EP0032007A2
Expired / Lapsed
EP
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Method for the regeneration of acid in the manufacture of regenerated cellulose
Assignee: British Sidac Ltd
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Filing: 1980-12-10
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Granted: —
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Expires: 2000-12-10
Abstract
Abstract A method of producing regenerated cellulose comprising regenerating cellulose by acidifying an alkaline cellulose solution, passing the regenerated cellulose through an acid bath 1, 2,3 to remove residual alkali therefrom, washing the regenerated cellulose with a countercurrent of washing water 8, passing liquid from the acid bath through the anode compartment of an electrolytic cell 10, and the washing water through the cathode compartment of the said cell, the said cell being provided with an ion-selective membrane cell 11 divider to define the said anode and cathode compartments, and electrolysing the solution in the cell to raise the acidity of the anolyte and lower that of the catholyte to produce a less acidic aqueous effluent.
Inventors
- 👤 James Peter Millington
- 👤 Donald Spetch
- 👤 William Scott
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:21
CPC Classifications
D; D01; D01F; D01F13/00; D01F13/02; C; C08; C08B; C08B16/00; Y; Y02; Y02P; Y02P70/00; Y02P70/50; Y02P70/62
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
114 words
A method of producing regenerated cellulose comprising regenerating cellulose by acidifying an alkaline cellulose solution, passing the regenerated cellulose through an acid bath 1.2,3 to remove residual alkali therefrom, washing the regenerated cellulose with a countercurrent of washing water 8, passing liquid from the acid bath through the anode compartment of an electrolytic cell 10, and the washing water through the cathode compartment of the said cell, the said cell being provided with an ion-selective membrane cell divider 11 to define the said anode and cathode compartments, and electrolysing the solution in the cell to raise the acidity of the anolyte and lower that of the catholyte to produce a less acidic aqueous effluent.
Claim 2
Independent Claim
114 words
A method of producing regenerated cellulose comprising regenerating cellulose by acidifying an alkaline cellulose solution, passing the regenerated cellulose through an acid bath 1.2,3 to remove residual alkali therefrom, washing the regenerated cellulose with a countercurrent of washing water 8, passing liquid from the acid bath through the anode compartment of an electrolytic cell 10, and the washing water through the cathode compartment of the said cell, the said cell being provided with an ion-selective membrane cell divider 11 to define the said anode and cathode compartments, and electrolysing the solution in the cell to raise the acidity of the anolyte and lower that of the catholyte to produce a less acidic aqueous effluent.
Claim 3
Dependent Claim
25 words
A method as claimed in claim 1, wherein the regenerated cellulose is passed through three acid baths, 1,2,3, before being washed with the washing water.
Claim 4
Dependent Claim
24 words
A method as claimed in claim 2,wherein the liquid passed to the anode compartment is liquid from the final or penultimate acid bath 2,3.
Claim 5
Independent Claim
25 words
A method as claimed in any one of the preceding claims, wherein the anolyte solution is reused for the acidification of the alkaline cellulose solution.
Claim 6
Independent Claim
29 words
A method as claimed in any one of the preceding claims, wherein the process conditions are arranged so as to produce an approximately neutral effluent from the cathode compartment.
Claim 7
Independent Claim
54 words
A method as claimed in any one of the preceding claims, wherein the regenerated cellulose is passed through a plurality of washing baths through which the washing water flows in countercurrent fashion, the flow of washing water to the cathode compratment being taken from the first bath 4 through which regenerated cellulose is passed.
Claim 8
Independent Claim
21 words
A method as claimed in any one of the preceding claims, wherein the ion-selective membrane 11 is a cation- selective membrane.
Claim 9
Dependent Claim
46 words
A method as claimed in claim 7, wherein the alkaline cellulose solution comprises Na OH, the acid used is H 2 S0 4 , and the concentration of sodium ions in the cathode compartment is maintained at not more than twice that in the anode compartment.
Claim 10
Dependent Claim
144 words
Apparatus for producing regenerated cellulose comprising a bath 1, 2, 3 for containing an aqueous acid solution, to produce regenerated cellulose, means 13, 14, 15 for passing the regenerated cellulose through an aqueous acid solution 5, 6, 7 in the said bath, a washing bath 4 for the regenerated cellulose, means 16 for passing the regenerated cellulose through washing water in the washing bath, an electrolytic cell 10 having a cell divider 11 which is an ion-selective membrane, and which defines cathode and anode compartments in the cell, means for passing acid from the acid bath 1, 2, 3 through the anode compratment of the cell, and washing water from the washing bath 4, through the cathode compartment of the cell, and means for supplying a D.C. voltage to the cell to raise the acidity of the anolyte and lower that of the catholyte.
Claim 11
Dependent Claim
144 words
Apparatus for producing regenerated cellulose comprising a bath 1, 2, 3 for containing an aqueous acid solution, to produce regenerated cellulose, means 13, 14, 15 for passing the regenerated cellulose through an aqueous acid solution 5, 6, 7 in the said bath, a washing bath 4 for the regenerated cellulose, means 16 for passing the regenerated cellulose through washing water in the washing bath, an electrolytic cell 10 having a cell divider 11 which is an ion-selective membrane, and which defines cathode and anode compartments in the cell, means for passing acid from the acid bath 1, 2, 3 through the anode compratment of the cell, and washing water from the washing bath 4, through the cathode compartment of the cell, and means for supplying a D.C. voltage to the cell to raise the acidity of the anolyte and lower that of the catholyte.
Claim 12
Dependent Claim
40 words
Apparatus as claimed in claim 9, including three acid baths, 1, 2, 3 and means 13, 14, 15 for passing the regenerated cellulose through each of the acid baths in turn before it is passed to the washing bath 4.
Claim 13
Dependent Claim
29 words
Apparatus as claimed in claim 9 or claim 10, including means for returning acid from the anode compartment of the cell 10 to the acid bath 1, 2, 3.
Claim 14
Dependent Claim
48 words
Apparatus as claimed in any one of claims 9 to 11, including means for discharging solution from the cathode compartment to waste, and means for varying the amount of washing water fed to the anode compartment in response to a change in pH of the said waste solution.
Claim 15
Dependent Claim
58 words
Apparatus as claimed in any one of claims 9 to 12, including a plurality of washing baths 4, means 16 for passing the regenerated cellulose through the washing baths sequentially, and conduits connecting the washing baths to permit a flow of washing water between the baths in countercurrent fashion to the direction of passage of the regenerated cellulose.
References Cited (Backward Citations)
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