The invention discloses a preparation and application method of a modified
ion exchange membrane for
electrodialysis, aiming at the problems of poor selectivity, low
mechanical strength,
high energy consumption and the like of the existing
ion exchange membrane, the high-performance modified membrane is prepared by a base membrane pretreatment-functional
grafting-gradient curing synergistic process. The preparation method specifically comprises the following steps: performing ultrasonic cleaning and acid-base activation on a polyethersulfone or sulfonated
polystyrene-based membrane, soaking the polyethersulfone or sulfonated
polystyrene-based membrane in a modification solution containing an amino / carboxyl / sulfo
functional monomer, a cross-linking agent and an initiator, and performing gradient heating curing to form a stable cross-linked network; the
grafting rate of the modified membrane is 15-35%, the
ion exchange capacity is 1.8-2.5 mmol / g, the
water content is 25-40%, and the
membrane surface resistance is less than 3
omega.cm < 2 >. When the membrane is applied to an
electrodialysis device, the membrane runs under the conditions of 10-30V direct-
current voltage, 5-15cm / s flow velocity and 25-45 DEG C, the high-
salinity wastewater desalination rate is greater than or equal to 95%, and the monovalent
ion selectivity coefficient reaches 5.8-7.2; when the catalyst is used for acid-base
recovery, the H < + > migration number is 0.92-0.96, and the
energy consumption is reduced by 18-25%.