Application Of Glow Discharge Electrolysis Plasma In Synthesis Of Polymer Composite Materials

Glow-discharge electrolysis plasma (GDEP) is a novel electrochemical process, which is not obeyed the Faraday electrolysis law. The plasma is sustained by DC glow discharge between an electrode and the surface of electrolyte. The conventional electrolysis is automatically developed into GDEP when the applied voltage is exceeding a certain threshold in aqueous solution. There are a lot of energetic species produced by GDEP, such as H·,·OH,H₂O₂,e^-_aq,HO₂·, and ultraviolet radiation as well as higher energy shock waves, then, diffusing into the solution. Therefore, GDEP can be considered as a rich active sources for chemical reaction in aqueous solution. In this study, we use this plasma to initiate polymerization and prepare some of polymer composite materials. The reaction mechanism and discharge process parameters concerning the polymerization were also discussed. The full thesis includes four parts:The first chapter is a mini-review, introducing the existence and characteristics of cold plasma, emphatically, the non-Faraday electrolysis process. Some applications such as in wastewater treatment, synthetic polymer materials, chemical synthesis, hydrogen generation from reforming of lower alcohols aqueous solution, and polymer surface modification are given. The progress indicated that the higher energy particles resulted from could be used to initiate some chemical reactions in aqueous solution, including polymerization and polymer surface modification.The second chapter describes a polymerization of poly(methyl methacrylate) (PMMA) in methanol solution. The polymerization was carried out directly by using glow discharge electrolysis plasma, in which ionic liquid (1-butyl-3-methylimidazolium bromide) was used as supporting electrolyte. The highest number-average molecular weight (Mn) and the lowest polydispersity index (PDI) of the PMMA were 1.37×10⁶ g·mol^-1 and 1.2, respectively. The following data were chosen as the optimal parameters: applied voltage 540 V, glow discharge time 14 min, methyl methacrylate to methanol mole ratio 0.38, polymerization temperature 90℃and polymerization time 8 h. Under those conditions the conversion rate of product was 62%. The obtained polymer was characterized by fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), gel permeation chromatographer (GPC), thermogravimetric analysis (TGA). The kinetic study results showed that the plasma initiated polymerization is obey the first order of reaction.The third chapter describes hydroxyethyl cellulose grafted with acrylic acid (AANa) and 2-acrylamido-2-methyl propane sulfonic acid composite material which was initiated by using glow discharge electrolysis plasma, giving a novel HEC-g-P(AANa-co-AMPS) hydrogel. The composite material was characterized by Fourier transform infrared spectroscopy (FT-IR), sanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The hydrogel with water absorbency about 2490 g/g for distilled water as well as 109 g/g for NaCl solution was obtained. The maximum water absorption appeared in aqueous solution of pH=7. The adsorption capacity on heavy metal ions and adsorption kinetic process of HEC-g-P(AANa-co-AMPS) were examined in detail. The maximum adsorption of heavy metal ions onto HEC-g-P(AANa-co-AMPS) from aqueous solution was 16.61, 15.35, 13.66, 9.51 and 9.37 mmol/g for Ni(II), Cu(II), Cd(II), Pb(II) and Hg(II), respectively. In the studied concentration range, its adsorption isotherm was well described with Langmuir isotherm model. Adsorption kinetics results showed that the fast adsorption rate is obeyed the second-order kinetic equations.The fourth chapter describesβ-cyclodextrin supported nano-Fe₃O₄ grafted with maleic acid and acrylamide composite material which was initiated by glow discharge electrolysis plasma to obtain a novelβ-CD-Fe₃O₄-g-P(AM-co-MA) adsorbent. The effects of various important parameters on the heavy metal ions adsorption of adsorbent, such as the discharge voltage, discharge time, monomer mass ratio, the amount ofβ-cyclodextrin, polymerization time, polymerization temperature and the amount of crosslinking agent added were examined in detail. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR). The maximum adsorption of heavy metal ions ontoβ-CD-Fe₃O₄-g-P(AM-co-MA) from aqueous solution was 4.574mmol/g for Cu(â…¡), and the adsorption process was reached equilibrium within 30min. The pseudo-first and pseudo-second order adsorption kinetic model was used to simulate the dynamic process. Results showed that the adsorption kinetics was well described with the second-order kinetic equations. The Langmuir and Freundlich isothermal adsorption equation was used to mathematical simulate the adsorption thermodynamics of adsorbent to copper(â…¡) ion. Results showed that the adsorption was well described with the Langmuir isothermal adsorption model.