ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 470 ! 474. + Pleiades Publishing, Inc., 2006.
Original Russian Text + I.I. Goncharik, F.F. Mozheiko, A.I. Voitenko, T.P. Kulikova, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79,
No. 3, pp. 478!482.
AND POLYMERIC MATERIALS
Foaming and Stabilizing Activity of Binary Solutions
of Sodium Carboxylates of Different Chain Length
I. I. Goncharik, F. F. Mozheiko, A. I. Voitenko, and T. P. Kulikova
Institute of General and Inorganic Chemistry, Belarussian National Academy of Sciences, Minsk, Belarus
Received April 26, 2005
Abstract-Influence of short-chain soda soap (sodium pentanoate) on the foaming and stabilizing activity
of long-chain sodium carboxylates (laurate, myristate, and palmitate) is studied.
Mixtures of sodium salts of homologous carboxylic
acids are produced at many chemical works as by-
products and wastes: alkaline waste from caprolactam
production (adipates), adipose tar (fat work waste),
sulfate soap and tall oil (products from distillation of
sulfate lye formed in pulping), etc. Generally they are
used as foaming agents or collectors in flotation of
potash, phosphorite, and other ores.
To understand the effect of these products on flota-
tion, we studied the foaming activity of mixtures con-
sisting of sodium salts of carboxylic acids with dif-
ferent chain length, particularly, of the short-chain
pentanoate with long-chain laurate, myristate, and
The experimental procedure was as follows.
A mixed aqueous solution containing fixed concentra-
tions of reagents (V = 20 ml) was foamed for 30 s in
a graduated cylinder. The foaming activity was esti-
mated by the foam volume and lifetime.
For comparison, initially we examined the foaming
activity of aqueous solutions of the individual sodium
salts of butyric (C
), octanoic (C
), lauric (C
), and palmitic (C
) acids. The foaming
activity of these compounds depends on their chain
length and concentration (Fig. 1). The foam formation
in the solutions considerably increases as the reagent
concentration approaches the critical micelle concen-
tration (CMC): 2.28 10
, 6.96 10
, and 2.1
M for the laurate, myristate, and palmitate, re-
spectively. The maximum of foaming activity near
CMC can be attributed to the completion of the for-
mation of the adsorption layer with the maximal
mechanical strength. With a further increase in the re-
agent concentration above CMC, association (micelle
formation) occurs in the bulk of the solution, which
decreases the diffusion rate of the molecules to the
adsorption layer, thus reducing the foaming activity.
Increase in the length of the hydrocarbon chain in
the homologous series of the soaps initially increases
their foaming activity from the octanoate to myristate
and then decreases on passing to the palmitate (foam
head height is 15.5, 18.0, 19.0, and 3.5 cm for the
aqueous octanoate, laurate, myristate, and palmitate
solutions, respectively). It should be pointed out that
the short-chain butyrate and pentanoate do not form
foam even in concentrated 25!50% solutions. With
increasing chain length, the soap concentration corre-
sponding to the maximal foaming activity decreases
from 0.6 M for the octanoate to 2.28 10
M for the laurate and myristate, respectively.
Fig. 1. (2, 4! 6) Foaming activity H and (1, 3, 7, 8) foam
stability J as functions of the sodium carboxylate concen-
:(1, 4) laurate, (2, 8) octanoate, (3, 5) myristate,
and (6, 7) palmitate.