Synthesis and water permeation studies of polysulfone based composite membranes having vertically aligned CNTs

Abstract

Polymeric membranes, including Polysulfone (PSf) membranes, are routinely used for water treatment. It is known for quite some time that water permeability of above membranes can be improved if one incorporates carbon nanotubes (single-walled, SWCNTs or multi-walled, MWCNTs) in to the membrane and aligns them in direction of flow of water. This paper reports a method of synthesizing polymeric membranes having vertically aligned hollow CNTs embedded in them. This involves mixing of nanomagnetic particles in the dope solution and casting of membrane in presence of moderate magnetic fields. A semi-automatic membrane casting machine which allows casting of membrane in presence magnetic field was designed and fabricated. PSf nanocomposite membranes, having vertically aligned MWCNTSs, were synthesized using above machine. The effect of magnetic field and the exposure time on the water permeation of above membranes was studied. It was seen that water permeability of membrane increases by a factor of 4 when the magnetic field is increased from 0 to 1500 Gauss. There was additional 40% increase in water permeability, when the time for which film was exposed to magnetic field was increased from 5 sec. to 10 sec.