Structural and functional design of geopolymer adsorbents : a review

The water pollution derived from the discharge of heavy metals, antibiotics, dyes and surfactants wastewater, etc. has seriously affected human survival and ecological security. As an efficient and low-cost physical wastewater treatment process, the adsorption is a continuous hot spot in related scientific research and applications. Geopolymers are non-crystal or semi-crystalline materials with high-efficiency adsorption performance due to the alkali metal ions that balance the electronegative aluminosilicate skeleton can be efficiently replaced by other cations in the aqueous environment. The related studies of different application conditions, service objects and morphological differences of geopolymer adsorbents based on structure–function design have been in-depth exploration and investigation. This review aims to summarize the research progress of the structure–function design based on the geopolymerization mechanism and kinetics and service requirements. An overview of service characteristics and progress of geopolymers in the wastewater treatment field (e.g., dyes, heavy metals, radionuclides, surfactants, antibiotics, ammonium, phosphorus, nitrogen and CO2, etc.) are systematically discussed. And the evolution and development of morphological differences and the relationship of structure–function design of geopolymer adsorbents were compared and reviewed. Finally, the challenge worth overcoming, the trends worth considering and perspectives worth developing are highlighted.