Superhydrophobic ball clay based ceramic hollow fibre membrane via universal spray coating method for membrane distillation

• Universal spray coating method with a composite of PVDF-HFP, C8, and ZnO nanoparticles as a coating in the fabrication of a superhydrophobic ball clay ceramic hollow fibre membrane. • Superhydrophobicity with water contact angle and its hysteresis contact angle were measured to be 154.4 and 3.2°, respectively. • The composite coating on the PH/C8/ZnO-C8/HFM significantly improved its LEPw as compared to C8/HFM. A trade-off was observed on comparison, where vapour permeability decreased with increasing wetting resistance (C8/HFM > PH/C8/ZnO-C8/HFM). • Both membranes had comparable vapour flux and salt rejection with superhydrophobicity when compared to other methods previously reported in the literature. In this work, the feasibility study of a superhydrophobic ball clay based ceramic hollow fibre membrane (HFM) through pre-fluorinating of poly(vinylidene fluoride)–co-hexafluoropropylene (PVDF-HFP) and ZnO nanoparticles composite with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (C8) followed by post-roughening on fluorinated ball clay based ceramic hollow fibre membrane (PH/C8/ZnO-C8/HFM) via universal spray coating. The coating was applied onto ball clay based ceramic hollow fibre membrane’s surface in order to achieve superhydrophobicity, which had not previously been reported. C8 was grafted on the ceramic hollow fibre membrane’s surface using the conventional immersion method and the prepared membrane (C8/HFM) was served as a control. The hierarchical structure of PH/C8/ZnO-C8/HFM is composed of a cooperative layer of fluorinated PVDF-HFP/ZnO nanocomposite in mechanical interlocking mode. PH/C8/ZnO-C8/HFM has better superhydrophobic properties, with a water contact angle of 154.4° and a hysteresis contact angle of 3.2°, than C8/HFM, which has a water contact angle of 151.7° and a hysteresis contact angle of 9.2°. The PH/C8/ZnO-C8/HFM outperforms the C8/HFM in the wetting resistance because the liquid entry pressure of water LEPw (PH/C8/ZnO-C8/HFM = 1.33 ± 0.4 bar, C8/HFM = 0.37 ± 0.1 bar) and salt rejection in MD for the PH/C8/ZnO-C8/HFM is better than C8/HFM.