The miscibility of carboxymethyl chitosan/polyethylenimine (CMCS/PEI) blends was analyzed by FT-IR, TGA and SEM. Defect-free CMCS/PEI blend membranes were prepared with polysulfone (PSf) ultrafiltration membranes as support layer for the separation of CO₂/N₂ mixtures. The results demonstrate that the CMCS/PEI blend is miscible, due to the hydrogen bonding interaction between the two targeted polymers. For the blended membrane without water, the permeability of CO₂ gas is 3.6 × 10⁻⁷ cm³ cm⁻² s⁻¹ cmHg⁻¹ and the corresponding separation factor for CO₂ and N₂ gas is about 33 at the pressure of 15.2 cmHg. Meanwhile, the blended membrane with water has the better permselectivity. The blended membrane containing water with PEI content of 30 wt% has the permeance of 6.3 × 10⁻⁴ cm³ cm⁻² s⁻¹ cmHg⁻¹ for CO₂ gas and a separation factor of 325 for CO₂/N₂ mixtures at the same feed pressure. This indicates that the CO₂ separation performance of the CMCS/PEI blend membrane is higher than that of other facilitated transport membranes reported for CO₂/N₂ mixture separation.

Reverse osmosis (RO) membranes might experience significant changes in surface structure and performance after disinfection has been applied, or after membrane cleaning, because of hydrolysis and oxidation processes. This study reports potential applications of aromatic polyamide RO membrane exposed to a sodium hypochlorite solution for desalination of dye solutions. Changes in the chemical composition, morphology and performance of such membrane were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), contact angle measurements, scanning electron microscope (SEM), atomic force microscopy (AFM) and streaming potential measurements. After chlorination, the water flux of RO membrane doubled, and the NaCl and Na₂SO₄ rejection of the RO membrane decreased to 46.2% and 86.2%, respectively. However, the rejection of congo red, methyl blue and direct red 80 were 99.4%, 98.0% and 100%, respectively. This indicates that abandoned RO membranes can be recovered as “nanofiltration functional membranes” after sodium hypochlorite exposure, and be suitable for fractionation purposes.

Co-Production of Activated Carbon and Bio-Oil from Agricultural Residues by Molten Salt Pyrolysis