Adsorption of surfactin produced from Bacillus subtilis using nonwoven PET (polyethylene terephthalate) fibrous membranes functionalized with chitosan.

This article deals with an alternative method for bio-separation of surfactin produced by Bacillus subtilis using sorption method on nonwoven PET (polyethylene terephthalate) fibrous membranes functionalized with chitosan. In the first part of the study, surface functionalization of the PET nonwoven fibrous membranes is carried out with aqueous 65% deacetylated chitosan solution with or without a prior surface activation using air-atmospheric plasma treatment. Very small modification of the PET fibrous nonwoven air-permeability confirms the functionalization of PET fibre surface with little reduction of membrane porosity. The functionalized membranes are then characterized by physico-chemical methods: X-ray Photoelectron Spectroscopy (XPS), Wettability and zeta potential. Chitosan increases drastically the zeta potential of PET at all pH values though a prior plasma treatment of the PET membrane reduces slightly the increase in zeta potential values. Sorption of surfactin quantified by HPLC shows that the extent of surfactin sorption on PET nonwovens depends on the surface functionalization method. Surface functionalization with chitosan results in immediate sorption of the entire quantity of surfactin. A prior surface activation by air atmospheric plasma treatment of the PET membranes before chitosan application retards the sorption of entire surfactin which takes place after 1.5h, only. Increased zeta potential and increased hydrophobic behavior in the presence of chitosan without plasma activation would explain the interesting surfactin sorption results.