TY - JOUR
ID - 10.1016/j.jes.2015.09.023
TI - Effect of non-solvent additives on the morphology, pore structure, and direct contact membrane distillation performance of PVDF-CTFE hydrophobic membranes
AU - Libing Zheng
AU - Zhenjun Wu
AU - Yong Zhang
AU - Yuansong Wei
AU - Jun Wang
VL - 28
IS - 7
PB -
SP - 28
EP - 39
PY -
JF - Journal of Environmental Sciences
JA - J. Environ. Sci.
UR - http://www.jesc.ac.cn/jesc_en/ch/reader/view_abstract.aspx?file_no=S1001074216000474&flag=1
KW - PVDF-CTFE; Additives; Phase inversion; Membrane distillation; Pre-gelation
AB - Four common types of additives for polymer membrane preparation including organic macromolecule and micromolecule additives, inorganic salts and acids, and the strong non-solvent H2O were used to prepare poly (vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) hydrophobic flat-sheet membranes. Membrane properties including morphology, porosity, hydrophobicity, pore size and pore distribution were investigated, and the permeability was evaluated via direct contact membrane distillation (DCMD) of 3.5 g/L NaCl solution in a DCMD configuration. Both inorganic and organic micromolecule additives were found to slightly influence membrane hydrophobicity. Polyethylene glycol (PEG), organic acids, LiCl, MgCl2, and LiCl/H2O mixtures were proved to be effective additives to PVDF-CTFE membranes due to their pore-controlling effects and the capacity to improve the properties and performance of the resultant membranes. The occurrence of a pre-gelation process showed that when organic and inorganic micromolecules were added to PVDF-CTFE solution, the resultant membranes presented a high interconnectivity structure. The membrane prepared with dibutyl phthalate (DBP) showed a nonporous surface and symmetrical cross-section. When H2O and LiCl/H2O mixtures were also used as additives, they were beneficial for solid–liquid demixing, especially when LiCl/H2O mixed additives were used. The membrane prepared with 5% LiCl + 2% H2O achieved a flux of 24.53 kg/(m2·hr) with 99.98% salt rejection. This study is expected to offer a reference not only for PVDF-CTFE membrane preparation but also for other polymer membranes.
ER -