GB641992A - Method of purifying liquids - Google Patents

Abstract

Aqueous solutions of organic acids and salts thereof are passed through one or more columns of granular activated carbon which in dry condition has a volume weight of at most 250 grams per litre, a heat of adsorption for benzene of at least 23 calories per gram of dry carbon, and an adsorption of benzene at 20 DEG C. from a flow of air 92.7 per cent saturated with benzene at that temperature of at least 60 grams per 100 grams of dry carbon, the entirely or partly exhausted carbon being regenerated in situ with an alkaline liquid. The liquid may be previously freed from coarse colloidal impurities by bentonite or bleaching earth, powdered active carbon, and carbonaceous materials treated with chemicals at low temperatures and may be subjected to an after-treatment with decolourizing carbon applied either in suspension or in secondary filters. The liquid to be purified should have an apparent time of contact with the carbon of at least half an hour, and the regenerant liquid, used hot and followed and/or preceded by a dilute acid, is preferably passed through the carbon in the opposite direction to it. The carbon should have a granular size not exceeding 2 mm., preferably 1/2 to 1 1/2 mm. Specifications 228,582 and 273,761, [both in Class 90], are referred to. The Specification as open to inspection under Sect. 91 comprises also the preliminary purification of the liquid with precipitates of calcium phosphate, calcium sulphite, calcium carbonate and aluminium hydroxide, preferably in the form of gel, or combinations of two or more of these substances. This subject-matter does not appear in the Specification as accepted.ALSO:Aqueous solutions of sugars are passed through one or more columns of granular activated carbon which in dry condition has a volume weight of at most 250 grams per litre, a heat of adsorption for benzene of at least 23 calories per gram of dry carbon, and an adsorption of benzene at 20 DEG C from a flow of air 92.7 per cent saturated with benzene at that temperature of at least 60 grams per 100 grams of dry carbon, the entirely or partly exhausted carbon being regenerated in situ with an alkaline liquid. The liquid may be previously freed from coarse colloidal impurities by bentonite or bleaching earth, powdered active carbon, and carbonaceous materials treated with chemicals at low temperatures, and may be subjected to an after-treatment with decolorizing carbon applied either in suspension or in secondary filters. The liquid to be purified should have an apparent time of contact with the carbon of at least half an hour, and the regenerant liquid, used hot and followed and/or preceded by a dilute acid, is preferably passed through the carbon in the opposite direction to it. The carbon should have a granular size not exceeding 2 mm., preferably 1/2 to 1 1/2 mm. Specifications 228,582 and 273,761, [both in Class 90], are referred to. The Specification as open to inspection under Sect. 91, comprises also the preliminary purification of the liquid with precipitates of calcium phosphate, calcium sulphite, calcium carbonate and aluminium hydroxide, preferably in the form of gel, or combinations of two or more of these substances. This subject-matter does not appear in the Specification as accepted.ALSO:Liquids such as aqueous solutions of sugars, organic acids and salts thereof are passed through one or more columns of granular activated carbon which in dry condition has a volume weight of at most 250 grams per litre, a heat of adsorption for benzene of at least 23 calories per gram of dry carbon, and an adsorption of benzene at 20 DEG C from a flow of air 92.7 per cent saturated with benzene at that temperature of at least 60 grams per 100 grams of dry carbon, the entirely or partly exhausted carbon being regenerated in situ with an alkaline liquid. The liquid may be previously freed from coarse colloidal impurities by bentonite or bleaching earth, powdered active carbon, and carbonaceous materials treated with chemicals at low temperatures, and may be subjected to an after-treatment with decolorizing carbon applied either in suspension or in secondary filters. The liquid to be purified should have an apparent time of contact with the carbon of at least half an hour, and the regenerant liquid, used hot and followed and/or preceded by a dilute acid, is preferably passed through the carbon in the opposite direction to it. The carbon should have a granular size not exceeding 2 mm, preferably 1/2 to 1 1/2 mm. Specifications 228,582 and 273,761, [both in Class 90], are referred to. The Specification as open to inspection under Sect. 91 comprises also the preliminary purification of the liquid with precipitates of calcium phosphate, calcium sulphite, calcium carbonate and aluminium hydroxide, perferably in the form of gel, or combinations of two or more of these substances. This subject-matter does not appear in the Specification as accepted.