Thin film nanocomposite forward osmosis membrane with exfoliated layered double hydroxide nanosheets embedded support for fouling-resistant microalgae dewatering

Abstract

Membrane technology is a feasible approach for microalgae dewatering. The features of membrane are essential for achieving efficient dewatering performance. Thin-film nanocomposite membrane with layered double hydroxide (LDH) nanosheet incorporated substrate has been developed for microalgae dewatering. The membrane modification aimed to address the drawbacks of FO in regards to concentration polarization, reverse draw solute diffusion, and fouling. The morphology, wettability, permeability, fouling resistance, and long-term stability of the membranes were improved by incorporating exfoliated LDH within the polyethersulfone (PES) support layer prior to the formation of polyamide selective layer. Dewatering of Chlorella vulgaris by FO in active layer facing feed solution (AL-FS) and active layer facing draw solution (AL-DS) was evaluated with 2 M NaCl as draw solution. The findings revealed the 0.5 % LDH embedded within PES support, the water flux improved by 111.43 % contrasted with neat membrane. The 0.5 % LDH-TFN showed improved antifouling properties during the 4-cycle microalgae dewatering. In addition, the incorporation of LDH supressed internal concentration polarization, thus rendering good flux stability throughout the 72 h operation. This research evidenced the prospect of exfoliated Zn–Al LDH as a promising additive to modify TFC membrane for high performance microalgae dewatering.