always when we would like to calculate the water content for the soil (sand and clay ) we use the temperature of 105° and for the organic matter we choose the temperatur of 50° up to 60° but, in the case of renforcement of an embankment with an organic matter(fibers) with different percentage of the organic matter (10% maximum of the organic fiber) which temperature we use
At 50-60 oC water also evaporates.
Suspending in MeOH and Karl-Fischer titration?
Laszlo Jicsinszky I am working on the soil improvement with organic fiber and i came acroos a bet issue in regard with the calculation of water content, I am confused which temperature i follow 50° up to 60° or 105° ; of course I could use 50° but , the problem this goining to take long time up to one week instead of one day.
Dear Adel,
Your question is not really clear. What is the goal of your measurements? If I understood well, your task is to measure the water contents and organic volatiles in various samples, isn't it? Regarding your main goal, the temperature is not a crucial point because water can evaporate at room temperature also, so if you dry your sample will lose almost all water content at 50 oC after a week and not only the organics.
If you want to know how many volatiles are in your samples, I recommend the following procedure.
1. Do a TG to see at which temperatures start the weight loss. My experiences suggest that quantitative TG needs many experiments, otherwise the calculated values might be misleading.
2. Measure the water content by Karl-Fisher titration. This method is practically selective for water.
3. Dry your sample at 105 oC to determine the total weight loss. Unfortunately, the difference between the total weight loss and the water content does not necessarily mean the volatile organic content, because, e.g. the NaHCO3 can be transformed to Na2CO3.
4. At room temperature in an exsiccator (without vacuum!) you can use in two different experiments P2O5 and KOH as drying materials. In all cases below, you need to correct the measured values to the initial weight, otherwise, your data will be not comparable.
4a. Without drying materials, using vacuum only, you can calculate the total volatiles at any temperatures during a given period. Measuring the water content of the same sample by KF titration, you can calculate the mass ratio of the water and other volatiles.
4b. The P2O5 experiments will give you information about the water content + volatile basic compounds (inorganic and organic types).
4c. The KOH drying gives you information about the water+ volatile acidic compounds (inorganic and organic types).
5. Keep in mind that water is evaporating even at 50 oC. That means you can measure the water content of your sample periodically during the drying, and calculate the water/other volatiles ratios. Please remember that all measured values should be corrected to the initial weights.
Good luck,
Laszlo
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