Preparation and characterization of different geometrical shapes of multi-bore hollow fiber membranes and application in vacuum membrane distillation

Abstract

Multi-bore hollow fiber membranes were prepared through phase inversion spinning process using new locally designed spinnerets of various geometrical shapes. The spun cylindrical-like, rectangular or ribbon-like, and triangular-like are prepared, dried, and characterized by scanning electronic microscope. Fibers of circular (seven, five, and four bores) shape, rectangular of five bores, and triangular of three bores were chosen to study the effect of both geometrical configuration and the number of bores on the amorphous structure and the mechanical properties of the membranes. Membrane geometry, surface amorphous, and bore arrangements are very sensitive to the operating conditions, especially the extrusion and drawing rates. Three polymeric blends of different compositions are used to prepare multi-bore hollow fiber membranes. This study revealed that the blend composition of PES 16%, PVP 2%, PEG 2%, diethylene glycol 2%, and NMP 78% gives excellent mechanical properties. Optimization of the preparation conditions also developed, where the dope flow rate, the bore flow rate, and the air gap were 1.14 cm3 s−1, 1.1 cm3 s−1, and 0 cm, respectively. Furthermore, this study proved that the circular arrangement has high mechanical strength. The prepared seven-MBHF membranes were applied in the membrane distillation process, a solution of 35 g/l NaCl was used to test the membrane performance, and the achieved flux and rejection were 28.32 L/m2 h and 98.9%, respectively. This performance demonstrated that the prepared membrane in this way is suitable to compete with conventional reverse osmosis technology that uses single track hollow fibers.

Maximizing Biochemical and Energy Recovery from Wastewater Using Vapor-Gap Membranes

“…Also, R f (or p) * = 1/ k f (or p) H f (or p) , where various models are available to express the mass transfer coefficient k f (or p) . For other membrane configurations (e.g., tubular module, hollow fiber module), geometrical factors of the modules must be incorporated. , …”

“…For other membrane configurations (e.g., tubular module, hollow fiber module), geometrical factors of the modules must be incorporated. 57,58 The relative magnitudes of transfer resistances are influenced by the solubility of the compound, represented by the Henry's constant. In the case of lowly soluble gas (e.g., CH 4 ), the membrane resistance (R m *) is relatively small, and the diffusion resistances in the boundary layers of the liquid streams (R f * or R p *) become more dominant.…”

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“…Osmosis is a process by which a solvent flow through membrane from low concentration side to high concentration side (Rohlfs et al 2016;El-Zanati et al 2020). Assuming a pure solvent is flowing on one side of the membrane, the osmotic flow lasts when the chemical potentials of the solutions are equal on two sides of membrane.…”