Research on Micro-Analysis System of Dye in Water Sample Based on Magnetic Nano-TiO₂

Magnetic Nano-Photocatalytic Material (NMPC) helps separate and recover nano photocatalyst in water treatment. However, it is rarely reported that a photocatalyst can be separated online in photocatalytic microreactors. In this paper, a typical dye methylene blue was photocatalytically degraded in glass microfluidic chip by using Fe₃O₄@ SiO2@ TiO₂ (FST) as the magnetic nanocatalyst, the UV-LED as the ultraviolet light source, and ultraviolet-visible spectrophotometer as the detector. The FST was easily separated by an external magnetic field, thereby realizing rapid online detection of methylene blue. During the preparation of FST, the hydrothermal method was used to treat the obtained FST nanoparticles in 100°C boiling water bath, and the titanium-iron ratio was optimized, so as to obtain FST nano-photocatalyst with high photocatalytic performance and good dispersibility. With 1.0 g/L FST/8%H₂O₂ being the catalytic oxidation system, the sample flow rate being 300 μL/h, the reaction temperature being 45 °C, the degradation rate of methylene blue has reached 100%. It only took 25 min to complete one measurement. The FST consumed per measurement was only 125 μg. The RSD of the photodegradation rate was 2.5% (n=9).