The nanoparticles tin oxide (SnO₂) has been successfully synthesized via a sol-gel method. The as-prepared SnO₂ was characterized using thermogravimetric analysis coupled with mass spectroscopy, X-ray diffraction and scanning electron microscope. Batch experiments were carried out to study the adsorption kinetics of Congo red azo dye on SnO₂. The effect of varying parameters such as contact time, initial dye concentration and adsorbent dose on the adsorption process was investigated. The results showed that the SnO₂ catalysts has high crystallinity with tetragonal rutile structure and average particle size about 13–23 nm. The untreated sample SnO₂-80 exhibited high efficiency (84.41 %) after 60 min of exposure time, which was 2 times as much as that of SnO₂-450 sample. The adsorption process was found to be highly dye concentration and adsorbent dose dependent. Pseudo-second-order kinetic model gave the best fit, with highest correlation coefficients (R ² ≥ 0.99). Regarding the adsorption equilibrium, the experimental results suggest that the Langmuir model was applicable. The formation of hydrogen bond and the electrostatic interaction between the Sn²⁺ center and the electron rich nitrogen atoms of CR moiety were believed to be the main adsorption mechanism. These findings should be valuable for designing effectively adsorbent material and practical interest in terms of ecology and sustainable development.

Mesoporous TiO₂ photocatalysts intended for the advanced removal of clofibric acid (CA) from water were synthesized by the sol-gel method in a medium containing cetyl-trimethyl-ammonium bromide (CTAB) and urea, using either ethanol or isopropanol to dilute the TiO₂ precursor. The activation of the samples was undertaken at 550, 650 and 750 °C. The XRD revealed that the nature of the solvent resulted in significant differences in the anatase-to-rutile ratios obtained at different temperatures. The specific surface area values were situated between 9 and 43 m²·g⁻¹ and the band gap values were similar for all the samples. The photocatalytic activity of the prepared samples was examined for the degradation of CA, an emergent water contaminant. The photocatalytic tests performed under UV-A irradiation revealed that the photo-reactivity of these materials depends on the calcination temperature. The best results were obtained for the samples calcined at 750 °C, which showed high yields of CA elimination, as well as almost complete mineralization (over 95%) after 180 min of reaction. Good results in terms of catalyst reusability in the reaction were found for the catalyst showing the highest photo-reactivity. Therefore, the samples can be considered good candidates for future water remediation applications.