Advanced geopolymerization is a novel approach for the manufacture of geopolymers via innovative solid-state chemistry mechanism in which tailored geopolymeric precursors in solid powder form are the one part requirement, and only water is needed for its conversion to advanced geopolymeric material, in contrast to conventional process, where first solution of alkali is prepared and then mixed with silicoaluminous source materials. This novel process comprises of tailored geopolymeric precursors in solid powder form which is obtained via mechanochemical dry grinding of raw materials for prolonged hours. The basic raw materials include vitreous silica- and alumina-containing waste material/by-products, e.g. fly ash, activated by sodium hydroxide with or without sodium silicate. The solid powder needs only addition of water to form geopolymeric material. The advanced process includes solid-state reactions during dry grinding process and enables sequencing of reactions for preparation of geopolymeric material.
Per- and polyfluoroalkyl substances (PFASs) are persistent and mobile contaminants of global concern, and, while granular activated carbon (GAC) is widely used for their removal, it is limited by the high regeneration and disposal costs. This study investigates surface-modified clinoptilolite zeolites as low-cost and thermally regenerable alternatives to GAC for PFAS removal from water. Natural clinoptilolite was modified through acid washing, ion exchange with Fe3+ or La3+, grafting with aminosilane (APTES) or hydrophobic silane (DTMS), dual APTES + DTMS grafting, and graphene oxide coating. The adsorption performance was evaluated for perfluorooctanoic acid (PFOA, C8) and perfluorobutanoic acid (PFBA, C4) at 100 µg L−1 in single- and mixed-solute systems, with an additional high-concentration PFOA test (1 mg L−1). PFAS concentrations were quantified by liquid chromatography–tandem mass spectrometry (LC–MS/MS) using a SCIEX 7500 QTRAP system coupled to a Waters ACQUITY UPLC I-Class. Raw zeolite showed limited PFOA removal (4%), whereas dual-functionalized APTES + DTMS zeolites achieved up to 93% removal, comparable to GAC (97%) and superior to single-silane or metal-exchanged variants. At lower concentrations, modified zeolites effectively removed PFOA but showed limited PFBA removal (<25%), highlighting ongoing challenges for short-chain PFASs. Overall, the results demonstrate that dual-functionalized clinoptilolite zeolites represent a promising and scalable platform for PFAS remediation, particularly for mid- to long-chain compounds, provided that strategies for enhancing short-chain PFAS binding are further developed.