In this study, nanoporous TiO₂ with hierarchical micro/nanostructures was synthesized on a large scale by a facile one-step solvothermal method at a low temperature. A series of characterizations was performed and carried out on the as-prepared photocatalysts, which were applied to the degradation of the antibiotic tetracycline (TC). The results demonstrated that nanoporous TiO₂ obtained at a solvothermal temperature of 100 °C had a spherical morphology with high crystallinity and a relatively large specific surface area, composed of a large number of nanospheres. The nanoporous TiO₂ with hierarchical micro/nanostructures exhibited excellent photocatalytic degradation activity for TC under simulated sunlight. The degradation rate was close to 100% after 30 min of UV light irradiation, and reached 79% only after 60 min of visible light irradiation, which was much better than the photodegradation performance of commercial TiO₂ (only 29%). Moreover, the possible intermediates formed during the photocatalytic degradation of TC were explored by the density functional theory calculations and HPLC-MS spectra. Furthermore, two possible degradation routes were proposed, which provided experimental and theoretical support for the photocatalytic degradation of TC. In this study, we provide a new approach for the hierarchical micro/nanostructure of nanoporous TiO₂, which can be applied in industrial manufacturing fields.

Analcime has demonstrated potential for a variety of applications in technology, especially in adsorption and heterogeneous catalysis. In this study, synthetic analcime was investigated by using sea sand as a silica source. Sea sand was first treated with HNO₃ and NaOH. The pretreated sea sand as the silica resource and Al(NO₃)₃ as the aluminum source were used for the hydrothermal synthesis of analcime with different ratios of Si/Al and Na/Si. The products obtained under different conditions were characterized by X-ray diffraction. The results showed that analcime synthesized using acid-treated sea sand was mixed with other impurities, such as quartz and sodalite. Pure analcime was obtained using alkali-treated sea sand as the silica source. The analcime prepared under an optimized synthesis condition was further investigated via SEM, FT-IR, and TG. The particle size of the prepared analcime ranged from 40 to 50 μm. The adsorption ability of analcime was studied, and the Cu²⁺ adsorption process was found to follow a pseudo-second-order kinetic model.