Model-guided intensification of photocatalytic reactions in a parallel-plate microfluidic reactor with immobilized $TiO_2$

Ambrožič, Rok (author), Žerjav, Gregor (author), Šketa, Borut (author), Finšgar, Matjaž (author), Pintar, Albin (author), Plazl, Igor (author)

We report the development of immobilized TiO$_2$ photocatalyst films integrated into a transparent microfluidic reactor for hydroxyl‑radical-based advanced oxidation. Spin-coated TiO$_2$ films using a TEOS binder were homogeneous, mechanically robust, and retained anatase crystallinity and optoelectronic properties. Structural and chemical characterization (FTIR, XRD, SEM-EDX, profilometry, CHNS) confirmed Ti–O–Si linkages, uniform elemental distribution, and UV-induced surface reorganization accompanied by increased roughness. Photocatalytic activity was evaluated using coumarin as a fluorescent probe to comparatively assess $^•$OH-related activity. The films exhibited reproducible radical generation after UV preconditioning, while prolonged irradiation caused only minor surface deactivation. In a parallel-plate microfluidic reactor, significantly higher 7-hydroxycoumarin formation was achieved compared to batch operation, reflecting pronounced process intensification. The microfluidic system exhibited substantially improved photon utilization (approximately sixfold higher apparent quantum yield) and nearly three orders of magnitude higher volumetric productivity, demonstrating more efficient coupling between photon absorption, mass transport, and surface reaction under continuous-flow conditions. A two-dimensional convection–diffusion model with pseudo-first-order surface kinetics reproduced experimental trends and enabled estimation of apparent surface rate constants. Simulated concentration fields revealed operation in a photon- and surface-kinetics-controlled regime under the applied conditions. Overall, this work establishes a model-guided framework combining reproducible catalyst immobilization, quantitatively demonstrated microfluidic process intensification, and predictive analysis to support rational reactor design and the development of intensified photocatalytic systems.

• Language: English
• Keywords: TiO$_2$ immobilized films, parallel-plate microfluidic reactor, advanced oxidation processes, hydroxyl radical generation, photocatalytic process intensification, model-based design
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 14 str.
• Numbering: Vol. 26, art. 101207
• PID: 20.500.12556/RUL-182368
• UDC: 66.097:544.526.5:546.82-31
• ISSN on article: 2666-8211
• DOI: 10.1016/j.ceja.2026.101207
• COBISS.SI-ID: 277360899
• Publication date in RUL: 08.05.2026

Record is a part of a journal

• Title: Chemical engineering journal advances
• Publisher: Elsevier B.V.
• ISSN: 2666-8211
• COBISS.SI-ID: 56312067

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: TiO$_2$ imobilizirani filmi, mikrofluidni reaktor z vzporednimi ploščami, napredni oksidacijski procesi, generiranje hidroksilnih radikalov, intenzifikacija fotokatalitskih procesov, modelno podprto načrtovanje