bluuebunny/crossref_metadata_2025_split huggingface dataset:
Removal of aromatic amines from aqueous solution by activated sepiolite
Authors: González‐Pradas E. , Valverde‐garcía A. , Villafranca‐sánchez M. 
Published: July 2010

AbstractThe adsorption processes of p‐toluidine, p‐bromoaniline and p‐acetylaniline, from aqueous solution at 20°C, on heat‐treated sepiolite have been studied. With regard to the kinetic study, the processes have resulted in being second order in relation to the vacant active centres of the sepiolite, the highest value of the specific rate constant corresponding to the p‐acetylaniline and the lowest one to the p‐toluidine. The adsorption isotherms may be classified as L‐type (Giles classification) and the values of the adsorption capacity have been calculated from the Langmuir equation applied to the experimental data points. The highest values of the adsorption capacity and specific surface area also correspond to the p‐acetylaniline, and the lowest ones to the p‐toluidine.
Study of ClO2 generation reaction via experimental data of aqueous mixed electrolyte solutions: HClO4–NaCLO3–H2O and HCLO4–NaCl–H2O
Authors: Tran F. , Rouleau D. , Couillard D. 
Published: July 2010

AbstractA new model for mixtures (two and more solutes) of aqueous electrolyte solutions was found to be as accurate as other models, or more accurate, in prediction of new experimental results of the ternary systems HClO4–NaClO3–H2O and HClO4–NaCl–H2O. The water activity values are then used to study the mechanism of the chloride–chlorate reaction, generating chlorine dioxide:2H+ + ClO−3 + Cl− → ClO2 + 1/2Cl2 + H2OSpectrophotometric measurements of the production rate of ClO2 have confirmed that the intermediary species in the proposed equilibriumH+(mH2O) → H+(m‐n)H2O + nH2OIs actually H(H20)+m‐n. The final kinetic expression for the reaction rate of chlorine dioxide generation, used in pulp bleaching, is then derived to explain the high order with respect to acid concentration.
Fly ash disposal and utilization
Authors: Ferraiolo Giuseppe , Zilli Mario , Converti Attilio 
Published: July 2010

AbstractThis paper presents a general review on the problem of the so‐called ‘fly ash’ deriving from the combustion of fossil coal for energy production.Preliminary information is given on the actual coal consumption for the aforesaid purpose as well as on the corresponding fly ash generation, with further regard to its average composition and other characteristics.Some further considerations on the main environmental problems, due to the present amount of fly ash to dispose of, are also developed.The main solutions to the problems are then examined and discussed, with particular reference to disposal as well as to civil engineering, technological, industrial, agricultural, environmental and biological applications of fly ash.
Clarification of suspensions by colloidal gas aphrons
Authors: Subramaniam Madhev B. , Blakebrough Norman , Hashim Mohd A. 
Published: July 2010

AbstractColloidal gas aphrons (CGAs), generated from dilute solutions of four surfactants, were used to clarify palm oil mill effluent (POME), suspensions of microalgae and suspensions of three inorganic minerals.In POME and the algal suspensions, each CGA was most effective at a pH value close to the pK value of the surfactant concerned. This effect was not tested in the inorganic suspensions.The efficiency of air utilization was directly related to the concentration of solids in the suspensions, the size, density and nature of the solids having secondary effects. Comparison with data in the literature led to a general correlation embracing a variety of suspensions and flotation systems.Shedding of collected material from the foam layer was also a direct function of solids concentration.CGAs offer advantages over other systems of air‐assisted flotation in relation to the requirements for equipment and to the management of process operations.
Factors influencing the activity and thermostability of immobilized porcine pancreatic lipase
Authors: Kéry Vladimír , Haplová Jana , Tihlárik Karol , Schmidt Štefan 
Published: July 2010

AbstractLipase from porcine pancreas was immobilized on cellulose beads having various degrees of hydrophobicity, by covalent linking and by hydrophobic adsorption. Lipolytic activity was measured in heterogeneous organicaqueous systems of various hydrophobicities using olive oil as a substrate. The main factors influencing lipase activity were hydrophobicity of the reaction mixture and of the carrier. Carriers with increased hydrophobicity enhanced lipase activity more than less hydrophobic ones. Lipase immobilized covalently on cellulose beads was less active than that adsorbed onto tritylcellulose but was considerably more thermostable.
Effect of longitudinal mixing on microbial growth in a multi‐stage column bioreactor
Authors: Nishiwaki A. , Dunn I. J. , Bourne J. R. 
Published: July 2010

AbstractThe performance of a multi‐stage column bioreactor for nonlimited microbial growth was studied. The back‐flow model was employed to describe the flow pattern of the microbial suspension. Analytical solutions for calculating the microbial cell concentrations under steady‐state and unsteady‐state operations, with and without cells in feed, were obtained and the cell growth behavior was examined. Only when microbial cells were present in the feed and the reaction number was less than a critical number was a stable steady state achieved: the microbial cell concentration was then significantly affected by the extent of longitudinal mixing. In the absence of microorganisms in the feed, the steady state was not stable with either washout or nonlimited growth resulting.
The effects of a biosurfactant on oxygen transfer in a cyclone column reactor
Authors: Sheppard John D. , Cooper David G. 
Published: July 2010

AbstractA laboratory‐scale cyclone column reactor was tested to determine how its oxygen transfer characteristics were affected by surfactants in the liquid medium. The volumetric oxygen transfer coefficient was greatly decreased by small quantities of the synthetic surfactants dodecyltrimethylammonium bromide and sodium dodecylsulfate, and the biosurfactant surfactin produced by Bacillus subtilis (ATCC 21332). Since the gas holdup fraction was generally increased due to foaming, the effectiveness of the surfactants was probably due to an increase in the interfacial film resistance. B. subtilis was grown in the cyclone column to 0.6 g dm−3 with a significant level of surfactin produced while maintaining at least 75% oxygen saturation in the broth. Process optimization and scale‐up of surfactin production will have to consider oxygen transfer as a key parameter.
Urease immobilized on chitosan membrane: Preparation and properties
Authors: Krajewska Barbara , Leszko Maciej , Zaborska Wiesawa 
Published: July 2010

AbstractUrease was covalently immobilized on glutaraldehyde‐pretreated chitosan membranes. The optimum immobilization conditions were determined with respect to glutaraldehyde pretreatment of membranes and to reaction of glutaraldehyde‐pretreated membranes with urease. The immobilized enzyme retained 94% of its original activity. The properties of free and immobilized urease were compared. The Michaelis constant was about five times higher for immobilized urease than for the free enzyme, while the maximum reaction rate was lower for the immobilized enzyme. The stability of urease at low pH values was improved by immobilization; temperature stability was also improved. The optimum temperature was determined to be 65°C for the free urease and 75°C for the immobilized form. The immobilized enzyme had good storage and operational stability and good reusability, properties that offer potential for practical application.
Electrically enhanced extraction of penicillin G into dichloromethane
Authors: Weatherley L. R. , Campbell I. , Kirton D. , Slaughter J. C. 
Published: July 2010

AbstractThe application of electrically enhanced liquid‐liquid extraction techniques to the recovery and purification of penicillin G from aqueous solutions and from untreated mycelial culture broth is described. Experiments at laboratory scale have shown that extraction rates into dichloromethane at pH 4.0 may be increased by factors of up to five‐fold by electrostatically spraying penicillin G solutions into a continuum of solvent held in electrical tension. The experimental studies revealed that in small spray column contactors, electrostatic spray conditions, once initiated at nozzle voltages in excess of 10 kV, could be sustained at nozzle voltages as little as 4 kV. The results demonstrate the potential of this technique as an alternative to mechanically augmented liquid‐liquid contact for the intensification of whole broth extraction processes.
Synthesis of zeolite beta using silica gel as a source of SiO2
Authors: Bhat Ramanath N. , Kumar Rajiv 
Published: July 2010

AbstractThe feasibility of synthesising pure zeolite beta in high yields using silica gel as the source of SiO2 is demonstrated. The phase‐purity and yield of beta is enhanced by using silica gels with high surface area. The influence of various synthesis parameters (Si/Al ratio, alkalinity, dilution level, concentration of the organic base, etc.) on the kinetics of synthesis as well as the quality and yield of the zeolite have been investigated. A correlation between XRD crystallinity of the samples with varying degrees of crystallinity and that estimated from framework IR spectroscopy, differential thermal analysis and adsorption of n‐hexane is demonstrated. The dependence of the yield of zeolite beta on SiO2/Al2O3 ratio of the gel is also reported. The results of the present study indicate the feasibility of a cheaper route for the manufacture of zeolite beta.
Oxidative detoxification of aqueous bark extracts. Part II: Alternative methods
Authors: Field Jim A. , Sierra‐Alvarez Reyes , Lettinga Gatze , Habets Leo H. A. 
Published: July 2010

AbstractThe most important problem associated with the high‐pH autoxidative detoxification of methanogenic toxins in debarking wastewater was its limited application to the aqueous extractives of bark from specific species. The autoxidative polymerization of coniferous bark extracts exhausted prior to complete removal of the toxic oligomeric tannins. As a result, highly toxic spruce bark extracts were only partly detoxified. Birch bark extracts were not detoxified, even though effective polymerization of the oligomeric tannins occurred. The non‐tannin toxins in birch bark extracts and toxic intermediates produced by high‐pH autoxidation of these extracts were responsible for the poor detoxification results. These problems can potentially be resolved by applying alternative oxidation methods. In this study a high level of detoxification was obtained for all bark species tested by short‐term destructive oxidations with H2O2, or by long‐term aerobic biological treatments which caused high levels of polymerization. The applicability of high‐pH autoxidation was also made feasible for all species of bark by applying a granular active carbon treatment after the autoxidation. The active carbon was able to adsorb the residual toxic oligomeric tannins of autoxidized spruce bark extracts and the non‐tannin toxins in autoxidized birch bark extracts. Additionally, a potential disadvantage of the autoxidative detoxification method is the formation of colored end products. Although these compounds are non‐toxic and are non‐biodegradable, their elimination from the wastewater would be necessary if discharge norms concerning color and non‐biodegradable COD must be fulfilled. The destructive oxidation with H2 O2 produced non‐toxic low‐molecular‐weight compounds which did not have much color. The autoxidation and long‐term aerobic biological treatments produced highly colored humic end products which could be eliminated by calcium precipitation.
Liver alcohol dehydrogenase immobilized on polyvinylidene difluoride
Authors: Roig M. G. , Bello J. F. , Moreno Vega M. A. De , Cachaza J. M. , Kennedy J. F. 
Published: July 2010

AbstractA physical method for immobilization of liver alcohol dehydrogenase (ADH) by hydrophobic adsorption onto a supporting membrane of polyvinylidene difluoride (PVDF) was performed. Simultaneously, a physicochemical characterization of the immobilized enzyme regarding its kinetic behaviour was performed. The activity/pH profile observed points to an effect of pH on activity that is completely different from the case of ADH in solution. The disturbance in the typical bell‐shaped profile owing to the fact that the enzyme was immobilized is explained on the basis of a potent limitation to the diffusion of the protons in the support. The findings of the present work also reveal the existence of an effect that limits free external diffusion of the substrate towards and/or the product from the support; this effect seems to be the determinant of the overall rate of the enzymatic reaction and is thus of great importance in the effective kinetic behaviour (v([S])) of immobilized ADH, whose kinetic behaviour is complex (non‐Michaelian), as may be seen from the lack of linearity observed in the corresponding double reciprocal and Eadie‐Hofstee plots. By non‐linear regression numerical analysis of the v([S]) data and application of the F‐test for model discrimination, the minimum rate equation necessary to describe the intrinsic kinetic behaviour ofPVDF‐immobilized ADH proved to be one of the polynomial quotient type of degree 2:2 (in substrate concentration).
Mathematical analysis of the performance of a packed‐bed coimmobilized bioreactor
Authors: Chithra N. , Baradarajan A. 
Published: July 2010

AbstractA model has been developed to describe the performance of a packed‐bed coimmobilized biochemical reactor. Each step in the consecutive reaction is assumed to follow Michaelis—Menten type kinetics. The model includes all the limiting steps controlling the rate of reaction and the additional effect of axial dispersion of bulk liquid. The model equations are solved by the explicit finite difference method from the transient to steady‐state condition. The effects of various parameters of physical importance on the reactor performance are discussed.
Effect of preparation pH on properties of silica gel
Authors: Balköse Devrim 
Published: July 2010

AbstractSilica gels were obtained by drying the silica hydrogels formed at pH values between 1 and 4 at 100°C. The bulk density of the 2–3 mm diameter fraction decreased from 0·62 g cm−3 to 0·20 g cm−3 as the preparation pH increased from pH 3 to pH 3·65. The apparent density of silica gels was between 1·43 and 1·95 g cm−3. Isotherms for the adsorption of water vapour on samples prepared at different pH values showed hysteresis in all cases. Thermogravimetry analysis showed that the amount of bound water was in the range of 4·4 to 5·5% on a dry weight basis. Specific heats were determined by a differential scanning calorimetry method using a sapphire standard and were between 0·82 and 0·97 J g−1 K1.
Immobilization of penicillin G acylase on methacrylate polymers
Authors: Koilpillai Leena , Gadre Rohini A. , Bhatnagar Shubra , Raman Rajan C. , Ponrathnam Surendra , Kumar Kamalesh K. , Ambekar Gangadhar R. , Shewale Jaiprakash G. 
Published: July 2010

AbstractMacroporous weak cation‐exchange methacrylate polymers were synthesized for the immobilization of penicillin G (Pen G) acylase. The role of certain factors such as pore‐generating solvent, cross‐linking agent, cross‐linking density, and comonomer, in enzyme adsorption and expression was studied. Kerosene was a superior pore‐generating solvent to paraffin oil. Ethylene glycol dimethacrylate and acrylic acid served as the best cross‐linking agent and comonomer, respectively, in the systems studied. 80·3% of the activity of the enzyme adsorbed onto polymer beads prepared with 0·05 mol of acrylic acid (polymer PM‐39) was expressed. Properties of the Pen G acylase, immobilized on PM‐39 by adsorption and cross‐linking with glutaraldehyde (IME‐PM‐39) were studied. The optimum pH, optimum temperature and Km of Pen G acylase shifted from 8·0 to 7·5‐7·8, 50°C to 55°C and 0·038 mol dm−3 to 2·4–3·0 mol dm−3, respectively, as a result of immobilization on PM‐39. IME‐PM‐39 was used repeatedly for 15 cycles in the production of 6‐amino penicillanic acid (6‐APA).
Amperometric Bi‐enzyme based biosensor for the detection of lactose—characterization and application
Authors: Pfeiffer Dorothea , Ralis Edmundas V. , Makower Alexander , Scheller Frieder W. 
Published: July 2010

AbstractBased on the glucose oxidase‐β‐galactosidase sequence an enzyme probe for the specific determination of lactose has been developed. β‐Galactosidases from different sources have been compared, the sensor containing β‐galactosidase from Curvularia inaequalis has been characterized in respect of optimal pH, enzyme loading, apparent activity and functional stability. The response of the bi‐enzyme probe depends linearly on lactose concentration between 0.02 and 3.00 mmol dm−3. The application to different milk and foodstuff samples resulted in good correlations toward enzymatic photometric (y = (0.956x‐1.67) mmol dm−3) and infrared detection (y = (1.0772x‐0.3909)%). Using a measuring frequency of 100 h−1 the serial imprecision is about 2% for diluted milk, urine, or foodstuff samples.
Synthesis of pyrazolo[4′,3′:5,6]pyrazino[2,3‐c]pyrazoles and pyrazolo[4′,3′:5,6]pyrazino[2,3‐d]pyrimidines and their application to polyester fibres
Authors: Rangnekar Dinesh W. 
Published: July 2010

Abstract4‐Nitroso‐1‐phenyl‐3‐methyl‐5‐aminopyrazole (1) was condensed with ethylcyanoacetate (2), malononitrile (4a) and 2‐cyanomethylbenzimidazole (4b) to yield 6‐hydroxy‐5‐cyano, 6‐amino‐5‐cyano and 6‐amino‐5‐(benzimidazol‐2‐yl)‐3‐methylpyrazolo [3,4‐b]pyrazines 3, 5a and 5b, respectively. 5‐Cyano‐6‐chloro derivative 6 obtained from 3 was converted to 3‐aminopyrazolo[4′,3′:5,6]pyrazino[2,3‐c]pyrazoles 8a and 8b by the treatment with hydrazin hydrate (7a) and phenylhydrazine (7b), respectively. Compound 5a was treated with formamide (9a), urea (9b) and thiourea (9c) to give 4‐aminopyrazolo[4′,3′:5,6]pyrazino[2′3′‐d]pyrimidines 10a–10c. With refluxing acetic anhydride compounds 8a, 8b and 10a gave corresponding acetamido derivatives 8c, 8d and 10d. Compound 5a was treated with ethylorthoformate (11), acetic anhydride (12) or benzoylchloride (13) to give fused benzimidazopyrazolo[4′,3′:5,6]pyrazino[2′,3′‐d]pyrimidines, viz., benzimidazol[1,2‐c]pyrazolo[4,3‐g]pteridines (14a–14c). Some of the compounds 8, 10 and 14 were applied to polyester as disperse dyes and their fastness properties were studied.
An immobilized cell bioprocess for the removal of heavy metals from aqueous flows
Authors: Macaskie Lynne E. 
Published: July 2010

AbstractMicroorganisms can be used to remove toxic heavy metals from liquid industrial wastes. In addition to the chemical toxicity of many of the latter, the production of long‐lived nuclides from nuclear power programmes has introduced additional radiotoxicological hazards. Associated problems of the presence of contaminating, non‐metal co‐pollutants and the presentation of dilute, high‐volume wastes have received little attention.Traditional biotechnological waste treatments have relied either on the use of non‐living biomass (‘biosorption’) or on the accumulation of metals by living cells with the associated problems of metal toxicity effects and the requirements for cell viability or growth. Identification of an enzymically‐mediated metal accumulation step can permit decoupling of cell growth from metal accumulation. Using pre‐grown biomass immobilized in a flow‐through filter (‘bioreactor’) the metal‐accumulative bioprocess can be described accurately applying traditional Michaelis—Menten kinetics. The effect of copollutants can be then quantified in order to run the bioreactor in the most efficient way.
Amphoterics in household detergents
Authors: Palicka Jadwiga 
Published: July 2010

AbstractAmphoteric surfactants are widely known for their extreme skin kindness, decreasing the irritation of otherwise irritant surfactants, especially anionics, giving low‐irritant shampoo ingredients.New high quality amphoteric compounds have been developed. These new amphoterics offer exciting possibilities in several new application areas. Considerable development work has been undertaken to investigate new detergent formulations based on these novel amphoterics.Because of the very low concentration of Ampholak 7TX, the formulations give most effective products with low biological load. Data concerning the increasingly important subject of biodegradability and toxicity are shown. This includes both primary and inherent biodegradability and toxicity of metabolites.
Decreasing effluent pollution by the use of soap‐based building kit detergents
Authors: Hack Jürgen 
Published: July 2010

AbstractBy their nature, detergents create a pollution problem for our inshore waters. Solutions have recently been proposed that could contribute to a lower level of contamination in the effluent. Two aspects are discussed.The first is to dispense separately major components of detergents such as bleaches and softeners in such a manner that only the quantities required for a specific wash cycle are used.The second is to select ingredients which are ecologically friendly. For example, as the surfactant, soap is preferred because it is 50 times less toxic to fish than common synthetic materials such as LAS. Soap is completely degraded in the sewage plant, leading to harmless end‐products. ‘Building‐kit system detergents’ can decrease contamination of effluents in a remarkable manner.
Detergency by surfactant/cosurfactant systems
Authors: Krüssmann Helmut , Bercovici Rodica 
Published: July 2010

AbstractThe influence of amphiphilic additives on phase transitions and detergency of nonionic surfactant was examined to solve low temperature detergency problems and to reduce the amount of surfactants necessary to achieve good cleaning results. Optimum detergency correlates to the formation of the lamellar liquid crystalline Lα‐phase and to the intermediate maximum of the phase‐inversion temperature curves. Medium chain alkanols showed as optimum additives which improved low temperature detergency and allowed a reduction of the amount of surfactants necessary. However, fatty acids were not effective, and low degree ethoxylates of fatty alcohols were less effective cosurfactants. The interrelations found could be transferred to solve practical washing problems.
Effect of preparation variables on the activity of Ni‐W/Al2O3 hydrotreating catalysts
Authors: Kural E. , Cant N. W. , Trimm D. L. , Mauchausse C. 
Published: July 2010

AbstractStudies have been carried out on the influence of preparation parameters on the activity of nickel‐tungsten (Ni‐W) catalysts, used to promote the hydrotreatment of model compounds representative of nitrogen, sulphur, oxygen and aromatic containing compounds which typically occur in coal derived liquids. The preparation variables considered for optimisation were the pH of the impregnating solution, the impregnation order, the starting Ni salts, the Ni/Ni + W ratio, the drying conditions and the calcination temperature.It was found that changes in pH, within the range where binding of the starting ions to alumina takes place, is not a significant variable influencing the activity. The use of nickel nitrate as a precursor yields better catalysts. If W is impregnated first it is redistributed during subsequent nickel impregnation, and better catalysts are obtained when Ni is impregnated first. The optimum Ni/Ni + W ratio is between 0.3 and 0.4, based on the total active metals present on the catalyst. The hydrodesulphurisation hydrodeoxygenation and hydrogenation activities decrease with increase in the drying temperature; the reverse is true for hydrodenitrogenation. An optimum activity is obtained when drying at 100°C in a closed oven. The optimum calcination temperature was found to be 500°C.