| Glow discharge electrolysis (GDE) is a novel electrochemical process in which plasma is sustained by dc glow discharge between an electrode and the surface of electrolyte. When the applied voltage is sufficiently high in aqueous solution, the conventional electrolysis is developed into GDE and produces various active species. Some component, such as hydroxyl radicals, hydrogen peroxide, and aqueous electrons, can be transmitted into the solution to induce some unconventionally chemical reations. Therefore, GDE can provide active intermediates for chemicl reaction in aqueous solution. This paper consists of five chapters, focussing on the application of glow discharge electrolysis plasma in the synthesis of poly-acrylic acid / clay superabsorbent via solution polymerization.Chapter 1: The general figure about glow-discharge plasma is given in brief. The formation, characteristics and application of glow-discharge electrolysis plasma (GDEP) are chiefly described. In addition, it makes an introduction of the application of plasma concerning wastewater treatment, chemical synthesis, initiation polymerization, as well as polymerization method and technology. The plasma-initiated polymerization and its application are emphasized. Finally, there was a mini-review concerning the absorbing mechanism, effect factors of absorbing property, and characterization method. It was indicated that the GDEP could initiate aqueous solution polymerization and synthesis an excellent property of superabsorbent resin instead of chemical initiator.Chapter 2: Crosslinking graft polymerization of poly (acrylic acid/ montmorillonite) superabsorbent resin in aqueous solution was prepared by using GDEP, in which acrylic acid and acid-activated montmorillonite were used as starting materials, N, N-methylenebisacrylamide as a crosslinking agent. The synthetic conditions of the graft-polymerization were examined in detail, such as the discharge voltage, discharge time, the neutralization of acrylic acid, post polymerization temperature, amounts of crosslinking agent, montmorillonite and acrylic acid used in this study. The structure, thermal stability and morphology of product were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), respectively. Results indicated that montmorillonite was effectively grafted with poly acrylic acid. Moreover, the superabsorbent prepared by GDEP had a higher water absorbency, water retention and thermal stability (1,834 g·g-1 for distilled water, 116 g·g-1 for 0.05 mol·L-1and 75 g·g-1 for 0.15 mol·L-1 sodium chloride solution). Such excellent character could be important to use in many fields, for example, in agricultural and horticultural applications.Chapter 3: Crosslinking graft polymerization of poly acrylic acid/vermiculite superabsorbent resin in aqueous solution was prepared by using GDEP, in which acrylic acid and vermiculite were used as starting material, N, N-methylenebisacrylamide as a crosslinking agent. Some effects of the graft polymerization such as the discharge voltage, discharge time, the neutralization of acrylic acid, post polymerization temperature, amounts of crosslinking agent, vermiculite and acrylic acid used on the polymerization were discussed in detail. The superabsorbent resin was characterized by FTIR, TGA, SEM, respectively. The relationships of water retention and centrifugation time were also studied. The results indicated that the swelling capacity for pure water and 0.15 mol·L-1 NaCl solution were found to be 1333 g·g-1 and 73 g·g-1, respectively. When the water retention of swollen superabsorbent prepared by GDEP has still exceeded 65% for distilled water after centrifugation at 4000 rpm for 120 min, which illustrates that the resin has a better retention capacity.Chapter 4: A novel sepiolite grafted acrylic acid superadsorbent has been synthesized via using GDEP, which was characterized by FTIR, TGA, respectively. Moreover, to optimize the synthesis conditions, the following parameters were studied: discharge voltage, discharge time, monomer content and polymerization temperature. Results indicated that sepiolite was effectively grafted with acrylic acid. And the GDEP could be used to synthesize an excellent property of superabsorbent resin.Chapter 5: A novel diatomite grafted acrylic acid superadsorbent has been synthesized via using GDEP, which was characterized by FTIR. The following parameters were studied, for example, discharge voltage, discharge time and polymerization temperature. Results indicated that diatomite could be effectively grafted with acrylic acid by in the presence of GDEP.
|
PDF Full Text Request