UV-LEDs assisted preparation of silver deposited TiO2 catalyst bed inside microchannels as a high efficiency microphotoreactor for cleaning polluted water

• Simple and inexpensive fabrication of a microreactor using CO2 laser technique.
• Sol–gel preparation of TiO2 catalyst bed inside microchannels.
• Photodeposition of Ag onto TiO2 catalyst bed under UV-LEDs light irradiation.
• Photocatalytic removal of terephthalic acid using Ag/TiO2 catalyst microreactor.
• Optimization of the effects of operational key factors using RSM technique.

In this study, first a stainless steel microreactor composed of an array of microchannels was fabricated using CO2 laser as a simple, rapid, and inexpensive technique. Then, TiO2 catalyst bed was synthesized using the sol–gel method by pumping titanium n-butoxide/ethanol and water into the microchannels. A silver nitrate solution was pumped into the TiO2 catalyst bed microchannels in the presence of UV-LEDs irradiation for Ag+ reduction to silver metal. Photocatalytic efficiency of Ag/TiO2 microreactor was studied in the removal of terephthalic acid as a model organic pollutant under UV-LEDs irradiation. The effect of silver content was investigated on the photocatalytic efficiency of the designed microreactor. The Ag/TiO2 catalyst bed microreactor with 0.8 wt% silver content indicated a higher photocatalytic efficiency than the other Ag/TiO2 and pure TiO2 catalyst beds, and commercially available TiO2-P25 catalyst. The optimum content of silver nanoparticles onto TiO2 catalyst bed extended the lifetime of photogenerated electron–hole pairs and improved its photocatalytic efficiency. The relationship of structure and performance of prepared catalyst beds has been established by using various techniques, such as XRD, SEM, HRTEM, EDX, DRS, and PL. In addition, the effects of operational variables were optimized by using response surface methodology and the reusability of microreactor was studied.

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