Purification and functional modification of natural palygorskite/attapulgite clay minerals for advanced environmental remediation: a review

Palygorskite (Pal), a naturally abundant fibrous clay mineral featuring one-dimensional nanochannels, abundant surface hydroxyl groups and intrinsic metal species, has attracted increasing attention as a sustainable material for environmental remediation. This review systematically summarizes recent advances in the purification, functional modification and environmental remediation applications of Pal, with particular emphasis on the structure–property–performance relationship that controls its environmental functionality. Purification is discussed as a structural regulation process rather than a simple impurity removal process, whereby mechanical separation, crystal-bundle disaggregation and integrated purification strategies improve particle dispersion, expose reactive surfaces and establish the structural foundation for subsequent functionalization. Functional modification strategies, including acid/alkali activation, thermal treatment, organic functionalization and elemental/composite engineering, are further classified according to their underlying regulation mechanisms, illustrating how they tailor the surface chemistry, pore architecture, electronic structure and active-site distribution of Pal. Building upon these structural optimizations, recent environmental remediation applications are discussed from the perspectives of adsorption, photocatalysis, Fenton-like oxidation and membrane separation, highlighting the evolution of Pal from a passive support to an intrinsically functional material capable of pollutant enrichment, interfacial charge transfer and catalytic activation. Finally, current challenges and future opportunities are outlined, particularly the controllable regulation of intrinsic active sites and the establishment of quantitative structure–property–performance relationships, guiding the rational design and high-value utilization of Pal-based environmental materials.