Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions

Abstract

On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology–fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01–0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics.

Review of Experimental Setups for Plasmonic Photocatalytic Reactions

“…These reactors characterized by a small size, low power consumption, and waste reduction properties, rendering them green technologies. MOFC reactors [70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85] have been used in some photocatalytic reactions. Although they have low processing volume, MOFC reactors have features that contribute to high processing efficiency in many applications: (i) Their small fluid channel size results in a high mass transfer rate, thus enabling effective transportation of reactants and products.…”

An Integrated Optofluidic Platform Enabling Total Phosphorus On-Chip Digestion and Online Real-Time Detection

“…The details and cross section of the Z-shaped flow cell are shown in Figure 1b, which is mainly constructed by PDMS-based microchannel with the dimension of 10 mm (L) × 1.5 mm (W) × 1.5 mm (H), and a couple of optical fiber collimators output with a multimode optical fiber (MMF) pigtail embedded on both sides of the flow cell [15]. The fabrication details are similar to our previous work [6]. Here, the length of flow cell and light path is designed as 1 cm by the Beer-Lambert law, and the outer diameter of the OFC is 1 mm for its assembly and easily alignment.…”

“…Firstly, the hollow optical fiber for phosphorus digestion reaction was spirally coiled fixed on a glass side by UV-curable adhesive on a glass slide as shown in Figure 1a inset. Then, the microchannels for the chromogenic reaction and the Z-shaped flow cell were fabricated by the standard photolithography [6]. Before molding the PDMS-based microchannel, the sites for fixing the OFC had also been designed and reserved in advance.…”

Paper-based Photocatalysts Immobilization without Coffee Ring Effect for Photocatalytic Water Purification

“…Water pollution is a serious problem especially in modern industrial cities, which is a bad by-product of the prosperity of industry. Photocatalytic water purification is important for the degradation of organic pollutants [1][2][3][4][5], attracting intensive interest and the development of various research works on photoreactors, photocatalysts, and illumination. However, the photocatalytic efficiency of the traditional slurry method is still disappointing due to the low surface to volume ratio (reported as <600 m 2 •m −3 ), long diffusion length, and low photon utilization [6].…”