The TiO₂/SiO₂ nanocomposite has been synthesized by a sol-gel method and investigated the effect of the SiO₂ content (0, 5, 10, 15, 20, and 50%) on the rutile-to-anatase phase transition of TiO₂ NPs. In order to increase the photocatalytic efficiency of the nanocomposite and decrease the price of material, the TiO₂/SiO₂ Nc with content SiO₂ of 15% sample is chosen for preparing silicate coating. The efficiency of photocatalytic MB and antibacterial ability in the air of W silicate coating (adding TiO₂/SiO₂ Nc (15%)) achieve almost 100% for 60 h and 94.35% for 3 h, respectively. While the efficiency of photocatalytic MB and antibacterial ability of WO silicate coating (adding commercial TiO₂/SiO₂) is about 25–30% for 60 h and 6.02% for 3 h, respectively. The presence of TiO₂/SiO₂ Nc (15%) with a larger surface area in W silicate coating can provide increased centers for absorption, photocatalytic reaction, and the contact between sample and bacteria lead to enhance the photocatalytic and antibacterial ability of W silicate coating.

This article describes the synthesis procedure of colloidal silicon quantum dot (Si QDs) from rice husk ash. The silicon quantum dots were capped with 1-octadecene by thermal hydrosilylation under argon gas to obtain octadecyl-Si QDs (ODE-Si QDs). The size separation of ODE-Si QDs was examined by the column chromatography method, which used silica gel (4063μm) as the stationary phase. Finally, we obtained two fractions of silicon quantum dot, exhibiting blue emission (B-Si QDs) with an average size of 2.5±0.73nm and red emission (R-Si QDs) with an average size of 5.1±0.68nm under a UV lamp (365nm). The PL spectra of B-Si QDs and R-Si QDs samples show maximum peak energy at 410nm (3.02eV) and 700nm (1.77eV), respectively, while the quantum yield of Si QDs decreases from 5.8 to 34.6 when the average size decreases from 2.5nm to 5.1nm. The above results of PL emission spectroscopy and UV-vis absorption show quantum confined effect in Si QDs.

The mixture of three metal ions (Cs⁺, Sr²⁺, and Co²⁺) is commonly found in radioactive waste, which induces several negative health effects. The removal of multiple metal ions is a true challenge for researchers due to the competitive adsorption of ions onto adsorbents. In this study, three metal ions, namely Cs⁺, Sr²⁺, and Co²⁺, have been successfully removed simultaneously from water using zeolite@magnetic nanoparticles (Z@Fe₃O₄ NPs). The optimized condition for the adsorption of ternary metal ions was obtained at an adsorbent weight of 0.2, pH of 6.0~7.0, and contact time of 60 min. The adsorption mechanism of ternary metal ions onto the surface of Z@Fe₃O₄ NPs was studied using the Pseudo-first-order, Pseudo-second-order, Elovich, and Intra-particle diffusion models. The Dubinin–Radushkevich Temkin, Freundlich, and Langmuir isotherm models were used to study the isotherm adsorption. The ternary metal ion adsorption (Cs⁺, Sr²⁺, and Co²⁺) on Z@Fe₃O₄ NPs was followed by the Pseudo-second-order model (PSO) with correlation coefficient (R²) range of 0.9826–0.9997. Meanwhile, the adsorption isotherms of ternary metal ions on Z@Fe₃O₄ NPs were in line with the Langmuir model with R² values higher than 0.9206, suggesting monolayer chemisorption with maximum adsorption capacities of 48.31, 15.02, and 10.41 mg/g for Cs⁺, Sr²⁺, and Co²⁺, respectively. Thus, the selectivity trend in the ternary metal ions system towards the Z@Fe₃O₄ NPs is observed to be Cs⁺ > Sr²⁺ > Co²⁺, which indicates that the competitive effect of Cs⁺ is the strongest compared to Sr²⁺ and Co²⁺ions.