, electrogenerative potentials. Channel flow reactors result in non‐uniform rate, current and selectivity distributions and exhibit apparent limiting currents before the onset of slow mass transport. With multipath competing reactions or in the presence of slow external transport, both reactors are amenable to maximisation of desirable product yields.
Mechanism of the photofading of Dye. Contribution of singlet oxygen in the catalytic fading of anthraquinone dye mixtures
Authors: Kuramoto Nobuhiro , Kitao Teijiro 
Published: July 2010

AbstractThe mechanism of the catalytic fading of some dyes has been investigated. The relative fading of quinophthalone in solution increases when C.I. Disperse Red 15 was added. The mechanism of catalytic fading proceeds via the singlet oxygen mechanism, since this phenomenon is suppressed by adding singlet oxygen quencher as DABCO or nickel dimethyldithiocarbamate (NMC). However, when quinophthalone mixed with C.I. Disperse Blue 14 was irradiated under the same conditions (λ > 520 nm), no catalytic fading occurred. Competitive photo‐oxidation experiments for these dyes with NMC, giving evidence for intermediacy of singlet oxygen by the self‐sensitised process, were carried out. The relative rate constants for reactions in solution were examined to predict the possibility of the catalytic fading in these dye mixtures.
Investigation on the textural characteristics of supported nickel hydrogenation catalysts
Authors: Srinivasan Ganapthy , Murthy Ramaraju Sreerama , Kumar Kallambella M. Vijaya , Kamat Prashant V. 
Published: July 2010

AbstractNickel catalysts supported on a range of carriers such as kieselguhr, silica, γ‐alumina, silica‐alumina and mordenite were investigated in order to gain an understanding of their structural properties. The surface area and pore distribution characteristics of the carriers and unreduced catalysts obtained from nitrogen adsorption isotherms gave strong indications that the formation of the nickel salt submerged the carrier. Metallic nickel produced after reduction at high temperature was perhaps present in the macropores or on the outer surface of the carrier forming a microporous network of fine crystallites. The metal surface area of the catalyst in its reduced state, calculated from hydrogen chemisorption data, was not influenced by the specific surface area of the carrier. Among the different carriers, the nickel‐carrier interaction was mainly found with kieselguhr and silica. Activity of the different catalysts in the hydrogenation of unsaturated fatty acid was found to be directly related to the metal area.
Preparation of gelatinous aluminium hydroxide by urea from aqueous solutions containing chloride, nitrate and sulphate of aluminium
Authors: Sato Taicho , Ikoma Shuji , Ozawa Fusaji 
Published: July 2010

AbstractThe preparation of gelatinous aluminium hydroxide from aqueous solutions containing a mixture of the chloride, nitrate or sulphate of aluminium and urea by heating at 95°C has been investigated under different conditions. The pH value of aqueous solutions, on heating for a given period of time, gradually increases, rises steeply at pH 4.0–7.5 and finally approaches a constant value. The precipitate appears at about pH 7 in the presence of chloride or nitrate ions and about pH 4 in the presence of sulphate ions. Although the gelatinous precipitates in the chloride and nitrate systems are apparently different from the granular, filterable one in the sulphate system, their compositions are not influenced by the species of aluminium salt. The fresh precipitates exist in an amorphous state, and go to pseudoboehmite by ageing. It seems that the amount of pseudoboehmite increases as the concentration of aluminium salt in aqueous solution decreases. However, the transformation from amorphous aluminium hydroxide to pseudoboehmite is reduced in the presence of sulphate ions. Furthermore, it is found that the X‐ray diffraction peak for the (200) plane, as an orthorhombic structure, in the pseudoboehmite precipitated from chloride or nitrate solution is more intense than that from sulphate solution.
Performance of electrolysis with two‐phase electrolyte. The trickle electrode for the electrochemical conversion of substances with low solubility in aqueous electrolytes with special respect to electrochemical extraction processes
Authors: Feess Hans , Wendt Hartmut 
Published: July 2010

AbstractThe electrochemical conversion of organic substances with low solubility in water which yield ionic products can be performed in aqueous electrolytes, as the main medium for the ionic charge transfer, by dissolving the organic depolariser in a nonaqueous solvent and conducting the electrolysis at the organic solvent‐electrode interface. Polarity of this second phase, as well as good contact between organic phase and working electrode are essential. The anodic oxidation of ferrocene dissolved in organic solvents (preferentially methylene chloride) to ferricinium salts was chosen as a model system to study the conditions of this type of two‐phase electrolyte electrolysis. Experiments with single CH2Cl2‐droplets on smooth nickel anodes covered by an aqueous electrolyte show that the most important parameters which govern the anodic conversion of ferrocene are: (a) electrical conductivity supplied to the organic phase by the anodically‐produced ferricinium salt; (b) small difference in surface tensions at the electrode‐organic phase interface and the electrode‐aqueous phase interface; and (c) direction and magnitude of the Galvani potential difference at the aqueous‐organic interface. Quantitative studies on the influence of the different parameters were performed at a well‐defined and stationary three‐phase boundary. The results were used for the construction of a trickle cell with particulated horizontal working electrodes (nets, perforated plates etc.) which offers the possibility for continuous processing of two‐phase liquid‐liquid electrolytes. Such electrodes show excellent mass and charge transfer characteristics and can be used for simultaneous electrochemical conversion of a neutral depolariser and extraction of its ionic conversion‐product out of the organic solvent into the aqueous electrolyte (electrochemical extraction).
Segregated flows in model cells
Authors: Marshall Rodney J. , Jansson Robert E. W. 
Published: July 2010

AbstractThe flow of an electrolyte in a parallel channel electrochemical reactor has been simulated in a simple Perspex flow channel, operating at Reynolds numbers between 20–1000. Age distribution information was obtained by the marker‐pulse technique and analysed with the aid of various simple mathematical models of the flow. It was found that the flow appeared to be segregated and that, in particular, electrogenerated species were retained for long periods in the vicinity of the electrode. Regression was performed in both the time domain and Laplace plane and the effect of experimental noise on the accuracy of the results was estimated. Fitting in real‐time was found to be inherently less sensitive to noise than fitting in the Laplace plane. Data are given for the highly structured flow within a model of an Mg‐AgCl sea water battery as well as for channel flow.
Porosity of alumina gels prepared from solutions of aluminium nitrate in various alcohols
Authors: Cormack Brian , Freeman John J. , Sing Kenneth S. W. 
Published: July 2010

AbstractMercury porosimetry and nitrogen adsorption measurements have been made on a series of alumina gels prepared by the passage of gaseous ammonia into solutions of aluminium nitrate nonohydrate in various alcohols. The values of surface area calculated from mercury intrusion curves and nitrogen isotherms (BET method) are in reasonable agreement with the macroporous gels, but the restricted penetration of mercury into the mesopore structures results in larger values of areas when calculated by nitrogen adsorption. Marked differences have been obtained in the pore size distribution of gels prepared in various alcohols, including the isomers of propanol and butanol. The alcohol appears to play a double role: (a) by replacing water at the solid‐liquid interface (it promotes aggregation‐cementation); (b) by decreasing the solubility (it reduces the rate of Ostwald ripening). Propan‐1‐ol and propan‐2‐ol tend to promote aggregation‐cementation and hence the formation of a well‐defined mesopore structure, whereas butan‐1‐ol and heptan‐1‐ol appear to favour particle growth and the development of larger pores.
The kinetics of the gaseous extraction of gallium from mica
Authors: Gesser Hyman D. , Vaidya Om , Baldwin W. George , Chow Arthur , Bock Ernest , McBride David W. 
Published: July 2010

AbstractThe gaseous reduction of gallium in white mica has been studied using natural gas as the reducing gas. From a study at three temperatures, the initial extraction was observed to be linear with time and independent of particle size. The results suggest that delamination of the mica lattice is important. The measured activation energy for the loss of gallium from the white mica is 184 × 21 kJ mol−1.
Simple and rapid spectrophotometric and titrimetric methods for the determination of ascorbic acid in pharmaceutical preparations
Authors: Aly Mohamed M. , Hassan Moustafa K. , Souliman Rafat M. 
Published: July 2010

AbstractAscorbic acid in pharmaceutical preparations can be determined by either spectrophotometric or titrimetric methods by its reaction with ferricinium trichloroacetate at pH 3. The latter is quantitatively reduced to ferrocene. This is extracted by chloroform and its concentration calculated from the absorbance at 440 nm. Alternatively, an aqueous solution of ascorbic acid is titrated with that of the blue ferricinium salt which acts as an indicator. Vitamins, minerals, hormones, dextrose and coloured additives do not interfere with the reaction. Both methods are simple, rapid and sensitive.