bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of alumina‐deficiency and promotion with platinum and rhenium on the catalytic and diffusional behaviour of mordenite catalysts
Authors: Aboul‐Gheit A. K. , Menoufy M. F. , El‐Morsi A. K. , Abdel‐Hamid S. M.
Published: July 2010

The hydroconversion of n‐heptane on catalysts containing platinum hydrogen‐mordenite, platinum/alumina‐deficient hydrogen mordenite and platinum‐rhenium/alumina‐deficient hydrogen mordenite was carried out in a continuous high‐pressure plug‐flow reactor system and product analysis was carried out by gas chromatography (GC). The effectiveness factor for each catalyst was calculated by iteration on estimated rate constant at various reaction temperatures and the effect of diffusion on the catalytic behaviour was correlated. Catalysts exhibiting larger values of effectiveness factor were found to enhance production of 2,3‐dimethylpentane on account of 3‐methylhexane, whereas the reverse is true with respect to catalysts exhibiting lower values of effectiveness factor.
Selective liquid‐phase hydrogenation of 2,6‐dinitrotoluene with platinum catalysts
Authors: Kut Oemer M. , Yücelen Füsun , Gut Günther
Published: July 2010

The kinetics of the consecutive liquid‐phase hydrogenation of 2,6‐dinitrotoluene to 2‐amino‐6‐nitrotoluene and 2,6‐diaminotoluene was studied in ethanol with 0·5% Pt/Al2O3 as a catalyst using a stirred tank slurry reactor in the temperature and pressure ranges of 313 to 348 K and 0·5 to 10 MPa, respectively. The intrinsic kinetics of the consecutive reaction can be described by a Langmuir‐Hinshelwood type model with non‐competitive adsorption of organic species and hydrogen on the catalyst surface. At 313 K a maximum yield for the intermediate 2‐amino‐6‐nitrotoluene of over 95% can be achieved if heat and mass transfer effects are eliminated.
The thermal degradation of zinc O, O‐dialkyl phosphorodithioates and related compounds in petroleum media. Part II. Kinetic studies of zinc O, O‐diisobutyl phosphorodithioate
Authors: Lake Peter J. , Marshall Roger A. G.
Published: July 2010

The period of usefulness and the mode of action of zinc O, O‐dialkyl phosphorodithioates as multipurpose oil additives are affected by their thermal decomposition. Therefore, solutions of the diisobutyl derivative in pentadecane solution were heated under a nitrogen atmosphere at temperatures from 176 to 228°C in an all‐glass apparatus which enabled periodic removal of samples. The rate of loss of zinc from solution and the rates of formation of the products O, O, S‐triisobutyl phosphorodithioate, isobutanethiol and isobutene were then determined by atomic absorption spectroscopy and gas chromatography. It was found that all the zinc O, O‐diisobutyl phosphorodithioate had reacted in a time varying from 225 to 324 min depending upon its concentration at 215°C, but that O, O, S‐triisobutyl phosphorodithioate and isobutanethiol underwent further reaction. Induction periods varying from 33 to 120 min were observed for loss of zinc from solution and the formation of all the products; these were ascribed to the formation of an elusive intermediate which reacted at a rate comparable to that at which it was formed.
Synthesis of (1RS, 2SR)‐(±)‐2‐amino‐1‐phenyl‐1‐propanol from (R)‐(−)‐1‐hydroxy‐1‐phenyl‐2‐propanone
Authors: Subramanian Prema M. , Chatterjee Sunil K. , Bhatia Mahesh C.
Published: July 2010

Synthesis of (1RS, 2SR)‐(±)‐2‐amino‐1‐phenyl‐1‐propanol (2) by reductive animation of (R)‐(−)‐1‐hydroxy‐1‐phenyl‐2‐propanone (1) using ammonia and Raney nickel as a catalyst was investigated. Compound 1 was produced by fermentation of molasses with a strain of yeast and benzaldehyde was added during the course of fermentation.
Investigation of asphaltenes association by a vapour pressure osmometric method
Authors: Al‐jarrah Mustafa M. F. , Apikian Rita L.
Published: July 2010

The number average molecular weights of asphaltenes have been studied by vapour pressure osmometry using benzene and tetrahydrofuran as solvents at three different temperatures, viz. 37, 45 and 60°C. The degree of association in each solvent at each temperature was determined and is found to be dependent on the nature of solvent and temperature. Results indicated that asphaltenes could be similar to macromolecules structurally.
Two‐step fermentation process for improved xanthan production by Xanthomonas campestris NRRL‐B‐1459
Authors: Vuyst Luc De , Loo Jan Van , Vandamme Erick J.
Published: July 2010

Xanthan formation by Xanthomonas campestris NRRL‐B‐1459 was optimised in a two‐step fermentation cycle. In conventional batch fermentation a cell growth phase was followed by a xanthan production phase. This was replaced by a two‐step process, comprising an initial biomass formation step followed by a xanthan formation step that required a high C/N ratio and higher aeration and agitation levels. The optimal moment of process change was critical and occurred 25–30 h after inoculation; at this time the contents of one biomass production fermenter could then be subdivided to feed 10 xanthan production tanks. Relatively high levels of residual sucrose remained even after the completion of xanthan formation.
Aerosol‐jet produced, magnetic carrageenan‐gel particles: A new affinity chromatography matrix
Authors: Lochmüller Charles H. , Wigman Larry S. , Kitchell Barbara S.
Published: July 2010

A new method was developed to produce uniform spherical magnetic carrageenan‐gel particles suitable for the affinity chromatography purification of large molecules. A sol‐phase of k‐carrageenan is pumped into an air jet to produce an aerosol of gel particles. The particle size can be varied by adjusting the air jet velocity. The gel particles are stable in 0‐5 mol dm−3 KCI to 190 psi. The gel particles were used to immobilize soy trypsin inhibitor for the affinity purification of trypsin. The affinity matrix was tested in a packed‐bed separator, fluidized‐bed separator and a magnetically‐stabilized fluidized‐bed separator with similar column capacity for each separator.
Desorption of copper from a copper‐chitosan complex
Authors: McKay Gordon , Blair Henry S. , Grant Stuart
Published: July 2010

Chitoson, a high molecular weight polymer, has the ability to sorb metals and form chitosan‐metal complexes. A complex using copper has been prepared and its desorption characteristics have been studied. The slow release of copper is of potential use in anti‐fouling paints and therefore the desorption of copper has been studied under various environmental conditions. Desorption rates were high in distilled water but low in sea water, and after further comparative tests with commercial marine paints, it was concluded that copper‐chitosan complexes are not as effective as the cuprous oxide anti‐fouling agent currently used in marine paint formulations.
Activated sludge treatment of wine‐distillery wastewaters
Authors: Sales D. , Valcárcel M. J. , Pérez L. , Martinez‐Ossa E.
Published: July 2010

Wine alcohol distilleries produce eight volumes of high‐strength waste from every volume of ethanol. This waste has an acidic character, an average COD of 21 g dm−‐3 and an average BOD of 13 g dm−‐3.

This paper examines aerobic treatment as an alternative to anaerobic digestion for the reduction of waste strength. The process from the start‐up of the digestors until attainment of steady‐state conditions, and the optimization of the process to achieve an adequate purifying performance were studied.

Once optimum operation conditions had been attained (at 8 days retention time), COD and BOD removals of 78% and 88%, respectively, were achieved.

A Substrate Utilization Model predicted accurately the performance of the purifying process, except at retention times of less than 3 days, where the system works in unsteady conditions.
The conversion of polysaccharides to hydrogen gas. Part I: The palladium catalysed decomposition of formic acid/sodium formate solutions
Authors: Hill S. P. , Winterbottom J. M.
Published: July 2010

The palladium catalysed decomposition, to H2+CO2, of solutions containing formic acid and sodium formate, in various proportions, has been studied in a stirred reactor in the temperature range 60–90°C. The production of hydrogen gas was at its optimum in the pH range 3.8–6.5 and the order of reaction varied with the solution composition from 0.33 (100 mol % formic acid) to 1.07 (100 mol% formate ion). Energies of activation lay in the range 20±9.5 kJ mol−1–41.8±7 kJ mol−1, the larger values occurring at the ends of the composition range. Electrode potential measurements were also performed and these were helpful in explaining the (i) cessation of hydrogen production at low HCOO− ion concentrations before completion of reaction and (ii) the possible nature of catalyst poisons. In no case was the theoretical quantity of hydrogen obtained, although yields >90% can be achieved.

It is proposed that reaction proceeds via a surface formate intermediate with different rate determining steps operating at high and low HCOO− ion concentrations. A number of reversible catalyst poisons are discussed including carbon monoxide and methyl formate, which appear to be the most likely.
The conversion of polysaccharides to hydrogen gas. Part III
Authors: Hill S. P. , Winterbottom J. M.
Published: July 2010

Cellulose has been subjected to alkaline degradation at temperatures between 100 and 200°C. The resulting products, after filtration and treatment with activated charcoal, yielded solutions containing formic acid, with conversions up to 7–8% by weight with respect to cellulose. The solutions were then reached in the presence of a palladium catalyst at 80°C at pH 4 and the hydrogen gas evolved was measured. A limited number of experiments were performed with cellulose containing waste materials and these were also converted to formic acid and hence to hydrogen gas. Additional studies with glyceraldehyde revealed that the latter is a possible intermediate in the formation of formic acid from cellulose and a speculative mechanism is proposed indicating how formate ions and formic acid may be generated from cellulose.
Removal of tetramethyl thiuram disulphide from aqueous solution by chemically modified bentonite
Authors: Pradas E. González , Sánchez M. Villafranca , Garcia A. Valverde , Viciana M. Socias , Bueno F. del Rey , Rodríguez A. García
Published: July 2010

The adsorption of tetramethyl thiuram disulphide (thiram) on bentonite, acid‐treated with H2SO4 (over a concentration range between 0.25 mol dm−3 and 2.00 mol dm−3), and heat‐treated at 110°C or at 200°C, from aqueous solution at 20°C has been studied. In general, the adsorption isotherms may be classified as L type of the Giles classification which suggests that there is no strong competition from the solvent for adsorption sites.

The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (K) of the samples; K values range from 230 μg g−1 for the sample acid‐treated with 0.25 mol dm−3 H2SO4 and heat‐treated at 110°C up to 2010 μg g−1 for the sample acid‐treated with 1.00 mol dm−3 H2SO4 and heat‐treated at 200°C. In all cases the K values for samples heat‐treated at 200°C were higher than those heat‐treated at 110°C. The removal efficiency (R) has also been calculated for all the samples; R values range from 42.8% up to 89.9%.
The adsorption of causticized cassava starch on coal‐washery effluent solids in relation to flocculation
Authors: Eligwe Christian A. , Okorie Boniface A. , Chukwudorue Cornelius O. , Orumwense Friday F. O.
Published: July 2010

The adsorption of causticized cassava starch on coal‐washery effluent (‘blackwater’) solids was investigated with a view to establishing how such factors as pH, starch concentration, aging and presence of complexing agent affect the extent and nature of the adsorption process. Also, the effect of starch concentration on the flocculation behavior of the blackwater slurry was studied.

The adsorption process does not exhibit a Langmuir type behavior but produces a characteristic S‐shaped curve and is essentially unaffected by pH except in the highly alkaline range (pH > 10.0), where a marked decrease in adsorption density occurs. Based on the data generated in this study and the results of studies on the electrokinetic properties of starch and blackwater solids reported in the literature, it is postulated that the adsorption mechanism is predominantly controlled by hydrogen bonding aided by hydrophobic interactions.

The flocculation studies established that high reagent (starch) concentration leads to low settling rates and the reasons for this phenomenon are discussed.
Infrared studies of the interaction between dihydroxybenzenes and their ethers with the surfaces of γ‐Al2O3, MoS2 and a CoMo/γ‐Al2O3 catalyst
Authors: Bredenberg Johan B‐Son , Sarbak Zenon
Published: July 2010

Hydroquinone and resorcinol are strongly chemisorbed on alumina by their oxygen atoms and form a flat adsorption mode. Catechol may be chemisorbed, but very weakly in a flat mode on molybdenum sulfide. On alumina it is adsorbed in an inclined mode through the oxygen atoms. For the CoMo/Al2O3 catalyst an inclined mode is preferred at lower temperatures although a flat mode may be competitive at higher temperatures.

The monomethyl ethers are chemisorbed through the phenyl oxygen. The mode of adsorption for the ring is probably flat for the meta and para compounds and inclined for the ortho compound. The ortho compound shows demethoxylation at 250°C followed with the para compound 300°C. Steric constraints evidently hinder to a part adsorption of the ortho compound on the catalyst surface.

The dimethyl ethers are chemisorbed in a flat mode on the supports. The adsorbed compounds react by demethylation on the alumina type supports with the para compound reacting at the lowest temperature, around 200°C, and the meta compound only at the highest temperature used, 300°C. The ortho compound has an intermediate reactivity.

Adsorption of all ethers on molybdenum sulfide is very weak.
Synthesis and antibacterial activity of some quinazolin containing oxadiazolin‐5‐thione moieties
Authors: Ahmed Abd El‐Hamid N. , Abd‐Alla Mohamed A. , El‐Zohry Maher F.
Published: July 2010

Several new quinazolin‐4‐one containing oxadiazolin‐5‐thione moieties were synthesized and evaluated for their antibacterial activity. Esterification of 2‐substituted phenyl‐3‐carboxyalkyl‐methyl‐3,4‐dihydroquinazolin‐4‐ones (I) with absolute ethyl alcohol in the presence of sulfuric acid afforded the corresponding esters (II). Hydrazinolysis of (II) with hydrazine hydrate in ethanol gave the acid hydrazides (III). Refluxing (III) with equimolar amounts of potassium hydroxide and slight excess of carbon disulfide afforded the corresponding oxadiazolin‐5‐thione derivatives (IV). The thiones undergo Mannich reaction using a formaldehyde/secondary amines mixture whereby the 4‐substituted amino‐methyl derivatives (V) were obtained. Microanalysis, IR, NMR spectra were used to elucidate the structures of the newly synthesized compounds. All the designed compounds were tested for their antibacterial activity. The morpholino derivatives showed an encouraging antibacterial activity.
Biological regeneration of nitrate‐loaded anion‐exchange resins by denitrifying bacteria
Authors: van der Hoek Jan Peter , Griffioen Anton B. , Klapwijk Abraham
Published: July 2010

For regeneration of nitrate‐loaded anion‐exchange resins large quantities of salt are needed while the voluminous concentrated brine, produced during regeneration, is difficult to dispose of. These problems can be avoided by using denitrifying bacteria in the regeneration process of the resins. Experiments showed that resins could be regenerated by a denitrifying sludge suspension containing 7 g dm−3 NaCl. However, the process proceeded slowly compared with conventional regeneration. After 24 h of regeneration the resin still contained 18% nitrate, relative to the total capacity. The breakthrough curve of a biologically regenerated ion‐exchange resin was characterized by nitrate leakage whereas nitrate breakthrough started sooner, resulting in a nitrate capacity which was only 72% as compared with a conventionally regenerated ion‐exchange column.
The development of a new food
Authors: Edelman J.
Published: July 2010

Mycoprotein (trade name Quorn) is a new food developed via a fermentation process by Ranks Hovis McDougall PLC (RHM) after some 20 years of R&D. RHM is now in partnership with ICI for its further development. Mycoprotein has been fully cleared toxicologically and nutritionally and a ‘Certificate of Free Sale’ was given by the UK Government in 1985; it appears that this is the first ever formal Government clearance of a new food. Much of the testing procedure required for food additives or drugs is unsuitable, even impossible, for food, and both the company and the Ministry had a learning curve to follow during the development of an appropriate safety‐testing programme.

Perception of safety by consumers is also vital to commercial success. Some hundreds of thousands of people have now bought and eaten Quorn products from supermarkets and in restaurants. So far there has not been a single reported case of imagined hazard relating to this totally novel foodstuff.
New medicines from industry
Authors: Finkle Bryan
Published: July 2010

There is a considerable history of natural and biosynthetic biologics used as drugs, and their development, evaluation, and regulation serves as a useful guide to the risks and safety of recombinant drugs in the context of medicine. These agents are human gene products or their analogs, and like traditional pharmaceuticals, have the potential for toxicity. They are purer and better characterized, have a known spectrum of bioactivity, but they are not to be assumed safe because they are components of natural self. The reality is they have their own risk‐to‐benefit ratios. They are made by very complex, large‐scale biochemical engineering capable of producing very pure product, but with the possibility of greater variation than occurs in small organic molecules synthesized by medicinal chemistry methods.

Many toxicology position papers have been published, but no firm guidelines have yet been established by Government Regulatory Agencies. At present, it is the combined judgment of the toxicologist, pharmacologist, and clinician that determines the rational progress of a protein (drug) from the gene to patient. This long, difficult journey in which toxicology plays such an important part can be illustrated by the development of human growth hormone and tumor necrosis factor, the former a recombinant product to replace a natural hormone extracted from human tissue, and the latter a previously unavailable cytokine with poorly defined biological effects, for the treatment of selected cancers. The history, hard work and hope for these and other protein drugs presents a clear story of how benefit‐to‐risk can be studied and understood.
EEC policy for regulation of biotechnology products
Authors: Scheibner Eckardt , Bass Rolf
Published: July 2010

The most important regulative EEC decisions concerning biotechnology products are the creation of the ‘concertation procedure’ for EEC‐wide registration (Council Directive 87/22/EEC), and the authorization of the CPMP to adapt test requirements according to technical progress (Council Directive 87/19/EEC).

Test requirements (Notes to Applicants) on pharmaceutical quality (MAB's, rDNA‐derived products‐cell substrates in preparation) and on preclinical safety testing have been published.

The pre‐clinical notes to applicants seek to overcome the current case‐by‐case procedure, which is unsatisfactory both for industry and regulatory authorities, by structuring the heterogeneous variety of products into product related test schemes, thus giving better orientation for applicants for marketing authorizations.

There is a horizontal structure (4 product groups: hormones, cytokines, regulatory peptides/blood products, MAB/immunizing agents) and a vertical structure (depending on the biochemical deviation from the naturally occurring product). Allocation of a given product horizontally will determine the strategy, and vertically the depth of testing. Additional remarks concerning methods allow for deviations from test schemes developed for chemical products, in relation to species‐restricted lack of response and immunotolerance. The concept of deriving test schemes from product characteristics has proved successful, but is subject to further improvement (e.g. including as additional structuring elements the generic familiarity, and use‐related criteria spanning from substitution to pharmacodynamic effectuation with supraphysiological dose regimes), and making better use of the present knowledge of sera, vaccines and other biologicals (and their regulation), thus facilitating easier planning and performance of relevant pre‐clinical safety testing.
Hydration kinetics of calcium sulphate hemihydrate: A comparison of models
Authors: Beretka Julius , Van Der Touw John W.
Published: July 2010

The kinetic equations derived by Schiller, Ridge, Taplin and, Combe, Smith and Braden, for the hydration of calcium sulphate hemihydrate, based on crystallisation theory, are compared in order to establish which model describes the reaction best. Schiller's, Ridge's and Combe's models show considerable departures from the data, whereas Taplin's model fits the data extremely well. A simple Product model also fits well if the rate is assumed to be temperature dependent.
Adsorption of gold‐thiourea complex on activated carbon
Authors: Soto Ana M. , Machuca Ruth A.
Published: July 2010

The adsorption kinetics of the gold‐thiourea complex on activated charcoal was studied. Experimental runs were made in a batch reactor at constant temperatures and stirred by a magnetic system. Samples were taken at different periods of time and were analyzed for gold in a Perkin‐Elmer Model 360 atomic absorption spectrophotometer. The samples were prepared with synthetic solution of gold with thiourea, sulfuric acid, and iron sulfate with concentrations similar to the ones in the leaching process. The gold adsorbed on activated charcoal was 99% at 20°C. The adsorption behavior was characterized by the Freundlich model at different temperatures (20°C, 35°C and 50°C).
Kinetic studies of adsorption of bitter principles and titratable acid from grapefruit juice
Authors: Johnson Robert L. , Chandler Bruce V.
Published: July 2010

Measurement of the initial rates of removal of limonin and naringin from grapefruit juices by several polystyrene and polyacrylic adsorbents has allowed these adsorbents, in the forms as supplied, to be ranked in their order of kinetic effectiveness for removal of the two bitter principles. Partition coefficients of bitter principles between juice and polystyrene adsorbent resins show that the capacity of such resins for naringin increases with specific surface area, but the capacity for limonin appears to increase with specific pore volume. With respect to titratable acid, the two weak base resins, Amberlite IRA‐93 and Duolite A378, were equally effective both kinetically and in their capacity for titratable acid; both adsorbed somewhat less than 1 mol of titratable acid from grapefruit juice per equivaient of weak base resin.
7H‐pyrazolo[5, 1‐a]benz[d,e]isoquinolin‐7‐ones: Yellow to orange dyes for synthetic‐polymer fibres
Authors: Peters A. T. , Saidi K.
Published: July 2010

N‐Amino‐1,8‐naphthalimides were condensed with ketones containing an α‐methylene group and the resulting hydrazones ring closed to afford derivatives of 7H‐pyrazolo(5,1‐a)benz(d,e)isoquinolin‐7‐one. These compounds coloured synthetic‐polymer fibres, particularly polyester, in brilliant fluorescent greenish‐yellow to orange hues of good fastness to light and sublimation. The colour of the dyes is discussed with respect to substituent effects in the pyrazole and naphthalene rings, and in relation to analogous 7H‐benzimidazo(2,1‐a)benz(d,e)isoquinolin‐7‐ones.
Axial dispersion and oxygen transfer in the transition from bubble column to airlift‐loop reactor
Authors: Verlaan Paul , Vos Jan‐Chris , Van T Riet Klaas
Published: July 2010

Axial dispersion and oxygen transfer were investigated in a bubble column (BC) with a circulation loop. A butterfly valve, situated at the bottom of the loop enabled the above‐mentioned physical characteristics in the transition regime between typical airlift‐loop‐reactor (ALR) flow and BC flow to be studied. The Bodenstein number was found to decrease when the liquid velocity was reduced, implicating a less established plug‐flow character. The number of circulations required to achieve complete mixing in the reactor was diminished if the liquid circulation was hampered and appeared to be proportional to the Bodenstein number. The volumetric oxygen‐transfer coefficient was estimated by an ideally stirred‐tank‐reactor (STR) model and a plug‐flow model. The STR model yielded reliable results for the whole range of operation while the plug‐flow model only appeared to be appropriate for the ALR operation mode. The kLa values obtained were included in a generalized correlation for the transition flow regime and were found to increase gradually when the circulation velocity was reduced.
The oxidation of peat and its thermal accompaniment
Authors: Jones J. C.
Published: July 2010

The oxidation of peat is monitored thermally and the ignition phenomenology investigated. Ignition theory is applied to the results and are an extrapolation made to induce safe stockpiling quantities.
Sodium bicarbonate effects on the anaerobic digestion of refuse
Authors: Kasali George B. , Senior Eric , Watson‐Craik Irene A.
Published: July 2010

Laboratory column and bottle cultures were used to examine the efficacy of NaHCO3 additions (1%, 2.5% and 5% w/v) to promote the solid‐state refuse fermentation. Buffering capacity increase, by addition of 2.5% NaHCO3, equivalent to 84 mg NaHCO3 g dry weight refuse‐1, promoted both acidogenesis and methanogenesis, with the latter accelerating by a factor of six, compared with glass‐distilled water controls. Increased addition, with 5% NaHCO3, however, mediated partial suppression of methanogenesis and acidogenesis with cation toxicity the most likely cause. Promotion of the refuse fermentation by NaHCO3 addition, therefore, necessitates careful control of the concentration applied.
Experimental studies on supercritical fluid separation processes
Authors: Li S. F. Y.
Published: July 2010

This review considers a selection of the experimental studies performed to develop supercritical fluid separation techniques and the potential applications of these techniques in extraction and chromatography.
The inhibitive action of dimethyltin dichloride towards the corrosion of aluminium in hydrochloric acid and sodium hydroxide solutions
Authors: Mourad M. Y. , Seliman S. A. , Ibrahim E. H.
Published: July 2010

The dissolution of aluminium in hydrochloric acid and sodium hydroxide solutions in the presence of dimethyltin dichloride as corrosion inhibitor has been studied using hydrogen evolution and thermometric methods. The two methods gave consistent results. The higher inhibition efficiency of this compound in acidic than in alkaline media may be due to the less negative potential of aluminium in hydrochloric acid solution, favouring adsorption of the additive. The adsorption of this compound was found to obey Frumkin adsorption isotherm.
Effects of natural oils and surfactants on cellulase production and activity
Authors: Suha Sukan S. , Güray Ayse , Vardar‐Sukan Fazilet
Published: July 2010

Emulsification of natural oils by a surfactant increases their efficiency as chemical antifoams. The presence of low concentrations of fatty acids or other surfactants have been reported to inhibit or stimulate microbial growth and/or product formation.

The effects of different natural oils, Tween 80 and saponin on growth and cellulase production by T. reesei and S. pulverulentum have been investigated. It was found that in general, emulsification leads to higher cellulase activities in both cultures, though there are variations in enzyme levels depending on the presence or absence of Tween 80 and of different oils in growth media as well as the substrates used for cellulase assay.
Liquid circulation time in concentric‐tube airlift columns with non‐newtonian fermentation broths
Authors: Kawase Yoshinori , Moo‐Young Murray
Published: July 2010

Liquid circulation times were measured in a 40‐dm3 concentric‐tube airlift fermenter with simulated media over a wide range of rheological properties. Circulation times decreased with increasing shear‐thinning, and the influence of draft‐tube geometry on circulation time was found to depend on the shear‐thinning of the media. A semi‐theoretical correlation for both Newtonian and non‐Newtonian fermentation media was developed.
Stability of 1,4‐dioxane, tetrahydrofuran and ethanol under hydrogenation conditions over various catalysts
Authors: Schumann Werner K. , Kut Oemer M. , Baiker Alfons , Gut Late Günther
Published: July 2010

The stability of 1,4‐dioxane, tetrahydrofuran and ethanol under hydrogenation conditions was investigated over six different catalysts. The reactions occurring in a fixed‐bed reactor in the temperature range between 150 and 350°C were characterized by chemical analysis of the reactor effluent stream and by measurement of the temperature—time profiles within the catalyst bed. On nickel catalysts, dioxane showed a runaway reaction with ignition at about 190°C (Mozingo, Org. Synth., 21 (1941)). (Ignition is referred to as the temperature where the initiation of the runaway reaction is observed.) Similar reactions were observed with tetrahydrofuran and ethanol over nickel, and with dioxane and ethanol over rhodium and cobalt. The predominant reaction was hydrogenolysis and the main products formed were methane and water. Under some conditions small amounts of ethane, propane, carbon monoxide and carbon dioxide were also observed. Dioxane did not show methane formation on platinum, palladium and copper chromite catalysts.
Removal of aromatic amines from aqueous solution by activated sepiolite
Authors: González‐Pradas E. , Valverde‐garcía A. , Villafranca‐sánchez M.
Published: July 2010

The 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

A 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 + H2O

Spectrophotometric measurements of the production rate of ClO2 have confirmed that the intermediary species in the proposed equilibrium

H+(mH2O) → H+(m‐n)H2O + nH2O

Is 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

This 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

Colloidal 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

Lipase 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

The 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

A 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

Urease 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

The 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

The 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

The 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

A 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

A 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

Silica 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

Macroporous 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

Based 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.