Monolith production technique

The most prominent production technique for metallic monoliths is the rolling up of a flat and of a corrugated metal foil. In this way, an alternating arrangement ofboth foils is achieved, as shown in Figure 10.5. 

CEC is a miniaturized separation technique that combines capabilities of both interactive chromatography and CE. In Chapter 17, the theory of CEC and the factors affecting separation, such as the stationary phase and mobile phase, are discussed. The chapter focuses on the preparation of various types of columns used in CEC and describes the progress made in the development of open-tubular, particle-packed, and monolithic columns. The detection techniques in CEC, such as traditional UV detection and improvements made by coupling with more sensitive detectors like mass spectrometry (MS), are also described. Furthermore, some of the applications of CEC in the analysis of pharmaceuticals and biotechnology products are provided. 

These reactions are responsive to both acid and base catalysis, and can be manipulated to give a variety of silica products, e.g., discrete particles, monolithic gels, films, and fibers. This technique of materials synthesis via alkoxide hydrolysis has become known as sol-gel processing (17). It should be noted, however, that under certain conditions, gelation may be confined only to the interior of discrete particles (base-catalyzed systems), while the sol may consist of polymeric networks rather than individual particles (acid-catalyzed systems). 

Molecular imprinting has recently attracted considerable attention as an approach to the preparation of polymers containing recognition sites with predetermined selectivity. The history and specifics of the imprinting technique pioneered by Wulff in the 1970s have been detailed in brilliant review article [40]. These materials, if successfully prepared, are expected to find applications in numerous areas such as the resolution of racemates, chromatography, substrate selective catalysis, and the production of "artificial antibodies". Imprinted monoliths have also recently received... 

Solidification refers to techniques that encapsulate the waste, forming a solid material, and does not necessarily involve a chemical interaction between the contaminants and the solidifying additives. The product of solidification, often known as the waste form, may be a monolithic block, a clay-like material, a granular particulate, or some other physical form commonly considered solid. Solidification as applied to fine waste particles, typically 2 mm or less, is termed microencapsulation and that which applies to a large block or container of wastes is termed macroencapsulation [29]. 

However, the preparation of materials with structures on different length scales typically involves more complicated synthetic procedures, e.g., for porous materials two or more porebuilding processes have to be synchronized. The implementation of these techniques toward the production of large monolithic systems exhibiting porous structures on different length scales is only just beginning to emerge [1,6]. 

Most of the work cited above has dealt with treating the soot in some way before doing the combustion experiments. We wish to report experiments conducted on soot from a diesel vehicle which has been deposited onto catalytic monolithic substrates. This sooted substrate is then placed in a laboratory apparatus where a synthetic gas mixture flows over the sample, and the soot combustion is monitored as a function of temperature. The laboratory set up simulates regeneration conditions on a vehicle. Using this technique we have been able to obtain kinetic information about the oxidation of soot and gaseous products. Comparisons of base metal and noble metal catalysts were also conducted and are reported. It is intended that this work will help elucidate the mechanism involved in the catalytic combustion of soot which should help in developing improved catalytic materials. 

Employing an HIPE technique, poly(aryl ether sulfone) monoliths were obtained by the copolymerization of maleimide-terminated aryl ether sulfone macromonomer with styrene, DVB, or bis-vinyl ether in a solution in which petroleum ether (80% by volume) was dispersed [373]. The resulting product possessed an open-cell structure with porous cell walls and enlarged thermostability compared with poly(styrene-co-DVB) mono-hths. Unfortunately the utilization of the material as a possible medium for chromatographic separation has not been reported. 

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