Cation-exchange capadty

Nylon 6-day nanocomposites of various day minerals with different cation exchange capadty (CEC) were prepared by in situ polymerization method, and properties such as mechanical, thermal, and gas permeability were compared with respect to pure nylon 6 (N6) polymer by Tsai et al. [35]. It is shown that the nature of the permeation of carbon dioxide gas depends on the exfoliation or intercalation of clay platelets. It is seen that the exfoliated clay platelets offer effective low permeability than the intercalated platelets as seen in Figure 8.2. 

Anion exchange resins are generally lower in their exchange capadty and durability than cation exchange resins and are seldom used for industrial separation. In general, ion exchange as a tool for separation is only used when other steps fail, because of its tedious operation, small capadty and high costs. 

The suspension copolymerization of acrylic esters, acrylonitrile, and DVB in presence of a free radical catalyst followed by the hydrolysis of the bead copolymer with alkali gives a carboxylic add cation-exchange resin with exchange capadty of... 

Resins with good hydrodynamic properties and sorption capadties for proteins and enzymes have been prepared by the polymerization of acrylic acid or methacrylic acid and a crosslinking monomer such as 1,3,5-triacryloylhexahydrotriazine (TAT) in aqueous acetic acid using a radical initiator. Methacrylic add-TAT copolymer prqjared by using a redox catalyst is useful as a cation-exchange resin for selective and reversible sorption of proteolytic enzymes such as terrilytin. 

A polyfunctional cation-exchange resin prepared by heating a mixture of furfural and /)-phenolsulphonic acid with a prepolymer from furylacrylic add at 60 °C for 5-6 h is stable up to 100 °C, swells 135 % in water (in H form), and possesses static exchange capadty of 4.9-5.0, 2.3, 2.7, and 3.5 meq/g for O.IN NaOH, O.IN CaQj, —COOH groups, and O.IN salsolidine, respectively. 

Figure 10.7 Separation of small amounts of ammonium in the presence of alkali and alkaline-earth metals in drinking water on a high-capadty weak acid cation exchanger. Separator column lonPac CS16 column dimensions 250 mm X 5 mm i.d. column temperature ...

The natural choioe of a sqMuation technique for both inorganic cations and anions is icm-exdiangB duomatography. The standard detection technique for these analytes is conductivity detection. This requires a low background conductance of the mol phase. Special techniques have been developed under the name of i< i diromatograpby that combine spedal low-capadty ion exchangers with special mobile phases. For many analytical proble cookbook methods have been worked out by the su q>Iiers of ion-chromatography equipment Therdore there is usually little need to develop new methods. 

---