摘要:

AbstractThis paper assesses the potential of natural zeolite utilization as a low‐cost ion‐exchange and sorbent material in pollution control and recovery of metals. The improvement of the purity of natural zeolites coupled with their chemical modification capabilities in order to provide specific properties may provide a cost‐effective alternative for the treatment of heavy metal contaminated soil and water. The application of natural zeolites in industrial pollution control is becoming important and the level of technical effort is increasingly expanding. The extent of application is unlikely to be related solely to their low cost, but also to improved properties and performance characteristics, which will advance the practical implementation of natural zeolites' techn

ISSN:0268-2575    

DOI:10.1002/jctb.280590202

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractSubstrate and intermediate metabolite degradation were monitored in a three‐stage anaerobic digester fed cellobiose as sole carbon source. The digester vessels were of different sizes and the resultant different dilution rates enabled separation of the trophic groups. Biofilms were allowed to develop on microscope slides suspended at different depths within each vessel and these were examined using phase contrast and fluorescence microscopy. Cell quantification was performed on these and planktonic samples using image analysis. All cellobiose degradation and sulphate reduction and most of the acidogenesis was performed in the first vessel, by an activated sludge‐like population (attached or in flocs). Eighty percent of the methanogenesis and some acetogenesis occurred in the second vessel where populations of attached fluorescent rods andMethanosarcina‐like cells were abundant. The low population levels in the third vessel were responsible for 8% of the total methanoge

ISSN:0268-2575    

DOI:10.1002/jctb.280590203

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractA silica‐based adsorbent for affinity chromatography of serine protease was prepared by bondingp‐aminobenzamidine (pABZ) to aminopropyl silica. Silanization of silica with both γ‐aminopropyltrimethoxysilane and γ‐amino‐propyltriethoxysilane under anhydrous conditions led to a monolayer density of primary amino groups. The aminopropyl silica was converted to primary hydroxylcontaining silica via diazotization, and consequently activated withp‐nitrophenyl chloroformate and immobilized with ligand pABZ. The resultant silica–pABZ has a ligand density of 13.8 μmol g−1. Pyridine was indicated by the data to increase the reactivity of the chloroformate toward the hydroxyl group more efficiently than 4‐dimethylaminopyridine. Two stages of adsorption were found in batch adsorption of trypsin with an equilibrium adsorption isotherm of the Langmuir type. When the chromatographic column packed with this silica–pABZ was operated under a higher flow rate (2·33 cm3min−1) and with 3 g dm−3of crude urokinase as the influence, the yield was 55%. Both the flow rate and the concentration of the crude protein were shown, by measuring the dynamic binding capacity from chromatographic experiments, to be the factors which influenced the

ISSN:0268-2575    

DOI:10.1002/jctb.280590204

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractA series of chromium‐promoted copper catalysts with various Cr to Cu molar ratios were prepared with the co‐precipitation method. The promotional effects of chromium on copper catalysts were examined by X‐ray powder diffraction (XRD), nitrous oxide decomposition, and the dehydrogenation reaction of ethanol. The dehydrogenation reaction was carried out in a continuous‐flow microreactor between 523 and 583 K under atmospheric pressure. The results indicated that the promotional effect was dependent on the Cr/Cu molar ratio, and the predominant decay of catalysts in this study was caused by sintering. The catalyst with the Cr/Cu molar ratio of 4/40 has the highest activity and stability. The surrounded well‐dispersed chromia strongly influenced the catalytic properties of copper metal. It also showed that the over‐promotation of a catalyst has a disastrous effect on the total make of product. The ethanol dehydrogenation reaction follows a first‐order reaction, and the kinetics for deactivation can be described by a second‐o

ISSN:0268-2575    

DOI:10.1002/jctb.280590205

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractEsterification of lactic acid with butanol catalysed by cation‐exchange resin was carried out in a batch reactor in dioxane and toluene. The reaction rate was found to be first order with respect to catalyst and acid concentrations. The inhibiting effect of water and butanol has been evaluated. The rate data were correlated with a kinetic model based on inhibition by water and butano

ISSN:0268-2575    

DOI:10.1002/jctb.280590206

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe use of phosphate as the limiting nutrient for scleroglucan formation bySclerotium glucanicumled to stimulation of glucan formation. Final exopolysaccharide concentrations achieved in phosphate‐limited (18·9 kg m−3) cultures were much higher than in the usual nitrogen‐limited fermentations (11·4 kg m−3). The mechanism by which phosphate limitation engendered glucan formation may be largely non‐specific, involving a generalised diversion of the carbon source away from biomass formation and towards glucan synthesis. The effect of stirrer speed was examined in a fermenter fitted with a 6‐bladed Rushton turbine impeller of 0·5 vessel diameter. It was noted that biomass and scleroglucan formation showed different optima. This may have been due to the markedly different oxygen requirements of the

ISSN:0268-2575    

DOI:10.1002/jctb.280590207

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractHydrolysis of 1,4‐dihydroxy‐2,3‐dicyanoanthraquinone gives 1,4‐dihydroxyanthraquinone‐2,3‐dicarboxylic anhydride, reaction of which with alkylamines and arylamines gives either the 2‐carboxamide or 2,3‐dicarboximide derivatives. These compounds colour polyester in brownish‐orange hues having good light fastness. The colour of the dyes is discussed in relation to other 2‐substituted derivatives of 1,4‐d

ISSN:0268-2575    

DOI:10.1002/jctb.280590208

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe evolution of alcohol fermentation in ten successive batches was analysed using three distinct media, all containing commercial sucrose as substrate. The first medium contained mineral salts and yeast extract, the second contained only soy flour as the nutrient source and the third only corn flour. The alcohol contents and yeast viabilities were determined during ten successive batches with each medium. There was no significant differentiation in ethanol yield during the total period of tests (60 h with each medium). However, the medium containing soy flour showed the best evolution of yeast viability. The best specific productivity of ethanol was obtained with the medium containing corn flour, which justifies the traditional and empirical use of the component in the fermentation step by the small producers of sugar cane spirits in Brazil.

ISSN:0268-2575    

DOI:10.1002/jctb.280590209

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe vapour‐phase dehydration and dehydrogenation of isopropyl alcohol (IPA) have been carried out over pure MoO3and Fe2O3, produced by calcination of ammonium heptamolybdate and of iron (III) nitrate respectively, as well as MoO3mixed with 0·5 and 50 mol% Fe2O3, prepared from the same materials. All catalysts were calcined in air, in the temperature range 200–600°C for 5 h, and were characterized by thermal analysis (TG, DTA), XRD, IR andSBET. Surface areas decreased with increasing calcination temperature, and the catalytic activity of the pure oxides MoO3and Fe2O3, as well as of MoO3–0.5 mol % Fe2O3, increased with theirSBET. The activity of MoO3–50 mol % Fe2O3, which was independent of itsSBET, could be attributed to the increased intensity of terminal Mo—O bonds as shown by IR spectra. The activation energies for the decomposition of IPA over catalysts calcined at 250 and 500°C a

ISSN:0268-2575    

DOI:10.1002/jctb.280590210

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractFor the immobilization ofBacillus licheniformisα‐amylase to porous glass beads, the performances of three possible linking agents, glutaric dialdehyde, benzoquinone andS‐trichlorotriazine were assessed in respect of the protein yield, the enzymic activity and the thermostability of the immobilized enzyme. These three properties are to be evaluated in view of the possible use of the enzyme preparations as time–temperature‐integrators (TTIs) for assessing the severity of heat pasteurization or sterilization processes of food or pharmaceuticals. All three linkers improved the enzymes's resistance to irreversible heat inactivation to a similar extent and in each case biphasic inactivation kinetics were observed, whereas the dissolvedB. licheniformisα‐amylase showed a simple first order decay. The immobilization yield, measured as protein per carrier weight, did not differ markedly for the three linkers, although the enzymic activity of the glutaric dialdehyde‐linked enzyme was lower than that of the benzoquinone‐ andS‐trichlorotriazine‐

ISSN:0268-2575    

DOI:10.1002/jctb.280590211

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY