Bioprocesses adsorption

Desulfurization processes are absolutely necessary for producing clean fuels. Possible strategies to realize ultradeep suffiirization currently include adsorption, extraction, oxidation, and bioprocesses. Oxidative desulfurization (ODS) combined with extraction is considered one of the most promising of these processes [13]. Ultradeep desulfurization of diesel by selective oxidation with amphiphilic catalyst assembled in emulsion droplets has given results where the sulfur level of desulfurized diesel can be lowered from 500 ppm to about 0.1 ppm without changing the properties of the diesel [12]. 

Expanded-bed adsorption (ERA) has gained popularity in bioprocessing since its commercial introduction in the 1990s because of its ability to handle a crude feedstock that contains cells or other particulates. ERA ehminates the need for a dedicated clarification step by combining sohd-hquid separation and adsorption into a single-unit operation [Hjorth et al., in Subramanian (ed.), op. cit., vol. 1, pp. 199-226 Mattiasson et al., in Ahuja (ed.), op. cit., pp. 417-451]. A... 

Qureshi, N., Hughes, S., Maddox, I.S., and Cotta, M.A. (2005) Energy efficient recovery of butanol from model solutions and fermentation broth by adsorption. Bioprocess Biosyst. Eng., 27, 215. 

Adsorption, e.g. on XAD resins Stripping and adsorption Extraction (two-phase bioprocess)... 

Adsorption is a physical phenomenon in which some components adsorbates) in a fluid (liquid or gas) move to, and accumulate on, the surface of an appropriate solid adsorbent) that is in contact with the fluid. With the use of suitable adsorbents, desired components or contaminants in fluids can be separated. In bioprocesses, the adsorption of a component in a liquid is widely performed by using a variety of adsorbents, including porous charcoal, silica, polysaccharides, and synthetic resins. Such adsorbents of high adsorption capacities usually have very large surface areas per unit volume. The adsorbates in the fluids are adsorbed at the adsorbent surfaces due to van der Waals, electrostatic, biospecific, or other interactions, and thus become separated from the bulk of the fluid. In practice, adsorption can be performed either batchwise in mixing tanks, or continuously in fixed-bed or fluidized-bed adsorbers. In adsorption calculations, both equilibrium relationships and adsorption rates must be considered. 

In the downstream processing of bioprocesses, fixed-bed adsorbers are used extensively both for the recovery of a target and for the removal of contaminants. Moreover, their performance can be estimated from the breakthrough curve, as stated in Chapter 11. The break time tg is given by Equation 11.13, and the extent of the adsorption capacity of the fixed bed utilized at the break point and loss of adsorbate can be calculated from the break time and the adsorption equilibrium. Affinity chromatography, as weii as some ion-exchange chromatography, are operated as specific adsorption and desorption steps, and the overall performance is affected by the column capacity available at the break point and the total operation time. 

Lindgren A, Johannson S, Nystrom L-E (1993) Scale-up of expanded bed adsorption. In Henon B (ed) BED - The seventh Bioprocess Engineering Symposium. The American Society of Mechanical Engineers, p 27... 

In this review, recent progress on integrated bioprocessing, including in situ adsorption using polymeric resins, in situ extraction with adequate solvents, application of cyclodextrins, and the use of aqueous two-phase systems, are summarized and their advantages and disadvantages are described in detail. 

Integrated bioprocesses can be used to enhance the production of valuable metabolites from plant cell cultures. The in situ removal of product during cell cultivation facilitates the rapid recovery of volatile and unstable phytochemicals, avoids problems of cell toxicity and end-product inhibition, and enhances product secretion. In situ extraction, in situ adsorption, the utilization of cyclodextrin, and the application of aqueous two-phase systems have been proposed for the integration of cell growth and product recovery in a bioreactor. The simultaneous combination of elicitation, immobilization, permeabilization, and in situ recovery can promote this method of plant cell culture as a feasible method to produce various natural products including proteins. 

Hjorth, R. (1997). Expanded bed adsorption in industrial bioprocessing Recent developments. Trends Biotechnol. 15, 230-235. 

Hsu, F. L., Wang, P. M., Lu, S. Y., and Wu, W. T. 2002. A combined solid-state and submerged cultivation integrated with adsorptive product extraction for production of Monascus red pigments. Bioprocess Biosyst. Eng. 25(3), 165-168. 

In the field of chemical analysis, biosensors have undergone rapid development over the last few years. This is due to the combination of new bioreceptors with the ever-growing number of transducers [1]. The characteristics of these biosensors have been improved, and their increased reliability has yielded new applications. Recently, a new technique of enzyme immobilization has been developed to obtain biosensors for the determination of enzyme substrates [2]. It is based on the enzyme adsorption followed by a crosslinking procedure. Therefore, a penicillin biosensor can be obtained and associated with a flow injection analysis (FIA) system for the on-line monitoring of penicillin during its production by fermentation [3-4]. This real-time monitoring of bioprocess would lead to optimization of the procedure, the yield of which could then be increased and the material cost decreased. 

Alternative and more sophisticated approaches based on biphasic in situ product removal have also been proposed and demonstrated recently, which include the use of ionic liquids as the nonaqueous phase [88], the inclusion of an organophilic pervaporation step [89], and the coupling of product removal with a continuous culture system [90]. The latter approach, which comprises two different units for culture and adsorption, separated by a ceramic membrane to prevent the cells from polluting and clogging the resin, allowed achieving the highest space-time yield (0.9 g 1 h) ever reported for this bioprocess. 

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