In the study of geopolymer, the researchers found very early that the end products of geopolymerization have zeolite-like structures. Because the Si/Al molar ratios and alkali component contents are not fixed in different geopolymers, it is difficult to determine the zeolite-like structure in geopolymer. As can be seen from the numerous studies, both the geopolymer and zeolite have similarities in composition and structure. This article identified the structural heredity characteristic between the geopolymer and zeolites, in order to provide a theoretical foundation for exploring geopolymer and broaden the application field of geopolymer. Nowadays, extensive studies have been conducted concerning the potential applications of geopolymers in adsorbing and immobilizing heavy metal in wastewater treatment based on its zeolite-like structure. As a green and low-cost heavy metal adsorbent, geopolymers have excellent performance on Pb2+, Cu2+, Ni2+, Cr3+, Cd2+ adsorption. The initial ion concentration, pH of heavy metal solution, adsorption temperature, and adsorbent dosage have significant impact on the adsorption amount of adsorbent. The kinetic and isotherm researches show that the adsorption process of geopolymer is fit to the second order kinetic model and is proved to be Langmuir adsorption, which is monolayer adsorption. There has been detail researches focused on adsorption conditions of geopolymer adsorbent, and excellent adsorption performance could be obtained under optimal condition. The adsorption amount of geopolymer adsorbent is obviously higher than 4A molecular sieve. It fully demonstrated the feasibility of using geopolymer as heavy metal adsorbent. |