Investigation Of Effects Of Alum And Potassium Sesquicarbonate On The Fire Characteristics Of Flexible Polyurethane Foam

Chrome alum

Chrome alum K2Cr(SO4)2 . 12H2O a dark violet crystalline double sulphate of chromium and potassium was used in tanning.

Selenate- containing alums

Alums are also known to contain selenium instead of sulphur. They are called selenium or selenate alums.

Alum solubility

The solubility of the various alums in water varies greatly, sodium alum being readily soluble in water while caesium and rubidium alums are only sparingly soluble. The various solubilities are shown in the table below:

Properties of alum

They are soluble in water

They have an astringent, acid and sweetish taste

They crystallize in regular octahedral

When heated they liquefy, and if the heating is continued, the water of crystallization is driven off, the salt froths swells and at last an amorphous powder remains.

Uses of alum

It is employed in medicine, for example, it can be applied to prevent or treat infection. It is also used in vaccines as an adjuvant to enhance the body's response to immunogens.

It is used as a chemical flocculants

It is used in cosmetic industry as an after shave, deodorant, base in skin whiteners and treatments.

It is used for domestic purposes e.g. as a preservative, acidic component of commercial baking powders.

It is used as a flame retardant

Potassium Sesquicarbonate

Potash is the name used for various inorganic compounds of potassium, chiefly the carbonate (K2CO3) a white crystalline material formerly obtained from wood ashes. The name is derived from the old method of making potassium carbonate by leaching wood ashes and evaporating the solution collected in large iron pots leaving a white residue called “pot ash”. Later “potash became the term widely applied to naturally occurring potassium salts and the commercial product derived from them.

Production of Potassium Sesquicarbonate (mild

vegetable caustic)

When a solution of potassium bicarbonate (KHCO3) in water is evaporated by boiling half of its carbonate acid is gradually given off and the normal carbonate (K2CO3) results. If evaporation is carried to the point where only one -fourth of its carbonic acid is given off, the solution contains potassium sesquicarbonate. It is claimed by some to be a crystallizable deliquescent substance of definite composition while others claim that the product is a mixture of mono and bicarbonate of potassium.

It can also be prepared by making a strong life of oak wood ashes and evaporating it in an iron kettle to dryness. This forms an impure caustic potash, of a dingy - gray or greenish colour. It is called “original vegetable caustic”. It is deliquescent and soluble in water. It is employed occasionally in cases where the latter exerts but little or no beneficial influence.