Hydrochloric Acid → Tetrasodium Pyrophosphate

Participants

Reaction Steps

Two solutions of tetrasodium pyrophosphate were prepared by dissolving 20 g. of tetrasodium pyrophosphate decahydrate in 80 ml. of water and adjusting the pH to 7.0 (Solution 1) and 8.0 (Solution 2), respectively, with hydrochloric acid. A total of 100 g. of native tapioca starch was suspended in 125 ml. water, adjusted to pH 7.0 (Starch 1) and filtered on a Buchner funnel as described in Example IV. A total of 60 g. of Solution 1 was poured onto the filter cake of Starch 1, uniformly covering the entire surface, and vacuum was applied until the liquid filtered through the starch cake. The amount of phosphate salt retained was about 12%, based on starch solids. The above filtering procedure was repeated except that before filtration the starch was adjusted to pH 8.0 (Starch 2), and Solution 2 was used instead of Solution 1. The amounts of filtrate and phosphorus content of each filtrate are indicated in Table III. The impregnated cakes were thereafter dried at 140° C., and a portion of each dried sample was further heat-reacted in a forced-air oven at 140° C. to form Starches 1B and 2B. As can be seen from Table III, phosphorylated materials were obtained with only minimal loss of phosphate to the filtrate.

Provenance & Evidence