Strong base cation resin

Eig. 5. Pressure drop as affected by resin type, flow rate, and temperature, where A, B, and C, correspond respectively to acryUc strong base anion exchanger (Amberlite IRA-458), styrenic strong base anion exchanger (Amberlite IRA-402), and styrenic strong acid cation exchanger (Amberlite IR-120), all at 4°C. D represents styrenic strong acid cation resin (Amberlite IR-120) at 50°C (14). To convert kg/(cm -m) to lb/(in. -ft), multiply by 4.33 to convert... 

Demineraliza tion of water is the removal of essentially all inorganic salts by ion exchange. In this process, strong acid cation resin in the hydrogen form converts dissolved salts into their corresponding acids, and strong base anion resin in the hydroxide form removes these acids. Demineralization produces water similar in quaHty to distillation at a lower cost for most fresh waters. 

Both strong-acid cation and strong-base anion resins are high ionized in water thus, they can work in the entire pH range. The pH does not affect the ion-exchange performances. Conversely, weak-acid cation and weak-base anion resins are more like weak acid (base). For example, their ionization strongly depends on pH. When pH is below 6.0, weak-acid cation resin s performance will be significantly decreased. Similar phenomenon will occur to weak-base anion resin at pH above 7.0. 

An important requirement for the successful operation of a mixed bed is the careful separation of the strong base anion resin from the strong acid cation resin by backwash fluidization. This is followed by contact of each type of resin with its respective regenerant in a manner which minimizes the... 

There are two types of anion units. Strong base anion resin units remove all anions including silica and carbon dioxide. Removal of silica and COj are specially important prior to distillation in a unit such as a WFI still. They typically produce a deionized water with a pH greater than 7. Weak base anion units are used when removal of silica and carbon dioxide are not required. Mixed bed units contain both the anion and the cation resins in one vessel. Mixed bed discharge pH is typically around 7.0, neutral. 

Strong-base anion resins are activated in a two-step process that consists of chloromethylation followed by amination. The two-step process begins with the same styrene-DVB material as is used for cation resins. The only difference is that the amount of DVB used is less, to allow for a more porous bead. The first reaction step is the attachment of a chloromethyl group to each of the benzene rings in the bead structure. This intermediate chloromethylated plastic material needs to be reacted with an amine in a process called amination. The type of amine used determines the functionality of the resin. A com-... 

Weak and strong acid-type resins are for removal of cations and are called cation exchangers. Weak and strong base resins remove anions and are called anion exchangers. In addition to these four resin types, there are specialty resins used in appHcations where higher specificity for certain ions under challenging conditions is a critical factor. 

---