# US 12,006,403 B2 · Methods for recycling cotton and polyester fibers from waste textiles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,006,403 B2 - Document ID: US12006403B2 - Status: Granted - Kind: B2 - Application number: 17/850,030 - Filed: 2022-06-27 - Published: 2022-11-03 - Granted: 2024-06-11 - Earliest claimed: 2018-01-12 - Assignees: Circ, LLC - Applicants: Circ, LLC - Inventors: Florin G. Barla; Todd Showalter; Hsun-Cheng Su; Jeremy Jones; Iulian Bobe - Web page: https://patentgrep.com/patent/US12006403B2 ## CPC - C08J 11/26: containing carboxylic acid groups, their anhydrides or esters - C07C 51/09: from carboxylic acid esters or lactones - C07C 63/26: 1,4 - Benzenedicarboxylic acid - C08B 16/00: Regeneration of cellulose - C08J 11/14: by treatment with steam or water - C08L 1/02: Cellulose; Modified cellulose - D06M 13/184: Carboxylic acids; Anhydrides, halides or salts thereof - C08J 2367/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) - C08J 2401/02: Cellulose; Modified cellulose - D01F 2/00: Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof - D01F 6/62: from polyesters - Y02W 30/62: Plastics recycling; Rubber recycling - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - D06M: TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS - D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract Systems and methods are provided that involve a subcritical water reaction to recycle the cellulose and polyester components of waste cotton and cotton/polyester blend textiles that would otherwise be discarded or disposed of. Specifically, the disclosed methods provide for treatment of the waste textiles to produce advanced materials including cellulose and terephthalic acid (TPA) with a low environmental impact. The cellulose and TPA that are produced are of a high quality allowing for production of regenerated cellulose and regenerated polyethylene terephthalate (PET) suitable for fiber spinning and textile applications. ## Claims ### Claim 1 A method of producing one or both of cellulose and terephthalic acid (TPA) from a waste textile material comprising a cotton/polyester blend material, the method comprising: treating the waste textile material in a subcritical water reactor, wherein one or both of a cellulose that comprises a degree of polymerization ranging from about 150-2500 and a dissolved TPA and ethylene glycol (EG) is produced. ### Claim 2 (depends on 1) The method of claim 1, wherein the treating is conducted at a temperature of about 105° C. to 190° C., a pressure of about 40 to 300 psi, or both. ### Claim 3 (depends on 1) The method of claim 1, wherein the treating is conducted at a pH ranging from 10-14. ### Claim 4 (depends on 1) The method of claim 1, further comprising recovering the TPA. ### Claim 5 (depends on 4) The method of claim 4, wherein the recovering the TPA is conducted at a pH adjustment of pH 2-pH 4. ### Claim 6 (depends on 4) The method of claim 4, wherein the recovering comprises precipitating the dissolved TPA and crystallizing the precipitated TPA. ### Claim 7 (depends on 1) The method of claim 1, further comprising recovering the ethylene glycol. ### Claim 8 (depends on 1) The method of claim 1, further comprising recovering the cellulose. ### Claim 9 (depends on 8) The method of claim 8, wherein the recovering comprises one or more steps of wash, disintegration, sour wash, activation process, dissolution dope, or wet spinning. ### Claim 10 (depends on 1) The method of claim 1, further comprising removing color from the waste textile material before, during, or after treating with the subcritical water reactor. ### Claim 11 (depends on 10) The method of claim 10, wherein the color removal comprises treatment with one or more of hydrogen peroxide, sodium peroxide, sodium hypochlorite, calcium hypochlorite, dimethyl sulfoxide, lithium hypochlorite, sodium perborate, ozone, oxygen, activated carbon, biochar, sodium carbonate, peracetic acid, potassium permanganate, persulfate, sodium chloride, calcium oxychloride, chloramine, chlorine dioxide, sulfur dioxide, sodium hydrosulfite, or TAED (tetra-acetyl-ethylene-di-amine). ### Claim 12 (depends on 1) The method of claim 1, wherein the subcritical water reactor treatment comprises one or more of methanol, ethanol, isopropanol, tetra-n-butylphosphonium bromide (TBPB), or benzyltributylammonium chloride (BTBAC), or co-polymers thereof. ### Claim 13 (depends on 1) The method of claim 1, wherein the ratio of waste textile material to water within the subcritical water reactor is about 1:5-1:95. ### Claim 14 (depends on 1) The method of claim 1, wherein the cellulose comprises a degree of polymerization ranging from about 150-2000. ### Claim 15 (depends on 1) The method of claim 1, further comprising adjusting the pH of water within the subcritical water reactor before subcritical water treatment. ### Claim 16 (depends on 15) The method of claim 15, wherein the pH is adjusted to about 2-4. ### Claim 17 (depends on 16) The method of claim 16, wherein the pH is adjusted using 0.01-5% (v/v) organic acid. ### Claim 18 (depends on 15) The method of claim 15, wherein the pH is adjusted to about 10-14. ### Claim 19 (depends on 18) The method of claim 18, wherein the pH is adjusted using 0.5-20% (w/v) sodium hydroxide or 0.5-20% (w/v) potassium hydroxide. ### Claim 20 (depends on 1) A recycled cellulose produced using the method of claim 1.