Preparation and Dye Adsorption of Low-cost Polyaniline-tea Saponin Nanocomposites

Four polyaniline-tea saponin (PTS) nanocomposites were prepared by an in-situ polymerization with tea saponin (TS) as a biosurfactant, and they were used to remove organic dyes from aqueous solution. The PTS nanocomposites were characterized by using field emission scanning electron microscopy, the Fourier transform infrared spectroscopy, the Ultraviolet-visible spectroscopy, and the thermogravimetric analysis. The adsorption performances of the PTS nanocomposites for organic dyes were studied by a static adsorption method. The experimental results reveal that adsorption capacities of the PTS nanocomposites are higher than that of pure polyaniline. Especially, the PTS nanocomposites exhibit excellent adsorption performances for anionic dyes because of the electrostatic interaction between the positively charged nitrogen atoms on the PTS chains and the negatively charged sulfonate ions in the anionic dyes. According to the adsorption kinetics and thermodynamics results, the adsorption processes of PTS20 for CR and AB74 follow well with the pseudo second-order and Langmuir isotherm models. It is indicated that TS should be very useful in the preparation of PTS nanocomposite and in removal of toxic dyes from waste water.