Improved Desalination Performance of Polyvinylidene Fluoride Hollow Fiber Membranes by the Intermediate Role of Surfactants

Abstract

Polymer hollow fiber membranes (HFMs) are the core or base membranes of various membrane processes (e.g., ultrafiltration and membrane distillation). Preparing polymer HFMs with higher water flux helps improve the efficiency of the membrane processes. Using pore‐forming additives is the commonly used and efficient method to improve the water flux. The current dilemma is that the conventional methods that increase the amounts or the molecular weight of the additives to improve the water flux usually lead to the decrease in membrane mechanical strength. Herein, different from the conventional research strategy, increasing the surfactant surface activity (SA) is first found to deeply promote the core of nonsolvent‐induced phase separation (NIPS) that of the mutual diffusion between water and dopes. As a result, this method distinctly improves the surface porosity (from 0.8% to 9.7%) and optimizes the pore size distribution of polyvinylidene fluoride (PVDF) HFMs. Benefit from these, the water flux of ultrafiltration (3.1‐fold increase, maximally) and direct contact membrane distillation (2.3‐fold increase, maximally) are increased greatly. Moreover, the mechanical strength is not negatively affected due to the additive amount of small molecule surfactants is constant and small (2.0 wt%).

Scale Up and Validation of Novel Tri-Bore PVDF Hollow Fiber Membranes for Membrane Distillation Application in Desalination and Industrial Wastewater Recycling

“…The bulk porosity of the TBHF membranes consistently remained within the range of 70-80%. These results are in agreement with the values reported in the literature for similar dope compositions [35,40,41]. The liquid entry pressure (LEP w ) is a critical parameter for membrane distillation applications that determines the antiwetting potential of the membranes at a given operating pressure.…”

Production of the Microfiltration Membranes of Wide Range Porosity, High Mechanical, Thermal and Chemical Stability by "Green" Fabrication Method

“…Apart from the above, production of the membranes with the wide range of the mean diameters pores will allow filtration of the various liquid foodstuff. Namely, synthesis of such varied membranes can allow their use for filtration of drinking water, wine, beer, soft and alcoholic beverages, cognac, mineral water, various water and alcoholic infusions, medicinal plants extracts [Otitoju et al, 2016;Kong et al, 2020;Mat Nawi et al, 2022].…”

Effect of Polymer Dissolution Temperature and Conditioning Time on the Morphological and Physicochemical Characteristics of Poly(Vinylidene Fluoride) Membranes Prepared by Non-Solvent Induced Phase Separation

“…PVDF is a polymer of growing interest for membrane fabrication, based on its low surface energy, relatively high hydrophobicity, high mechanical strength, chemical resistance and thermal stability compared to other commercial polymer materials [ 2 , 24 , 25 ]. It also shows a very good processability as film [ 26 , 27 ], membranes [ 28 , 29 , 30 ], electrospun membranes [ 31 , 32 ], hollow fibres [ 33 , 34 ] or tubular membranes [ 35 ]. The non-solvent induced phase separation (NIPS) process is widely used to produce the membranes; in this process a polymeric solution contacts with a non-solvent inducing a phase separation into two different phases, one with high concentration of polymer and another with low concentration, enabling the formation of polymeric porous structures [ 2 , 36 , 37 , 38 ].…”