Part 1'.
ADSORPTION BE' METALLIC HYDROXIDES A Comparative Study of the Adsorptive Power of Iron, Aluminium and Chromium Hydroxides for Acids and Alkali BY KSHITISH CHANDRA SEN
From the experimental results already given in the previous papers, it will be observed that all these hydroxides show a great adsorptive power when acids or bases are used as the adsorbable solutes. X o comparative study has however been made so far on the adsorptive power of these hydroxides. As the three hydroxides are very allied in their chemical and physical properties, a comparison of their adsorbing powers appears to be interesting, and as such the result of adsorption of acids will be given in the following tables. Before however one can make some comparison, it is evident that the samples which has been used for the adsorption experiments should be comparable to each other. It has already been pointed out in previous papers, that the variation in the physical character of the adsorbent affects appreciably the amount of adsorption and it is reasonable therefore that, the precipitates of the different hydroxides should be as similar as possible. This condition is however impossible to attain owing to the variability of the nature of the precipitate which is dependent upon a large number of factors. Attempt was therefore made to obtain what may be termed, average samples, which will give a t least the general order of the adsorption values. All the three hydroxides were precipitated from the solutions of the chlorides of the respective metals by means of a slight excess of ammonia, and then fret4 from electrolytes by means of decantation and dialysis. The concentration of the chloride solutions was about zr\T in each case, and the precipitation was always carried out in the cold. All the hydroxides were allowed to age for 2 5 days after which the adsorption was measured. Since the amount of adsorption was measured. Since the amount of adsorption calculated per gram adsorbent depends upon the actual amount of the adsorbent taken for the experiment, the amount of the three hydroxides used was kept almost the same. It will thus be observed that the adsorption values determined for the three hydroxides are fairly comparative. In Table I, the results obtained with the arsenious oxide are shown. TABLE 1 Original conc. of .4szOsin grams
0.30 0.20
Adsorption per gram
