Waste‐to‐resource synthesis of TiO 2 /activated carbon nanocomposites from coffee husk and ilmenite for tetracycline removal

A waste‐to‐resource TiO 2 /activated carbon (TiO 2 /AC) nanocomposite was synthesized from Vietnamese Robusta coffee husk and locally sourced ilmenite for tetracycline (TC) removal from aqueous solution. Coffee husk was converted into porous activated carbon, while ilmenite was used as the titanium precursor, enabling the integration of agricultural and mineral‐resource valorization into a single photocatalytic material. The TiO 2 /AC composite was prepared through in situ deposition followed by calcination, producing an anatase–rutile TiO 2 phase anchored on a porous carbon matrix. Scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller, UV–vis diffuse reflectance spectroscopy, and photoluminescence analyses confirmed the formation of a hierarchical TiO 2 /AC structure with preserved mesoporosity, improved light absorption, and suppressed charge recombination. The activated carbon exhibited a high specific surface area of 535.53 m 2 g −1 and a pore volume of 0.16 cm 3 g −1 , whereas TiO 2 /AC retained a surface area of 211.36 m 2 g −1 with an increased pore volume of 0.38 cm 3 g −1 , indicating the formation of additional interparticle mesoporosity. Dark adsorption experiments showed that TC uptake on TiO 2 /AC was mainly surface‐controlled and heterogeneous, with pseudo‐first‐order and Elovich models providing better kinetic fitting than the Bangham model. Under simulated sunlight, TiO 2 /AC achieved 97.01% TC removal, exceeding pristine TiO 2 and AC, demonstrating the combined contribution of adsorption enrichment and photocatalytic oxidation. Radical scavenger tests identified photogenerated holes, hydroxyl radicals, and superoxide radicals as the principal reactive species. The composite retained high activity after five cycles, with removal efficiency remaining above 91%. These findings indicate that coffee‐husk‐derived activated carbon can act as an effective adsorptive and interfacial modifier for ilmenite‐derived TiO 2 , offering a low‐cost and environmentally compatible strategy for antibiotic‐contaminated wastewater treatment.