Preparation And Properties Of Charged Quaternized CTS Membranes By LbL Technology

A positively charged (HTCC/PSS)nHTCC composite nanofiltration membrane was prepared by using polystyrene sulfonate(PSS) as anionic polyelectrolyte, N-[(2-hydroxy-3-trimethylammonium)propyl] chloride chitosan(HTCC) as cationic polyelectrolyte and epichlorohydrin (ECH) as cross-linking reagen and alternate deposited on ultrafiltration(PES) membrane. The (HTCC/PSS)nHTCC-Ag membrane was prepared by photoreduction technique on the base of (HTCC/PSS)nHTCC membrane which had ehanced antibacterial property. The performance of the prepared (HTCC/PSS)nHTCC and (HTCC/PSS)nHTCC-Ag LbL membranes were also investigated. The prepared NF membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Contact angle, atomic force microscopy (AFM) and X-ray diffraction (XRD). The effect of preparation conditions such as the concentration of casting solution, ionic strength, and immersion order were also investigated.The results indicated that the (HTCC/PSS)nHTCC membrane from 5g/L HTCC casting solution,0.1 g/L NaCl as a supporting salt,4.5 semi-assembled composite film, cross-linked 21h, the (HTCC/PSS)4HTCC was found to have optimum performance. The optimal conditions for (HTCC/PSS)4HTCC-Ag preparation:concentration of AgNO3 solution is 0.lmol/L, the adsorption time of silver ions on the (HTCC/PSS)4HTCC composite membrane surface is about 22min. The membranes were finally obtained under 200w UV lamp irradiation for 20min. The SEM and AFM analysis indicated that the prepared composite NF membrane surface was relatively uniform and smooth. The pure water permeability of the (HTCC/PSS)4HTCC composite membrane is 17.93 kg-m-2·h-1·MPa-1, its MWCO is about 1412 (in nanofiltration range). The rejection of salt solutions follows the decreasing orde of MgCl2, NaCl, KC1, Na2SO4, K2SO4, revealing the positively charged characteristic of the membrane. The rejection of PPCPs follows the decreasing order of Atenolol, Carbamazepine, Ibuprofen. In addition, the antibacterial properties of the (HTCC/PSS)4HTCC-Ag membranes were compared to elucidate the existence of Ag nanoparticles which have synergistic effect on improving antibacterial activity against Gram-negative E.coli (DH5a, Rosetta) and Gram-positive Bacillus subtilis. It was obvious that membranes had a better antibacterial performance towards E. Coli than Bacillus subtilis, especially for E.coli DH5a.