Citric Acid → Aluminum Sulfate

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Reaction Steps

This example shows the formation of an alumina using gluconic acid, a mono-carboxylic acid, as an additive and serves as a comparison for example 2 which contains citric acid, a polycarboxylic acid. 20.25 gallons of water were heated to 125° C. 130 grams of NaOH and 2250 grams of sodium aluminate having a 1.14 molar ratio of Na2O/Al2O3 and containing 46% Al2O3 were added with good mixing to a container. 235 ml of a 50% gluconic acid solution and 75 ml of a 50% Na2SiO3 solution were added to the mixture with continued mixing. In a separate container, a solution of aluminum sulfate was prepared by mixing 9 gallons of water, 165 ml. concentrated H2SO4 and 34.75 lbs. of Al2 (SO4)3 18H2O. This solution was titrated into the reaction vessel at a rate of about 500 ml. per minute. The final pH of the reaction mixture which contained precipitated aluminum hydroxide was 8.8 at a temperature of 122° F. The gel was dewatered by filtering on buchner funnels.

Provenance & Evidence