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1

Adsorptive properties of natural water surfactant films. Dead Vistula catchment water studies

Pogorzelski S. J., Kogut A. D.

Oceanologia

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2003

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No. 45 (3)

373-394

EN

The paper contains the results of natural film experiments carried out on inland waters in the Dead Vistula (Martwa Wisła) catchment area during 1999-2002 using the integrated Langmuir trough-Wilhelmy plate system, which "cuts out" an undisturbed film-covered area without any physicochemical sample processing. The static film parameters result from the generalized scaling procedures applied to the surface pressure-area isotherms. They appear to correspond well to observations of the film composition Alim, MW, Eisoth, film solubility and the miscibility of its components (via R, ΔSc and y factors), and surface concentration Πeq, Γeq. A novel approach is presented for the adsorption dynamics on the basis of the mixed kinetic-diffusion model and analyses of the dynamic surface pressure plots, which leads to the determination of the effective relative diffusion coefficient Deff / D and activation energy barrier Ea / RT. There is reason to believe that certain classes of film-forming components or "end-members" may dominate the static and dynamic surface properties. Some of these substances can be used as source-specific surface-active biomarkers to trace temporal and spatial changes due to environmental factors or the production of biological matter. The concept was tested for the Dead Vistula river and its tributaries. The results demonstrate that natural films are a complex mixture of biopolymeric molecules covering a wide range of solubilities, surface activities and molecular masses with an apparent structural film architecture. Such studies could lead to the development of film structure parameters - indicators of ecosystem quality and the state of the environment.

2

Static and dynamic properties of surfactant films on natural waters

Pogorzelski S.J., Kogut A. D.

Oceanologia

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2001

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No. 43 (2)

223-246

EN

The paper contains the results of natural surface film surface pressure - area experiments carried out in inland waters and shallow offshore regions of the Baltic and Mediterranean Seas during 1990-99 under calm water conditions using the Langmuir trough - Wilhelmy filter paper plate system, which "cuts out" an undisturbed film-covered sea area without any initial physico-chemical sample processing. The limiting specific area Alim (268–3157 A2/molecule-1) and mean molecular mass (0.65-9.7 kDa) of microlayer surfactants were determined from the 2D virial equation of state applied to the isotherms. Film structure signatures were derived from π– A isotherm hysteresis and application of the 2D polymer scaling theory. The stress-relaxation measurements revealed a two-step relaxation process at the interface with characteristic times τ1 (1.1–2.8) and τ2 (5.6-25.6) seconds suggesting the presence of diffusion-controlled and structural organization relaxation phenomena. The results demonstrate that natural films are a complex mixture of biomolecules covering a wide range of solubilities, surface activity and molecular mass with an apparent structural organization exhibiting a spatial and temporal variability.

3

Kinetics of marine surfactant adsorption at an air water interface. Baltic Sea studies

Pogorzelski S.J., Kogut A. D.

Oceanologia

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2001

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No. 43 (4)

389-404

EN

The paper contains the results of studies of natural surface film adsorption kinetics carried out in inland waters and in shallow offshore regions of the Baltic Sea during 2000-01 under calm sea conditions. The novel approach presented here for the adsorption dynamics is based on the mixed kinetic-diffusion model and analyses of the surface pressure-time plots at short (t →0) and long( t →∞) adsorption time intervals. Values of the effective relative diffusion coefficient Deff / D (= 0.008-0.607) and energy barrier for adsorption Ea / RT (= 0.49-7.10) agree well with the data reported for model non-ionic surfactant solutions of pre-cmc concentrations. Wind speed is one of the factors affecting the adsorption barrier via the increased surface pressure of the natural film exposed to wind shear stress (~ U102), and enters the relation Ea / RT = 1.70 U101/3.