摘要:

AbstractA systematic study of the removal of the radioactive fission product strontium from aqueous solution by ferric hydroxide flocs has shown that strontium can be removed effectively, in contrast to caesium which is poorly removed (⩽5%) under all conditions examined. Removal of strontium was enhanced by raising pH to a maximum of 10.5, increasing the iron/strontium ratio, or by adding phosphate ion, provided the phosphate/iron mole ratio did not exceed 0.33. In the absence of phosphate the optimum conditions for strontium removal, over the range of iron and strontium concentrations examined, were pH 10 and strontium/iron mole ratio 0.08. Addition of phosphate reduced the pH at which significant removal was obtained to about 8. The mechanism of removal has been identified as an ion‐exchange reaction at the surface of the ferric hydroxide particles; consequently, when considering the process for the removal of stron‐tium‐90 from hard natural or process waters competitive effects from the larger concentrations of calcium and magnesium present in the water would become im

ISSN:0375-9210    

DOI:10.1002/jctb.5020251102

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractQuantitative measurements of increase in lightfastness of direct dyes on cellophane on after‐treatment with different metallic salts, e.g. sulphates of copper, cobalt, nickel, chromium and (ferrous) iron have been carried out. Copper sulphate has been found to be the best of all these salts. About 2% copper sulphate is found to cause considerable increase in the lightfastness. Measurements ofy/xratios of dyed and after‐treated cellophane and also slopes of CF curves have shown that the higher fastness is due to higher aggregation of the dye in the fibre on after‐treatment with copper sulphate. Metal complex formation with dye structures of the typeo‐hydroxy‐o′‐methoxy (oro′‐hydroxy or ethoxy) azo has been found to be more useful for copper after‐treatment than complex formation with dyes with a sal

ISSN:0375-9210    

DOI:10.1002/jctb.5020251103

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effect of pH on the retention of various inorganic fillers has been studied. It is found that the isoelectric point of the filler has no effect on its retention characteristics with our particular sulphate bleached pulp. This is due to the fact that the surface of the filler is modified by either the adsorption of or the flocculation with the fines and colloidal material originating from the fibre surface. This surface modification produces a shift of the apparent isoelectric point of the fillers and in many cases gives rise to heteroflocculation of the fibres and filler particles only when the pH is at more acid values than 4.0.

ISSN:0375-9210    

DOI:10.1002/jctb.5020251104

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effect of aluminium sulphate on the retention of inorganic fillers during the process of papermaking has been investigated. It is found that increased filler retention is achieved mainly in the pH range 4–9, this increase being attributed to the fact that adsorption of charged aluminium species occurs in this pH range giving rise to a decrease in mobility, and hence ζ potential, of the fibres and a reversal of ζ potential of the filler particles. The filter is then retained by heteroflocculation of the fibres with the filler partic

ISSN:0375-9210    

DOI:10.1002/jctb.5020251105

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractSpecific surface areas and pore structure studies were carried out on hardened slag‐cement pastes. Water and nitrogen adsorption isotherms were measured, and the derived parameters were critically compared. Nitrogen areas and total pore volumes were found to be much smaller than water values. For water vapour adsorption, the specific surface areas derived from the adsorption branches are found to be lower than those derived from the resorption isotherms. Some evidence is presented in this paper that the surface area values derived along the adsorption branches are underestimated values, and that the resorption values might be considered to be nearer to the actual areas of the various pastes. Calculations of the hydraulic radii refute the hypothesis that the areas inaccessible to nitrogen are interlayer area

ISSN:0375-9210    

DOI:10.1002/jctb.5020251106

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe total surface areas, total pore volumes, and the distribution of pore surface and pore volume in pores of different sizes were determined on the hardened slag‐cement pastes. Adsorption isotherms of four different adsorbates, namely water, methanol, nitrogen and cyclohexane, were used for surface area and pore structure determinations. The results obtained indicated that water can penetrate into the total pore system, namely both the micropores and the wide pores; whereas methanol can measure wide pores and some of the micropores; moreover, nitrogen and cyclohexane molecules tend to measure only wider groups of pores. The indication gained from this result is that the molecular sieve property plays the most significant role in surface area and pore structure determinations of the hardened cement pastes. The polarity of the molecules seems to be important at low relative vapour pressures, and at high pressures it causes expansion of the paste

ISSN:0375-9210    

DOI:10.1002/jctb.5020251107

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe anodic oxidation of methyl alcohol in the presence of different carboxylic acids was found to give the methyl ester of these acids as the main product. Neither Kolbe products nor formaldehyde were formed. These results are interpreted in terms of a free radical mechanism which involves attack of the carboxylic acids by methoxyl radicals to give the ester.

ISSN:0375-9210    

DOI:10.1002/jctb.5020251108

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstractα‐Amylase production byBacillus subtilisin fermentation was markedly increased by reduction of aeration at the end of the exponential growth phase. The resultant decrease in pH seems to be a limiting factor and without pH control the aeration rate could be reduced from 1 litre/litre/min to 0.2 litre/litre/min for optimum α‐amylase production. Alteration of temperature at the same stage did not result in improved y

ISSN:0375-9210    

DOI:10.1002/jctb.5020251109

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractA new model based on the concept of axial dispersion has been developed for predicting the performance of a hollow fibre enzyme reactor. It is shown that a simple closed form analytical solution for the prediction of the reactor performance results. The model parameters are obtaineda priorifrom the welldefined hydrodynamic conditions. The agreement between the model predictions and the numerical solutions is excellent over a wide range of variables. The comparison of the model predictions with the experimental data shows good agreement. The model can be easily extended to include further complications. The extension to non‐Newtonian substrates is discussed and results for reactor performance under these conditions are give

ISSN:0375-9210    

DOI:10.1002/jctb.5020251110

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

ISSN:0375-9210    

DOI:10.1002/jctb.5020251101

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY