Improving antifouling property of alumina microfiltration membranes by using atomic layer deposition technique for produced water treatment

Drinking water supply sustainability is one of the biggest challenge of the century, necessitating efficient and economical technologies for water purification. ZnO atomic layer deposition (ALD) modified membranes were developed for treating produced water from wells in Oklahoma, as a model of produced water, having very high salt and oil content. ZnO ALD membranes increased hydrophilicity with an oil contact angle increasing from 165° for an α-alumina support to 171° for a ZnO ALD membrane (120 cycles), which induced a dramatic rise in the pure water flux from 148 to 192 L m⁻² h⁻¹. ZnO ALD on the membranes enhanced Total Organic Carbon (TOC) rejection from 96% to 99% and decreased Total Dissolved Solids (TDS) content from 53,205 ppm to 10 ppm. It was found that the average roughness (S_a) was 509 nm for the pristine α-alumina support and was reduced to 332 nm for the ZnO ALD membrane (120 cycles). Additionally, the anti-fouling property of membranes with flux recovery ratio increased from 93% to 99%. Overall, the ZnO ALD membrane showed great potential to purify produced water.