So, what will the maximum permissible temperature beyond which the properties of silica gel will not change (should not affect its regeneration property) ? Is it 120°C ? And if so, what is the simplest and cheapest possible way to obtain such temperature ? And also suggest which type of silica gel should be used
In silica gel, the physically adsorbed water can easily be removed when kept in an air oven at temperature around 150 degree centigrade temperature for 2-3 hours. Time duration may vary depending upon the spreading of silica gel. The indicator cobalt(II) chloride added to indicate the hydrous form of silica gel (pink) and anhydrous form (blue) should indicate dehydration of silica gel from anhydrous to anhydrous form.
Put the silica sample in a Vacuum oven at 120 oC. Type of the silica type depends on your further need. You can use any sort of silica particles.
However, please note that there can be three different type of water molecules adsorbed on the silica. Physical, germinal and vicinal.
The physically adsorbed water can be removed at 120 oC. But to remove the germinal and vicinal water, the sample should be heated up to 800 oC.
In my experience silica gel degrades after very few cycles if heated to 110°C or more. For maximum longevity dry it at just 80°C. It won't take much longer but will last longer and work just as well as a desiccant.
The best option is if your silica gel has a colour indicator for moisture. In most cases it is blue (dry) to red or colourless (moist). In such a case just heat it carefully until blue colour change; watch the weight reduction also.
Oven drying at 120-130 degree temperature is the most convenient method to reactivate the silica gel which is indicated with blue colour (anhydrous state) from the pink colur (hydrous state)..
The moisture of silica gel can be removed by putting the silica gel in hot air oven at 80-100 degree Celcius for 1 hr.
Any idea about using high temperature steam (which are freely available) outlet from any generator or any other devices. As these oven heating consumes electricity which is not accepted.
According to Dry & Dry producer of silica gel, you should dry for 0.5 to 2 hours at 200 to 250 F in a conventional oven.
I do not think high temperature steam will work as we need a form of dry heat to extract moisture from the saturated silica
In silica gel, the physically adsorbed water can easily be removed when kept in an air oven at temperature around 150 degree centigrade temperature for 2-3 hours. Time duration may vary depending upon the spreading of silica gel. The indicator cobalt(II) chloride added to indicate the hydrous form of silica gel (pink) and anhydrous form (blue) should indicate dehydration of silica gel from anhydrous to anhydrous form.
Silica gel in the breather., After absorbing the moisture in full length the blue coloured silica gel can be turned into pale pink.,In such a case just heat it carefully until blue colour change;
Is it Safe and effective to heat the silica gel packets which have absorbed moisture in a pan on gas burner to recharge them ?
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