Development of fly ash and iron ore tailing based porous geopolymer for removal of Cu(II) from wastewater

This work aims to verify the feasibility of utilizing iron ore tailing (IOT) in porous geopolymer and intends to broaden the application of porous geopolymer in heavy metal removal aspect. Porous geopolymer was prepared using fly ash as resource material, which was partially replaced by IOT at level of 30%, by weight, with H₂O₂ as foaming agent and removal efficiency, adsorption affecting factors, adsorption isotherms and thermodynamics of Cu²⁺ by the developed porous geopolymer were investigated.The experimental results uncover that the porous amorphous geopolymer was successful synthesized with total porosity of 74.6%. The transformation of fly ash and IOT into foaming geopolymer leads to the formation of porous structure encouraging Cu²⁺ sorption. Batch sorption tests were carried out and geopolymer dosage, Cu²⁺ initial concentration, pH, contact time and temperature were the main concern. Both Langmuir and Freundlich models could explain the adsorption of Cu²⁺ on the porous geopolymer due to the high fitting coefficients. The uptake capacity reaches the highest value of 113.41 mg/g at 40 °C with pH value of 6.0. The thermodynamic parameters ΔHº, ΔSº and ΔGº suggests the spontaneous nature of Cu²⁺ adsorption on porous geopolymer and the endothermic behavior of sorption process.