Abstract:

Photofluidics can combine photocatalytic reaction with microfluidic technology, greatly improve light utilization and reaction rate, and achieve efficient enhancement of photocatalytic water treatment. The design and optimization of microreactor structure is one of the research focuses. In this work, we first use computational fluid dynamics simulation to optimize the number of channels, and design a 5-level tree-shaped microfluidic planar reactor. The planar microreactor has a 12 mm × 12 mm reaction chamber enclosed by TiO₂ coated glass slide as bottom substrate and polydimethylsiloxane board as the top cover, and a microstructured UV-cured NOA-81 layer is as the sealant and flow input/output. Subsequently, photocatalytic performance is investigated by tuning the microreactor overall height. This is evidenced by our findings in this paper that the degradation and continuous operation performance of the 50 μm microreactor is better than that of 100 μm microreactor. In the photocatalysis experiment, the methylene blue is used as a simulated wastewater to study the performance of planar microreactors and tank reactors, including reaction kinetics, microreactor pollution problems and continuous operation performance. It is shown that when the microreactors operate at different flow rates, the methylene blue can achieve continuous and high-efficiency photocatalytic degradation, and the degradation rate is much higher than the tank reactor. When the flow rate is 55 μl/min, the degradation rate of 5×10^-5 mol/L methylene blue can reach 95%, which means that the planar microreactors can maintain good continuous operation performance and reusability. Planar micreactor inherits the merits of microfluidics, such as huge specific surface area, efficient and stable reaction, and easy control, and offers an efficient and feasible scheme for water treatment.

Key words: microreactor, microchannels, photocatalysis, degradation, stability

摘要：

光流体学可以将光催化反应与微流控技术结合，大幅提高光利用率和反应速率，实现对光催化水处理的高效强化，其中微反应器结构的设计与优化是研究重点之一。首先利用流体力学模拟分析优化通道级数，设计了5级树状通道平板反应器。进而，通过调控通道高度，研究不同高度的微通道对其光催化性能的影响。研究发现50 μm微反应器的降解性能及连续操作性能均优于100 μm。同时以亚甲基蓝为模拟废水对微反应器及釜式反应器的反应动力学、微反应器污染问题、连续操作性能等进行研究。研究表明，微反应器在不同流速下对亚甲基蓝均能实现连续高效降解，降解率远高于釜式反应器。当流速为55 μl/min时对5×10^-5 mol/L亚甲基蓝可达到95%的降解率并保持较好的连续操作性能及重复使用性能。

关键词: 微反应器, 微通道, 光催化, 降解, 稳定性