ISSN:0268-2575    

DOI:10.1002/jctb.280500402

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractLignin derivatives are major components of wastewater streams generated in the chemical processing of wood. The objective of this study was to evaluate the inhibitory effect of various lignins isolated from forest industry wastewaters, and selected lignin model compounds, on methanogenic bacteria. The methanogenic inhibition was determined at 30°C in standard toxicity assays, utilizing anaerobic granular sludge as inoculum. The wastewater lignins differed considerably in their inhibitory activity. Some lignin samples were nontoxic, whereas others caused 50% inhibition at concentrations ranging from 3320 to 5950 mg COD dm−3. Experiments with ultrafiltered lignins revealed that the toxicity of the inhibitory lignin samples originated from the low molecular weight fraction. In additional studies with low molecular weight lignin model compounds, it was observed that the inhibitory activity of these compounds was related to the functional groups on the aromatic ring. Compounds with aldehyde groups or apolar substituents were highly toxic, whereas those with carboxylic groups only caused significant inhibition at high concentrations. These results indicate that low molecular weight lignin derivatives in forest industry wastewaters are potential inhibitors of anaerobic treatment syste

ISSN:0268-2575    

DOI:10.1002/jctb.280500403

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractAutomated assay techniques are described for on‐line measurements of fumarase activity and total protein concentration, including in‐line sample dilution and sample multiplexing during continuous aqueous phase extraction. Fumarase was determined by following the conversion of L‐malate to fumurate at a wavelength of 250 nm, while the protein assay was based on the Biuret reaction. Actual assay times of 2 and 4 min were achieved for the fumarase and protein measurements, respectively, with an effective measurement cycle time of 2 min. Standard deviations of c. 3.2 and 2% of the measured values were calculated for the enzyme and protein values, respectively. The assay system was coupled to a computer to allow on‐line data visualization and

ISSN:0268-2575    

DOI:10.1002/jctb.280500404

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper introduces electrochemical ion exchange (EIX) as a technique for the removal of ionic species from aqueous waste streams. The basic mechanistic principles behind EIX are presented and experimental procedures described. Typical experimental results for a number of applications are given. A comparison is made between EIX and electrodialysis and electrodialysis combined with conventional exchange.

ISSN:0268-2575    

DOI:10.1002/jctb.280500405

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractGaseous mixtures of oxygen and toluene have been passed through a 50 Hz electrical discharge reactor at low pressure. Oxidation reactions produced benzaldehyde, benzene, benzyl alcohol and cresols. Reaction rates varied with partial pressure of reactants, electrical field strength and temperature, although, in the absence of an electrical discharge the thermal reaction was negligible. A fit to experimental data was obtained with an equation which included reactant concentrations, temperature and applied voltage.

ISSN:0268-2575    

DOI:10.1002/jctb.280500406

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

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 5

ISSN:0268-2575    

DOI:10.1002/jctb.280500407

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe kinetics of biosorption and desorption of lindane, diazinon and 2‐chlorobiphenyl by inactive activated sludge and Rhizopus arrhizus biomass was studied. The effects of solution initial concentration, temperature and type of biomass on the observed biosorption and desorption rates were also examined. The results of the present work show that the biosorption rates are reasonably rapid, with equilibrium attained within 4 h by activated sludge and 1 h by R. arrhizus. The observed biosorption kinetics consist of a rapid initial stage followed by a slower second stage. The observed rate of organic pollutants biosorption by activated sludge during the first stage can be described by second order kinetics. The biosorption of lindane by both biomass types is reversible and the desorption process is rapid and could be described by zero order kinetics when activated sludge is used as adsorbent. The type of biomass can have a significant effect on the observed biosorption and desorption rate

ISSN:0268-2575    

DOI:10.1002/jctb.280500408

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractAn efficient procedure for the isolation of reduced ‐(L‐α‐aminoadipyl)‐L‐cysteinyl‐D‐valine (ACV) from culture supernatants of β‐lactam antibiotic‐producing microorganisms is described. The method utilises covalent chromatography to isolate thiols from culture broths that have been deproteinised and undergone borohydride reduction. 2‐Pyridyl disulphide activated thiopropyl Sepharose was employed batchwise to isolate the thiols present in such broths from cultures of the known ACV excreter Cephalosporium acremonium N2 and the penicillin producer Penicillium chrysogenum P2. ACV was separated from these mixtures of thiols by gel permeation chromatograhy. Reversed‐phase HPLC analysis showed the ACV to be of a high purity unless isolated from a highly

ISSN:0268-2575    

DOI:10.1002/jctb.280500409

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractInvestigation of the hydrocarbon rate formation behaviour during the Fischer—Tropsch synthesis under periodic concentration forcing reveals the existence of resonance peaks for certain choices of cycle parameters. These peaks appeared under symmetrical cycling with a mean feed composition of 17–5% CO (balance H2) at both low (less than 0‐001 cps) and high (greater than 0‐01 cps) frequencies for the alkanes. Although methane was more strongly stimulated under periodic operation than other hydrocarbons, the rate enhancement observed for C2to C6products signalled the potential for ‘tuning’ selectivity in this mode o

ISSN:0268-2575    

DOI:10.1002/jctb.280500410

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractHydrolysis and esterification in a triolein/oleic acid system were compared with Candida cylindracea lipase attached to celite, hydrophobic zeolite and hydrophilic zeolite. The hydrophilic zeolite blocked the hydrolysis but mediated the esterification. Esterification with celite or hydrophobic zeolite as carrier was poor.

ISSN:0268-2575    

DOI:10.1002/jctb.280500411

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY