An Improved Process for Removing the Green Colour from Paraffin, Vaseline, and Lubricating Oils which have had that Colour Imparted to them by Bodies Containing Oxygen.
Year: 1894

page_text: COMPLETE SPECIFICATION.
An Improved Process for Removing the Green Colour from Paraffin,
Vaseline, and Lubricating Oils which have had that Colour
Imparted to them by Bodies Containing Oxygen.
I, AUGUST WENDTLAND, of 2/II Marienstrasse Berlin, in the German Empire,
Doctor of Philosophy and Analytical Chemist, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :--
The object of this process is to decolour the various classes of paraffin, vaseline
and lubricating oils which have been coloured green owing to the presence of bodies
containing oxygen.
To accomplish this object the substances to be decoloured are thoroughly mixed
with a solution of soap in a state of fine division, and such solution is afterwards
separated again together with the green colouring bodies which it has bound or
retained.
In bleaching the substances above named by means of bone black, it is found
that owing to the influence of the oxygen condensing upon the bone black, the said
substances assume a green colour. To prevent such colouring, the substances to
be bleached are treated, before or during the employment of the bone black with
aethyl alcohol, methyl alcohol, aldehydes acetones, oleic acid or vegetable oils
(especially quick drying oils) and train oil. To illustrate this process, I will take
the example of petroleum residues having undergone a preliminary purifying
operation by means of sulphuric acid.
The residues obtained in distilling naphtha, when treated with sulphuric acid, in
the manufacture of thick lubricating oils or viscous vaseline, become coloured green.
To remove this colouring, the paraffin mass is thoroughly mixed with soap solution
in a finely divided condition. The best way to effect this mixture is to mix first
the soap solution with from 3 to 10 per cent. of fatty acids, acid or rosin or, prefer-
ably, oleic acids, and then slowly to add thereto a small surplus quantity of oxides
hydroxides or carbonates of the alkalies, which in mixing with the water will
saponify. Instead of the fatty acids or rosin acids, it will be understood that the
fat or rosin itself may, if preferred, be employed.
The separation of the soap solution, which now contains the dark coloured
impurities, from the mass of paraffin, takes place simply by the soap and impurities
being allowed to settle at the bottom. In the case of particularly thick substances,
the separation may be brought about by the aid of centrifugal force.
The products thus obtained, after having been freed from the soap solution, are
washed several times over with soft hot water, and finally washed again with a
weak solution of chloride of barium.
The soap solution thus separated, when the light is allowed to fall upon it, will
appear to be coloured a deep green, and if held against the light, will be transparent
and assume a reddish brown hue. Such solution, in order to extract the fatty acids
from it again, should be mixed with a diluted mineral acid, when the green products
will separate and may be removed by mechanical appliances.
Where the residues from the distillation of naphtha, after having been treated
with sulphuric acid, and after having or not, undergone a preliminary purifying
operation as may be preferred, are bleached with bone black, they will be found to
absorb the oxygen condensed upon the bone black, the products of such oxidation
being green. To remove this green colour, and to obtain a more thorough bleaching,
either the residues, (after being treated in the above mentioned manner,) or the
bone black, are heated with the following reducing materials: æthyl or methyl

page_text: alcohol, aldehydes, ketones, oleic acid, vegetable oils, (more particularly such as
dry readily,) or train oil.
For this purpose, the residues, having been treated as above mentioned, are mixed
with the reducing materials at a temperature of 50° centigrade.
Or again the warm bone black, contained in an open or close vessel, is besprinkled
with alcohol, aldehydes, ketones, or oils. The best temperature for the bone black
is 80° centigrade. If the temperature is raised, the purification of the bone black
can be completed in less time.
Or, thirdly, the vapours of the alcohols, aldehydes, or ketones are conducted into
a close vessel containing the bone black. The effect produced by the vapours is
completed in about an hour. The temperature of the bone black should be as
above mentioned.
The proportions of the reducing materials may be theoretically calculated from the
quantity of oxygen contained the bone black. In practice, the proportions are
determined by some preliminary experiments. A quantity of from to 1% of the
reducing material is generally sufficient.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
First. A process for removing the green colour from paraffin, vaseline, and
lubricating oils of every description, having had their colour imparted to them by
bodies containing oxygen; such process consisting in thoroughly mixing the
paraffin, vaseline or oil with the soap solution, and subsequently separating the soap
solution therefrom.
Second. In connection with the process referred to in the first claim, the
bleaching of the paraffin, vaseline and lubricating oil, which have assumed a green
colour through being treated with bone black, by the employment of æthyl or
methyl alcohol, aldehydes, ketones, vegetable oils, especially such as dry rapidly,
and train oil, either before or during the treatment with bone black.
Dated this 8th day of May 1894
MARKS & CLERK,
18, Southampton Buildings, London, W.C., Agents.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., Agents.