SODIUM ALIZARATE AND ALUMINA BY F. S. WILLIAMSON
It has been suggested by Liechtil that when hydrous aluminum oxide and sodium or ammonium alizarate are brought together, a true aluminum alizarate is formed. It is known that when hydrous chromic oxide or hydrous ferric oxide2 is mixed with sodium alizarate no true compound is formed, but that it is a case of adsorption. Due to the similarity between these substances and hydrous alumina, it seemed probable that an adsorption complex of hydrous aluminum oxide and sodium alizarate would result when hydrous alumina is mixed with sodium aliaarate and not a definite compound, aluminum alizarate. The following experiments were conducted in order to establish the fact that the compound “aluminum alizarate” does not exist. If sodium alizarate reacts with hydrous aluminum oxide to form an aluminum alizarate, sodium hydroxide must be set free by the reaction. If it is a case of adsorption, the sodium alizarate will be taken up unchanged and there will be no sodium hydroxide found in the solution. The first experiment was performed to settle this point. A solution of aluminum acetate was prepared and the alumina precipitated from this solution by the addition of ammonium hydroxide. The precipitate was allowed to settle and was washed thoroughly by decantation with distilled water. The alumina suspension was then analyzed and found to contain 0.5708 gram of AL03 per 25 cc. A sodium alizarate solution was then made up containing 2.84 grams per liter. Twenty-five cc of the alumina suspepsion were placed in each of five 1 5 0 cc glass stoppered bottles. To each of these five portions was added a definite amount of sodium aliaarate. The volume of the mixture in each bottle was made up to 50 cc and the bottles shaken in an automatic shaker for ten hours. The bottles were then removed from the shaker, the contents allowed to settle, and the supernatant liquid tested for sodium hydroxide. The quantities of sodium alizarate used were so chosen that practically complete adsorption of the dye by the alumina occurred even at the highest concentration. The shaking was done at room temperature. NO.
cc. Alumina
r c Sodium
Alizamt c
grs. Sodium Alixaratc
I
25
5
G
2
25
10
G
3
25
15
c.0426
0142 0284
4 25 20 o ,0568 5 25 25 0.0710 The tests showed that the supernatant liquid from each of the botltles contained no sodium hydroxide. The liquid gave no color with phenolphthalein and a neutral color with methyl orange, and required but one drop of N/ro J. Soc. Chem. Ind. 4, 587 (1885); 5, 523 (1886). J. Phys. Chem. 25, 660 ( I ~ z I ! .
* Bull and Adams:
892
F. S. WILLIAMSON
HCI to turn it acid. This proves that no sodium hydroxide is set free when sodium alizarate is adsorbed by alumina, but that it is taken up unchanged, This would indicate that it is a case of adsorption and that a definite conipound is not formed. The effect of acid upon the lake produced in the first experiment was now studied. To bottle number two, from the preceding experiment, small portions of N/zo acetic acid were added, the bottle and its contents being t,horoughly shaken after each addition, A similar procedure was carried out with bottle number four using N/Io hydrochloric acid. It was found that the addition of more than sufficient acid to react with the sodium alizarate present had no effect upon the lake formed. After a time some peptization occurred, but the color of the lake remained unchanged, When the hydrochloric acid was added before the sodium alizarate, no different result was obtained. However, when strong acid was added to the lake, the color was changed, varying from yellow to brown, depending upon the amount of acid used. This is probably due to the decomposition of the sodium alizarate by the acid with the formation of yellow alizarine. The action of aluminum chloride upon ammonium alizarate was nest tried out. It was found that upon mixing aluminum chloride and ammonium alizarate alone very little of the aluminum chloride hydrolyzed to form aluminum hydroxide. To overcome this difficulty enough sodium hydroxide was added to react with all the aluminum chloride present, thus assuring the formation of enough aluminum hydroxide. Several mixtures were made up in which the amounts of AlsCls and sodium hydroxide were kept constant and the amounts of ammonium alizarate steadily decreased. These mixtures were boiled for three hours using a return condenser. At the end of this time the precipitate was allowed to settle and the supernatant liquid decanted off. The precipitate was washed once by decantation and then dried carefully over a low flame. The colors of the various precipitate? obtained were compared and the colors of the liquid portions as well, It was found that as the amount of ammonium alizarate in the mixture was cut down, the color of both the precipitate and the supernatant liquid became lighter. The results of this experiment seem to prove that when sodium or ammonium alizarate is taken up by alumina, a definite compound is not formed but that the alumina adsorbs more alizarate as the amount of alizarate in the original mixture is increased. Summary Experimental evidence has been produced to show that an adsorption complex results when hydrous aluminum oxide and sodium or ammonium alizarate are mixed together, and that no definite aluminum alizarate is formed under these circumsta.nces. Cornell University.
