Porous geopolymers as innovative adsorbents for the removal of organic and inorganic hazardous substances: a mini-review

The geopolymerization process is a cost-effective, innovative, and promising green technique for the synthesis of geopolymer materials from industrial residues and natural materials. These materials found many applications in the environmental field like water treatment. In the last years, geopolymer materials are elaborated and applied for the remediation of inorganic and organic pollutants from wastewaters, as they are also modified by agents to improve their specific surface area and type of surface function to increase the adsorption performances. This mini-review reports the elaboration of the porous geopolymers by several feedstocks rich in aluminosilicate materials, solution activators, and foaming agents and their effectiveness in the remediation of contaminated aqueous mediums. Adsorption nature and mechanism of hazardous compounds onto porous geopolymers are summarised and discussed. The capacity and reuse of porous geopolymer materials to eliminate hazardous contaminants from aqueous environments and wastewater were considered comparable to that of other materials. Future investigations could focus on monitoring the porosity and surface type of porous geopolymer in order to improve its application to other pollutants, such as pharmaceutical pollutants, active radials, salts, pesticides, and herbicides, as well as monitoring their effectiveness in other treatment processes, such as immobilisation, encapsulation, and photodegradation.