No abstract

No abstract

No abstract

No abstract

The design and synthesis of a zwitterionic polyimide open up new avenues for development of antifouling membranes.

Cellulose acetate (CA) is widely used in the preparation of ultrafiltration membranes due to its many excellent characteristics, especially chemical activity and biodegradability. To improve the inherent hydrophobic and antifouling properties of CA membrane, in this work, CA was successfully modified with dopamine (CA-2,3-DA) through selective oxidation and Schiff base reactions, which was confirmed by FTIR and 1 H NMR measurements. Then, CA-2,3-DA membrane with high water permeability and excellent antifouling property was prepared by the phase inversion method. Compared with the original CA membrane, the CA-2,3-DA membrane maintained a higher rejection ratio for BSA (92.5%) with a greatly increased pure water flux (167.3 L m −2 h −1 ), which could overcome the trade-off between permeability and selectivity of the traditional CA membrane to a certain extent. According to static protein adsorption and three-cycle dynamic ultrafiltration experiments, the CA-2,3-DA membrane showed good antifouling performance and superior long-term performance stability, as supported by the experimental results, including flux recovery ratio, flux decline ratio, and filtration resistance. It is expected that this approach can greatly expand the high-value utilization of modified natural organic polysaccharides in separation engineering.

A novel composite adsorbent was prepared by using cellulose acetate modified with zwitterion, for zwitterionic cellulose acetate (ZCA), then blended with graphene oxide (GO). The adsorbent was prepared by solgel method and used to remove Cu 2+ and Cd 2+ from aqueous solution. The morphologies, surface chemical structures, and crystallinity of the obtained adsorbents were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffractometer (XRD), respectively. N2 adsorptiondesorption measurements revealed that the surface area and pore volume were 45.3 m 2 g -1 and 0.249 cm 3 g -1 . For adsorption, effect of time, and pH, adsorbate concentration was investigated; different adsorption models were also evaluated. The results showed that the maximum adsorption capacity was 32.0 mg/g for Cu 2+ and 27.6 mg/g for Cd 2+ , observed at pH 5.5 and 298 K. Simultaneously, the adsorption isotherms were well-fitted to the Langmuir model, and kinetics study showed that the adsorption process was fitted well by the pseudo-second-order model. Further regeneration experiments revealed that the adsorption of ZCA/GO was about 90% of the initial saturation adsorption capacity after repeated use 5 times, indicating that they are promising absorbents for practical application in industry.

No abstract