Article

Oxidation of polystyrene aerosols by VUV-photolysis and/or ozone.

Lehrstuhl für Umweltmesstechnik, Engler-Bunte-Institut, Universität Karlsruhe, Germany.
Photochemical and Photobiological Sciences (Impact Factor: 2.92). 08/2009; 8(7):944-52. DOI: 10.1039/b902749a
Source: PubMed

ABSTRACT Aerosols of submicron polystyrene particles were oxidized by either vacuum-ultraviolet (VUV) irradiation in the presence of molecular oxygen (O(2)) and/or by ozone (O(3)). Different degrees of oxidation and oxidative degradation were reached by VUV-photolysis depending on radiant energy, O(2) and H(2)O concentrations in the bulk gas mixture as well as on particle diameter. The same functionalization was obtained by exposing the aerosol to O(3), however, oxidation, in particular oxidative degradation, was less efficient. The evolution of hydroxyl and carbonyl functions introduced was quantified by ATR-FTIR spectroscopy of filtered particles, and oxidative degradation of the polymer particles was confirmed by determining size and number of aerosol particles before and after oxidation. Efficiency analyses are based on the results of an O(3) actinometry and on an evaluation of the rate of absorbed photons by the aerosol particles in function of their size.

0 Bookmarks
 · 
134 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: To use amphiphilic polymer nanoparticles as a new nano-absorbent for improving environmental process, urethane acrylate nonionomer (UAN) chain having hydrophobic polypropylene oxide-based segment and hydrophilic polyethylene oxide-based segment at the same backbone was synthesized and dispersed as nanoparticles at water phase without using a surfactant or dispersion agent. These UAN nanoparticles were converted to crosslinked amphiphilic polymer (CAP) nanoparticles through soap-free emulsion polymerization and suspension agent-free suspension polymerization process. Emulsion polymerization process exhibited higher conversion of polymerization compared to suspension polymerization process. CAP nanoparticles showed interfacial activity and solubilize hydrophobic pollutants (phenanthrene and toluene) like surfactant micelles. This result indicates possible application of CAP nanoparticles as nano-absorbent for improving efficiency of soil washing and micellar-enhanced ultrafiltration (MEUF) process.
    Journal of Nanoscience and Nanotechnology 12/2007; 7(11):4000-4. · 1.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Fourier-Transform infrared (FTIR) spectroscopy and surface energy analysis (contact angle measurements) have been performed as a means of identification and quantification of the functionalization of polystyrene surfaces upon vacuum ultraviolet- (VUV-) photochemically initiated oxidation. Photochemical oxidation was performed in the presence of water vapor and molecular oxygen using a pulsed Xe2-excimer radiation source (lambda(exc): 172 nm). Surface oxidation was studied as a function of two parameters: irradiation time and distance between sample and radiation source. During the first 1-2 min of irradiation, an increase of the concentrations of hydroxyl (OH) and carbonyl (C=O) groups on the surface was observed, both reaching limiting values. As expected, the rate of oxidation diminished exponentially with increasing distance between the radiation source and the surface of the polystyrene film. Changes in the surface energy due to the introduction of these polar (i.e. OH and C=O) groups were also determined. The densities of the functional groups decreased upon washing with acetonitrile, and analysis of the washing solution by means of gas chromatography-mass spectrometry (GC-MS) revealed the presence of a large number of products. The application of pulsed Xe2-excimer radiation sources as a valuable alternative to conventional means (i.e. laser and plasma) for the photochemical oxidation and surface modification of polystyrene is discussed.
    Photochemistry and Photobiology 01/2005; 81(4):777-82. · 2.29 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Technical development work is presented, where the VUV photochemically induced oxidative degradation is used: (i) for analytic purposes, and (ii) for small to medium scale (< 10 m2/d) waste water treatment processes or ultrapure water production. In the first case, small Xe-excimer radiation sources with an integrated reaction space designed for optimal conditions, as far as incident photon flux density, turbulence and concentration of dissolved molecular oxygen are concerned, have been built and tested. Under conditions of exhaustive oxidation and/or mineralization of pollutants in a continuous regime, they may be used for sample pre-treatment modules prior TOC, TOX and electrochemical trace metal analysis. Under conditions of partial oxidation or mineralization, the same lamp/reactor combination may be used for functionalization purposes prior to e.g. GC or HPLC analyses. In the second case, mass transfer limitations between the non-irradiated bulk volume and the irradiated volume are overcome by the electrochemical generation of molecular oxygen within or close to the irradiated volume and by the design of the photochemical part of the reactor.
    Water Science & Technology 01/2004; 49(4):235-40. · 1.10 Impact Factor

Full-text

View
67 Downloads
Available from
May 30, 2014