Fig. 4: Cycling performance of the membranes and surface morphology.

A Total transmembrane flux for unloaded PVDF-PVA and PVDF-PVA-TBB 1.0 mg cm⁻² membranes in multi-cycle OD tests carried out at 48 °C calculated at the end of each cycle. The error bars represent standard deviations for three measurements. B Instantaneous transmembrane flux as a function of the operating time for undoped and PVDF-PVA-TBB (doped) membranes in multiple OD cycles. After each cycle, the membranes were flushed with milliQ water for 20 min at room temperature. C, D SEM micrographs of undoped PVDF-PVA membrane at room temperature (C) and after heating to 50 ^oC (D). E, F SEM micrographs of doped membrane PVDF-PVA-TBB 1.0 at room temperature (E) and after heating to 50 °C (F). The green circles indicate the embedded TBB crystals while the red circles indicate the large pores or holes generated after some of the TBB crystals have detached during the phase transition.