Patent GB-669281-A (GB)
Title: Method of cleansing undyed materials contaminated with heavy metal oxides or water-insoluble heavy metal salts, and manufacture of preparations therefor
IPC: C11D3/00
Filed: 1947-06-10
Abstract: Undyed materials contaminated with heavy metal oxides or water-insoluble heavy metal salts are cleansed by treatment with an alkaline solution free from heavy metal salts and containing a salt of an organic acid free from nitrogen and capable of forming water-soluble complex heavy metal compounds, a water-soluble salt of hydrosulphurous acid and a substance of alkaline reaction. The organic acid may be oxalic, lactic, malic, tartaric, citric, saccharic or thioglycollic; or salts of sulphonic acids such as guaiacol sulphonic acids or those present in sulphite cellulose waste liquor may be used.  Sodium hydrosulphite is preferably employed and alkalinity may be ensured by adding ammonia, sodium bicarbonate or sodium carbonate.  Wetting agents such as sodium di-isobutyl naphthalene sulphonate may be present and the solution may be thickened with cellulose ethers, gums, starch paste, dextrin, wood meal or bentonite.  When solutions are used, air may be excluded by covering the liquid with mineral oil or butyl alcohol.  Metals or textiles may be treated.  Specifications 378,874, [Group II], 382,618, 474,082, and 622,316, [Group II], are referred to.ALSO:Undyed materials contaminated with heavy metal oxides or water-insoluble heavy metal salts are cleansed by treatment with an alkaline solution free from heavy metal salts and containing a salt of an organic acid free from nitrogen and capable of forming water-soluble complex heavy metal compounds, a water-soluble salt of hydrosulphurous acid and a substance of alkaline reaction. The organic acid may be oxalic, lactic, malic, tartaric, citric, saccharic or thioglycollic; or salts of sulphonic acids such as guiacol sulphonic acids or those present in sulphite cellulose waste liquor may be used.  Sodium hydrosulphite is preferably employed and alkalinity may be ensured by adding ammonia, sodium carbonate or sodium bicarbonate.  Wetting agents such as sodium di-isobutyl naphthalene sulphonate may be present and the solution may be thickened with cellulose ethers, gums, starch paste, dextrin, wood meal or bentonite.  When solutions are used, air may be excluded by covering the liquid with mineral oil or butyl alcohol.  Metals or textiles may be treated.  Specifications 378,874, [Group II], 382,618, 474,082 and 622,316, [Group II], are referred to.ALSO:Metals contaminated with heavy metal oxides or water-insoluble heavy metal salts are cleaned by treatment with an alkaline solution free from heavy metal salts and containing a salt of an organic acid free from nitrogen and capable of forming water-soluble complex heavy metal compounds, a water-soluble salt of hydrosulphurous acid and a substance of alkaline reaction. The organic acid may be oxalic, lactic, malic, tartaric, citric, saccharic or thioglycollic; or salts of sulphonic acids such as ginacol sulphonic acids or those present in sulphite cellulose waste liquid may be used.  Sodium hydrosulphite is preferably employed and alkalinity may be ensured by adding ammonia, sodium bicarbonate or sodium carbonate.  Wetting agents such as sodium di-isobutyl naphthaline sulphonate may be present and the solution may be thickened with cellulose ethers, gums, starch paste, dextrin, wood acid or bentonite.  Air may be excluded by covering the solution with mineral oil or butyl alcohol. Specifications 378,874, 382,618, 474,082, [both in Group III], and 622,316, are referred to.