Inorganic membrane science and technology is an attractive field of membrane separation technology, which has been dominated by polymer membranes. Recently, the inorganic membrane has been undergoing rapid development and innovation. Inorganic membranes have the advantage of resisting harsh chemical cleaning, high temperature and wear resistance, high chemical stability, long lifetime, and autoclavable. All of these outstanding properties made inorganic membranes good candidates to be used for water treatment and desalination applications. This paper is a state of the art review on the synthesis, development, and application of different inorganic membranes for water and wastewater treatment. The inorganic membranes reviewed in this paper include liquid membranes, dynamic membranes, various ceramic membranes, carbon based membranes, silica membranes, and zeolite membranes. A brief description of the different synthesis routes for the development of inorganic membranes for application in water industry is given and each synthesis rout is critically reviewed and compared. Thereafter, the recent studies on different application of inorganic membrane and their properties for water treatment and desalination in literature are critically summarized. It was reported that inorganic membranes despite their high synthesis cost, showed very promising results with high flux, full salt rejection, and very low or no fouling.
We have prepared two xanthate precursor polymers (6) and one sulfinyl precursor oligomer (7). In this way the polymerization behavior of three xanthate-containing monomers (3, 4, and 5) was studied. The chemical modifications on the monomer stage allowed to evaluate the outcome of the polymerization in relation to the chemical structure of the monomer. Polymerizations were performed in dry THF at different temperatures. The thermal conversion to the conjugated PPV structure, as well as its stability, was studied with different analytical techniques such as in-situ FT-IR spectroscopy, in-situ UV-vis spectroscopy, thermogravimetric analysis (TGA), and direct insert probe mass spectroscopy (DIP-MS). By combining the information obtained from these techniques, we were able to obtain a very detailed picture about the elimination process. These measurements also confirmed the formation of cis double bonds in xanthate precursor polymers on conversion. However, subsequent cis-trans isomerization in the end leads toward an all-trans-PPV polymer.
The kinetics of p-quinodimethane formation in the sulfinyl precursor route for the poly-(p-phenylenevinylene) (PPV) polymerization was studied using stop-flow UV-vis spectroscopy and theoretical first principle calculations. Different sulfinyl monomers were studied by means of quantitative kinetic experiments regarding the p-quinodimethane formation in 2-butanol. The influence of the solvent, the nature of the aromatic moiety, and the substituents on the phenyl core was analyzed by means of qualitative experiments. Quantitative measurements, using pseudo-first-order reaction conditions, were performed in order to assess the effect of the polarizer and the leaving group on the reaction rates. To obtain additional fundamental insight into the pathway leading to p-quinodimethane formation, density functional theory calculations were performed and subsequent reaction rate coefficients were determined from a theoretical point of view, enabling a profound comparison with experiment. From all these data, an E 2 mechanism is proposed for the p-quinodimethane formation in the sulfinyl precursor route.
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