Agitated vessels adsorption

Enzymes are immobilized by attachment to or confinement in water-insoluble materials (Fig. 1). Enzymes can be immobilized by adsorption on biologically inert carriers like organic polymers, glass, mineral salts, metal oxides, and different silicates. Since enzymes retain their activity for a longer time in an undissolved form, many reactions catalyzed by enzymes can be carried out in continuous systems. Immobilized enzymes can be used in agitated vessels, fluidized or Fixed bed tower reactors40). 

Mesliko et al. (2001) sUidied the adsorption of a basic dye (Maxilon Goldberg GL EC 400% or MG-400) using zeolite in an agitated vessel of 0.5-L volume, under agitation (200 ipm) at ambient temperaUue (20 °C). Uie initial concenhation of dye was 100 mg/L, tlie... 

The effect of the time of adsorption following the formation of a suspension was determined by agitating the adsorption vessels for 18-185 hours. While the adsorbance did not change significantly for the conditions selected, the bound fraction decreased from 0.24 to 0.13 over this time period. This could be interpreted as a rearrangement toward a more extended conformation possible at very long adsorption times or as a mechanical degradation of the polymer. 

The initiator usually constitutes less than 1% of the final product, and since starting the process with such a small amount of material in the reaction vessel may be difficult, it is often reacted with propylene oxide to produce a precursor compound, which may be stored until required [6]. The yield of poloxamer is essentially stoichiometric the lengths of the PO and EO blocks are determined by the amount of epoxide fed into the reactor at each stage. Upon completion of the reaction, the mixture is cooled and the alkaline catalyst neutralized. The neutral salt may then be removed or allowed to remain in the product, in which case it is present at a level of 0.5-1.0%. The catalyst may, alternatively, be removed by adsorption on acidic clays or with ion exchangers [7]. Exact maintenance of temperature, pressure, agitation speed, and other parameters are required if the products are to be reproducible, thus poloxamers from different suppliers may exhibit some difference in properties. 

For adsorption on flocculated particles, the polymer was added in a drop-by-drop-wise manner from a burette containing a 50 cc solution to a 50 cc solution containing the solids. Flocculation was performed in an unbaffled vessel, 58 ram in diameter. Agitation was achieved with a 3-bladed propeller, 35 mm in... 

Many kinetic studies investigating reactions on soil constituents have used batch techniques. The traditional batch or tube technique involves placing an adsorbent and the adsorptive in a vessel such as a centrifuge tube. The suspension is stirred or agitated using a reciprocating shaker. Then the suspension is usually centrifuged or filtered to separate a clear supernatant solution for subsequent analysis. 

The reaction vessels for the kinetic studies were 4000-ml. resistant glass bottles, in which solutions were agitated with Teflon-coated stirring rods extending directly into the adsorbate solution and connected to synchronous motors operating at 1550 r.p.m. Previous kinetic studies in similar systems had shown that rate of adsorption is independent of stirring rate at rotations greater than a few hundred r.p.m. (8). Tempera-... 

Solid-catalyzed reactions usually involve adsorption of reactants onto the surfaces of the catalyst particles where the reactions take place, followed by the desorption of the reaction products from the surface. A uniform suspension of catalyst particles ensures a uniform concentration of reactants and reaction products throughout the vessel. In addition, agitation reduces the diffusional mass transfer boundary layer, thus enhancing the solid-liquid mass transfer. 

Grbber [33] computed the approach to equilibrium temperature of spherical particles immersed in an agitated fluid of constant temperature. Since the concentration of the solution in a well-stirred vessel in continuous flow is essentially uniform throughout at the effluent value, Grober s result can be adapted to cocurrent adsorption through the heat- mass-transfer analogy, as in Fig. 11.27. Here the approach of the particles to equilibrium concentration with the effluent liquid is expressed as the Muiphree stage efficiency,... 

---