Using sodium alginate hydrogel as skeleton, in combination with chitosan and magnetic Fe₃O₄, a new type of magnetic chitosan/sodium alginate gel bead was prepared. On this basis, through the orthogonal experiment and single-factor experiment, the authors optimized the preparation conditions for composite gel bead, and determined the optimum one. The influences of many preparation impact factors on adsorption performance were examined. Results show that the optimal preparation conditions for the composite gel bead is as follows. Concentration of calcium chloride is 2.5 g/L, concentration of sodium alginate is 24 g/L, the amount of chitosan addition is 5 g/L, and the amount of magnetic liquid addition is 4.64 g/L. The optimal gel bead is a smooth, uniform, black ball with about 2 mm in diameter. By Fourier transform infrared spectroscopy (FTIR), synchronous thermal analysis (TGA) and other means of characterization, the adsorption mechanism is analyzed. Thermogravimetric analysis results show that the gel bead has good thermal stability. FTIR results prove that many active functional groups (amino group, hydroxyl group and carboxyl group) exist on the surface of gel bead. The adsorption performance test shows that adsorption ratio of 20mg MCSB on 40mL 25mg/L Cu²⁺ solution is 78.13%. The magnetic chitosan/sodium alginate gel bead is a novel simple-prepared and effective composite adsorbent.

The polyaniline/vapor grown carbon fiber (PANI/VGCF) was synthesized by in-situ polymerization, and SEM, FTIR, and TGA were used to investigate the microstructure, polymerization mechanism, and thermal stability. SEM images showed that polyaniline/vapor grown carbon fiber was at nano-scale, and the microstructure was similar with purified vapor grown carbon fiber, which indicated that the polymerization of aniline occurred on the surface of the carbon fibers. FTIR spectra gave further explanation of the composite mechanism and there was no new bond generated. The maximum power density of the microbial fuel cell with polyaniline/vapor grown carbon fiber as modification with a specific loading of 5 mg/cm² was 299 mW/m², which was 6.5 times higher than the unmodified microbial fuel cell. The EIS spectra fitted well to the Nyquist model and the equivalent circuit model was given. Polyaniline/vapor grown carbon fiber could be regarded as one economical and potential cathode catalyst for oxygen reduction reaction in microbial fuel cell.

Surface-engineered yeast (Saccharomyces cerevisiae) cells were magnetically modified using water based magnetic nanoparticles to prepare a new type of magnetically responsive adsorbent. Infrared spectroscopy analysis revealed that magnetically modified cells remained the functional groups of engineered yeast and magnetic materials. The kinetic and adsorption isotherm law and factors influencing adsorption (such as time, temperature and pH) were analyzed. The results showed that adsorption equilibrium was achieved within 18 min. The optimal condition for the Ag⁺ adsorption was 20~30℃, pH 7.0. The pseudo-first-order kinetic model and Langmuir model fitted the adsorption data well. The results of multi-metal competitive adsorption indicated that magnetically modified cells still showed adsorption selectivity for Ag⁺ than other heavy metal ions. The adsorption amount of Ag⁺ was 10.6 times that of Ni²⁺, 9.0 times that of Zn²⁺, 7.5 times that of Co²⁺, 3.0 times that of Cu²⁺.