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This paper described a plasma degradation of Brilliant Green (BG) by glow discharge electrolysis. Various influencing factors such as the voltage, the distance between cathode and anode were examined. Ultraviolet (UV) absorption spectra, gas chromatogram-mass spectrum (GC-MS), and chemical oxygen demand (COD) were used to monitor the degradation process and to identify the major oxidation intermediates. It was confirmed that benzoic acid, 1,2,3,4,5,6-cyclohexanehexaol, and carboxylic acids (e.g., oxalic acid, succinic acid and hydroxyacetic acid) were produced in the degradation process. The results showed that BG rapidly underwent degradation and eventually mineralized into CO(2) and H(2)O.

Abstract: In this work, an acrylic acid/vermiculite (AA/VMT) hydrogel was prepared by glow‐discharge‐electrolysis plasma initiated graft copolymerization, in which N,N′‐methylenebisacrylamide was used as a cross‐linker. The structure, thermal stability, morphology and surface area of AA/VMT hydrogel were characterized by FT‐IR, TG, SEM, and automated porosimeter. Cationic dyes such as Crystal violet (CV) and Methylene blue (MB) were used for testing the adsorption property. Factors influencing adsorption such as pH, contact time, concentration were investigated by batch experiments. Adsorption kinetics and adsorption isotherms were employed to illustrate the hydrogel‐dye interaction. The results showed that the best parameters for the adsorption of dyes were pH = 6 and contact time 2 h. The adsorption kinetic followed the pseudo‐second‐order model with multi‐step diffusion process. Both Langmuir and Redlich‐Peterson isotherms were well agreed with the experimental data. The maximum adsorption capacities of CV and MB on AA/VMT hydrogel were 2575.2 and 2674.0 mg g−1, respectively. [ABSTRACT FROM AUTHOR]

Using Pearson's hard and soft acids and bases (HSAB) principle as the design guideline, a novel chitosan/poly(ethylene glycol)/poly(acrylic acid) (CS/PEG/PAA) hydrogel adsorbent containing hard Lewis base adsorption site (i.e., amino group, hydroxyl group, ether linkage, carboxylate ions) was prepared by glow-discharge electrolysis plasma (GDEP) technique and then applied for the selective adsorption of Pb. A copolymerization mechanism initiated by GDEP was proposed. The structure, thermal stability, and morphology of CS/PEG/PAA adsorbent were characterized by FT-IR, thermogravimetry/differential thermogravimetry (TG/DTG), and SEM. The effects of the solution pH and contact time on the single-component adsorption were examined by batch experiments. Competitive adsorptions of Pb and Cd were carried out under equal mass concentration and equal molar concentration. In addition, regeneration and reusability of adsorbent were also investigated in detail. The results showed that the maximum adsorption capacities for Pb and Cd are 431.7 and 265.0 mg g, respectively. The kinetic behaviors of the adsorption and the fourth desorption for single component and the competitive adsorption for Pb follow the pseudo-second-order model with pH = 4.8. The CS/PEG/PAA adsorbent has good adsorption selectivity for Pb with the coexistence of Cd. The adsorbent displays excellent regeneration and reusability in the EDTA-4Na solution. [ABSTRACT FROM AUTHOR]

A palygorskite/poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylamide) (PGS/P(AMPS-co-AM)) superabsorbent hydrogel was prepared in aqueous solution using glow-discharge electrolysis plasma (GDEP) as an initiator and N, N′-methylene-bis-acrylamide as a cross-linker. A possible copolymerization mechanism initiated by GDEP was proposed. The structure, thermal stability, and morphology of PGS/P(AMPS-co-AM) were characterized by FT-IR, XRD, TG-DTG, and SEM. The swelling kinetics, pH-reversibility, and influence of various pH and salt solutions on the swelling were investigated. Adsorption kinetics and adsorption mechanism of hydrogel for dyes were studied in detail. The results indicated that the equilibrium swelling of hydrogel is 652.6 g g in distilled water. The swelling of the hydrogel in salt solutions from highest to lowest is Na > Mg > Fe. The hydrogel has pH-reversibility responsive to the pH and salts solutions. The adsorption process of dyes follows the pseudo-second-order kinetic model with multi-step diffusion process. In addition, PGS/P(AMPS-co-AM) hydrogel can be regenerated and reused. [ABSTRACT FROM AUTHOR]

This article exploits a new approach for synthesis of acrylic acid/carboxymethyl cellulose (AA/CMC) superabsorbent hydrogel in aqueous solution by a simple one-step using glow-discharge electrolysis plasma, in which N, N′-methylenebisacrylamide (MBA) was used as a crosslinking agent. The reaction parameters affecting the equilibrium swelling, that is, discharge voltage, discharge time, mass ratio of AA to CMC, content of crosslinker, and degree of neutralization, were systematically optimized to achieve a superabsorbent hydrogel with a maximum equilibrium swelling. The structure, thermal stability, and morphology of AA/CMC superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. The swelling kinetics in distilled water and swelling behaviors in various pH solutions and salts solutions (NaCl, KCl, MgCl2, CaCl2, AlCl3, and FeCl3) were investigated in detail. The effect of six cationic salt solutions on the equilibrium swelling had the following order K+ > Na+ > Mg2+ > Ca2+ > Al3+ > Fe3+. In addition, the pH-reversibility was preliminarily investigated with alternating pH between 6.5 and 2.0. The results showed that the equilibrium swelling of AA/CMC was achieved in 90 min. The hydrogel was responsive to the pH and salts, and was reversible swelling and deswelling behavior. POLYM. ENG. SCI., 54:2310-2320, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Highly swelling P(2-acrylamido-2-methyl-1-propanesulfonic acid- co-acrylic acid) (P(AMPS- co-AAc)) superabsorbent hydrogel was synthesized in aqueous solution by a simple one-step using glow-discharge electrolysis plasma technique, in which N,N'-methylenebisacrylamide was used as a crosslinking agent. The structure, thermal stability and morphology of P(AMPS- co-AAc) superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A mechanism for synthesis of P(AMPS- co-AAc) superabsorbent hydrogel was proposed. The reaction parameters affecting the equilibrium swelling (i.e., discharge voltage, discharge time, macroscopic temperature of the liquid phase, mass ratio of AMPS to AAc, and content of crosslinker) were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The hydrogel formed which absorbed about 1,685 g HO/g dry hydrogel of the optimized product was used to study the influence of various pH values and salts solutions (NaCl, KCl, MgCl, and CaCl) on the equilibrium swelling. In addition, swelling kinetics in distilled water and on-off switching behavior were preliminarily investigated. The results showed that superabsorbent hydrogel was responsive to the pH and salts. [ABSTRACT FROM AUTHOR]

A novel polymeric superabsorbing composite was prepared using the graft copolymerization of acrylic acid (AANa, 70% neutralization with NaOH) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) onto the hydroxyethyl cellulose (HEC) [HEC- g-P(AANa- co-AMPS)], which was initiated by means of a glow-discharge electrolysis plasma rather than a chemical initiator. The composite material was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). We obtained absorbencies of 2490 g g−1 for distilled water and of 109 g g−1 for 0.9 wt% NaCl solution. Results show that the maximum adsorption capacities for Ni(II), Cu(II), Cd(II), Pb(II), and Hg(II) from aqueous solution were 974.84, 975.43, 1535.52, 1970.47, and 1879.53 mg g−1, respectively. The adsorption isotherm followed the Langmuir isotherm model very well. Adsorption kinetics results indicate that the fast adsorption rate followed the pseudo-second-order kinetics equations. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A highly absorptive resin was prepared by glow-discharge electrolysis plasma initiated suspension copolymerization, in which methyl methacrylate and butyl acrylate were used as monomers, N, N′-methylenebis(acrylamide) as crosslinking agent, polyvinyl alcohol as dispersant, and NaSO solution as supporting electrolyte. To optimize the synthesis conditions, the discharge voltage, discharge time, polymerization temperature, the ratio of monomers, the amounts of crosslinking agent and supporting electrolyte, as well as the ratio of water to oil, were examined in detail. The structure and properties of the obtained resin were characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), respectively. The oil absorbency, absorption rate, absorption selectivity, and network parameters of the resin were also examined. Results showed that under the optimal conditions, the oil absorbency was about 28.5 g/g for benzene, 25.4 g/g for toluene, 28.0 g/g for xylene, 38.1 g/g for chloroform, and 37.0 g/g for carbon tetrachloride. [ABSTRACT FROM AUTHOR]

Crosslinking graft polymerization of poly acrylic/montmorillonite superabsorbent composite in aqueous solution was prepared by using glow-discharge electrolysis plasma, in which acrylic acid and acid-activated montmorillonite were used as starting materials, N, N-methylenebisacrylamide as a crosslinking agent. To optimize the synthetic conditions, seven important parameters 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, thermogravimetric analysis, scanning electron microscopy, respectively. The absorbency of poly acrylic/montmorillonite superabsorbent was examined to yield the following results: 1,834 g/g for distilled water, 116 g/g for 0.05 mol/L and 75 g/g for 0.15 mol/L sodium chloride solution. Such excellent character could be important to use in many fields, for example, in agricultural and horticultural applications. [ABSTRACT FROM AUTHOR]