Studies in Adsorption by Textile Fibres

Tolia, Arunkumar Harilal (1963) Studies in Adsorption by Textile Fibres. PhD thesis, University of Glasgow.

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This thesis describes a series of investigations designed to apply the available fundamental knowledge of the adsorption process to the understanding of some of the problems concerned with the surface characteristics of textile fibres, and its effect on adsorption process. Part I of the thesis is concerned with investigations to study the effect of the size of adsorbate molecule on the rate of adsorption on wool fibres and the influence of pores of varying sizes in the wool. The physical state of dye in air-dry wool fibres has also been investigated. The vapour phase adsorption technique has been followed and it is shown that vapours with similar active groups but different molecular size show a considerably slower rate of adsorption on wool fibres with increase in adsorbate molecule size, the saturation adsorption decreasing at the same time. This has been attributed to the presence of pores on the wool surface, the size and distribution of these pores determining both the rate of adsorption and the saturation adsorption. An attempt has been made to calculate the pore-size distribution in wool fibres. The similar experiments on dyed wool fibres indicate a lower rate of adsorption for these vapours and also a lower saturation adsorption. Since the rate and the saturation adsorption are not very much lower at high concentration of dye in fibres, it is suggested that the process is affected by the blocking of pores by dye aggregates rather than the inactivation of similar adsorption sites for dyes and vapours. Part II is concerned with the study of relative rates of adsorption by wool and gelatin for a number of series of sulphonated azo acid dyes and 2:1 dye-metal complexes. It is shown that: (i) The rate of adsorption of each dye by a given area of the external surface of gelatin is about four times that by the same area of the external surface of wool; (ii) the logarithm of the rates falls linearly with both the number of substituent groups in the dye molecule and with its molecular volume; each series of dyes giving points lying on a different line. A statistical study of wash fastness and migration property data for a number of acid dyes shows that these properties are significantly dependent on the total number of atoms or the number of carbon atoms alone, in a dye molecule. Thus wash fastness is shown to increase with increasing size of the dye molecule, while the ease of migration falls. A few experiments, including measurements of absorption spectra, are described in which benzyl alcohol, and to a less extent dioxan, tends to disaggregate dyes of low basicity when added to their aqueous solutions, but D-glucose and inositol do not do so. Of these solutes, only benzyl alcohol is effective in accelerating dyeing. It is considered that the mechanisms already proposed to account for the acceleration of dyeing by addition of solvents probably all operate, but the most important may be the effect of adsorption of the solvent by the fibre. On the basis of these results, the very rapid adsorption of benzyl alcohol by wool is attributed to its low molecular volume and non-ionic nature. Part III is concerned with the development of a new chemical method for the measurement of the external surface areas of textile fibres and the method has also been used on paper pulp fibres. The method is based on the solution adsorption method for measuring surface areas of powders etc., but modification was necessary when applying it to textile fibres because of their porous structure. The adsorption isotherms at short intervals of time are determined, instead of at equilibrium, and the surface areas calculated from these isotherms are extrapolated to zero time. The apparent surface area at zero time has then been assumed to be related to the true external surface area of fibres, and the results compared with those obtained by microscopic and air-permeability methods. A good agreement between the results by different methods has been observed. Chemically modified wool fibres and paper pulp fibres beaten for different intervals of time showed changes in external surface areas reflecting the changes in the fibre surface with different treatments. External surface areas are found to vary with different non-polar solvents when p-nitrophenol is the solute, and this has been related to the solubility of the solute in different solvents. Use of non-polar solvents in which p-nitrophenol is sparingly soluble is recommended.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Textile research
Date of Award: 1963
Depositing User: Enlighten Team
Unique ID: glathesis:1963-79483
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 09:05
Last Modified: 05 Mar 2020 09:05

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