(167au) An Overview of the Fundamentals and Recent Advances in the Synthesis and Sustainable Applications of Porous Geopolymers

Geopolymers are novel inorganic polymeric materials synthesized from aluminosilicate sources via alkaline activation at relatively low temperatures. There are three common categories of aluminosilicate materials that can be used for geopolymer synthesis, namely, coal fly ash and incineration ash, slags such as granulated blast (steel) or furnace (iron) slag, and clays such as metakaolinite or calcined clay. Geopolymers are well-known materials which often consists of high pore volume and large surface area. Besides powdered form, porous geopolymer can be fabricated into different shapes of larger size, such as spherical and monolith, as porous geopolymeric adsorbent has higher porosity. For example, porous geopolymer is a modified conventional geopolymer adsorbent that contains relative high volume of voids or pores (elevated surface area and pore volume). Spherical porous geopolymer adsorbent can be fabricated through suspension and solidification methods. Geopolymerisation is not a new concept and has been used as low-cost and environmentally-benign alternative to conventional energy-intensive Portland cement-based construction materials. Also, it has been used as barriers in immobilizing toxic and radioactive metals via the combination of physical encapsulation and chemical stabilization, and/or physicochemical, electrostatic, and sorption mechanisms. However, emerging applications of geopolymers are in the environmental (adsorption of contaminant in liquid and gas phases); catalysis and energy (photocatalysis – water splitting & H₂ production, CO₂ conversion, and energy conversion & storage - supercapacitors); advanced materials; and medicine & health systems (e.g., production of biomaterials for drug delivery) areas, and as functional-surface-coating materials for inhibiting the growth of bacteria. This paper will examine the recent scientific advances in the synthesis of porous and conventional powdered geopolymers; and their potential sustainable utilization technology fields, with insights into future research directions, prospects and challenges for economic large-scale production.

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