Observations sur l'action détersive des solutions de savon : Deuxième communication : Les solutions de savon et les composés ferriques

Spring, W. Recueil des Travaux Chimiques des Pays-Bas et de la Belgique (1910), 28, 424-43; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010).

see C. A., 3, 1599-1613; 4, 138. In this investigation finely divided hematite (Fe2O3) containing 4.6% H2O) was treated in a manner similar to the C described) in preceding communication. It was found that in pure H2O it remains in suspension for days, but in acid or alkaline solns. it settles in 0.5 hr. When subjected to action of electric current the tendency is to migrate toward the cathode; hence particles must be positively charged. When Fe2O2 is shaken with soap solns. of varying strength all except those with about 0.5% soap settle in 5 days or less. Those with 7-8% show a ferric color in the clear soln. The residue on evapn. of the clear 7% soln. shows 17.66% and 17.50% ash, after deducting 1.13% Fe2O3; from the same soln. not shaken with Fe2O3 18.31%. Dilute KOH solns. (less than 0.1%) do not cause settling, but as little as 0.0001% HCl does so. A soln. of soap in MeOH was shaken with Fe2O3. The residue on evapn. of the clear soln. showed 17.68% ash; from the original soln. 18.24%. This shows a decomp. of the soap into a basic and an acid portion, the latter combining with the Fe2O3. Suspension of Fe2O3 in H2O filters clear after 16 filtrations, through same paper in alc., after 4. This is due to adsorption, and not to blocking of the pores, for if H2O be poured on the paper through which alc. suspension filtered clear, it comes through more and more turbid as the alc. is washed out. If 2% soap soln. be used instead, it looks as if filter had been pierced. This indicates that Fe2O3 forms an adsorption-combination with soap more stable than with cellulose or other materials. When colloidal Fe(OH)3 solns. are shaken with soap solns. clarification is found to depend on the relative amts. of Fe(OH)3 and soap. It is most rapid when the proportion is between 2.16 and 3.47 mols. Fe2O3 to 1 of soap. By a titration method the ratio was found to be 3.10-3.25:1 when Fe(OH)3 was run into the soap; 1 when soap was run into Fe(OH)3. The ppts. in the 2 cases were almost the same in comp., and were entirely different from the Fe soap prepared by adding FeCl3 soln. to soap soln., in which the ratio is 3 mols. soap to 1 mol. Fecl3.

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