Аннотация
Hydroxyapatite (HAp)–clay composites have attracted increasing interest as multifunctional materials for environmental remediation and biomedical applications owing to the complementary physicochemical properties of calcium phosphate and clay minerals. However, the influence of clay mineralogy on composite formation, interfacial interactions, and functional performance remains insufficiently integrated into existing application-oriented reviews. This review critically examines HAp–clay composites from a mineralogical and structure–function perspective, focusing on how clay crystal structure, morphology, layer charge, surface and interlayer chemistry, and chemical modification influence composite formation, reactivity, and functionality. Environmental applications are evaluated for the removal of heavy metals, radionuclides, fluoride, dyes, and pharmaceutical contaminants, with particular attention to adsorption mechanisms, solution chemistry, and limitations in cross-study comparisons. Biomedical applications are discussed in relation to bone tissue engineering, implant coatings, mineralization, and therapeutic delivery. The analysis highlights the distinct roles of expandable layered montmorillonite, tubular halloysite, and fibrous palygorskite in controlling HAp distribution, interfacial organization, and composite architecture. Montmorillonite provides exchangeable interlayer cations and tunable interlayer environments, whereas halloysite offers tubular surfaces and internal lumens for particle organization and functional loading. Both minerals can provide nanoscale confinement through different structural environments. The reviewed evidence indicates that composite performance depends not only on the constituent mineral phases but also on modifying species, preparation routes, and application-specific conditions. Further systematic investigations using well-characterized clay minerals and standardized experimental conditions are required to establish reliable mineralogy–interface–structure–function relationships for the rational design of HAp–clay composites.