SYNOPSISThis study was to improve the performances of nylon 4 membranes for washing wastewater treatment of nuclear power plants, e.g., removal of detergent and salt by membranes. The effects of the degree of grafting and ionization on the reverse osmosis performances of acrylic acid ( AA) -grafted nylon 4 membranes by y-ray irradiation modification were investigated. The relationships of operating conditions, such as feed concentrations of salt and detergent, operating temperature, and pressure, and the performances of water flux and solute rejection of the prepared membranes were obtained. Water flux of the prepared membranes was highly sensitive with the operating temperature. It was found that an increase in the operating pressure could increase the water flux and the impaction effect directly. Water flux and salt rejection were significantly improved by both ionized and nonionized AA-grafted nylon 4 membranes compared to ungrafted nylon 4 membranes. Water flux increased rapidly and solute rejection dropped off slightly as the grafted membranes were ionized. The 100% detergent rejection could be obtained by the nonionized AA-grafted nylon 4 membranes with 38.6 and 69.6% degrees of grafting under various operating conditions. Results obtained showed that these modified nylon 4 membranes were usable for washing waste-water treatment of nuclear power plants. 0

SYNOPSISTo enhance the degree of grafting, homografting copolymerization of 2-hydroxyethyl methacrylate ( HEMA) onto nylon 4 using a chemical initiator has been attempted. The factors that affect the grafting copolymerization are the concentration of reactants, reaction time, and temperature. The dialysis permeabilities of solutes, water content, surface energy, mechanical properties, and blood compatibility of the membrane were investigated. Under the same reaction conditions, the degree of grafting by the homografting method is remarkably higher than that of the heterografting method for the nylon 4-HEMA grafting system. The dialysis permeabilities of NaCl, vitamin BIZ, and ovalbumin of the homografted membrane with a 14.8% degree of grafting are 2.760, 0.392, and 0.073 X cm2/min, respectively. These permeabilities are higher than the corresponding ones of ungrafted nylon 4 membrane. The mol ratios of adsorbed fibrinogen/albumin ( F / A ) of the heterografted membranes were found to decrease from 0.53 to 0.33, and the surface energy, to increase from 40.6 to 46.4 dyn/cm with the degree of grafting in the range of 12.5-29.9%, and their relationship is not remarkable for the homografted membranes for which the mol ratios of F / A are about 0.22-0.32 with the degree of grafting in the range of 14.8-103.8%. Observed from scanning electron micrographs of the membrane surface, denseness was found to be important to improve blood compatibility. Based on the dialysis permeabilities of solutes and the blood compatibility observed in this study, the homografted nylon 41 HEMA membrane can be considered as a hemodialysis material.