Glow-discharge Electrolysis Plasma Induced Synthesis of Polyvinylpyrrolidone/Acrylic Acid Hydrogel and its Adsorption Properties for Heavy-metal Ions

Polyvinylpyrrolidone/acrylic acid (PVP/AAc) hydrogel is synthesized using glow-discharge electrolysis plasma (GDEP) technique in an aqueous solution. To optimize the synthesis conditions, the following parameters are examined in detail: discharge voltage, discharge time, mass ratio of PVP to AAc, and content of crosslinker to acrylic acid. The properties of hydrogels are characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The results show that both chemical complexation and ion-exchange play an important role for Pb(II) adsorption onto PVP/AAc hydrogel. Langmuir and Freundlich adsorption models are applied to describe the isotherms at room temperature, and a good agreement between the Langmuir model the experimental data is obtained.