scholarly journals Properties of PTFE tape as a semipermeable membrane in fluorous reactions

2015 ◽  
Vol 11 ◽  
pp. 980-993 ◽  
Author(s):  
Brendon A Parsons ◽  
Olivia Lin Smith ◽  
Myeong Chae ◽  
Veljko Dragojlovic
Keyword(s):  
Surface Tension ◽  
Organic Compounds ◽  
Polymer Films ◽  
Semipermeable Membrane ◽  
Reaction Vessel ◽  
Dimethyl Phthalate ◽  
Delivery Tube ◽  
Selective Permeability ◽  
Solvent Uptake ◽  
Solvent Adsorption

In a PTFE tape phase-vanishing reaction (PV-PTFE), a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better describe the process of solvent transport in PV-PTFE bromination reactions. Though PTFE tape has been reported as impermeable to some compounds, such as dimethyl phthalate, solvent adsorption to the tape altered its permeability and allowed diffusion through channels of solvent within the PTFE tape. In this case, the solvent-filled pores of the PTFE tape are chemically more akin to the adsorbed solvent rather than to the PTFE fluorous structure. The solvent uptake effect, which was frequently observed in the course of PV-PTFE reactions, can be related to the surface tension of the solvent and the polarity of the solvent relative to the reagent. The lack of pores in bulk PTFE prevents solvents from altering its permeability and, therefore, bulk PTFE is impermeable to most solvents and reagents. However, bromine, which is soluble in liquid fluorous media, diffused through the bulk PTFE. A better understanding of the PTFE phase barrier will make it possible to further optimize the PV-PTFE reaction design.

Photocatalysed Oxidation of Toxic Organics

1987 ◽  
Vol 19 (3-4) ◽  
pp. 381-390 ◽  
Author(s):  
M. Brett Borup ◽  
E. Joe Middlebrooks
Keyword(s):  
Hydrogen Peroxide ◽  
Ultraviolet Radiation ◽  
Organic Compounds ◽  
Hydroxyl Radicals ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Dimethyl Phthalate ◽  
First Order ◽  
Toxic Organics ◽  
Catalyzed Oxidation

The feasibility of treating water contaminated by two toxic organic compounds with an ultraviolet light catalyzed oxidation process using hydrogen peroxide as an oxidant is investigated. In this process hydrogen peroxide is decomposed by ultraviolet radiation producing hydroxyl radicals. The hydroxyl radicals will then oxidize organic compounds via a complex chain of radical reactions. Tests showed that this photooxidation process could successfully remove isophorone and dimethyl phthalate from contaminated waters. A reaction rate expression which adequately describes the process was developed. The reaction rate was found to be first order with respect to hydrogen peroxide concentration, zero order with respect to organic concentration and a function of ultraviolet radiation intensity. The reaction did not exhibit autocatalytic characteristics.

scholarly journals SURFACE TENSION OF SERUM

1922 ◽  
Vol 35 (5) ◽  
pp. 707-735 ◽  
Author(s):  
P. Lecomte du Noüy
Keyword(s):  
Surface Tension ◽  
Surface Layer ◽  
Free Surface ◽  
Organic Compounds ◽  
Sodium Oleate ◽  
Mean Value ◽  
Physiological Solution ◽  
Optimum Concentration ◽  
Initial Value ◽  
Ring Method

The application of the ring method to the measurement of solutions of serum and of certain organic compounds has brought forth new facts, mainly the decrease of the surface tension of such solutions in function of time. 1. In serum diluted at such a low concentration as 1:1,000,000 in NaCl, physiological solution, the surface tension of the liquid is lowered by 3 or 4 dynes in 2 hours; at 1:100,000, by about 11 dynes (mean value) in 2 hours, and by 20 dynes in 24 hours; at 1:10,000 by about 13 to 16 dynes in 2 hours. 2. The drop in surface tension is much more rapid in the first 30 minutes and follows generally the law of adsorption in the surface layer in function of the time. 3. Stirring or shaking after the drop causes the surface tension to rise, but generally below its initial value. 4. The same phenomena occur when using sodium oleate, glycocholate, or saponin instead of serum. 5. For every serum, as well as for the substances mentioned above a maximum drop occurs in certain conditions at a given optimum concentration. 6. Not only are the substances which lower the surface tension adsorbed in the surface layer, in the case in which they are present with crystalloids, but also the crystalloids themselves, in contradiction to Gibbs' statement. This is plainly shown by the evaporation of such solutions in watch-glasses which, instead of a small group of sharp, large, well defined crystals at the bottom, leaves a white disc almost as large as the initial free surface itself, due to the liberation of the salt by the surface layer as it crawls down the concave surface of the glass. 7. In these conditions, solutions of serum are characterized by a very peculiar periodic and concentric distribution of the crystals, at a concentration of 1:100 only. The same ring-like aspect is observed with sodium oleate, glycocholate, and saponin, but not at the same concentration, as was to be expected, since serum is a solution in itself.

scholarly journals Modeling the surface tension of complex, reactive organic–inorganic mixtures

2013 ◽  
Vol 13 (21) ◽  
pp. 10721-10732 ◽  
Author(s):  
A. N. Schwier ◽  
G. A. Viglione ◽  
Z. Li ◽  
V. Faye McNeill
Keyword(s):  
Surface Tension ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Goodness Of Fit ◽  
Cloud Droplet ◽  
Aqueous Mixtures ◽  
Surface Tension Data ◽  
Inorganic Systems ◽  
Experimental Surface ◽  
Using Data

Abstract. Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic–inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2–6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski–Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic–inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (χ2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

scholarly journals Bidirectional Control of Flow in Thin Polymer Films by Photochemically Manipulating Surface Tension

2015 ◽  
Vol 27 (13) ◽  
pp. 4538-4545 ◽  
Author(s):  
Chae Bin Kim ◽  
Dustin W. Janes ◽  
Sunshine X. Zhou ◽  
Austin R. Dulaney ◽  
Christopher J. Ellison
Keyword(s):  
Surface Tension ◽  
Polymer Films ◽  
Thin Polymer Films ◽  
Thin Polymer ◽  
Control Of Flow
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