Facile fabrication of inorganic polymer microspheres as adsorbents for removing heavy metal ions

Abstract

Abstract This work reports a simple preparation process of slag-based inorganic polymer microspheres (IPMs) using the suspension dispersion solidification (SDS) method. The SEM results showed that the microspheres exhibit good spherical shape with controllable diameter range within 40–1000 μm. The size of the microspheres is closely related to the temperature and dispersion rate of the suspension. Based on the results obtained by varying the temperature and dispersion rate of the suspension, it was found that the best spherical shape and the highest yield are obtained at 80°C and 800 r/min. The H2O/Na2O molar ratio of the geopolymer paste affected the BET surface area of the microspheres. The microspheres exhibited outstanding adsorption capacity towards the removal of Pb2+ (310.84 mg/g), Cu2+ (47.71 mg/g) and Cd2+ (36.26 mg/g), with their high adsorption rate attributed to their large surface area. Selectivity adsorption experiments show that the IPMs have high selectivity for Pb2+.