Fractionator sizing component recoveries

The reverse-phase analysis was carried out on a SUPELCOSIL LC-18, 3-/zm particle size, 150 X 4.6-mm ID column (solvent system A, acetonitrile B, acetonitrile-tetrahydrofuran-chloroform (50 27.5 22.5) linear gradient from 30% to 100% of B in 70 min, flow rate 0.5 ml/min) (Fig. 22). The upper part of Fig. 22 shows that various chain lengths (C12 to C24 with one-carbon increment) of PNB-TBDMS-OHFA separated well enough in 30 min for effective recovery of the components by an absorbance slope-detecting fraction collector-detector combination. The separation of the positional isomers present in the used mixture was only minor, and it did not interfere with the fractionation according to chain length. 

Humic substances account for 40-70% of the DOC in rivers and 5-25% of the DOC in the ocean (Table I). It is important to note that recoveries of adsorbed humic substances from XAD resins are not quantitative, so the chemical characteristics of the recovered humic substances are not necessarily representative of all the humic substances retained by the resin. Tangential-flow ultrafiltration retains 45-80% of the DOC in rivers and 25-40% of the DOC in the surface ocean (Table I). Essentially all of the DOC retained during ultrafiltration is recovered for chemical characterization. In general, ultrafiltration recovers a larger fraction of the DOM from these systems. These methods also isolate DOM based on different mechanisms. Adsorption onto XAD resins at low pH chemically fractionates the DOM and isolates the more hydrophobic components, whereas ultrafiltration principally separates components of DOM on the basis of size and shape. 

Processes for the bioproduction of ethanol from cellulosic materials have been studied extensively. Some of the process steps are specialized and beyond the scope of this chapter. However, there are many recent review articles dealing with some specific subjects. Basically, the processes consist of a number of steps. They are availability and collection of raw feedstock [20], size reduction, pretreatment, fractionation of biomass components, enzyme production [21, 22], saccharification, enzyme recycle [23, 24], pentose fermentation, improvement of pentose-fermenting biocatalyst, overcoming of product inhibition, overcoming inhibition by substrate-derived inhibitors, ethanol recovery [25], steam generation and recycling [26], waste treatment, and by-product utilization. 

Oily additives are used in various technologies (e.g., paper and pulp production, ore flotation, fermentation) and commercial products (detergents, paints, some pharmaceuticals) to avoid the formation of an excessive foam, which would impede the technological process or the product application [1-3]. In other cases (oil recovery and refinement, shampoos, emulsions for metal processing machines) oil drops are present, without being specially introduced for foam control, and can also affect the foamability of the solutions. Small fractions of hydrophobic solid particles of micrometer size, such as hydrophobized silica or alumina, plastic grains, or stearates of multivalent cations, are often premixed with the oil because the solid-oil compounds obtained exhibit a much stronger foam destruction effect than the individual components taken separately [4-8]. Such oily additives are termed antifoams in the literature and can be based on hydrocarbons, poly-dimethylsiloxanes (PDMSs, silicone oil) or their derivatives [1,4]. 

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