|Abstract or Summary
- The dyeing of paper is one of the most important
processes in the manufacture of that material. Fully 95 percent
of the paper that is produced is colored to a greater or
lesser extent, and in many eases the reproduction of a shade
is essential. That pH is an important factor in the dyeing
of paper has been realized, but very little has been done to
determine the quantitative effect. This latter was the purpose
of this work, and in order that the nature of the process
be more fully realized, theories of dyeing were discussed.
Experimental results are as follows:
The adsorption of Methylene Blue from water solutions
of different concentrations was studied and found to follow
Freundlich's adsorption law.
Adsorption of Methylene Blue at different pH values,
where the pH was controlled by means of McIlvaine's buffers,
showed a rather steady increase with increased pH, with the
exception that on alumina the adsorption rose to a maximum
and thereafter decreased. With the same dye, but with the pH varied by means
of Al₂(SO₄)₃ - NaOH solutions, adsorption followed, for all
cases, the same trend as for alumina above.
Adsorption of Victoria Green increased continuously
with increased pH when the pH was regulated by Al₂(SO₄)₃ - NaOH solutions. In the higher pH values the adsorption on
the fillers and cellulose did not differ materially from
the adsorption on alumina alone. Albolith and china clay,
however, showed a relatively great affinity for the dye at
lower pH values.
A study of Alizarine Blue, with pH controlled by
Al₂(SO₄)₃ - NaOH solutions, demonstrated that the maximum
adsorption was between a pH of about 5.8 and 6.6. Adsorption
was very great in this range, but in no case much greater
than on alumina alone.
Adsorption of Orange R. O., with pH controlled as
above, proceeded much as for Alizarine Blue, the maximum
adsorption falling between about pH 4.9 and 5.4. Adsorption
on albolith and china clay was much greater than on alumina
alone, but for the other substances this was not true. Adsorption of the dye was not so great as for Alizarine Blue.
A colloidal viewpoint was adopted, as far as possible,
for the explanation of the process of dyeing in the cases
That alumina is very important in the dyeing of paper