Ion-exchange resin bed

Ultrafiltration is particularly useful as a pretreatment roughing filter for the type of ion-exchange resin beds and EDR technologies... 

There are two steps in the basic process the upstroke and the downstroke (see Fig. 24.1). During the upstroke, feed brine solution bearing impure salt is pumped into the bottom of the ion-exchange resin bed. The impurity (MX) is sorbed by the resin particles according to Equation 24.1 and a purified brine solution is collected from the top of the bed. Next, during the downstroke, water is pumped into the top of the bed, desorbing the brine impurity from the resin according to Equation 24.2 so that a solution of the brine impurity is collected from the bottom of the bed. The total cycle typically takes about 2-10 min to complete and repeats successively. 

The sorbitol solution produced from hydrogenation is purified in two steps [4]. The first involves passing the solution through an ion-exchange resin bed to remove gluconate and other ions. In the second step, the solution is treated with activated carbon to remove trace organic impurities. The commercial 70% sorbitol solution is obtained by evaporation of the water under vacuum. The solid is prepared by dehydration until a water-free melt is obtained which is cooled and seeded. The crystals are removed continuously from the surface (melt crystallization). The solid is sold as flakes, granules, pellet, and powder forms in a variety of particle size distributions. 

An ion exchange resin bed 32 inches deep made up of equal volumes of C-20 and A-102 resins was used in each of the two columns. The bed was supported by several inches of gravel covered with 2 to 3 inches of coarse sand. In one run (No. 7—1) the two columns were used in series to approximate a deeper bed (64 inches). 

Countercurrent process schemes for replacing ions of one kind by ions of another are analogous to those carried out in fixed ion-exchange resin beds. The use of countercurrent columns enables one, in these cases, to employ ion-exchanger capacity more effectively, to reduce expenditures for resin regeneration, and to decrease the amount of waste. It also permits automated control of the process. 

Preuse validation of deionizing systems used to produce purified water should include consideration of such factors as microbial quality of feed water (and residual chlorine levels of feed water where applicable), surface area of ion-exchange resin beds, temperature range of water during processing, operational range of flow rates, recirculation systems to minimize intermittent use and low flow, frequency of use, quality of regenerant chemicals, and frequency and method of sanitization. 

A fluidized resin-liquid contact was chosen for several reasons. Turbidity in the incoming sea water presents no problem, because the suspended material is carried over with the softened sea water. It is difficult, if not impossible, to force raw sea water through an ion exchange resin bed at reasonable flow rates because of the rapid buildup of a sludge blanket in the top few inches of the bed, which results in a rapid increase in pressure drop. 

Diffbsion-Controlled Sorption by Ion Exchange Resin Beds, Ind. Eng. Chem. Fundam., 8(2), 193-198 (1969). 

Electrochemical methods can be used in the destruction of nitrate [34], which may arise as part of ion exchange operations. Regeneration of the effluent from ion exchange resin beds can be achieved by a combined process of cathodic reduction and anodic oxidation. 

The electrodeionization process is very similar to conventional electrodialysis. The main difference is that the dUuate compartment is filled with a mixed ion exchange resin bed. Ions present in the diluate diffuse into the resin and are exchanged with or OH. When a difference of potential is applied, the ions exchanged migrate from the resin bed to the adjacent concentrate compartments. The resin allows the dissolution of diluate to keep acceptable values of electrical conductivity although the salt content is very low, because water dissociates into or OH at the point of contact of the diluate with the cationic and anionic resin beds. In this way, you... 

The ion-exchange resin beds were generally about 1.0 to 1.5 cm in diameter and about 20 to 25 cm in length. The columns were equipped with water jackets so that they could be operated either at 0°C, if ice water was circulated through the jackets, or at room temperature. 

K. Berg, G. Malamet, A. Eitel and C. Wulff, Optimized ion exchange resin bed for synthesis of Bisphenol-A, Japanese Patent 06320009, assigned to Bayer AG, November 22,1994. 

In ion exchange processes, the regeneration is achieved by passing a different solution with different composition or pH through the ion exchange resin bed. The energy cost is not directly available. 

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