Multiphysics computational fluid dynamics (CFD) modelling of diclofenac amide removal by photocatalytic oxidation on Fe-TiO2/N-TiO2 thin films microreactor.

• CFD model implements radiation field, species transport, and reaction kinetics. • Model was employed to predict both dark adsorption and photocatalytic oxidation. • Model enables estimation of adsorption and apparent kinetic constant (RSS < 0.03). • CFD model revealed elimination of mass transfer limitations in the kinetic regime. An improved multiphysics computational fluid dynamics (CFD) model, which couples radiation field modeling, species transport, and kinetics was developed to determine the dark adsorption–desorption (k ads,m k ads,n , k des,m , k des,n) and apparent reaction rate (k app) constants for the photocatalytic oxidation of diclofenac amide (DCFA) in a recirculating thin-film micro-slit reactor. The photocatalytic oxidation of DCFA under UV irradiation was investigated by changing the initial concentration (C o) (0.73–1.7 ppm) and recirculation flow rate (Q) (0.15–3.73 L h−1). The ratio of estimated adsorption–desorption rate constants by fitting the CFD model to experiments were k ads,m /k ads,n = 0.45, and k des,m /k des,n = 1.5, and k app varied from 1.08 to 1.68 × 10-3 mmol m-3 h−1(W m−2)-0.5 with Q (0.15–3.73 L h−1). The CFD model unveiled the switch from mass transfer to kinetics-controlled oxidation of DCFA. The proposed CFD model can be employed as a rapid and flexible tool for the determination of intrinsic kinetic constants in photocatalytic thin-film MRs in the reaction kinetics regime. [ABSTRACT FROM AUTHOR]