| Rayleigh scattering (RS) is an elastic scattering with the scattering wavelength being equal to the incident wavelength(A,j) and the scattering particle being much smaller than A.J. When the scattering wavelength is close to or situated on the molecular adsorption band, the scattered intensity deviates from 11 A/ dependence and becomes quite large at some wavelength. This phenomenon is known as resonance Rayleigh scattering (RRS) or resonance enhanced Rayleigh scattering (RERS).This dissertation introduced the elementary properties of Rayleigh scattering and resonance Rayleigh scattering and their applications in scientific research, reviewed the developing course of this technique and discussed mainly the theoretical basement and recent development of studying RS &RRS spectra, the present situation of application and the development of RS or RRS as analytical technique. Then, taking the following five systems including anionic surfactant and cellulose derivatives such as nitro-cellulose (NC), sodium Carboxymethyl cellulose (CMC) as well as reaction product for the examples, this dissertation studied the spectral characteristics, the affecting factors, the properties of analytical chemistry and their analytical application.1. Anionic Surfactant-Cationic Surfactant mixtures systemsIn pH4.0-4.8 acetic acid-sodium acetate buffer medium, the SDS, SDBS and SLS and cationic surfactants such as Cetylpyridinium bromide(CPB), Tetradecane pyridinium bromide (TPB), Hexadecyl pyridinium chlorid (CPC), Tetradecyldimethyl benzylammonium chloride (Zeph), Benzyl-dimethyl-hexadacylammonium chlorid (BCDAC), Cetyl trimethylammonium bromide (CTAB) by virtue of electrostatic forces and hydrophobic interaction can lead to the great enhancement of RS intensity. The Rayleigh scattering spectra of the six systems aresimilar and the maximum RRS peaks are located at 277nm. The concentration of AS is proportional to scattered intensity in specified range. The method for anionic surfactants has high sensitivity and the detection limits of the six systems are between 19.1ng/mL and 85.0ng/mL. Among them, the BCD AC-AS systems are the most sensitive. The detection limits is 19.7ng/mL for SDS, 35.9ng.mL for SDBS and 36.9ng/mL for SLS. This dissertation investigated the suitable reaction conditions and affecting factors as well as the relation between AS concentration and scattered intensity, and discussed sensitized effect of Na2SO4.The effect of some coexisting substance was investigated and the method was applied to the determination of anionic surfactant with BCDAC in environmental water sample and in synthetic sample with satisfactory results. This dissertation discussed reaction mechanism and cause of enhancement of Rayleigh scattering.2. Ethyl Viqlet -Anionic Surfactant systemsIn weak acid media, the anionic surfactants reacts with basic triphenylmethane dyes (BTPMD) such as Ethyl Violet, Crystal Violet, Methyl Violet, Methyl Green, Brillant Green, Malachite Green to form ion-association complexes. The formation brings about an increase of scattered intensity depending on different dyes and new scattering peaks. The sensitivity order is EV>MV>CV>MeG>GB>MG. Taking EV-AS systems for example, we studied the interaction of EV and three kinds of anionic surfactants. The result shows that there are two scattering peaks such as 330nm and 508nm in resonance Rayleigh scattering spectra. At the same time, the reaction product has second-order-scattering and double frequency scattering spectra. This method has fairly high sensitivity, and the detection limit for SDBS is l.lng/mL, 2.5ng/mL for SDS, 269.1ng/mL for SLS. This dissertation investigated the suitable reaction conditions and affecting factors as well as the relation between anionic surfactant concentration and scattered intensity, and discussed mainly the influence of ion strength, organic solvent and temperature. The effect of some coexisting substance was investigated and the method was used successfully to the determination of trace amounts of anionic surfactant in...
|
PDF Full Text Request