摘要:

AbstractFour torches of different design were constructed and evaluated. Injection of silicon tetrachloride vapour directly into the plasma resulted in instability and rapid extinction of the latter when the reagent flow rate exceeded 4 g/min. In the preferred design, the reagent was injected into the plasma tail flame through radial ports. With this system silicon tetrachloride was completely oxidised at a flow rate of at least 67 g/min.

ISSN:0021-8871    

DOI:10.1002/jctb.5010190201

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractCrystallinity is, ideally, the fraction or percentage of perfectly crystalline matter in a material which is partially crystalline. Because transition structures can exist, however, measured crystallinity will depend largely on the method used.The differences in the infra‐red spectra of the same substance in the crystalline and amorphous states can be exploited for quantitative measurement. Methods based on bands that appear only in the ‘amorphous spectrum’, such as the method described here, have definite advantages over those based on ‘crystalline bands’. While testing the method it was found that the rate of cooling has only a small effect on the crystallinity of Fischer–Tropsch waxes. Surface effects play an important role, however. Thin slices cut from the central parts of thick discs were used for measurements. Before they were sampled, certain waxes had to be homogenised by melting. Results were reproducible within ± 1·5 to ±6 per cent for different waxes. Because of the dependence of crystallinity upon the method used, however, the value of this method lies in its use in compa

ISSN:0021-8871    

DOI:10.1002/jctb.5010190202

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe selectivity of the formation of glycerol from saccharides and hexitols by catalytic hydrogenolysis is determined by a number of reaction variables. Evaluation of the results of variations in operating conditions was effected by the use of the parameters: cleavage selectivity, hydrogenation selectivity, and cleavage percentage. There were strong indications that the cleavage selectivity was controlled by the molecular structure of the saccharide used, being considerably higher for a fructofuranose structure than for a pyranose one.The main reactions were cracking, isomerisation, acid formation, hydrogenation, dehydrogenation, and dehydration. Of these, cracking and hydrogenation reactions had the greatest influence on the glycerol yield. The choice of the catalyst is difficult, because of the conflicting demands for maximum hydrogenation selectivity and maximum cleavage percentage.

ISSN:0021-8871    

DOI:10.1002/jctb.5010190203

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractMethods of production and application of titanium dioxides and basic titanic salts have been summarised and the appropriate physical properties of the products have been studied. Variations in phase composition, surface area and crystallite and aggregate sizes have been correlated with experimental conditions.When titanic sulphate or chloride is hydrolysed by sodium hydroxide, the basic salts initially formed are decomposed subsequently to hydrous titanium dioxide as the pH becomes stabilised at higher values. The specific surface of the basic sulphate increases considerably when it hydrolyses to anatase. On calcination at temperatures up to about 750°, the anatase crystallites can grow from about 0·006 μm to the requisite 0·1–0·5 μm range, but the aggregate sizes vary widely. Shock‐heating at temperatures between 600° and 900° removes the remaining water and breaks up the larger aggregates.At higher temperatures, the anatase is transformed to rutile which subsequently sinters. The rutile produced by shorter calcinations at 1100°–1150° is similar in crystallite size to that obtained by complete oxidation (‘burning’) of titanic chloride vapour at the same temperatures. Results emphasise the need for close control of residence time in the high‐temperature zone in the production of pigmen

ISSN:0021-8871    

DOI:10.1002/jctb.5010190204

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe kinetics of the dissolution of uranium dioxide in nitric acid were investigated at temperatures up to 150° and oxygen and argon gas pressures up to 1150 psig. A mechanism for the high‐pressure process is proposed which is consistent with experimental reaction rates and the mechanism proposed previously for temperatures below 10

ISSN:0021-8871    

DOI:10.1002/jctb.5010190205

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe conditions for the flotation of silver using α‐nitroso‐β‐naphthol and β‐nitroso‐α‐naphthol, that of uranium using α‐nitroso‐β‐naphthol and benzoylacetone, and that of gold using phenyl‐α‐pyridylketoxime were examined. Recoveries of over 90% were possible from 5 × 10−5M solutions of silver, 10−4M solutions of uranium (VI) and 3 × 10−4M solutions of gold (III). Extractions were best in the pH range 7–9, 6–9 and 3–5 respectively. Silver could be separated from 10‐fold molar excesses of copper, zinc and lead; uranium from 10‐fold molar excesses of gold and iron and 100‐fold molar excesses of sulphate and manganese: gold from a 10‐fold molar excess of uranium. Methods are suggested whereby redispersion in precipitate flotation of the second kind can be avoided. The

ISSN:0021-8871    

DOI:10.1002/jctb.5010190206

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractAn experimental investigation is presented of the foam separation of powdered active carbon, equilibriated with an aqueous, synthetic waste water containing phenol and a cationic (ethylhexadecyldimethylammonium bromide (EHDA‐Br)), anionic (dodecyl sodium sulphate), or non‐ionic (alkyl phenoxy polyethoxy ethanol) surfactant. The effect of surfactant, of pH, of initial carbon concentration, and of initial surfactant concentration on the flotation of carbon is investigated. At pH 3, 7, and 10, the cationic surfactant yields the best flotation of carbon, which increases with increasing pH. At pH 7, a suspension containing 800 mg/1 carbon can be reduced to 24 mg/1 in 10 min. with 0·37 mM EHDA‐Br. The relative concentrations of carbon and of surfactant must be controlled carefully to yield sufficient free surfactant to obtain a foam but not excessive free surfactant to impair the foam separation process. Foam volumes are controlled by free (non‐adsorbed) su

ISSN:0021-8871    

DOI:10.1002/jctb.5010190207

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010190208

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY