Resin-based adsorption processes

Resin-Based Adsorption Processes for Reactions in High-Temperature Water... 

In adsorption processes, contaminated water is contacted with a solid adsorption medium, such as GAC or resin. Based on their equilibrium properties relative to the specific adsorption medium, contaminants will partition from the water to the solid until the system reaches equilibrium.93 The maximum concentration of a given contaminant that can be adsorbed is dependent on... 

Certain types of adsorption media have been shown to preferentially adsorb certain contaminants. For example, research has shown that, in some cases, coconut shell-based GAC removes MTBE better than typical coal-based GAC. In addition, synthetic resins have been developed to preferentially adsorb some oxygenates, such as TBA, that are less absorbable by GAC. Often, adsorption processes also take advantage of the biodegradability of MTBE and other oxygenates by promoting bacterial growth on the adsorption. 

Saturable dye absorber, 14 677 Saturated aqueous salt solution, 9 34 Saturated calomel electrode (SCE), 9 571 Saturated fatty acids, 10 829, 830 Saturated hydrocarbons adsorbent affinity, 1 674 adsorption by zeolites, 1 624 fluorine reactivity with, 11 831 isomerization of, 12 172—173 Saturated polyester resins, based on trimethylpentanediol, 12 673 Saturated polyesters, 10 7 Saturated synthetic rubber, 10 705 Saturation and coating processes, 10 12-13 Saturation bonding, 17 509-510 Saturation color, 19 262 Saturation concentration, 15 677 Saturation index... 

Another adsorption system evaluated was a high-volume, high-pressure, macroporous-resin-based concentrator system designed to provide a 10,000-fold concentrate. This system used four stainless steel columns in series. Columns one through four were filled with AG MP-1 (Bio-Rad), AG MP-50 (Bio-Rad), XAD-2 (Rohm and Haas), and XAD-7 (Rohm and Haas), respectively. Unlike the other adsorption processes, a pump system was employed for both the adsorption and desorption phases of the evaluation. The use of acetonitrile as the elution solvent permitted UV monitoring of the eluant. 

However, a second equilibrium process can occur in which the molecular form of the eluent solute is adsorbed by the resin matrix. This adsorption process also shifts the acid-base equilibrium so that a greater proportion of the eluent is in the molecular form. When a sample is injected that contains no benzoate or benzoic acid, a new equilibrium is established in which some of the adsorbed benzoic acid passes from the stationary phase into the mobile phase. After the zone occupied by the sample has passed, the resin re-equilibrates with the mobile phase to replace the adsorbed benzoic acid it has lost. This creates a vacancy in the mobile phase that contains a lower total concentration of benzoate plus benzoic acid. In the example described, a decrease in the detector signal is observed when the vacancy passes through the detector. This is commonly called the system peak even if it is in the negative rather than the positive direction. 

Most commonly used radiochemical protocols for radionuclides isolation are based on precipitation or coprecipitation processes, adsorption processes, ion exchange using anionic and cationic resins. 

Displacer based desorption is practiced more often in liquid-phase processes, particularly in ion-exchange resin based processes. Conventional adsorption based liquid-phase processes are not particularly suitable for displacer based processes. Further, displacer based processes are invariably used in multicomponent separations (Rhee and Amundson, 1982) and are properly considered under chromatographic processes (see Section 7.1.5) (Frenz and Horvath, 1985). 

Since the early 1970s p-xylene has grown to become a large volume petrochemical. It is used primarily for the production of polyester fibers, films and resins, such as PET (polyethylene terephthalate) [7]. Demand for p-xylene has increased tenfold since 1970 to about 26xl0 t/year. Almost all of this additional production has been by the UOP Parex process as shown in Figure 7.1. A baseline production ofp-xylene is maintained by crystallization based sites that existed before the SMB adsorptive separation technology was established [8]. 

Immobilized enzymes based on the adsorption may obtain high activities. Another interesting aspect of the technology is that the so-called on column loading (OCL) process is possible. At the beginning the ion exchange resin is only partly loaded with... 

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