Activated carbon-filled cellulose acetate hollow-fiber membrane for cell immobilization and phenol degradation

The activated carbon-filled cellulose acetate (CA) hollow-fiber membranes were prepared by using phase-inverse technique and subsequently characterized by scanning electronic microscopy (SEM), atomic force microscopy (AFM), dynamic mechanical analysis (DMA), thermal mechanical analysis (TMA), and tensile analysis. The SEM observation demonstrated that the activated carbon-filled CA hollow-fiber membranes possess four-layer structure, which consists of an external skin dense layer, an external void layer, a central sponge layer, and an internal skin dense layer, whereas the pure CA hollow-fiber membranes lack the macrovoid layer. As the measurement of AFM, the roughness of both internal and external surface of activated carbon-filled fibers is much higher than that of pure CA fiber, respectively. Higher Young's modulus and storage modulus of filled membranes indicate that the activated carbon particles were homogeneously dispersed in the polymeric matrix. To investigate the feasibility of the newly developed hollow-fiber membranes for cell immobilization cells and to evaluate the inhibitory effect of phenol on immobilized cells, Pseudomonas putida ATCC 17484 was chosen to be immobilized on both pure CA and activated carbon-filled hollow-fiber membranes. Batch experiments for phenol biodegradation were carried out for both free suspension and immobilized cells at the initial concentration of 1500 mg/L phenol. In the case of free suspension, neither cell growth nor phenol degradation occurred to any measurable extent up to 35 h. We found that both pure CA fiber and activated carbon-filled fiber immobilization systems can completely degrade the phenol. However, the biodegradation rate of activated carbon-filled fiber system was higher than that of pure CA fiber system.