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THERMOMETRIC TITRIMETRIC DETERMINATION OF REACTIVITY WITH ACIDS AND BASES BY SMELTER GRADE ALUMINA

Smith T, Haider C, Smith M

Novel procedures for the thermometric titrimetric determination of the reactivity with acids and bases by smelter grade alumina are proposed as an adjunct to the traditional BET method for determining specific surface area, an important parameter for evaluating the suitability of the product for use in modern aluminium smelters. The information derived from these new methods is intended to provide workers in the field with additional insight into the chemisorptive performance of smelter grade aluminas in absorbing exhaust gases from the smelting process. Both determinations are conducted in anhydrous, non-aqueous media. The determination of acid reactivity is performed by back-titration of an excess of n-butylamine after reaction of the test alumina, with methanesulfonic acid as titrant. Similarly, reactivity with bases is determined by back-titration of an excess of methanesulfonic acid, using n-butylamine as titrant. Samples of alumina from three different alumina refineries were tested. The BET specifi c surface areas of the alumina samples under test ranged from 37 to 98 m2/g, with corresponding acid reactivity ranging from 0.05 to 0.15 mmol/g and reactivity with bases ranging from 0.49 to 0.94 mmol/g. The procedures are robust and reliable, and suitable for routine quality control purposes. The thermometric sensor requires no conditioning, calibration or maintenance.