The Preparation and Purification of Hydrous Lanthanum Hydroxide Sols

The Observations on the Rare Earths. LVI. Spectrophotometric Studies on Colloidal "Lanthanum Blue."

“…They are readily flocculated to blue precipitates by electrolytes, among them lanthanum salts and acetates or propionates when present in excessive quantities. Because of the high-basicity of lanthanum hydroxide (12,13), they absorb atmospheric carbon dioxide readily and are thereby destroyed.…”

“…This was diluted to 0.001 M before being used. To obviate carbon dioxide absorption, which is so characteristic of hydrous lanthanum hydroxide sols (12,13) and which effects their flocculation and destruction, all solutions were prepared with carbon dioxide-free water and were protected from the carbon dioxide of the atmosphere.…”

Hydrous Lanthanum Hydroxide as an Emulsifying Agent.

“…For the experiments which follow a sol was prepared which contained 1.492 g. of lanthanum oxide and 0.031 g. of chloride per liter, the purity ratio being 15.7 (3,4). Carbon dioxide-free water was used throughout, and the organic compounds were of analytical reagent quality.…”

An Investigation of Certain Properties of Hydrous Lanthanum Hydroxide Sols.

“…A method eliminating these difficulties has been described (16). Data for some of the sols prepared by this procedure and dialyzed with carbon dioxide-free water (16) are given in table 1. In each instance the purity ratio is to be taken as the ratio of the equivalents of lanthanum oxide present to the equivalent of chloride.…”

“…A method eliminating these difficulties has been described (16). Data for some of the sols prepared by this procedure and dialyzed with carbon dioxide-free water (16) are given in table 1. In each instance the purity ratio is to be taken as the ratio of the equivalents of lanthanum oxide present to the equivalent of chloride. The impossibility of purifying hydrous lanthanum hydroxide sols by dialysis with water containing dissolved carbon dioxide and the necessity of protecting sols from the air have been discussed (16).…”