Interdependence of Kinetics and Fluid Dynamics in the Design of Photocatalytic Membrane Reactors

Abstract

Photocatalytic membrane reactors (PMRs) are a promising technology for wastewater reclamation. The principles of PMRs are based on photocatalytic degradation and membrane rejection, the different processes occurring simultaneously. Coupled photocatalysis and membrane filtration has made PMRs suitable for application in the removal of emerging contaminants (ECs), such as diclofenac, carbamazepine, ibuprofen, lincomycin, diphenhydramine, rhodamine, and tamoxifen, from wastewater, while reducing the likelihood of byproducts being present in the permeate stream. The viability of PMRs depends on the hypotheses used during design and the kinetic properties of the systems. The choice of design models and the assumptions made in their application can have an impact on reactor design outcomes. A design’s resilience is due to the development of a mathematical model that links material and mass balances to various sub-models, including the fluid dynamic model, the radiation emission model, the radiation absorption model, and the kinetic model. Hence, this review addresses the discrepancies with traditional kinetic models, fluid flow dynamics, and radiation emission and absorption, all of which have an impact on upscaling and reactor design. Computational and analytical descriptions of how to develop a PMR system with high throughput, performance, and energy efficiency are provided. The potential solutions are classified according to the catalyst, fluid dynamics, thickness, geometry, and light source used. Two main PMR types are comprehensively described, and a discussion of various influential factors relating to PMRs was used as a premise for developing an ideal reactor. The aim of this work was to resolve potential divergences that occur during PMRs design as most real reactors do not conform to the idealized fluid dynamics. Lastly, the application of PMRs is evaluated, not only in relation to the removal of endocrine-disrupting compounds (EDCs) from wastewater, but also in dye, oil, heavy metals, and pesticide removal.

Recent Advances in the Remediation of Textile-Dye-Containing Wastewater: Prioritizing Human Health and Sustainable Wastewater Treatment

“…The PMS framework facilitates the separation of TiO 2 particles for the purpose of reuse. The hybrid process, known as PMS, utilizes a compact reactor and demonstrates energy efficiency while effectively eliminating complex and toxic pollutants [278,279]. This study investigates the photodegradation of Reactive Black 5 (RB5) in a slurry membrane reactor, examining both batch and continuous operational modes.…”

An Overview of Photocatalytic Membrane Degradation Development

“…As schematically shown in Figure 2a, degradation reactions are driven by the elec trons transferred from the valence to the conduction band. Typically, a photocatalyst's band-gap energy (E a ) should be equal to or less than the emitted photon energy [39][40][41] Electron transfer results in formation of an associated hole (h VB + ) in the valence band [42,43] Electron-hole pairs promote both oxidation and reduction of the adsorbed layer by gen eration of radicals [17,44]. Radicals are active oxidizing and reducing species that attack to and degrade contaminants in the aqueous solution [45,46].…”

CFD-Assisted Process Optimization of an Integrated Photocatalytic Membrane System for Water Treatment

“…Photocatalytic degradation and membrane separation have emerged as the most promising technologies in removing recalcitrant pollutants such as pharmaceuticals [1][2][3][4]. However, these technologies might not achieve the desired efficiency when applied as a stand-alone, necessitating additional treatment processes [4,5]. Integrating membrane separation and photocatalytic degradation can couple the constituent technology's advantages while removing their drawbacks [4].…”

“…However, these technologies might not achieve the desired efficiency when applied as a stand-alone, necessitating additional treatment processes [4,5]. Integrating membrane separation and photocatalytic degradation can couple the constituent technology's advantages while removing their drawbacks [4]. The relevance of photocatalysis is attributed to its ability to mineralize pollutants unselectively or, at the very least, degrade pollutants into less harmful products using reactive radicals [6,7].…”