Original scientific paper

Influence of N-Alkanes on Adhesion of an Air Bubble to the Surface of Low-Rank Coals

Bronislaw Janczuk ; Department of Physical Chemistry, Institute of Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
Wieslaw Wojcik ; Department of Physical Chemistry, Institute of Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
Tomasz Bialopiotrowicz ; Department of Physical Chemistry, Institute of Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland

Abstract

Measurements of the detachment force of an air bubble from
the surface of coals of the ranks: 31.1, 31.2, 32.1 and 32.2 were
carried out. The coal surface was precovered with n-alkane film
in the homo logous series from n-hexane to n-hexadecane. The
forces were compared with those calculated theoretically on the
basis of the previously determined values of the surface free
energy components and of the contact angles measured in a
coal/n-alkane film - air bubble - water system. On the basis
of the conducted measurements and calculations we confirmed
that the stability of the coal/n-alkane film - air bubble - water
systems depends on the rank of the coal studied, the thickness
and kind of the hydrocarbon film present on the coal surface,
and on the water film pressure under the air bubble. We also
confirmed that the stability of n-alkane films on the surface of
the coals studied is smaller than the stability of these films on
the surface of typical hydrophobic solids.
By comparison of the measured and calculated stabilities of
the coal/n-alkane film - air bubble - water system it appeared
that the stabilities of such systems may be predicted on the basis
of the contact angle of the coal/n-alkane film - air bubble -
water system and of the dispersion and nondispersion components
of the surface free energy of coal.

Keywords

Hrčak ID:

175804

URI

https://hrcak.srce.hr/175804

Publication date:

10.10.1989.

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