THE ABSORPTION OF NAPHTHOL DERIVATIVES BY CELLULOSIC FIBRES.
THE ABSORPTION OF NAPHTHOL DERIVATIVES BY CELLULOSIC FIBRES.
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Date
1968-07
Authors
Atanu, Emmanuel Yahaya
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Abstract
The azoic dyes are obtained by coupling between, a naphthalene
derivative end a diazotized amine The naphthalene derivative is
referred to variously as a coupling component, arylamide or by its
commercial name e.g. Breathol, Naphthol, etc. It is first adsorbed
onto the textile material and the desired colour developed by
immersing the fibre or fabric in a solution of the appropriate
diazotized amine. The depth of the shade depends mainly on the
amount of coupling component adsorbed on the fibre, prior to colour
development.
The scope of the present work was to study the uptake of these
compounds by cellulosic fibres under various conditions e.g.
different alkali, salt and naphthol concentrations; temperature;
and the effect of modifying the cellulose structure on absorption.
It was also thought that a possible mechanism for the combination of
naphthol with cellulose could be worked out and an attempt made to
see if the general laws of sorption of solids from solution could be
applied to the cellulose naphthol system.
As an introduction to the thesis an account is first given of the
structure of cellulosic fibres, describing in outline the early theories
of fine structure and the concept of crystallinity and accessibility
and their relation to the absorption of dyes and other molecules by
cellulosio fibres. An account is also given of the principal results
of previous studies on the absorption of arylamides and direct dyes
by cellulose.
The abaorption of free alkali (the solvent for the
Naphthols) was first studied, followed by napthol absorption
under various conditions by the different cellulose samples.
The sain results of the present investigations indicate that:
1) the hydroxyl groups of the cellulose chain are mainly
responsible for naphthol absorption as shown by the
reduction in absorption when these are oonverted to
carbosyl groups.
2) primary hydroxyl groups account for higher equilibrium
absorption than secondary ones.
3l oxidation of the hydroxyl groups reduces absorption.
4) opening up the cellulose structure by mereerization
increases considerably the absorptive capacity of cellulose.
The absorption of two naphthols by standard cellulose at
different starting concentrations was also studied and the results
used to test several adsorption theories. Agreement was obtained
for the treatment of Saruwalla and Kulkarni leading to the suggested
mechanism that only the dye anions are adsorbed on specifio sites,
while the sodium ions are diffusely adsorbed. The treatment
adopting Hill's statistical approach also yielded a positive
agreement. The concurrence of the theories tested lies in the fact
that their formulation depends on the basic assumption of an initial
monolayer absorption on which is superimposed a diffuse layer.
Description
Thesis
presented to
The Ahmadu Bello University for the degree of Master of Science
in the faculty of Science
by
Emmanuel Yahaya Atanu,B.Sc. (A.B.U)
Department of Chemisrty,
The Ahmadu Bello University,
Zaria.
july, 1968.
Keywords
ABSORPTION,, NAPHTHOL,, DERIVATIVES,, CELLULOSIC,, FIBRES,