David,
There are a few "caveats" to microwave drying. The sample can get hotter
than the 105-110 degC specified for conventional oven drying and this can
result in an over-estimation of moisture content because, depending on soil
type, you could also loose some water of crystallisation from clay minerals
and oranic matter can be burnt off. This may not be a great problem in a
student exercise.
The other thing to consider is the effect on the oven itself. Running
microwaves empty is not recommended for the long-term good of the magnetron
(is that the word?)and when you completely dry out a sample it is
effectively "empty" because there is nothing left to adsorb the microwaves.
You will probably need to include some form of dummy load to soak up
microwaves. I am not sure on this point, it is best to check with the
manufacturer.
Regards,
Kevin.
Dr Kevin Privett
Principal Engineering Geologist
SRK Consulting
9-10 Summit House
Windsor Place
Cardiff CF10 3SR, UK
tel +44 (0)29 2023 5566
fax +44 (0)29 2066 5413
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