Physical surface modification of nanoporous TFC membranes using UV irradiation for water desalting; determination of best conditions

Abstract

The main goal of this study was to determine the desirable conditions to modify the surface properties of poly(piperazineamide) thin-layer membranes using UV irradiation without using any chemical reagents. The obtained membranes were exposed to UV irradiation under different conditions such as irradiation time (30, 60, and 120 s) and its power (125 and 250 w) as well as irradiation distance (5, 10, and 15 cm) between the UV lamp and the thin layers. SEM, AFM, ATR-IR, water contact angle, and nanofiltration setup were utilized to determine the properties of the obtained thin layers. SEM images clearly illustrated the alterations in the surface morphology. Reduction in pore sizes of the thin layers was proven by AFM results under different conditions. The rejection capability of the unmodified thin layer against NaCl and Na₂SO₄ was 12 and 60%, respectively; which was increased to about 42 and 82%. Flux recovery ratio test showed the ability of the modified thin layers to prevent the settlement of foulants. The results showed that irradiation time was more important than irradiation distance and irradiation power.

Keywords:

• Surface modification
• Thin film
• UV irradiation
• Performance
• Fouling