Search

The UV, UV/VUV photolysis and their combination with persulfate (S2O82−) were studied for the elimination of trimethoprim and 5-fluorouracil. Methods were examined in terms of transformation and mineralization rate and the matrix effect. The relative contribution of the direct UV photolysis and radical-based reactions (•OH, SO4•−) were also investigated. Without S2O82−, the efficiency of UV/VUV photolysis highly exceeds that of UV photolysis due to the •OH formation, while in the presence of S2O82−, the dominant reaction partner is SO4•−. However, SO4•−-based methods proved to be efficient for both transformation and mineralization; they are sensitive for the matrix components. [ABSTRACT FROM AUTHOR]

Phenothiazine oligomers were synthesized by oxidative oligomerization. Optimal reaction conditions were found: phenothiazine reacts with ammonium persulfate and silver (I), nickel (II), copper (II), and iron (III) nitrates in mechanochemical conditions in a mixture with p-toluenesulfonic acid. Effect of oxidants on the structure and morphology of oligomers was demonstrated by complex of physical methods, most prominent structural difference is demonstrated by MALDI mass-spectrometry and method of scanning electron microscopy. The use of metal nitrates leads to formation of oxidized oligophenothiazines (mass peaks correspond to side reactions leading to hydroxyl groups) which form bulk, granular material, the use of ammonium persulfate leads to formation of mesoporous material. Dielectric permittivity of oxidized oligomers is 2.9 – 10.2 in the case of metal nitrates while the maximum of permittivity was obtained for nanostructured oligophenothiazine – 4027.3 which was synthesized with ammonium persulfate as an oxidizing agent. We conclude that side reactions affect the morphology and dielectric permittivity – i.e. hydroxyl, quinone groups participate in forming intermolecular hydrogen bonds while in oligophenothiazine these interactions are less significant, which leads to mesoporous structure. [ABSTRACT FROM AUTHOR]

Acrylic acid, polyacrylamide and poly(methyl acrylate)) and waste polystyrene foam via chain growth polymerization technique in the presence of Potassium Persulphate as redox initiator, N,N'-Methylenebisacrylamide as crosslinker and Sorbitane Monooleate (Span 80) as nonionic surfactant were utilized. In this project, hydrogels based on acrylic acid (AA), acrylamide (AAm) and methyl acrylate (MA) were grafted with waste polystyrene foam (WPSF). The effect of monomer types and ratios of absorption and swelling equilibrium in distilled water was investigated. This is followed by an analysis of hydrogels absorption in saline water and urea solution as well as Fourier Transform Infrared (FTIR) characterization. In swelling studies, hydrogel based on WPSF-graft-acrylic acid showed an ultimate absorption at 6:1 mass ratio of acrylic acid to waste polystyrene foam. Meanwhile, hydrogel based on WPSF- graft-acrylamide and WPSF-graft-methyl acrylate, both showed continuous increased in water uptake with increasing monomer content. Upon characterization with FTIR, a significant hydrophilic functional groups exist in the spectrum that corresponds to the acrylate monomer, WPSF and crosslinker unit. [ABSTRACT FROM AUTHOR]

Raman spectroscopy was used for in-situ monitoring of styrene emulsion polymerization with sodium dodecyl sulfate and potassium persulfate as the surfactant and initiator, respectively. A new method for analyzing Raman data and calculating monomer conversion was proposed on the basis of the shift of peak corresponding to aromatic ring breathing. It was demonstrated that monomer conversion calculated with this method was similar to the one calculated using the area of vinylic bond as well as to off-line gravimetric determination. Moreover, the kinetic intervals were detected. The conversion measured at the transitions was similar to the literature data. [ABSTRACT FROM AUTHOR]

The synthesis of polyaniline has been reported using three different oxidative reagents: ammonium persulfate, potassium iodate and potassium iodate+sodium hypochlorite. This polyaniline has been used to prepare several nanocomposites with different percentage of Montmorillonite. The DC conductivity of the nanocomposites was determined by impedance spectroscopy. The oxidative reagent that gives higher conductivity is ammonium persulfate. The temperature dependence of the conductivity was studied. [ABSTRACT FROM AUTHOR]

Polyaniline colloidal nanoparticles (PANI CNs) were synthesized, employing biopolymer pectin (Pec) as a stabilizer along with hydrochloric acid dopant and ammonium persulfate oxidant. Chemical nature and electronic structure was studied by FT-IR and UV-visible spectroscopy respectively. FE-SEM revealed spindle like morphology of PANI CNs and displayed the nearly discrete particles without aggregation, showing stabilizing capacity of the Pec. Cyclic voltammetry and galvanostatic charge-discharge measurements demonstrated the electroactivity and supercapacitive property of the PANI CNs in 1 M HCl. The specific capacitance of PANI CNs in 1 M HCl at 1.5 A/g was found to be 197 F/g, where 70% of specific capacitance was retained even after 1000 cycles. These findings establish the feasibility of using the PANI CNs as a potential material for energy storage in aqueous acidic medium. Furthermore, this colloidal dispersion can find potential application in electrodes of flexible supercapacitor device and printable electronics. [ABSTRACT FROM AUTHOR]

Persulfate (PS) oxidation process was studied to remediate dieselcontaminated site. Various methods have been suggested to increase the reactivity of PS and feasibility of PS activation by base solution was evaluated in this study. It was reported by other researchers that base could activate PS in homogenous system, but it was ambiguous in heterogeneous system. First of all, soil was characterized and it was contaminated by commercial diesel (i.e. 5000 mg/kg). Degradations were conducted using a batch reactor without mixing, and sodium hydroxide (NaOH) was used as a source of base. Effects of initial pH and a molar ratio of PS/NaOH were tested. The highest diesel degradation was observed with 0.5 M of PS and 3 M of NaOH, and diesel was degraded as much as 23% for 12 h of reaction time. The pH of the system was maintained as 12 and residual PS was 0.425M. Moreover, treatment efficiency (Adiesel/Aoxidant) was 0.04 indicating PS could be activated with NaOH without a mixing. Other activation methods will be further tested to improve treatment efficiency of PS. [ABSTRACT FROM AUTHOR]