CHROMIUM HYDROXIDE HYDROSOLS AND THE BURTONBISHOP RULE EMORY FISHER
AND
C. H. SORUM
Department of Chemistry, University of Wisconsin, fifadison, Wisconsin Received M a y 7, 1084 INTRODUCTION
Burton and Bishop (3), working with copper, gum mastic, and arsenious sulfide hydrosols, concluded that the flocculation values increase with decreasing concentration of sol for monovalent ions, remain about the same for divalent ions, and decrease for trivalent ions. This conclusion is referred to as the Burton-Bishop rule (4). It has been demonstrated that, whereas moderately purified ferric oxide and chromic oxide sols do not follow the above rule for monovalent ions (2, 5, S ) , highly purified ferric oxide sols do (4). The experimental results presented in this paper show that highly purified chromic hydroxide hydrosols, like ferric oxide hydrosols, follow the Burton-Bishop rule. PREPARATION OF SOLS
Normal ammonium hydroxide was slowly dropped into a normal chromium chloride solution at 60-70°C. with constant shaking until six-tenths of the stoichiometric amount had been added. Two purified sols were prepared from the stock sample by dialysis in collodion bags. Table 1 gives data on the preparation and some of the properties of the two sols. RESULTS
Flocculation values were determined in the usual standard manner (4) and are reported as millimoles of electrolyte per liter of solution. With all sols flocculation values were determined with the original sol, referred to as 100 per cent, and concentrations of 80, 60, and 40 per cent of the original, dilution being made with water and, in some instances, with ethyl alcohol. The data that follow are typical of the results obtained. Table 2 shows the flocculation values for different electrolytes with sol No. 1, dilutions being made with water. Table 3 shows the flocculation values for the same sol, dilutions being made with 95 per cent ethyl alcohol. Table 4 and figure 1 show flocculation values for sol No. 2, dilutions being 283
284
EMORY FISHER AND C. H. SORUM
TABLE 1 Data on preparation and properties of the two sols TIME OF DIALYSIS
SOL NO.
TEMPDRATuRE OF
CONCENTRATION
---
RELATIVE VISCOSITY
PH
PURITY
CHII&Y
hourre
. . . . . . .. 2 . . . . .. . . . .. .. 1. . . . *
{
::
96
degree8 C. g r a ~ ~ ~ w
60 85
0.814
1.580
0.769
Too viscous to measure
Slight precipitate with AgNOs No precipitate with AgNOs
3'7 6.1
FLOCCULATION VALUES WHEN SOL CONCENTRATION IS EILECTROLYTE
NaCl ........... . . . . . . . . . ... . . .. KCI.. ... . . .. ..... , . . .... . .... . BaCla ..... . , , ,. . , . .. . . . . . . . . . . . NazSOc... . . . . , , . , . . . . . . . . . . . . . NaaP04.., , . . . . . . . . , . . . . . . . . . . .
100 per oent
80 per cent
1.4 1.5 0.9 0.05 0.03
1.8 1.7 1.3 0.06 0.03
,
80 per cent
40 per cent
2.2 2.3 1.6 0.05 0.03
2.7 2.7 1.9 0.06 0.02
TABLE 3 Flocculation valuer for different electrolytes with sol No. 1 FLOCCULATION VALUES WHEN SOL CONCENTRATION IS ELECTROLYTE
NaCI. . . . . . . . . . . . . . . . . . . . . . . . . . NazSO,. . . . . . . . . . . . . . . . . . . . . . . . NasPOd. . . . . . . . . . . . . . . . . . . . . . . .
100 per cent
80 per cent
60 per cent
40 per cent
1.4 0.05 0.03
1.7 0.05
1.9 0.05 0.03
2.3 0.04 0.03
0.03
TABLE 4 Flocculation values for different electrolytes with sol No. d FLOCCULATION VALUES WHEN SOL CONCDNTRATION I8 ELECTROLYTE
100 percent
NaCl. . . . . . . . . . . . . . . . . . . . . . . . . . K C l . . . .. . . . . . . . . . .. . .. . . . .. . . . BaCla ... .. . . . . . . . . . . . . . . . . . . . . . NanSOd.. . . . . . . . . . . . . . . . . . . . . . . NasP04... . . . . . . . . . . . . . . . . . . . . .
0.3
0.4 0.3 0.04 0.032
I
80 percent
0.9 0.9 0.8 0.04 0.03
I
60 percent
1.5 1.4 1.o 0.04
0.024
1
40 percent
2.2 2.3 1.2 0.04 0.02
.
HYDROSOLS AND BURTON-BISHOP RULE
ca
9
h3
n
285
286
EMORY FISHER AND C. H. SORUM
made with water. Table 5 shows flocculation values for the same sol, dilutions being made with 95 per cent ethyl alcohol. Stock samples of sol No. 2 were made impure by adding respectively 0.1 and 0.4 millimoles of chromium chloride per liter. Dilutions were made with water and flocculation values for sodium chloride determined as above. The results are given in table 6 and figure 2. TABLE 5 Flocculation values jor diflerent electrolytes with sol No, 2 ~~
~~~
FLOCCULATION VALUE6 W E E N 8OL CONCENTRATION I8 ELECTROLYTl
100 percent
NaC1. ......................... Na2S0,. ....................... NarP04........................
I
0.3 0.04 0.032
80 percent
1
60 percent
0.7 0.06 0.04
0.5
I
40peroent
0.04
