Atomic layer deposition of TiO₂ film on a polyethersulfone membrane: separation applications

In the current study, a titanium dioxide (TiO₂) nanostructured film was grown on a polyethersulfone (PES) substrate membrane using atomic layer deposition (ALD) with the aim of tailoring the membrane surface properties to be suitable for desalination applications. Scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA) and zeta potential measurements and a tensile meter were used to characterize the membrane morphology, surface properties and mechanical stability, respectively. In addition, the separation performance of all of the prepared membranes was evaluated in terms of water flux and salt rejection. The results showed that the TiO₂ nanostructured film deposited-PES membrane exhibited excellent performance with a rejection of ≥90 % at room temperature for NaCl, which is four times greater than that of a PES membrane alone. It is interesting to note that the deposition of the TiO₂ film resulted in a marginal decrease in the water flux from 60 ± 2 Lm⁻² h⁻¹ to 47 ± 2 Lm⁻² h⁻¹ of the resulting membrane due to the TiO₂ film’s nanometre-scale thickness. Moreover, the ALD of the TiO₂ film enhanced the mechanical strength of the membrane as it tightly wrapped the skeleton of the membrane.