Scale-Up from Microreactors: Coupling Kinetics and Radiation Absorption Modeling for Photocatalytic Removal of Pharmaceuticals

The kinetic parameters of the photocatalytic degradation of single and binary solutions of the pharmaceuticals tetracycline (TC) and clofibric acid (CA) were assessed in a planar microreactor with TiO2 immobilized on the window and irradiated with simulated sunlight. The kinetics were described using a Langmuir–Hinshelwood rate model that explicitly accounts for the effect of photon absorption. A total of five parameters were fitted: two for each pollutant and one radiation-related parameter common to both compounds. These parameters were subsequently used to simulate the performance of a laboratory-scale, annular reactor filled with TiO2-coated glass rings and irradiated with UV-LED lamps. The model successfully predicts the behavior of both single-compound solutions and binary mixtures in the lab reactor under different irradiation conditions, with estimation errors of 14.7% for TC and 12.8% for CA. These results confirm that the estimated kinetic parameters are independent of the experimental setup, demonstrating the suitability of this methodology for scaling up photocatalytic reactors.