T H E ADSORPTIOS OF CERT-LIS .ACIDS BY WOOL BY Jv. Tv. P A D D O S During the course of experiments suggested by Professor Bancroft concerning the dyeing of wool by acid dyes, it was found necessary to obtain dat,a for the adsorpt,ion of various acids by wool under the ordinary dyeing conditions. Such data were obtained for sulphuric and hydrochloric acid.. Similar dat,a for tartaric acid had been previously determined by A h . X. Yi. Bull of this laboratory and are included herein. The wool used was pure, white sweater, yarn, all of the samples being taken from the same hank. A series of eleven baths of varying concentrations was made up for each acid. One gram of wool was used in each bath, and the adsorption allowed to proceed a t the boiling point for one hour, preliminary experiments showing that by this time equilibrium had been reached in every case. The wool entered the boiling bath cold and dry, and was removed hot a t the end of the hour. The amount of unadsorbed acid was determined by titrating the bath with KaOH solution using phenolphthalein as an indicator. The data thus obtained are shown in Table I. TABLE I
Total volume of bath in each case 2 jo cc. One gram of wool. Bath heated to boiling for one hour. 1Iilligram 1101s Acid at start
Milligram 1101s Acid left in bath
Milligram 1101s Acid adsorbed
Hydrochloric Acid 0.16 0.04
Mlligram 1101s Acid a t start
lIilligram 3101s Acid left in bath
Milligram 3101s Acid adsorbed
Sulphuric Acid 0.08
0.04
0.04
0.41
0.32
0.09
0.16
0.09
0.07
0.62
0.14 0.19
0,23
0.13
0.10
I .03
0.48 0.84
0.24
0.14
I .64 3.08
1.39 2.79
0 . 2 j
0.38 0.61 1.15
0.43 o .91
0.18
0.29
j.Ij
4.64 ;.68
0 .j I
I
0.54
3 .06
2.71
4.18
0.20
8,24
.91
I
12.34
11 . 6 2
0.72
4.60
16,48 20.60
Ij.80
0.68
19.90
0.70
6.14 j.70 7.24 7.65 Tartaric Acid
Tartaric Acid
0.25
.64
0.2;
0.35 0.42 0,44 0.41
0.0;
0.03
0.02
1.25
1.14
0.11
0 . IO
0.08
0.02
2.00
0.12
0.Ij
0.12
0.03
3.00
1.88 2.86
0 . 2 j
0.20
0.05
4.00
3,83
0.40 0.7;
0.34
0.06
5.00
4.83
0.17 0.17
0.6;
0.08
0.12
The data are qiion.n in tlic form of c u n - r y Fig. I. llilligraiii inolpculeq of acid adsorbed arc plotted :igain$t grain niolrculcs of acid !cft in the bath. It will be noticed that up tu coiicpntrntioni of 2 milligram; per z;c cc.! riilphuric acid is slightly i i i o w strongll- atiorbed than I~ydrochlot~ic acid. 13cyond this point the reverse is trcc. In :ill concentration. tartaric acid i.
0.5 0
0.3 0
02 0
ai o I
---L
0.5
1.5
2.5
4.0
5.0
MILLIGRAM-MOLS. ACID LE-
60 IN
70
-
8.0
BATH
FIG. I
much less strongly adsorbed than either sn2phiiric hydroch!oric acids. There arc no abrupt breaks in : h ~C I I I T C ~ ~indicating that no chpinical cornpouncls are formed. It is therefore concluded that, Altthe teniperatiire of boiling nater, n ~ ~ adsorbs o l tartaric acid m u c h I. less than it does either lij-drochloric 01'sulphuric acids. In concent,rations up to 2 rni1ligr:m molecules per 2 5 0 cc. wool ad2. sorbs a t the temperature of boiling Tvatrr more sulphuric, acid tlian it doe3 hydrochloric acid. .Iboie that concentration more hydrochloric acid is adsorbed. j, Thprc i. nt-~rvidence of the formation of cheniicai conipoLiiid+ betneeri any of the tlirce acids and t!ie wool substance, throughout the raiige nf concentrations Psperimentcd ~ ~ i t l i . I ani greatly indebted, for a ,tance aiid suggestions t o Professor Rancroft, under whose direction these experiments wew performed. Theie experiments were made possible by a grant froin the Chemical Foundation. Cornel1 17iiii,eraitU, Jwie. 132%.
