Dendrimer–titania nanocomposite: synthesis and dye-removal capacity

Dendrimer–titania nanocomposite (DTN) was synthesized, and the product was characterized by use of Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The dye-removal capacity of DTN was investigated for direct blue 78 (DB78) and direct red 80 (DR80). The effects of pH and amount of adsorbent on dye removal were determined, and the isotherm, kinetics, and thermodynamics were studied. The point of zero charge (pH_pzc) of the nanocomposite was 6.4. The Longmuir isotherm model was the best fit to the experimental data. The maximum adsorption capacity of DTN was 1,250 mg/g for DB78 and 990 mg/g for DR80. The kinetic data were a good fit to the pseudo-second order model. Thermodynamic data indicated that adsorption of the dyes by DTN was endothermic and spontaneous, and occurred by physisorption.