Bai Bo

Adsorption of organic dyes by TiO 2 @yeast-carbon composite microspheres and their in situ regeneration evaluation

TiO2@yeast-carbon microspheres with raspberry-like morphology were fabricated based on the pyrolysis method. The obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). Effects of initial dye concentration and contact time on adsorption capacity of TiO2@yeast-carbon for cationic dye methylene blue (MB) and anionic dye congo red (CR) were investigated. Experimental data were described by Langmuir, Freundlich, Temkin, and Koble-Corrigan isotherm models, respectively. It was found that the equilibrium data of MB adsorption were best represented by Koble-Corrigan, and CR adsorption was best described by both Freundlich and Koble-Corrigan isotherm models. The kinetic data of MB and CR adsorption fitted pseudo-second-order kinetic model well. The results demonstrated that TiO2@yeast-carbon microspheres achieved favorable removal for the cationic MB in comparison with that for the anionic CR. In addition, regeneration experimental results showed that TiO2@yeast-carbon exhibited good recycling stability, reusability, and in situ renewability, suggesting that the as-prepared TiO2@yeast-carbon might be used as the potential low cost alternative for recalcitrant dye removal from industrial wastewater. One possible mechanism for regenerating dye-loaded TiO2@yeast in situ was also proposed.