A Comparative Study on Optofluidic Fenton Microreactors Integrated with Fe-Based Materials for Water Treatment

The catalysts employed in catalytic reactors greatly affect the reaction efficiency of the reaction system and the reactor’s performance. This work presents a rapid comparative study on three kinds of Fe-based materials integrated into an optofluidic Fenton reactor for water treatment. The Fe-based sheets (FeSiB, FeNbCuSiB, and FeNi) were respectively implanted into the reaction chamber to degrade the organic dyes with the assistance of H2O2. In the experiment, by adjusting the hydrogen peroxide concentration, flow rate, and light irradiation, the applicable conditions of the Fe-based materials for the dye degradation could be evaluated quickly to explore the optimal design of the Fenton reaction system. The results indicated that FeNi (1j85) exhibits excellent degradability in the microreactor, the reaction rate can reach 23.4%/s at the flow rate of 330 μL/min, but its weak corrosion resistance was definitely demonstrated. Although the initial degradability of the microreactor by using FeNbCuSiB (1k107) was not as good as that of 1j85, it increased after being reused several times instead, and the degradation efficiency reached >98% after being reused five times. However, the FeSiB (1k101) material shows the worst degradability and recycling. Therefore, in contrast, 1k107 has the greatest potential to be used in Fenton reactors for practical water treatment

Rapid-Response and Wide-Range pH Sensors Enabled by Self-Assembled Functional PAni/PAA Layer on No-Core Fiber

The measurement of pH has received great attention in diverse fields, such as clinical diagnostics, environmental protection, and food safety. Optical fiber sensors are widely used for pH sensing because of their great advantages. In this work, an optical fiber pH sensor is fabricated, by combining the merits of the multimode interference configuration and pH-sensitive polyaniline/polyacrylic acid (PAni/PAA) coatings, which was successfully in situ deposited on the no-core fiber (NCF) by the layer-by-layer (LBL) self-assembly method. The sensors’ performance was experimentally characterized when used for pH detection. It has a high sensitivity of 0.985 nm/pH and a great linear response in a universal pH range of 2–12. The response time and recovery time is measured to be less than 10 s. In addition, its temperature sensitivity is tested to be about 0.01 nm/°C with a low temperature crosstalk effect, which makes it promising for detecting pH in the liquid phase with temperature variation. The sensors also demonstrated easy fabrication, good stability, and repeatability, which are adapted to pH detection in most practical applications