No description available.

The Rayleigh scattering of light, in which light is scattered with the same frequency as that of the incident beam, has been known for many years, and explained theoretically in terms of the polarizability of the molecules which make up the scattering media. The type of scattering known as the Raman effect, where the frequency of the incident light is altered in the scattered radiation, is of more recent discovery; its theoretical basis is very similar, but depends upon the changes of polarizability of the scattering molecules which occur with vibration and rotation. The attempt to explain and predict the intensities and depolarization factors of lines in a Raman spectrum must, therefore, consider in detail the theories of the origin within a molecule of its polarizability. Part I of this work is concerned with a modification of one of these theories, in Part II its results are applied to give predictions of the characteristics of some Raman lines.

No description available.

No description available.

No description available.

The cold-lime water softening reaction was simulated by the precipitation of calcium carbonate following the addition of lime water, to prepared solutions of calcium bicarbonate. A laboratory batch crystalliser was used. The overall rate of calcium ion removal was followed using an ion selective electrode and samples were removed for Coulter Counting to enable the variation in crystal size with time to be studied. The effect on the crystallisation rate due to some organic materials likely to be present in raw water or added during processing was studied. These experiments were done with and without added calcium carbonate to simulate conditions in a retained sludge type of reactor. The calcium ion measurements enabled the induction period before precipitation, the half-life of the precipitation and the precipitation rate to be determined. High molecular weight polyacrylamides of anionic, cationic and nonionic type, had no significant effects whereas an extract of water humic substance and low molecular weight polyacrylate had a marked effect on the induction period, half life and precipitation rate. A starch was intermediate in its effects. The optimum does and the adsorption isotherms of the flocculants on calcium carbonate were also determined. The crystal size distribution over the range 2-37 um was determined by Coulter Counter for several runs. Although high product recovery was obtained attempts to use the population balance method for a detailed study of the nucleation kinetics were less successful. From the results obtained-possible reasons for the observed differences in inhibition behaviour were discussed, with particular reference to the solution diffusivity of the species concerned.

No description available.

Soon after the demonstration of the suitability of the glass electrode for measuring pH it was found that it had. the disadvantage of showing deviations from the 59mV per pH unit response in acid (pH<2) and alkaline (pH >9) solutions. Early in the development of the electrode as an analytical tool a great deal of work was carried out on the nature of these deviations. Howevert examination of the literature of 20 years ago reveals several discrepancies between the data obtained by different investigators, notably concerning the behaviour of electrodes made from lithia glass and the magnitudes of the errors shown by soda glass electrodes in different acid solutions. Although the major discrepancies have now been resolved, they clearly underline the unreliability of the early work as a whole. The whole question of the errors of pH responsive glass electrodes has therefore been re-exanined in this department using modern electronic measuring equipment and a recently developed and proven experimental technique which enables variations in the glass electrode potential to be followed relative to a hydrogen electrode immediately after placing the glass electrode in a solution.

The selective oxidation of methanol to formaldehyde over iron molybdate catalysts has been investigated. It has been shown that when Fe2C 3 is present at the surface CO2 and H2 are observed from surface formates, while neighbouring pairs of molybdena sites leads to the production of formaldehyde and water from surface methoxys. When molybdenum sites are isolated then the surface methoxy is stabilised and a direct pathway to CO and H2 is created. On molybdena rich surfaces the production of CO is observed, but as a secondary oxidation product following the linear pathway: CH3OH &rarr; CH2O &rarr; CO &rarr; CO 2, established by varying bed lengths. Catalysts with addition of small amounts of molybdena added to the surface of Fe2O 3, are similar to those with a low bulk ratio of Mo:Fe showing increased activity over Fe2O3. Selectivity is dictated by the presence of isolated or pairs of molybdena sites, which guide the reaction to the primary products of CO and formaldehyde respectively. Structural analysis showed the phases of a-Fe2O3, (X-MoO3 and a-Fe2(MoO4)3, depending on the ratio of the cations present. Molybdenum has been shown to concentrate at the surface of iron molybdates by reactor results from low ratio catalysts, Raman spectroscopy, XP spectroscopy and STEM/EEL spectroscopy. The normal reaction of iron molybdates is via the Mars-van Krevelen mechanism, so tests were made without the presence of gaseous oxygen. The reduction of the surface layer can occur at temperatures as low as 200&deg;C. At temperatures above 250&deg;C diffusion of lattice oxygen to replace the lost surface oxygen can occur, leading to the production of further oxidised products. If the oxidation state of surface molybdenum drops below +6 then formaldehyde selectivity drops markedly, with direct production of CO and secondary production of CO2 observed.

The synthesis, characterisation and anion binding properties of a series of bifunctional boryl-substituted ferrocene systems, and monofunctional boryl-substituted ferrocene and cymantrene systems are reported. Thus, the bis-borylated ferrocene systems: Fe rj5-C5H4B(OR)2 2 and Fe n5-C5H4Bcat 2 where (OR)2 = OCH(Ph)CH(Ph)0 (la) or OCH2CH(2-napthyl)0 (5a), and cat = catecholate (2a), 3,5-di-terr-butylcatecholate (3a), or 3-methoxycatecholate (4a) and the mono-borylated ferrocenes and cymantrenes (t 5-C5H5)Fe r 5-C5H4B(OR) 2 (lb), -n.5-C5H4B(OR)2 Mn(CO) 3 (7), (n5-C5H5)Fe n5-C5H4Bcat (2b), and n5-C5H4Bcat Mn(CO)3 (8) where (OR) 2 = OCH(Ph)CH(Ph)0 and cat = catecholate have been synthesised and characterised by NMR, UV/Vis and IR spectroscopy, mass spectrometry, elemental microanalysis, and in most cases by X-ray diffraction. Electrochemical analyses of all ferrocene-based compounds has demonstrated the electronic and redox properties associated with boryl-substituted metallocenes, and allowed a comparison to be made between mono- and disubstituted systems. The anion binding characteristics of the borylated metallocenes and half-sandwich compounds have been probed by spectroscopic (including NMR, UV/Vis, fluorescence and IR spectroscopy) and electrochemical techniques, revealing a specific affinity for binding of the fluoride ion. Binding is shown to occur through monodentate coordination of fluoride, even for the bifunctional Lewis acids such that two equivalents of the anion are bound by the ferrocenyl-host system. In particular, the bis-borylferrocene receptors display remarkable behaviour on complexation of two equivalents of fluoride, such that a colorimetric response is observed on fluoride binding, attributable to the redox chemistry of the ferrocene moiety to which the binding site is covalentfy linked. The synthesis, characterisation and potential hydrogen fluoride binding capabilities of mixed Lewis acidic boron-Lewis basic nitrogen containing systems are also presented here. Both (ri5-C5H 5)Fe ri5-C5H4B(OCH2CH2)NCH 3 (9a) and (n5- C5H5)Fe r 5-C5H 4B(OR)2 where (OR)2 = OCH2CH(CH 2NC5Hi0)O (10a) have been synthesised and characterised by standard techniques, and the former shown by X-ray diffraction to display an intramolecular N-B dative bond. In addition to these newly synthesised Lewis acid-Lewis base-containing systems, hydrogen fluoride binding studies involving the literature compound 2-(AAdimethylaminomethyl)ferrocene boronic acid (11a) are also presented. Analyses of the reactions of different hydrogen fluoride sources with these three compounds have been performed via NMR spectroscopy, electrochemistry, and in the cases of 9a and 11a, by X-ray crystallography. The results indicate that HF treatment of 9a and 10a, causes B-0 bond cleavage leading to loss of the amine function. The Lewis basic component is preserved in the treatment of 10a with HF, however, leading to formation of an HF adduct.