Hybrid nanomaterials integrating magnetic and semiconductor phases offer promising multifunctional platforms for wastewater remediation; however, their stabilization and recovery remain challenging. In this study, Fe3O4 and ZnTiO3/TiO2 nanoparticles were incorporated into a rice husk ash-based geopolymer matrix to develop hybrid nanocomposites for synergistic adsorption–photodegradation of methylene blue (MB) and methyl orange (MO). The materials were synthesized via alkaline activation followed by nanoparticle incorporation, and characterized by XRD, XRF, FTIR, SEM, EDX, BET surface area analysis, and pHPZC determination. XRD confirmed the presence of nanocrystalline Fe3O4 and ZnTiO3/TiO2 phases while preserving the amorphous aluminosilicate framework. Modified powders exhibited higher specific surface areas (up to 198 m2 g−1) compared to the unmodified geopolymer. Adsorption followed the Langmuir isotherm and pseudo-second-order kinetics, with spontaneous and exothermic behavior. Under UV irradiation, the ZnTiO3/TiO2-modified composite achieved photodegradation efficiencies up to 94% for MB and 92% for MO, whereas the Fe3O4-modified material combined adsorption capacity with magnetic recoverability. These results demonstrate that nanoparticle incorporation enables multifunctional performance while maintaining structural integrity of the geopolymeric matrix.
Jaramillo-Fierro et al. (Sun,) studied this question.