Thesis-1987-Patel.pdf (4.39 MB)
A study of heterogeneity of barium sulphate surfaces partially covered by absorbed material
thesis
posted on 2012-11-30, 14:49 authored by Suresh S. PatelThe main objective of this work was to study the sensitivity of
the Heterogeneity Analysis surface characterisation methods in the
detection of the surface modification of barium sulphate due to the
presence of various amounts of preadsorbed sodium tripolyphosphate
(STPP). The main method considered was HILDA (1974) and three
isotherms were also analysed using CAEDKON (1975).
A series of adsorbates: krypton, argon, nitrogen and carbon monoxide
were used to probe the surface of barium sulphate. Precipitated barium
sulphate was prepared and solution adsorption isotherms of STPP were
determined at pH 7.6 and pH 9.0. The barium sulphate samples were
characterised by the following techniques: x-ray diffraction, electron
spectroscopy for chemical analysis and scanning electron microscopy. A grease and mercury-free volumetric adsorption apparatus was
employed which consisted of four pressure gauges ranging from 10-5 to
103 mmHg. All the adsorption measurements were determined with great
accuracy and detail at 77.SK. Isosteric heats were estimated from
nitrogen adsorption isotherms at 77.S, SO.S and Sl.6K on barium sulphate.
The Heterogeneity Analysis was used to analyse the nitrogen and
carbon monoxide data for the preadsorbed samples, which showed the high
energy sites present on the surface of barium sulphate were reduced
considerably by adsorbing STPP. Furthermore, within the HILDA method,
the Langmuir, Hill-de Boer and Fowler-Guggenheim models were compared,
methods of termination of the data was investigated, and the stability of
results was studied. A normalisation procedure for submonolayer data was
applied.
The specific surface area of the samples used were estimated and
compared with various adsorbates, different batches of barium sulphate
and increasing coverage of STPP.
History
School
- Science
Department
- Chemistry
Publisher
© S.S.PatelPublication date
1987Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.561155Language
- en