Preparation of a Porous Geopolymer (SPG) to be Used as an Adsorbent for Cu2+ Removal

A porous geopolymer was synthesized using steel slag (accounting for 71.6 wt %) with the aim of effectively removing Cu2+ ions. The chemical composition and microstructure of this material were investigated using X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope analysis, and BET method. The effects of H2O2 doping, H2O doping, and the curing temperature on the properties of this porous geopolymer were systematically investigated. Subsequently, the adsorption behavior of the porous geopolymer toward Cu2+ was explored through static adsorption experiments. The findings reveal that there are a higher specific surface area and pore capacity for the porous geopolymer compared to the original steel slag, with a total porosity of 90.3%, compressive strength of 0.29 MPa, and volume water absorption rate of 69.4%. The adsorption capacity of this material toward Cu2+ is found to be 36.8 mg·g–1, which is slightly superior to that of commercial spherical 4A molecular sieves. The adsorption process follows the quasi-first-order kinetic model, while the isothermal adsorption conforms to the Freundlich model.