Photocatalytic activity of TiO2 films over commercial 3D printing polymers

CLAUDIO PASSALIA; FLORES, MARINA; DOPAZO MANUEL; BRANDI, RODOLFO J.

Buenos Aires

Congreso; WCCE11 - 11th WORLD CONGRESS OF CHEMICAL ENGINEERING; 2023

Asociación Argentina de Ingenieros Químicos AAIQ

Introduction: 3D printing is an emerging technology with recent developments and applications in the industry sector,particularly in medical and chemical fields. The use of 3D printing is a low-cost method for creating functional parts andmechanisms that are capable of a variety of functions. 3D printing polymers are interesting substrates for photocatalyticTiO2 thin films and may have an extensive application in photocatalytic processes. The aim of this work is to evaluateand compare the performance of different substrate polymers for a photocatalytic reactor, using titanium dioxide (TiO2)and near UV radiation. The selected target pollutant for the activity tests is dichloromethane. Methodology: three printingmaterials namely PLA, ABS and PETG were selected considering their market availability. Rectangular samples of eachplastic were fabricated. Different sample sizes were used for the determination of catalyst loading, catalyst adherence,optical properties, and photocatalytic activity tests. The TiO2 catalyst (Aeroxide P25) was immobilized onto the polymericsupport by a series of dip-coating cycles in a 100 g/L aqueous suspension. Catalyst loading and adherence weredetermined by gravimetric methods. The transmittance and reflectance of the samples were determined in aspectrophotometer with integrating sphere (Optronic OL50). For the photocatalytic activity tests, the coated sampleswere put inside a sandwich-type acrylic reactor. In order to avoid mass transfer limitations to the catalyst surfaces, thecoated plastic flat plate is located at a distance of 3mm from each reactor window. The UVA radiation sources are twosets of actinic lamps (Sylvania F15W T12) which provide a uniform flux over the reactor window. The reactor operatesin continuous mode, in one pass with no recycle. A continuous air stream feeds the reactor with a known concentrationof dichloromethane and relative humidity. Dichloromethane gas was delivered online by a custom-made pressurizedgas cylinder. The desired dichloromethane concentration at the reactor inlet is obtained by adequate regulation of massflow controllers. A set of experimental runs were conducted by variation of the substrate material and the number ofcatalyst coating cycles. In order to make the results comparable, all operating variables were kept constant: inletdichloromethane concentration, total flow rate, radiation flux, and relative humidity. Results and conclusion: All threeplastic materials could be coated with TiO2. The catalyst loadings achieved are PETG > PLA > ABS. The measuredoptical properties are consistent with the high absorption of the catalyst for wavelengths < 385 nm. The photo oxidationtests performed with dichloromethane showed the feasibility of organic removal from air. The obtained conversion levelsfor dichloromethane oxidation are as follows: PETG 15-17%; ABS 17-19%; PLA 25-30%. Our study indicates thatcommodity plastics employed in 3D printers can be functionalized by deposition of photocatalytic TiO2. Thesemiconductor provides them with novel properties and opens up new fields of application for these materials. Thesethermoplastic materials, have great potential in the reactor design and optimization in the field of environmental andchemical engineering in general, for the elimination of chemical pollutants by advanced oxidation processes and thecombination with solar radiation.