title: Evaluation of effective diffusion coefficient and intrinsic kinetic parameters on azo dye biodegradation using PVA-immobilized cell beads.
abstract: An immobilized mixed culture (Aeromonas hydrophila, Comamonas testosteroni, and Acinetobacter baumannii) was prepared by entrapment into phosphorylated polyvinyl alcohol (PVA) gel beads. The unsteady-state diffusion mechanism in a gel bead was applied to estimate the effective diffusion coefficients (D(e)) and the partition coefficients (K(p)) of azo dye. In addition, a simple method was developed to determine the intrinsic kinetic parameters of immobilized cells from observed reaction rates and the intrinsic kinetic parameters were then verified by fitting the experimental data into the reaction-diffusion model in a batch reactor running at a well-stirred state. The calculated effectiveness factor (eta(cal)) approached unity at Thiele modulus (Phi) < 0.3 (i.e., d(p) < 0.475 mm). The experimental effectiveness factor (eta(exp)) was in the range of 0.71-0.45 for a corresponding sphere diameter (d(p)) of 1.91 +/- 0.16 to 4.43 +/- 0.07 mm at an initial dye concentration of 200 mg/L. The results show that intraparticle diffusion resistance has a significant effect on the azo dye biodegradation rate.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300, R.O.C. kcchen@che.nthu.edu.tw
authors.forename: Kuo-Cheng
authors.initials: KC
authors.lastname: Chen
authors.forename: Jane-Yii
authors.initials: JY
authors.lastname: Wu
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Yang
authors.forename: Sz-Chwun John
authors.initials: SC
authors.lastname: Hwang
mesh_terms: D040981:Acinetobacter baumannii / Q000302:isolation & purification / Q000378:metabolism; D016980:Aeromonas hydrophila / Q000302:isolation & purification / Q000378:metabolism; D001391:Azo Compounds / Q000378:metabolism*; D018533:Biomass; D001709:Biotechnology; D018914:Cells, Immobilized / Q000378:metabolism; D004396:Coloring Agents / Q000378:metabolism*; D020604:Comamonas testosteroni / Q000302:isolation & purification / Q000378:metabolism; D004058:Diffusion; D005782:Gels; D007700:Kinetics; D008433:Mathematics; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010766:Phosphorylation; D011142:Polyvinyl Alcohol; D011506:Proteins / Q000032:analysis
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D005782:Gels; D011506:Proteins; D011142:Polyvinyl Alcohol