Surface morphology of homogeneous and asymmetric membranes made from poly(phenylene oxide) by tapping mode atomic force microscope

Studies on the selective Am3+ transport, irradiation stability and surface morphology of polymer inclusion membranes containing Cyanex-301 as carrier extractant

Transport behaviour of Am(3+) across cellulose triacetate (CTA) based polymer inclusion membranes (PIM) containing Cyanex-301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) as the carrier extractant and tri-n-butyl phosphate (TBP) or 2-nitrophenyloctylether (NPOE) as the plasticizer was investigated from different feed and strip conditions. The TBP plasticized membrane resulted back transport of Am when alpha-hydroxy iso-butyric acid was used as the complexing agent in the strip phase while no such effect was seen when ethylene diamine tetraacetic acid (EDTA) was used as the complexant. Effect of varying Cyanex-301 concentration and bipyridyl (bipy) concentration on Am transport was also investigated. Long term reusability of the membrane was studied by measuring the permeability coefficient (P) after exposing the PIMs to a maximum gamma ray dose of ∼ 200 kGy. The surface morphology of the membranes was analyzed by atomic force microscopy and the roughness parameter was correlated to transport efficiency.

Structure and permeation properties of cellulose esters asymmetric membranes

The permeation properties of a series of membranes of cellulose esters, presenting a wide range of characteristics, were studied and correlated to the structure of water in the pores, to the polymer hydrophilicity/hydrophobicity, and to the morphology of the surface of the active layer. Asymmetric membranes of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate were prepared by the phase inversion method and their preferential permeation performance tested. The surface morphology and the structure of the water in the pores of the active layer were studied by atomic force microscopy (AFM) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, respectively. Results show that higher rejection to NaCl and low fluxes are generally associated with smaller clusters of water in the pores. On the other hand, the surface of the membranes presenting smaller clusters of water in the active layer show generally surfaces with lower roughness as measured by AFM.