Novel positively charged chiral chitosan composite nanofiltration membrane

Abstract

Chitosan was modified with a chiral compound and a positively charged compound. Series of novel composite nanofiltration (NF) memebranes were prepared by over-coating the polysulfone ultrafiltration membrane with the mixture of chitosan and chitosan derivative. The chiral compound, the positively charged compound and their chitosan derivatives were characterised by infrared spectrophotometer (IR) and polarimeter. The structure of the membrane was characterized by scanning electron microscopy (SEM). The performance of membrane was strictly related to the chiral compound and the positively charged compound grafted to chitosan and its composition. The rejection of P_2–7 composite NF membrane reached the maximum of 95·2%, and the flux remained to be as high as 687·4 L m⁻² h⁻¹ at 0·4 MPa with 1000 mg L⁻¹ CaCl₂. Electrostatic effect had no effect on NaCl, while excellent effect on CaCl₂. It was typical positively charged NF membrane, which was suitable for separating the multivalent cation solutes from the feed solution.

Keywords:

• polysulfone
• chitosan
• chiral compound
• positively charged compound
• composite nanofiltration membrane

Acknowledgement

Financial support from the National Key Technology Support Program of China (no. 2008BAL55B03) is gratefully acknowledged.