Vahid Jabbari - The role of solution and coagulation temperatures in crystalline structure, morphology, roughness, pore diameter distribution, and separation properties of nanoporous membranes fabricated via phase inversion

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      Publication Details (including relevant citation   information):

      Separation Science and Technology 47 (13), 1866-1873


      In this study, fabrication of poly(vinylidene fluoride) (PVDF)   flat sheet membranes and correlation of membrane morphology,   roughness, crystalline structure, and pore diameter distribution   as functions of coagulant temperature (TC) and   precursor-solution preparation temperature (TS) in the   phase inversion (PI) process of PVDF-DMF-H2O mixture   with 20%wt of PVDF concentration was investigated. The results   demonstrated that membranes have a typical asymmetric structure   with a dense skin top layer and a porous substructure. An   increasing amount of macrovoids was observed in the membrane   substructure when TS is decreased. It was found that   at lower TC, the membrane solution precipitated into a   uniform morphology composed of spherical crystallites that   exhibited the β-form crystal structure. By contrast, when PVDF   was precipitated at higher temperatures, the formed membrane   became largely in the α-form crystal structure. The pore size was   estimated by Barett-Joyner-Halenda (BJH) method, ranging from   15 nm to tenth of hundred nm, depending on TC.   The performance of the prepared membranes has been tested by the   measure the effects of TC and TS on the   separation characteristic of nanoporous PVDF membranes. We   observed that the removal of Acid Yellow 23 (AY23) decreases as   TS increases and extremely high dye removal efficiency   of 99.37% was achieved.

      Address (URL): DOI:   10.1080/01496395.2012.666309