Patent GB-955677-A (GB)
Title: Process for separating acids from salts and/or non-electrolytes
Inventor: WOLF FRIEDRICH
Filed: 1960-07-06
Abstract: A process for the separation of an acid from a salt and/or a non-electrolyte from an aqueous solution containing them, comprises causing the solution to diffuse through a diaphragm consisting of an anion-selective synthetic resin. Acids which may be separated are hydrochloric, sulphuric and nitric acids, while the salts may be NaCl, KCl, MgCl2, CaCl2, MgSO4, Na, SO4 or NaNO3.  A particularly good separation is obtained when the salt contains a bivalent cation. The separation of an acid from non-electrolytes is applicable to those non-electrolytes having large molecules, e.g. glycerol. Suitable diaphragms are all those which comprise an anion-selective resin.  Examples are those consisting of condensation or polymerization resins incorporating aliphatic, aromatic or heterocyclic amines, and also those made from a copolymer of styrene, chlorostyrene, alkylstyrene and/or alkoxystyrene, and a cross-linking agent such as divinylbenzene or butadiene. The anion-selective diaphragms may be arranged in the form of a filter press so as to obtain as large a surface area as possible, and the solution to be dialysed and the solvent into which the acid is to diffuse may be caused to flow in counter-current past the diaphragm. Examples 1 and 2 illustrate the separation of hydrochloric acid from solutions containing various concentrations of hydrochloric acid and sodium chloride, and Examples 3 and 4 illustrate the separation of sulphuric acid from magnesium sulphate and glycerol respectively.ALSO:A process for the separation of an acid from a salt and/or non-electrolyte in aqueous solution, comprises causing the solution to diffuse through a diaphragm consisting of an anion-selective synthetic resin.  Acids which may be separated are strong acids such as hydrochloric, sulphuric, and nitric acids, while the salts may be NaCl, MgCl2, CaCl2, KCl, MgSO4, Na2SO4, or NaNO3.  A particularly good separation is obtained when the salt contains a bivalent cation.  The separation of an acid from non-electrolytes by diaphragm dialysis can be applied where the non-electrolytes have large molecules, e.g. glycerol, or other organic compounds containing several carbon atoms in the molecule.  Suitable diaphragms are all those which comprise an anion-selective resin. Examples are those consisting of condensation or polymerization resins incorporating aliphatic, aromatic, or heterocyclic amines, and also those made from a copolymer of styrene, chlorostyrene, alkylstyrene, and/or alkoxystyrene and a cross-linking agent such as divinylbenzene or butadiene.  The anion-selective diaphragms may be arranged in the form of a filter-press so as to obtain as large a surface area as possible, and the solution to be dialysed and the solvent into which the acid is to diffuse may be caused to flow in counter-current past the diaphragm.  Examples 1 and 2 illustrate the separation of hydrochloric acid from solution containing various concentrations of hydrochloric acid and sodium chloride, and Examples 3 and 4 illustrate the separation of sulphuric acid from solutions containing sulphuric acid and magnesium sulphate (in Example 3) or glycerol (in Example 4).