Preparation of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) hollow fiber cation-exchange membranes and immobilization of cellulase thereon

For cellulase immobilization, a hollow fiber cation-exchange membrane (HFCEM) as a support were prepared from bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) by amination and carboxylation, and the two-step modification was confirmed by Fourier transform infrared spectroscopy (FTIR) spectra and cation-exchange capacity measurement. The prepared membrane exhibited similar cross-section morphologies as the BPPO base membranes: water uptake, 22.3–40.1%; cation-exchange capacity, 0.53–2.31 mmol/g; mechanical stress, 0.18–5.89 MPa. Then, cellulase was covalently immobilized onto the membrane, and the optimum immobilization conditions were as follows: EDC (N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide) concentration, 40 mg/mL; activation time, 20 h; immobilization time, 25 h; enzyme concentration, 5.0 mg/mL; pH3.8. As compared to free cellulase, the immobilized cellulase exhibited greater stability against heat and pH, suggesting that the membrane was suitable as a support for enzyme immobilization.