Preparation of novel polysulfone capsules containing zirconium phosphate and their properties for Pb2+ removal from aqueous solution

Zirconium phosphate (ZrP) was immobilized by microencapsulation process of polysulfone (PSF) to form the polysulfone capsules containing ZrP (PSF@ZrP capsules) successfully by using phase inversion precipitation technique, and the PSF@ZrP was employed as capsules adsorbents to remove Pb(2+) presented in aqueous solution. The result shows that an encapsulation capacity of 50% (mass ratio, PSF: ZrP = 1:1) should be the optimal proportion of ZrP encapsulated with PSF. The characterization of the macroscopical and microcosmic physical properties of the resulting PSF@ZrP capsules was carried out by the DTA-TG, XRD, BET and SEM. Meanwhile, the adsorption properties of the PSF@ZrP capsules for Pb(2+) were investigated by batch methods. It was found that the adsorption of the PSF@ZrP capsules for Pb(2+) would be pH dependent due to the ion-exchange mechanism, and the uptake of Pb(2+) was slightly influenced with the concentration of coexisting cations (Na(+), K(+)) in a low range. Furthermore, the calculated thermodynamics parameters exhibit that the nature of the adsorption process is spontaneous and exothermic. After six times of adsorption-regeneration cycles, no significant loss of adsorption capacity was observed, indicating the good stability of the PSF@ZrP capsules. Consequently, the PSF@ZrP capsules in this work can provide a potential application for treatment process of Pb(2+)-containing wastewater.