Critical Issues and Guidelines to Improve the Performance of Photocatalytic Polymeric Membranes

Abstract

Photocatalytic membrane reactors (PMR), with immobilized photocatalysts, play an important role in process intensification strategies; this approach offers a simple solution to the typical catalyst recovery problem of photocatalytic processes and, by simultaneous filtration and photocatalysis of the aqueous streams, facilitates clean water production in a single unit. The synthesis of polymer photocatalytic membranes has been widely explored, while studies focused on ceramic photocatalytic membranes represent a minority. However, previous reports have identified that the successful synthesis of polymeric photocatalytic membranes still faces certain challenges that demand further research, e.g., (i) reduced photocatalytic activity, (ii) photocatalyst stability, and (iii) membrane aging, to achieve technological competitiveness with respect to suspended photocatalytic systems. The novelty of this review is to go a step further to preceding literature by first, critically analyzing the factors behind these major limitations and second, establishing useful guidelines. This information will help researchers in the field in the selection of the membrane materials and synthesis methodology for a better performance of polymeric photocatalytic membranes with targeted functionality; special attention is focused on factors affecting membrane aging and photocatalyst stability.

Thermodynamic Modeling and Validation of the Temperature Influence in Ternary Phase Polymer Systems

“…Non-solvent induced phase inversion (NIPS) is a synthesis technique commonly used to manufacture asymmetric polymeric membranes for separation processes [ 1 ], both in laboratory and industrial scale [ 2 , 3 ]. The mechanism of membrane formation using NIPS consists in the precipitation of a polymer solution when it is introduced in a non-solvent bath by the exchange between solvent and non-solvent or coagulant [ 4 ]. The liquid–liquid demixing that occurs in the NIPS process, and ultimately the membrane structure, are strongly affected by the thermodynamics and kinetics of the system.…”

“…Polyethersulfone (PES) and polyvinylidene fluoride (PVDF) are polymers classically used to manufacture membranes for different industrial separation applications. Particularly PVDF is a polymer with interest to be used for the development of photocatalytic membranes [ 4 ]. Temperature plays an important role in the manufacture of polymeric membranes.…”

Exploitation of Lignocellulose Fiber-Based Biotemplates to Improve the Performance of an Immobilized TiO2 Photocatalyst

“…Recent works [6][7][8][9] have summarized the most relevant achievements regarding the syntheses of materials with excellent photochemical features, as well as the preparation of photocatalytic membranes. Several authors have focused their efforts on the photoactivity improvement impacting the physical properties of photocatalysts (particle size, crystalline phase, preferred orientation) by controlling the synthesis parameters, by doping the semiconductor with a co-catalyst [10][11][12][13] or even by combining the photocatalyst with other materials [14][15][16].…”

Preparation and Characterization of Reduced Graphene Oxide /TiO2 Blended Polyphenylene sulfone Antifouling Composite Membrane With Improved Photocatalytic Degradation Performance

“…The strong oxidizing radicals (•O 2 − and •OH) and h + could directly participate in the decomposition of organic pollutants ( Georg and James, 1995 ). Furthermore, the superhydrophilicity of TiO 2 will modulate surface morphology, improve permeability, and boost the self-cleaning and antifouling ability of membranes ( Romay et al, 2020 ). However, UV light is an important factor to accelerate the aging of polymer membrane and shorted the service life of photocatalytic membranes.…”