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.