Geopolymers as sustainable eco-friendly materials: Classification, synthesis routes, and applications in wastewater treatment

Over the past few decades, polymers have been extensively employed in various sectors attributed to their exceptional properties. The presence of vast quantities of non-degradable polymers in the environment, in addition to industrial effluents, has become one of the serious global issues. The chemically sourced polymers/ composites are potentially hazardous to the biosphere due to their slow degradation mechanism. Currently, there is a growing interest in geopolymers as upcoming competitors over synthetic polymers, efficaciously extracted from natural resources. These environment-substitutes geopolymers are exceptionally beneficial in environmental applications, particularly wastewater treatment processes. Therefore, this review article comprehensively discusses the synthesis of geopolymers/composites from different precursors. The most prevalent analytical methods used to characterize geopolymers are discussed to get insights into their physico-chemical characteristics. Moreover, the potential of different wastewater treatment technologies using geopolymers-based materials (i.e., adsorption, photocatalytic degradation, membrane filtration, and solidification/stabilization pathway) is briefly discussed to highlight the developments in the engineering treatment processes. Furthermore, the circular economy model framework proposes potential approaches to applying circular economy principles in the wastewater management sector. Overall, geopolymers can be considered as promising materials, making strides in cutting down the dependency on non-degradable polymers in wastewater remediation.