The Application of Alkali Dissolution Techniques in the Study of Aluminium Hydroxides and Oxyhydroxides

The effect of treatment with 5% sodium carbonate solution on aluminium hydroxides and oxyhydroxides likely to occur in soils has been investigated. Ultrasonic pretreatment, sample to solution ratio and temperature were factors studied. It is shown that particle size and degree of order of the sample influence the amount of alumina dissolved in 5% sodium carbonate solution in a fixed time; it is apparent, however, that both dissolution rate and solubility can be determining factors. Consequently, extraction with alkali at a low temperature and with a low solid: solution ratio is desirable for the preferential dissolution of poorly‐ordered aluminous material from soil clays.