No abstract

No abstract

No abstract

2015): Effect of hydrophilic Cu 3 (BTC) 2 additives on the performance of PVDF membranes for water flux improvement, Desalination and Water Treatment,In this study, a polyvinylidene fluoride (PVDF) membrane for water treatment was modified by dispersing hydrophilic metal-organic framework (MOF) particles, namely Cu 3 (BTC) 2 and acidified Cu 3 (BTC) 2 , in a PVDF solution. The effects of the Cu 3 (BTC) 2 and acidified Cu 3 (BTC) 2 additives on the PVDF membranes were investigated in terms of hydrophilicity of the membrane surface and the water flux through the membrane. The PVDF membranes modified with hydrophilic MOF particles demonstrate improved water flux and maintain similar rejection values due to their improved hydrophilicity. Water fluxes of Cu 3 (BTC) 2 and acidified Cu 3 (BTC) 2 added membranes were 295.66 and 558 LMH which were 47 and 72.3% higher than those of the pure PVDF membrane, respectively. Acidified Cu 3 (BTC) 2 was more stable and well immobilized in the PVDF membrane as no leaching of the metallic element was observed during the water permeation.

Polyvinylidene fluoride (PVDF) hollow fiber membranes prepared by thermally-induced phase separation (TIPS) have excellent porosity but weak tensile strength. In this study, we stretched and annealed these hollow fiber membranes in an attempt to improve their tensile strength and water permeability. This was done by introducing a stretching process into the manufacturing process. In this study, the stretching temperature ranged from 30 to 90 o C, the stretching speed ranged between 4 and 60 mm/s, and the stretching ratio was varied between 100 and 200%. According to field-emission scanning electron microscopy (SEM) images, the structure of the surface varied under different stretching conditions. The tensile strength was increased as the degree of stretching increased, and annealing conditions of 130 o C for 2 h resulted in an increase in the crystallinity. These results indicate that changing the stretching conditions can increase the water permeability and the mechanical strength of the membrane by more than 20%; these improvements are brought about by changes in the surface structure of the membrane.