Lynne Wong's PhD thesis

Determinations were effected for 5, 10, 20, 30, 40, 50 and 60% (m/m) sulfuric acid at each
of 30, 45, 55 and 60 °C. Duplicate determinations were carried out for each acid
concentration and temperature.
The whole experiment was repeated for the nine cane components of variety R 570 aged
36 weeks.
A number of precautions were taken:
• A mercury thermometer was placed in the middle of the air oven to ensure that the
required temperature was reached, although there was a dial gauge thermometer on the
oven.
• Half-way through the adsorption process, the samples were gently shaken to break up
any lumps formed. This was necessary especially with fine samples, e.g. pith, which
had a tendency to cake.
• At high temperature and high humidity, any condensation collected after equilibrium
on or in the bottle, was wiped dry before weighing.
• During drying at 105 °C, the samples were shaken gently to allow all moisture to
escape.
Table 5.6. Number of days to reach equilibrium in aqueous
sulfuric acid at various temperatures.
Concentration of
sulfuric acid
solution/% (m/m)
30 °C 45 °C 55 °C 60 °C
5 4 4 4 5
10 3 3 4 4
20 2 2 2 2
30 1 1
40 1 1
50
60 1 1 1
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