Prototyping of Photocatalytic Microreactor and Testing of Photodegradation of Organic Dye

Abstract

A photocatalytic microreactor is defined as a microfluidic device, which is integrated with a photocatalytic coating of TiO 2 deposited on the inner surface of microchannels. This device is capable of degradation of organic dye solution in water in a continuous flow under the action of ultraviolet light. The objectives of this work were to present a rapid and economically viable approach for the prototyping photocatalytic microfluidic devices and to evaluate their photodegradation capability for organic dyes by ultraviolet-visible spectrophotometry. Prototyping of polydimethylsiloxane PDMS/TiO 2 /glass microreactors includes several procedures such as mold preparation, microchannel confection on PDMS surface, deposition of TiO 2 on these microchannels, O 2 plasma treatment of PDMS/TiO 2 and glass surface for sealing these two parts. The efficiency of the photocatalytic microreactors was evaluated by fluxing two organic dye solutions, rhodamine B and methylene blue, with different flow rates of between 2 and 4 mL h -1 . When the flow rate at 2 mL h -1 was applied, discoloration of ~ 65% was achieved for both dye solutions, while PDMS/glass microchannels, without TiO 2 film, demonstrated much lower discoloration of between 24 and 42% for rhodamine B and methylene blue, respectively. This confirmed that TiO 2 was successfully deposited onto PDMS microchannels. ]]>

Prototyping of Meso- and Microfluidic Devices with Embedded TiO2 Photocatalyst for Photodegradation of an Organic Dye

“…Recently, Lamberti [50] incorporated TiO 2 nanoparticles directly on the surface of PDMS to build a photocatalytic device constituted completely by PDMS. Differently to Pandoli et al [40], who built a photocatalytic device PDMS-TiO 2 -glass, this author used a PDMS-TiO 2 -PDMS reactor to study the photodegradation of a methylene blue solution (6 × 10 −5 mol/L) with a high intensity UV light powered at 60 mW/cm 2 . In this work, we propose a rapid and low-cost construction of meso-and microfluidic devices with embedded TiO 2 photocatalyst on PDMS for the photodegradation of rhodamine B, more stable than methylene blue as shown on our previous work [40].…”

“…Differently to Pandoli et al [40], who built a photocatalytic device PDMS-TiO 2 -glass, this author used a PDMS-TiO 2 -PDMS reactor to study the photodegradation of a methylene blue solution (6 × 10 −5 mol/L) with a high intensity UV light powered at 60 mW/cm 2 . In this work, we propose a rapid and low-cost construction of meso-and microfluidic devices with embedded TiO 2 photocatalyst on PDMS for the photodegradation of rhodamine B, more stable than methylene blue as shown on our previous work [40]. In order to evaluate and compare the photocatalytic efficiency in both devices, we used as the test model the photodegradation of rhodamine B dye solution (10 −5 mol/L), applying different UV LED light power, 25 and 12.5 mW/cm 2 .…”

“…There are several techniques for prototyping photocatalytic meso-and microfluidic devices [22,25] and various methods to integrate TiO 2 into flow reactors systems, such as chemical vapor deposition on pyrex [41], drop casting on PDMS [40], electrospun nanofibrous TiO 2 on glass [42], calcination [43] on glass, coating on fiber glass [44], and adhesive substrate [45]. These techniques should be rapid, simple, avoiding the use of a clean room with expensive photolithography techniques, and should have a low cost from the design stage to the final test.…”

Microfabricação De Reatores Poliméricos E Lignocelulósicos Para Fotocatálise E Reação De Cuaac Em Fluxo Contínuo

“…3 Outro grande desafio nesse processo ainda é a possibilidade de criar um protótipo simples e de rápida fabricação, com baixos recursos e de fácil reciclagem. 4 Nesse sentido, o bambu gigante (Dendrocalamus Giganteus) surge como uma fonte de biomassa, abundante em biopolímeros e feixes vasculares contendo microcanais internos retos e paralelos entre si, podendo ser modificados quimicamente e funcionalizados, e empregados como moldes (biotemplates) para microrreatores e suportes sólidos lignocelulósicos em catálise heterogênea. A utilização do bambu como biotemplate exclui a necessidade de um modelo mestre e técnicas caras de microfabricação.…”

“…Representação do processo fotocatalítico na superfície do TiO2. Adaptado dePandoli et al, 2015 O TiO2 comercial mais utilizado em fotocatálise é o P25, que é constituído por 30% rutilo e 70% anatase, formas alotrópicas do TiO2. O seu uso está ligado à sua grande área específica em comparação com outros semicondutores (50 m 2 /g), à sua complexa microestrutura cristalina resultante de seu método de preparação que promove melhor separação de cargas inibindo a recombinação, alta estabilidade, baixo custo, alto desempenho fotocatalítico, e segurança para os seres humanos e o meio ambiente92,93 .…”