Development of photocatalytic titanium dioxide membranes for degradation of recalcitrant compounds

Abstract

BACKGROUND Immobilization of TiO2 photoactive nanoparticles on a nanofiltration membrane without loss of permselectivity properties is currently a challenge. In this study, immobilization of TiO2 nanoparticles on a ceramic commercial membrane surface by direct current reactive magnetron sputtering was addressed. The best membrane was compared with an unmodified membrane and a membrane modified by a generic chemical–physical method in terms of membrane permselectivity and photocatalytic properties. RESULTS Magnetron sputtering was able to achieve similar photocatalytic activity to the chemical–physical method, where Evonik P25 TiO2 nanoparticles were used, while maintaining membrane rejection and permeability. The layer formed by magnetron sputtering exhibits uniformly distributed nanostructured columns, aligned perpendicularly to the membrane surface. Furthermore, the membrane hydrophilicity increase achieved is promising for fouling control. A shorter sputtering time and distance between the titanium target and the membrane were preferable to effectively degrade the pesticides diuron and chlorfenvinphos. Under optimum sputtering conditions, 95% and 78% increases were attained for the degradation of diuron and chlorfenvinphos, respectively, compared with the unmodified membrane. CONCLUSION The photocatalytic membranes developed are potential candidates for the simultaneous retention and photocatalytic degradation of recalcitrant micropollutants. However, if the purpose is to retain low molecular weight molecules, retentive properties should be improved. © 2016 Society of Chemical Industry

Solvent-Free Process for the Development of Photocatalytic Membranes

“…Titanium dioxide (TiO 2 ) is the most commonly used material for the fabrication of photocatalytic membranes due to its high reactivity, chemical and thermal stability, low cost, reusability, and high photocatalytic performance [7][8][9].…”

Overview of Photocatalytic Membrane Reactors in Organic Synthesis, Energy Storage and Environmental Applications

“…There are several reports on the removal of dyes, such as methylene blue (MB) [57,64,143], rhodamine B (RhB) [144] and eosin yellow [30]; pharmaceuticals, including ibuprofen [59], diclofenac [58], carbamazepine [53] and tetracycline [61]; or other pollutants, e.g., phenol [66], humic acids [60,65], and pesticides such as diuron and chlorfenvinphos [145]. There are also reports on using PMs for purification of simulated brackish water and seawater from methyl orange and diphenhydramine [134], as well as secondary effluents from pharmaceuticals [146].…”

Investigation of the reaction kinetics of photocatalytic pollutant degradation under defined conditions with inkjet-printed TiO2 films – from batch to a novel continuous-flow microreactor

“…Immobilizing the catalyst as a coating can avoid extra catalyst separation. TiO 2 has been coated on various substrates including glass slides, 15,16 nanofibers, 17 polymer 18 and ceramic membranes, [19][20][21][22][23] and used for water decontamination either in batch, 16,18,22 or continuous-flow reactors. 15,[17][18][19][20][21]23,24 However, there are three obvious constraints of continuous-flow reactors with immobilized photocatalysts: 25 1) external mass transport may limit the overall reaction kinetics especially in laminar flow conditions at low fluid flow rate, since the diffusion of the reactant from the bulk fluid to the catalyst layer may not be sufficiently fast;…”