Photo-initiated generation of a selective layer on polyacrylonitrile (PAN) composite membranes

Asymmetric polyacrylonitrile (PAN) membranes (average pore size of about 12 nm) were used as support for polymeric pervapouration (PV) separation phases which were in situ prepared by heterogeneous photo-initiated graft copolymerization. The impact of different substituted methacrylates or acrylates and preparation parameters (UV irradiation time and degree of grafting) were analysed using PV with toluene/heptane (20/80 w/w; 80 °C) as model feed. High selectivity and high permeate fluxes were achieved. Major reasons for the excellent performance were the small effective PV barrier thickness (<5 μm) and the covalent anchoring of the coated polymer.