Pretreatment methods for cotton textile waste fabric

Abstract

This invention discloses a mechanical and decolorizing pretreatment of cotton-containing fabrics, such as "waste" raw materials from cotton fabrics at the end of their lifespan, which can be used to produce sugar without using harsh pretreatment conditions.

Description

Technical Field

[0001] This invention relates to a process for producing sugar from self-contained cotton fabrics. Prior Technology

[0002] The Environmental Protection Agency (EPA) estimates that the United States burned 3.2 million tons of textile waste and received 11.3 million tons of textile waste in landfills in 2018. (EPA "Textiles: Material-Specific Data," EPA website, 2021). If disposed of in landfills, these textiles contribute to greenhouse gas emissions (e.g., methane) as they degrade. Additionally, the degradation process for synthetic fibers (e.g., polyester) can take hundreds of years. If textile waste is incinerated, toxic gases can be released, especially from more complex textile mixtures. (BBC website "Why Clothes are so hard to recycle," July 12, 2020).

[0003] Textile waste represents 3% of the global waste market share. (See Hamawand et al., "Bioenergy from Cotton Industry Wastes: A review and potential," Renew. Sustain. Energy Rev., Vol. 66, pp. 435-448, 2016; Johnson et al., "Supply Chain of Waste Cotton Recycling and Reuse: A Review," 2020). Textile waste is the 10th generation of newly generated waste after food, paper, and plastics, as well as glass-derived waste. The degradation time of cotton fabrics is approximately 50% to 77% within 90 days. (See Li, Frey, and Browning, "Biodegradability study on cotton and polyester fabrics," J. Eng. Fiber. Fabr., Vol. 5, No. 4, pp. 42-53, 2010).

[0004] This technology requires a method for processing textile waste into sugar and other value-added products. Summary of the Invention

[0005] In one embodiment, a method for pretreating cotton-containing fabric materials may include refining the cotton-containing fabric materials in a PFI refiner at a speed between about 2,000 and 20,000 revolutions.

[0006] In one embodiment, a method for pretreating cotton-containing fabric materials may include decolorizing the cotton-containing fabric materials and refining the cotton-containing fabric materials in a PFI refiner at a speed between about 2,000 and 20,000 revolutions.

[0007] The method may further include additional pretreatment. Additional pretreatment includes mechanical pretreatment, chemical enzymatic pretreatment, or a combination thereof. The method may further include: shredding the cotton-containing fabric, cutting the cotton-containing fabric, and pulping the cotton-containing fabric before refining it in a PFI refiner.

[0008] In one embodiment, a method for processing cotton-containing fabric material may include: (a) shredding the cotton-containing fabric material; (b) cutting the cotton-containing fabric material; (c) pulping the cotton-containing fabric material; (d) refining the cotton-containing fabric material in a PFI refiner at a speed between about 2,000 and 20,000 revolutions; and (e) subjecting the pretreated cotton-containing fabric material to hydrolysis to produce a hydrolysate. In one embodiment, the method may further include decolorizing the cotton-containing fabric material after cutting and pulping but before refining.

[0009] In one embodiment, a method for processing cotton-containing fabric material may include: (a) shredding the cotton-containing fabric material; (b) cutting the cotton-containing fabric material; (c) pulping the cotton-containing fabric material; (d) decolorizing the cotton-containing fabric material; (e) refining the cotton-containing fabric material in a PFI refiner at a speed between about 2,000 and 20,000 revolutions; and (f) subjecting the pretreated cotton-containing fabric material to hydrolysis to produce a hydrolysate.

[0010] In one embodiment, the decolorization step may include bleaching. The bleaching may comprise a treatment with ozone, sodium hypochlorite, hydrogen peroxide, Fenton's reagent, or a combination thereof. The hydrogen peroxide may be in the range of about 1.0% to about 8.0% (w / w). Specifically, the hydrogen peroxide may be in the range of about 2.0% to 6.0%, 4.0% and 8.0%, or 5.0% and 7% (w / w).

[0011] In one embodiment, bleaching may further comprise a treatment with sodium hydroxide. The sodium hydroxide may be in the range of 1.0% to about 6.0%, or optionally in the range of 2.0% to 4.0% (w / w). The sodium hydroxide may be in the range of about 2.0% to 4.0%, 3.0% to 5.0%, 4.0% to 6.0%, or 1.0% to 5.0% (w / w). The sodium hydroxide may be in an amount of about 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, or 6.0% (w / w).

[0012] In one embodiment, the method may further include adding Cu²⁺. Cu²⁺ may be added in the range of 100 ppm to 250 ppm. The range may be from about 120 ppm to 170 ppm.The amount can be about 100 ppm, 101 ppm, 102 ppm, 103 ppm, 104 ppm, 105 ppm, 106 ppm, 107 ppm, 108 ppm, 109 ppm, 110 ppm, 111 ppm, 112 ppm, 113 ppm, 114 ppm, 115 ppm, 116 ppm, 117 ppm, 118 ppm, 119 ppm, 120 ppm, 121 ppm, 122 ppm, 123 ppm, 124 ppm, 125 ppm, 126 ppm, 127 ppm, 128 ppm, 129 ppm, 130 ppm, 131 ppm, 132 ppm, 133 ppm, 134 ppm, 135 ppm, 136 ppm, 137 ppm, 138 ppm, 139 ppm, 140 ppm, 141 ppm, 142 ppm, 143 ppm, 144 ppm, 145 ppm, 146 ppm, 147 ppm, 148 ppm, 149 ppm, 150 ppm, 151 ppm, 152 ppm, 153 ppm, 154 ppm, 155 ppm, 156 ppm, 157 ppm, 158 ppm, 159 ppm, 160 ppm, 161 ppm, 162 ppm, 163 ppm, 164 ppm, 165 ppm, 166 ppm, 167 ppm, 168 ppm, 169 ppm, 170 ppm, 171 ppm, 172 ppm, 173 ppm, 174 ppm, 175 ppm, 176 ppm, 177 ppm, 178 ppm, 179 ppm, 180 ppm, 181 ppm, 182 ppm, 183 ppm, 184 ppm, 185 ppm, 186 ppm, 187 ppm, 188 ppm, 189 ppm, 190 ppm, 191 ppm, 192 ppm, 193 ppm, 194 ppm, 195 ppm, 196 ppm, 197 ppm, 198 ppm, 199 ppm, 200 ppm, 201 ppm, 202 ppm, 203 ppm, 204 ppm, 205 ppm, 206 ppm, 207 ppm, 208 ppm, 209 ppm, 210 ppm, 215 ppm, 220 ppm, 225, 230 ppm, 235 ppm, 240 ppm, 245 ppm or 250 ppm.

[0013] In one embodiment, the method may further include the addition of Fe²⁺. Fe²⁺ may be added in the range of 100 ppm to 250 ppm. The range may be from about 120 ppm to 170 ppm.The amount can be about 100 ppm, 101 ppm, 102 ppm, 103 ppm, 104 ppm, 105 ppm, 106 ppm, 107 ppm, 108 ppm, 109 ppm, 110 ppm, 111 ppm, 112 ppm, 113 ppm, 114 ppm, 115 ppm, 116 ppm, 117 ppm, 118 ppm, 119 ppm, 120 ppm, 121 ppm, 122 ppm, 123 ppm, 124 ppm, 125 ppm, 126 ppm, 127 ppm, 128 ppm, 129 ppm, 130 ppm, 131 ppm, 132 ppm, 133 ppm, 134 ppm, 135 ppm, 136 ppm, 137 ppm, 138 ppm, 139 ppm, 140 ppm, 141 ppm, 142 ppm, 143 ppm, 144 ppm, 145 ppm, 146 ppm, 147 ppm, 148 ppm, 149 ppm, 150 ppm, 151 ppm, 152 ppm, 153 ppm, 154 ppm, 155 ppm, 156 ppm, 157 ppm, 158 ppm, 159 ppm, 160 ppm, 161 ppm, 162 ppm, 163 ppm, 164 ppm, 165 ppm, 166 ppm, 167 ppm, 168 ppm, 169 ppm, 170 ppm, 171 ppm, 172 ppm, 173 ppm, 174 ppm, 175 ppm, 176 ppm, 177 ppm, 178 ppm, 179 ppm, 180 ppm, 181 ppm, 182 ppm, 183 ppm, 184 ppm, 185 ppm, 186 ppm, 187 ppm, 188 ppm, 189 ppm, 190 ppm, 191 ppm, 192 ppm, 193 ppm, 194 ppm, 195 ppm, 196 ppm, 197 ppm, 198 ppm, <199 ppm>, 200 ppm, 201 ppm, 202 ppm, 203 ppm, 204 ppm, 205 ppm, 206 ppm, 207 ppm, 208 ppm, 209 ppm, 210 ppm, 215 ppm, 220 ppm, 225, 230 ppm, 235 ppm, 240 ppm, 245 ppm or 250 ppm.

[0014] Note: There seems to be a formatting issue with the "199 ppm" in the original Chinese text which was not clearly separated like the others. I've left it as it is in the translation with angle brackets around it to indicate it might be a formatting anomaly. If this is incorrect, please clarify the original text.In one embodiment, bleaching can be performed at a temperature range of 60°C to 120°C. The temperature can be in the range of about 80°C to 100°C. Bleaching can be performed at a temperature between about 100°C to 110°C, 90°C to 100°C, 90°C to 110°C, or 95°C to 120°C. The temperature can be approximately 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃, or 120℃.

[0015] In one embodiment, bleaching can be performed for a duration ranging from 60 minutes to 120 minutes. The duration can be in the range of approximately 80 minutes to 110 minutes. The duration can be in the range of approximately 80 to 90 minutes, 90 to 100 minutes, 95 to 120 minutes, or 110 to 120 minutes. The time can be approximately 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, or 120 minutes.

[0016] In one embodiment, decolorization can be performed at a pH value between approximately pH 7 and pH 11. Decolorization can be performed at a pH value above pH 10. Decolorization can be performed at approximately pH 11. Decolorization can be performed at approximately pH 11.5. Decolorization can be performed at approximately pH 11.75. Decolorization can be performed at approximately pH 12.

[0017] In one embodiment, the solvent may be added to the cotton-containing fabric material prior to refining in the PFI refiner. The solvent may be water.

[0018] In one embodiment, the method may further include enzymatic hydrolysis of pretreated cotton-containing fabric materials to produce a hydrolysate.

[0019] In one embodiment, the method may further include cutting cotton-containing fabric materials.

[0020] In one embodiment, the method may further include pulping the cotton-containing fabric material.

[0021] In one embodiment, the method may further include decolorizing the cotton-containing fabric material.

[0022] In one embodiment, mechanical pretreatment may include shredding, cutting, pulping, refining, and combinations thereof.

[0023] In one embodiment, the method may further include adding a solvent to the cotton-containing material during mechanical pretreatment. The solvent may be water. The solvent may be added before, during, or before and during refining. The solvent may be added in an amount where the mechanically pretreated cotton-containing material:solvent weight / weight ratio is between approximately 1:0.01 and 1:30. The amount of solvent added to the cotton-containing material may be between 1:0.1 and 1:20, 1:0.1 and 1:10, 1:0.1 and 1:5, or 1:0.1 and 1:0.5. The amount of solvent added to the cotton-containing material may be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1 mechanically pretreated cotton-containing material:solvent weight / weight ratio. The amount of solvent added to cotton-containing fabrics can be 1:0.2 for mechanical pretreatment of cotton-containing fabrics: solvent weight / weight.

[0024] In one embodiment, mechanical pretreatment can be performed at temperatures between about 0°C and 50°C. Mechanical pretreatment can be performed at temperatures between about 10°C and 40°C. Mechanical pretreatment can be performed at temperatures of approximately 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, or 40°C. Mechanical pretreatment can be performed at a temperature of approximately 25°C.

[0025] In one embodiment, the mechanically pretreated cotton fabric material may contain between 1% and 50% fine particles by weight. The mechanically pretreated cotton fabric material may contain between 1% and 20% fine particles by weight, between 25% and 50% fine particles by weight, between 10% and 30% fine particles by weight, between 30% and 50% fine particles by weight, or between 15% and 35% fine particles by weight. The mechanical pretreatment of cotton fabric materials may contain fine particles ranging from the following by weight: approximately 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.

[0026] In one embodiment, the fiber length LWL (mm) of the mechanically pretreated cotton-containing fabric material can be between about 0.1 mm and 2.00 mm. The fiber length LWL (mm) of the mechanically pretreated cotton-containing fabric material can be between about 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2.00 mm.

[0027] In one embodiment, the refining level may be between approximately 2,000 and 20,000 PFI rpm. The refining level may be between approximately 2,000 and 10,000 PFI rpm; 5,000 and 15,000 PFI rpm; 5,000 and 20,000 PFI rpm; or between 10,000 and 20,000 PFI rpm. Refining levels are available at approximately 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, or 20,000 PFI revolutions.

[0028] In one embodiment, the Canadian Standard Freeness (CSF) of mechanically pretreated cotton-containing materials can be between approximately 100 and 900 CSF ml. The CSF of mechanically pretreated cotton-containing materials can also be between approximately 100 and 900 CSF ml, 200 and 400 CSF ml, and 400 and 600 CSF ml. The scouring level can be between approximately 100 and 900 ml CSF ml.

[0029] In one embodiment, the mechanical pretreatment of cotton-containing fabrics may be in the form of powder. The average particle size of the powder may be between about 0.10 mm and about 2.0 mm.

[0030] In one embodiment, the Willy grinder can be used for the cutting step.

[0031] In one embodiment, mechanical pretreatment can be performed before the cotton fabric material is decolorized.

[0032] In one embodiment, hydrolysis may include enzymatic hydrolysis, which involves adding at least one hydrolytic enzyme.

[0033] In one embodiment, enzymatic hydrolysis may include the addition of a combination of cellulase and β-glucosidase.

[0034] In one embodiment, the hydrolysate may contain sugar. The sugar may be dextran, xylan, arabinogalactan, mannan, galactan, glucose, sucrose, hexose, or a combination thereof.

[0035] In one embodiment, enzymatic hydrolysis can be carried out at a temperature between about 20°C and 75°C. Enzymatic hydrolysis can also be carried out at temperatures between about 40°C and 75°C, about 45°C and 75°C, 50°C and 75°C, about 55°C and 75°C, 60°C and 75°C, or about 65°C and 75°C. Enzymatic hydrolysis can also be carried out at 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, or 75°C.

[0036] In one embodiment, enzymatic hydrolysis can be carried out at a pH value between approximately pH 4.5 and pH 8.5. Enzymatic hydrolysis can be carried out at the following pH values: 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, or 8.5.

[0037] In one embodiment, enzymatic hydrolysis can be carried out for a period of approximately 1 hour to 300 hours. Enzymatic hydrolysis can be carried out for a period of approximately 12 hours to 300 hours, 24 hours to 144 hours, 24 hours to 180 hours, 48 ​​hours to 240 hours, or 24 hours to 96 hours. Enzymatic hydrolysis can be carried out for a period of approximately 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, 180, 192, 204, 216, 228, 240, 252, 264, 276, 288, or 300 hours. Enzymatic hydrolysis can be carried out for a period of approximately 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, 180, or 192 hours.

[0038] In one embodiment, the amount of enzyme used in the enzymatic hydrolysis may be between about 1 FPU and 50 FPU / g cotton. The amount of enzyme used in the enzymatic hydrolysis may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 FPU.

[0039] In one embodiment, the amount of enzyme used in the enzymatic hydrolysis may be between about 0.01% and 10% enzyme / cotton (w / w), and as needed, between about 0.02% and 0.05% enzyme / cotton (w / w).

[0040] In one embodiment, the enzymatic hydrolysis efficiency may be at least 50%, at least 60%, at least 65%, or at least 70%.

[0041] In one embodiment, enzymatic hydrolysis may further include the addition of an acid, a base, or both for pH control. The acid may be acetic acid, citric acid, or a combination thereof.

[0042] In one embodiment, the method may further include filtering the hydrolysis product to produce a permeate and a residue, wherein the permeate may contain the hydrolysate and the residue may contain a residue.

[0043] In one embodiment, the method may further include subjecting the hydrolysate to fermentation, oxidation, reduction, or hydrogenation to produce a terminal product.

[0044] In one embodiment, the method may further include subjecting the hydrolysate to fermentation.

[0045] In one embodiment, the end products generated by fermentation include alcohols, sugar alcohols, acids, fatty acids, gases, amino acids, chemicals, and mixtures thereof. Sugar alcohols may include sorbitol, xylitol, ethylene glycol, glycerol, erythritol, threitol, arabinitol, ribitol, mannitol, galactitol, fucitol, inositol, heptaheptaol, isomaltitol, lactitol, and mixtures thereof. Alcohols may include ethanol, butanol, methanol, propanol, and mixtures thereof. Acids may include 2,5-furandicarboxylic acid, itaconic acid, acetopropionic acid, succinic acid, lactic acid, malic acid, citric acid, acrylic acid, fumaric acid, hydroxypropionic acid, acrylic acid, and mixtures thereof. Chemicals may include glycerol, 3-hydropropionic acid, 2,5-dimethylfuran (DMF), 5-hydroxymethylfurfural (HMF), furfural, aldehydes, amines, terephthalic acid, hexamethylenediamine, isoprene, polyhydroxyalkanoates, 1,3-propanediol, or mixtures thereof. The gas may contain methane, ethane, CO, CO2 and H2 or mixtures thereof.

[0046] In one embodiment, enzymatic hydrolysis and fermentation can occur simultaneously.

[0047] In one embodiment, enzymatic hydrolysis and fermentation can be carried out separately.

[0048] In one embodiment, the method may not include a pretreatment step requiring neutralization with an acid or base, recovery of any solvent, or a rinsing step requiring the removal of components prior to hydrolysis and / or fermentation.

[0049] In one embodiment, a method may not include a step that requires the use of acid.

[0050] In one embodiment, mechanical pretreatment may be substantially chemical-free.

[0051] In one embodiment, a system for producing sugar from a cotton-containing material may include all components, cutting components, grinding components, refining components, and an enzyme hydrolysis reactor, all mechanically coupled together in series. Simple Explanation of the Diagram

[0052] Figure 1 depicts cotton fibers after mechanical refining: (A) shredding, (B) Willie milling; (C) PFI 2500 rpm; (D) PFI 5000 rpm; (E) PFI 10000 rpm; and (F) PFI 20000 rpm. The following figures include fiber length (LWL) (mm) and the percentage of weighed fiber particles.

[0053] Figure 2 depicts the enzymatic hydrolysis results of unrefined cotton waste (50°C, pH=5.2, 6 FPU) over 96 hours versus 192 hours. Cotton conversion rate (%) is plotted on the left X-axis, and the percentage of fine particles is plotted on the right X-axis. The refining level by PFI is measured as per revolutions. Finally, the energy consumed per ton of cotton equivalent to each refining level is plotted at the bottom. For example, 900 kWh would be needed to refine 1 ton of cotton at 5,000 PFI revolutions.

[0054] Figure 3 depicts the cotton conversion rate (%) of refined cotton as measured by the number of PFI revolutions. Enzymatic hydrolysis was carried out at 50°C, pH=5.2, and 5FPU for 48, 72, 96, or 192 hours. The cotton conversion efficiency, as measured as a percentage (%) of the initial mass of cotton, increases with increasing PFI revolutions.

[0055] Figure 4 depicts the cotton conversion rate (%) as measured by the number of hours of reaction time. Enzymatic hydrolysis was carried out at 50°C, pH 5.2, and 5 FPU. The cotton conversion efficiency, as measured as a percentage (%) of the initial mass of cotton, increases with increasing reaction time.

[0056] Figure 5 depicts the cotton conversion rate (%) as measured by the number of PFI rotations. Enzymatic hydrolysis was carried out at 50°C, pH 5.2, with 5 FPU (4.4% g enzyme / g OD cotton) or 6 FPU (5.1% g enzyme / g OD cotton) for 96 hours. The experiment was performed in duplicate. The cotton conversion efficiency, as measured as a percentage (%) of the initial cotton mass, increased with increasing PFI rotations, with 6 FPU producing approximately 6% higher cotton conversion rate than 5 FPU.

[0057] Figure 6 depicts the cotton conversion rate (%) as measured by the PFI rotation number. Enzymatic hydrolysis was carried out at 50°C, pH 5.2, at 5 FPU (4.4% g enzyme / g OD cotton) or 6 FPU (5.1% g enzyme / g OD cotton) for 192 hours. The experiment was performed in duplicate. The cotton conversion efficiency, as measured as a percentage (%) of the initial cotton mass, increased with increasing PFI rotation number. The two reactions performed at 5 FPU or 6 FPU yielded a cotton conversion rate of 92%. Implementation

[0058] The method of the present invention obtains a high sugar yield from cotton-containing fabrics, and the method includes mechanical pretreatment in a PFI refiner to refine the cotton-containing fabrics.

[0059] Cotton textile waste has been found to be a promising biomass fuel source for producing bioethanol. According to the invention, cotton textiles, such as "waste" materials from end-of-life cotton textiles, can be used to produce sugar without the same stringent pretreatment required for other biomass fuels such as grains, grass, or wood. Cotton is known to have a high degree of crystallinity (compared to other such biomass fuels), which makes obtaining extremely high sugar yields from cotton very challenging. The inventors have found with satisfaction that cotton in textile form, despite its high crystallinity, can be used to obtain high sugar yields using the methods described herein.

[0060] The method described herein provides a more efficient pretreatment of cotton fabrics containing waste, wherein the cotton fibers produced by the pretreatment have shorter fiber lengths, a larger percentage of fine particles by weight, and more thoroughly altered cellulose fibers. This results in an unexpected improvement in the processing of pretreated cotton fabrics containing waste into sugars and downstream processing into chemicals. definition

[0061] In the following, some definitions are provided for terms that are frequently used in this specification to characterize the invention. These terms will have separately defined and preferred meanings in each example of their use, as will be defined in the remainder of the specification.

[0062] As used in this specification and the accompanying claims, the singular forms “a” and “the” include the plural of indicators, unless the content clearly indicates otherwise.

[0063] "Fine particles," as used broadly in this article, refer to fibers small enough to pass through a mesh screen with a perforation diameter of 76 μm, which contribute to the final properties of the product. See Fischer et al., "Pulp Fines - Characterization, Sheet Formation, and Comparison to Microfibrillated Cellulose," Polymers 9(366):2017.

[0064] "Fiber length (LWL)" as used in this article refers broadly to the slurry term related to average length and weighing length. "The Application of Fiber Quality Analysis (FQA) and Cellulose Accessibility Measurements To Better Elucidate the Impact of Fiber Curls and Kinks on the Enzymatic Hydrolysis of Fibers", Richard P. Chandra, Jie Wu, and Jack N. Saddler, ACS Sustainable Chemistry & Engineering 2019 7(9), 8827-8833.

[0065] "Filter paper cellulase activity (FPU)," as used herein, broadly refers to the amount of enzyme that produces 2.0 mg of releasing sugar from 50 mg of filter paper (Watman 1) within 1 hour.

[0066] "Cotton fabrics" as used in this article broadly refers to any fabric containing cotton fibers.

[0067] "Textile cotton" or "recycled textile cotton," as used broadly in this article, refers to the collected raw materials from waste (e.g., clothing at the end of its service life, fabric scraps from the garment industry, soft linen), and the cotton component is essentially composed of more than 90% cellulose (which can be converted into sugar).

[0068] "Canadian Standard Freeness (CSF)," as used herein, broadly refers to mechanically pre-treated cotton fabrics. CSF directly relates to the intensity of mechanical scouring. It provides a measure of the rate at which a diluted suspension of a slurry (e.g., cotton fibers) is dehydrated under specified conditions. The dehydration rate changes inversely with the level of scouring. Textile waste and disposal

[0069] Current methods for converting cellulosic textile waste into bio-building blocks are few, and these methods are based on the chemical use of acids or bases at yields between 40% and 90% under highly aggressive conditions (high chemical charge). These proposed pathways result in high conversion costs due to their high chemical usage and capital-intensive follow-up issues related to chemical recycling, thus leading to a high carbon and environmental footprint. Alvira et al., "Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: A review", Bioresour.Technol. (2010) 101(13):4851-4861. The development of technologies capable of converting recycled / used clothing into sustainable and industrially viable bio-building blocks could represent a significant contribution to the cotton and recycled waste industries. Abbati De Assis et al., "Risk management consideration in the bioeconomy", Biofuels, Bioprod. Biorefining (2017) 11:549-566.

[0070] Because of the aggressive pretreatment required to obtain sugars from cotton biomass fuels (e.g., plants, stalks, pine nut distillers' grains), cotton has not yet been considered a high-value biomass fuel feedstock. Furthermore, cotton has a higher degree of crystallinity compared to other sources of cellulose, which make bioconversion even more challenging. (OJ Rojas, Cellulose Chemistry and Properties: Fibers, Nanocelluloses and Advanced Materials, 2016). However, cotton in woven form is 90%+ pure cellulose (and subsequently glucose), which has already been processed and is essentially a free feedstock for bioprocessing at the end of the lifespan of consumer goods. Utilizing end-of-life cotton clothing, rather than the biomass fuels grown from it, would yield both economic and environmental benefits.

[0071] The use of external solvents, high-level acids, or high-level corrosives at low temperatures to produce sugars from cotton fabrics has presented obstacles to commercialization. These methods are not commercially feasible due to the cost of neutralizing the high-level acids or corrosives, the additional materials required, the cost of regenerating and recycling the solvents, and the need to maintain near-freezing temperatures for the corrosives. In addition to neutralizing the acid or corrosive, the neutralized components require further rinsing.

[0072] Cellulose has been used as a feedstock for ethanol and glucose production through enzymatic hydrolysis and fermentation. Various pretreatment methods have been employed to inhibit the effects of hemicellulose and lignin on enzymatic hydrolysis, thus making cellulose usable for enzymes. In the case of cotton waste, cellulose, due to the extremely low content of hemicellulose and lignin residues, is further suitable for enzymatic hydrolysis. Therefore, other issues must be addressed to increase the yield of glucose and ethanol, such as cellulose crystallinity, degree of polymerization, fiber size, and porosity.

[0073] Enzymatic hydrolysis has been used to degrade cellulose into glucose. However, in cotton waste, the conversion of cellulose to glucose is slow due to its high crystallinity and small pore size, unless the fibers undergo some form of pretreatment. This presents a challenge to the usability of cellulose molecules for enzymatic reaction. (See Chandra et al., "Substrate pretreatment: The key to effective enzymatic hydrolysis of lignocellulosics?", Adv. Biochem. Eng. Biotechnol. (2007) 108: 67-93). The usability of cellulose for enzymatic hydrolysis of cotton waste materials is a factor in increasing the yield of glucose and ethanol. Among the physicochemical properties affecting the glucose yield in the enzymatic hydrolysis of cellulose are specific surface area, cellulose crystallinity, and degree of polymerization.

[0074] The method described herein efficiently disrupts the cellulose structure and allows for enzyme accessibility during the hydrolysis (saccharification) of cellulose to produce sugars (e.g., glucose). No harsh pretreatment is required. The inventors have found that treating unrefined cotton fabrics results in low cellulose conversion. The mechanical refining method described herein results in the stratification and fibrillation of cotton fibers at 5,000 rpm in a PFI refiner, which leads to greater cellulose conversion and does not require the use of any chemicals. For example, using a PFI refiner at 10,000 rpm with enzyme 5 (FPU) results in 84% conversion and 90% conversion with enzyme 6 (FPU). [Units of cellulase activity in filter paper]. Cotton fabrics

[0075] Cellulose is a natural polymer composed of a straight chain of hundreds to thousands of D-glucose units linked by β-(1,4)-glycosidic bonds. Cellulose content varies depending on the biomass fuel source. Among natural fibers containing cellulose, cotton is a biomass fuel source, containing the highest percentage of cellulose; its lignin content is essentially zero, indicating a processing advantage. (See Bajpai, "Pretreatment of Lignocellulosic Biomass", Springer, Singapore, (2016), pp. 17-70; Singh and KB Satapathy, "Conversion of Lignocellulosic Biomass to Bioethanol: An Overview with a Focus on Pretreatment", Int. J. Eng. Technol., Vol. 15, pp. 17-43, 2018.)

[0076] Cotton fibers have primary walls, secondary walls, and a central core or lumen. The width of cotton fibers varies between 12 and 20 μm. The average degree of polymerization of cotton ranges from 9,000 to 15,000; the average crystallinity is 73; both of these values ​​are extremely high compared to other lignocellulosic materials similar to wood pulp (DP = 600 to 1,500 and crystallinity = 35) and viscose (DP = 250 to 450 and crystallinity = 60). (OJ Rojas, Cellulose Chemistry and Properties: Fibers, Nanocelluloses and Advanced Materials, 2016.)

[0077] The typical complexes of raw cotton fibers are illustrated in Table 1. Cotton contains approximately 90% or more cellulose. The non-cellulose components of cotton include proteins, amino acids, and nitrogenous compounds, which are primarily present in the surface and lumen forms. Table 1: Cotton fiber compounds Element typical(%) scope(%) Cellulose 95 88.0-96.0 protein 1.3 1.1-1.9 Pectin 0.9 0.7-1.2 ash 1.2 0.7-1.6 wax 0.6 0.4-1.0 Total sugar content 0.3 0.1-1.0 organic acids 0.8 0.5-1.0 other 1.4 — Heinze et al. Cellulose Chemistry and Properties: Fibers, Nanocelluloses and Advanced Materials, Volume 271, Springer International Publishing, 2016.

[0078] Cotton-containing fabrics treated by the methods described herein may include any cotton or cotton blend garments, including but not limited to cotton-polyester blend garments or mixtures thereof. Mechanical pretreatment

[0079] Mechanical pretreatment of cotton fabrics may include mechanical processes for tearing cotton fabrics, including but not limited to grinding, shredding, cutting, pulping, refining, dicing, or packing. Mechanical pretreatment efficiently and physically tears the fabric into smaller components, increases the surface area of ​​the fabric components, reduces the crystallinity of the fabric, or combinations thereof, thereby aiding subsequent hydrolysis.

[0080] Equipment commonly used for fiber size reduction includes refiners, extruders, and fibrillators. The effects of mechanical treatment are primarily attributed to the high shear forces generated during the grinding and refining processes. Fiber fragments of different sizes aggregate with the largest particles (>0.1 to 2 mm), while finer particles increase in size with increasing shear stress intensity during processing. Disc refining, which produces greater fiber structure separation and stratification, has proven to be more effective than hammer refining in enhancing cellulose hydrolysis. Grinding, refining, and refining require high energy input; therefore, they are cost-intensive, which is detrimental to their widespread application. (Hendriks and G. Zeeman, "Pretreatments to enhance the digestibility of lignocellulosic biomass", Bioresour. Technol., Vol. 100, No. 1, pp. 10-18, January 2009.)

[0081] Mechanical refining consists of three mechanisms that alter the fiber structure and morphology: cutting (reducing fiber length), shearing (fiber surface fibrillation), and compression (fiber delamination). These mechanisms occur simultaneously but at different relative levels depending on the refining technique.

[0082] Fiber length reduction occurs as the two refining bars pass each other, attributed to the cutting action of the refining mill blades. Fiber fibrillation is typically an external effect and involves smaller fiber segments due to shear forces autonomously stripping the fiber mass. Finally, delamination is generally an internal effect originating from the repeated compression and decompression of the fibers as they are squeezed between the bars and grooves of the refining mill blades. The refining level can be between approximately 5,000 and 20,000 PFI revolutions.

[0083] Mechanical refining can maximize fiber properties by maximizing enzymatic hydrolysis with lower energy consumption. Microscopic imaging analysis has shown that refining induces cell separation, surface fibrillation, internal stratification, and fine particle formation. These changes typically contribute to an increase in the accessible surface area of ​​cellulose and a higher yield of cellulose enzymatic hydrolysis (an increase in conversion rate of 10% to 30%).

[0084] Mechanical pretreatment may involve tearing cotton-containing fabrics by shredding, cutting, pulping, and subsequently refining them. Exemplary equipment includes ball mills or PFI mills for pulping, Willie mills for cutting, and refiners such as PFI refiners, single-disc refiners, double-disc refiners, and double-disc refiners.

[0085] A preferred mechanical pretreatment method involves refining cotton fabrics in a PFI refiner at speeds between approximately 5,000 and 20,000 PFI revolutions, depending on the desired speed. The inventors have found satisfactory results that refining cotton fabrics using a PFI refiner produces pretreated material containing more fine particles, smaller, and more thoroughly altered cellulose, resulting in unexpected improvements in the outcome. For example, cotton fabrics can be refined in a PFI refiner at approximately 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, or 20,000 revolutions. Cotton fabrics can be refined in a PFI refiner at approximately 5,000 PFI rpm and 20,000 rpm, 5,000 rpm and 10,000 rpm, 7,500 rpm and 15,000 rpm, 7,000 rpm and 10,000 rpm, 10,000 rpm and 20,000 rpm, 15,000 rpm and 20,000 rpm, or 17,500 rpm and 20,000 rpm.

[0086] The PFI refiner is a machine developed by Papirindustriens Forskningsinstitut (The Norwegian Pulp and Paper Research Institute). In this technology, the PFI refiner is referred to as a PFI refiner. The PFI refiner is a highly reproducible, characteristic agitator used to study the relationship between the degree of beating and physical properties of pulp. This machine can be used in the preparation stage of papermaking. Beating mechanism: A constant load is supplied to the pulp circulating between stainless steel rollers and a cylindrical refiner chamber, applying mechanical effects such as shearing and compression. Beating is performed by friction between fibers. The stainless steel rollers and the cylindrical refiner chamber rotate at a constant circumferential speed difference. The number of revolutions is read by a counter. The degree of beating is evaluated by a freeness tester. The refining results are measured, compared, and standardized by properties related to dewatering, also known as freeness using a quantitative scale, specifically the Canadian Standard Freeness. See description number 0027. See also TAPPI (2000) Laboratory pulping of slurries (PFI pulping method). T 248 sp-00.

[0087] Mechanical pretreatment of cotton-containing fabrics, including refining in a PFI refiner, opens up the cotton fibers to allow for better enzyme access during hydrolysis. Furthermore, the inventors used HPLC analysis to provide better analytical results and to better develop the method.

[0088] Mechanical pretreatment may include, as needed, grinding the cotton-containing fabric into powder using a PFI refiner, wherein the average particle size of the powder is between about 0.10 mm and about 2.0 mm. Alternatively, the average particle size may be between about 0.15 mm and about 1.60 mm. Or, the average particle size may be between about 0.20 mm and 1.5 mm. Or, the average particle size may be less than about 2.0 mm. Or, the average particle size may be less than about 1.70 mm. For example, the average particle size may be greater than zero and less than about 0.10 mm, 0.20 mm, 0.30 mm, 0.40 mm, 0.50 mm, 0.60 mm, 0.70 mm, 0.80 mm, 0.90 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2.0 mm.

[0089] The inventors discovered that the mechanical refining action of the PFI refiner produces unexpected improvements in the pretreatment of cotton fabrics. The PFI mechanical refining action consists of three mechanisms that significantly alter fiber structure and morphology: cutting (fiber length reduction), shearing (fiber surface fibrillation), and compression (fiber delamination). These mechanisms occur simultaneously but at different relative levels depending on the refining technique. Chen et al. (2013) Bioresour. Technol. 147: 401-408; Park et al. (2016) Bioresour. Technol. 199: 59-67. Fiber length reduction occurs as the two refining bars cross each other, attributable to the cutting action of the refining blades. Additional fiber cutting leads to the generation of fine particles. Fibrillation is generally an external effect and involves the autonomous shearing of smaller fiber fragments from the fiber mass attributable to shear forces. Finally, delamination is generally an internal effect originating from the repeated compression and decompression of the fibers as they are squeezed between the bars and grooves of the refining blades. Corbett et al. (2020) Biotechnol. Bioeng. 117: 924-932; De Assis et al. (2018) Biotechnol. Biofuels 11. Forces involved in mechanical refining are described, for example, in Gharehkani et al. (2015) Carbohydr. Polym. 115: 785-803.

[0090] The method of this invention can also be used for cotton-containing fabrics that have already undergone mechanical pretreatment. The cotton-containing fabrics may be ground, shredded, cut, diced, stuffed, or a combination thereof. The cotton-containing fabrics may be in powder form.

[0091] Mechanical pretreatment may further include adding a solvent to the cotton-containing fabric before, during, or before and during pretreatment. The solvent may be water. The amount of solvent added to the cotton-containing fabric, by weight / weight ratio, may be between 1:0.01 and 1:30 for mechanical pretreatment of the cotton-containing fabric. For the PFI mechanical refining process, the amount of solvent added to the cotton-containing fabric may be 1:0.2. The amount of solvent added to the cotton-containing fabric may be between approximately 1:0.1 and 1:20, 1:0.1 and 1:10, 1:0.1 and 1:5, or 1:0.1 and 1:0.5. The amount of solvent added to the cotton-containing fabric may be approximately 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1. For example, PFI can be operated with approximately 5% solids (w / w) and 95% water (w / w). This can be expressed as a 1:20 fabric:solvent (water) ratio.

[0092] Mechanical pretreatment can be carried out at temperatures between approximately 0°C and 100°C.

[0093] The inventors were pleased to find that they could achieve extremely high cotton conversion rates without using any chemicals in the pretreatment of cotton fabrics. For example, previous studies used corrosive chemicals, high heat, and enzyme consumption to achieve cotton conversion. matrix Preprocessing methods Optimal pretreatment conditions enzymes Output rate Polyester recycling Author Blue denim / cotton Chopping and grinding / NaOH 12% NaOH, 0°C, 96 hours Cellulase and β-glucosidase 20 FPU 85.1%, 24 hours 99.1%, 96 hours - (Jeihanipour &Taherzadeh, 2009) 50 / 50 Polyester / Cotton (Figure 5) Chopping and grinding / N-methylmorphorline-N-oxide (NMMO) NMMO 85%, 120 ℃, 2 hours Cellulase and β-glucosidase 90% - (Jeihanipour et al., 2010) 40 / 60 Polyester / Viscose Chopping and grinding / N-methylmorphorline-N-oxide (NMMO) NMMO 85%, 120 ℃, 2 hours Cellulase and β-glucosidase 90% - (Jeihanipour et al., 2010) Blue denim polyester / cotton Pulping / Phosphoric Acid H₂PO₄ 385%, 50℃, 7 hours Cellulase and β-glucosidase 7.5 FPU 79% 100% (Shen et al., 2013) 40 / 60 Polyester / Cotton Pulping / NaOH / Urea NaOH 7%, urea 12%, -20℃, 1 hour Cellulase and β-glucosidase 70% 98% (Gholamzad et al., 2014) 40 / 60 Polyester / Cotton Chopping / Pressure / Sodium Carbonate Na₂CO₃ 3lM, 150 ℃, 72 hours Cellulase and β-glucosidase 48% - (Hasanzadeh et al., 2018) Paper towels (87.7% cotton) Steam eruption 5.5 MPa, 271℃, 5 minutes Cellulase and hemicellulase 42% - (Sasaki et al., 2019) Paper towels (87.7% cotton) microwave H₂SO₄ 41%, 180 ℃, 5 minutes Cellulase and hemicellulase 80.70% - (Sasaki et al., 2019) 60 / 40 Polyester / Cotton Pulping / NaOH / Urea NaOH 7%, urea 12%, -20℃, 6 hours Cellulase and β-glucosidase 98% - (X. Li et al., 2019) Medical cotton waste contains 95% cellulose Thermomechanical + H2SO4 22.5 mM H2SO4 0.22%, 180 to 220 °C, 20 to 40 minutes Cellulase and β-glucosidase CTEC2 20 mg / g biomass fuel 95.2% - (Giakoumakis et al., 2020)

[0094] In short, previous studies relied on high temperatures, large amounts of enzymes, irritating chemicals, and mixtures thereof to achieve cotton conversion. In contrast, the method described herein does not rely on high temperatures, large amounts of enzymes, irritating chemicals, and mixtures thereof to achieve cotton conversion. For example, the inventors have found that by pretreatment with pulping in a Willy refiner followed by refining at 10,000 rpm in a PFI refiner and gradual hydrolysis with 5 FPU or 6 FPU for 96 hours, 84% or 90% conversion is remarkably achieved. (5 FPU = 4.4% g enzyme / g cotton, and 6 FPU = 5.1% g enzyme / g cotton).

[0095] For example, cotton-containing fabrics can be shredded, cut, pulped, and then water is added, with the process constrained between approximately 5,000 and 20,000 revolutions in a PFI refiner. Following this operation, the pretreated cotton-containing fabric material is hydrolyzed using, for example, 5-FPU or 6-FPU. This process yields over 80% conversion of the cotton fibers, and the only chemical used during the enzymatic hydrolysis step is acetic acid or citric acid for pH control. No chemicals are used in the mechanical pretreatment step. The only solvent used in the mechanical pretreatment step is water. Bleaching

[0096] If cotton fabrics are dyed or printed in colors other than bleached cotton, or if cotton fabrics have finishes applied to them, such as, but not limited to, softeners, durable heat-pressing resins, moisture-wicking / moisture-wicking finishes, abrasion-resistant finishes, antibacterial finishes, or flame-retardant finishes, then the efficiency of enzymatic hydrolysis is reduced. See Buschle-Diller & Traore (1998). The effects of direct and reactive dyes on the enzymatic hydrolysis of cotton. Textile Research Journal, 68(3), 185-192.

[0097] Next, cotton-containing fabrics can be decolorized to remove dyes or finishes before pretreatment, hydrolysis, and / or saccharification. Dyed or finished cotton-containing fabrics can undergo a decolorization process to remove dyes or finishes that can interfere with enzymatic hydrolysis. The inventors have found with satisfaction that the decolorization method described herein allows decolorization without interference with the later stages of hydrolysis and saccharification. For example, decolorization using the method described herein increases yield from about 40% to about 80% to 90%. For example, cotton-containing fabrics can be decolorized after cutting and pulping but before mechanical refining.

[0098] Decolorization treatment may involve removing all dyes or exposing the cellulose in cotton fabrics to a hydrolyzed material. Decolorization methods may involve using at least one bleaching compound. Bleaching compounds may be ozone, sodium hypochlorite, hydrogen peroxide, Fenton's reagent, or a combination thereof.

[0099] The bleaching compound may be hydrogen peroxide. Cotton-containing materials can be bleached with hydrogen peroxide in the range of about 1.0% to about 8.0%, and optionally in the range of about 2.0% to 6.0%. Hydrogen peroxide may be combined with sodium hydroxide, which may be in the range of about 1.0% to about 6.0%, optionally in the range of 2.0% to 4.0%. Hydrogen peroxide and sodium peroxide may be further combined with metals such as Fe²⁺ and Cu²⁺ in the range of 100 ppm to 250 ppm, and optionally in the range of 120 ppm to 170 ppm. During the process, the cotton content, measured as a percentage (%) of the total mixture, may be in the range of 1% to 20%.

[0100] The decolorization temperature is preferably in the range of 60°C to 120°C, and may be in the range of 80°C to 100°C if necessary. The time is in the range of 60 minutes to 120 minutes, and may be in the range of 80 minutes to 110 minutes if necessary. The pH value is preferably in the range above 10. For example, the pH value range can be between approximately 9 and 11.

[0101] Ozone can be the bleaching compound. Ozone pretreatment procedures are disclosed, for example, in "Kinetics of ozone bleaching of eucalyptus kraft pulp and factors affecting the properties of the bleached pulp" BioRes. 13(1), 425-436. Cotton-containing materials are bleached by ozone at a flow rate ranging from about 0.1 L / min to 20 L / min, or as needed from about 0.5 L / min to 10 L / min, or as needed from about 1 L / min to 5 L / min, at a concentration ranging from about 1.0% to about 20.0% wt, or as needed from about 2.0% to 10.0%. The ozone flow rate is 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, 1 L / min, 1.1 L / min, 1.2 L / min, 1.2 L / min, 1.3 L / min, 1.3 L / min, 1.4 L / min, 1.5 L / min, 1.6 L / min, 1.7 L / min, 1.8 L / min, 1.9 L / min, or 2 L / min. The ozone decolorization time ranges from approximately 1 minute to 60 minutes, and may be from 10 minutes to 30 minutes as needed. In a preferred embodiment, the range is 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, or 30 minutes. Ozone decolorization is best performed within a pH range of 2 to 11, and may be performed within a pH range of 3 to 11 as needed. The pH value can be 3, 7, or 11. During the process, the cotton content, measured as a percentage (%) of the total mixture, can be between 1% and 30%.

[0102] In one embodiment, the neutralization reaction is carried out after the bleaching pretreatment. The neutralization reaction is carried out with sulfuric acid until the pH value reaches 7. A subsequent rinsing process with water is performed at room temperature. Acid pretreatment / cooling / neutralization

[0103] Cotton fabrics may be subjected to acid treatment as needed. The acid pretreatment in step (c) comprises at least one acid. The at least one acid may comprise a weak acid. Examples of weak acids include, but are not limited to, phosphoric acid, citric acid, nitrous acid, lactic acid, benzoic acid, acetic acid, and carbonic acid. In one embodiment, the weak acid is known to be not completely free in water compared to a strong acid. The at least one acid used in the acid pretreatment may comprise phosphoric acid. The concentration of the at least one acid in step (c) is between about 0.01 M and about 0.5 M, depending on the requirement, between about 0.10 M and about 0.25 M, depending on the requirement, between about 0.15 M and about 0.20 M.

[0104] At least one acid is added to the powder in a liquid ratio ranging from about 2:1 to about 12:1, or as needed from about 4:1 to about 10:1, or as needed from about 6:1.

[0105] If necessary, step (c) does not involve the addition of alkali—that is, alkali is not used in the pretreatment of cotton fabrics. In one embodiment, step (c) does not involve a pretreatment requiring neutralization with a strong acid or alkali, the recovery of any solvent or pretreatment acid, or a rinsing step required by a pretreatment that requires the components to be removed prior to hydrolysis and / or fermentation.

[0106] The high temperature in step (c) can be in the range of about 115°C to about 210°C, depending on the need, in the range of about 121°C to about 137°C, depending on the need, in the range of about 126°C to about 132°F, depending on the need, and is about 130°C. The heating time in step (c) is in the range of about 0.5 to about 5 hours, depending on the need, in the range of about 1 to about 3 hours, depending on the need, and is about 2 hours. A stirrer may be added to the slurry as needed to enhance internal mixing of the slurry. Due to the acid pretreatment, the resulting slurry has a much lower viscosity.

[0107] Step (c) may include cooling the slurry to a temperature ranging from about 48°C to about 71°C, or as needed from about 54°C to about 65°C, or as needed about 60°C.

[0108] Step (e) may include adding at least one alkali to the slurry from (c), and stirring the slurry as needed. The at least one alkali may include a strong alkali. Examples of strong alkalis include, but are not limited to, potassium hydroxide, sodium hydroxide, barium hydroxide, cesium hydroxide, strontium hydroxide, lithium hydroxide, and rubidium hydroxide. The at least one strong alkali used in step (e) may include sodium hydroxide. The concentration of sodium hydroxide may be in the range of about 0.01 M to about 0.5 M. The concentration of sodium hydroxide is sufficient to effectively neutralize the previously added acid. The presence of sodium hydroxide neutralizes phosphoric acid to form sodium phosphate in situ. The slurry is then stirred as needed between 1 and 120 minutes and at a temperature in the range of about 48°C to about 70°C, or as needed between about 55°C and about 65°C, or as needed at a temperature of about 60°C.

[0109] Step (e) may include adding at least one additional acid to the cotton slurry from step (d) to form a buffer solution in situ, and stirring the slurry as needed. The at least one acid used in step (e) may comprise a weak acid. Examples of weak acids include, but are not limited to, phosphoric acid, citric acid, nitrous acid, lactic acid, benzoic acid, acetic acid, and carbonic acid. Weak acids are not completely free in water. The at least one acid used in step (e) may comprise citric acid.

[0110] The citric acid from step (e) can form a buffer solution containing sodium phosphate from step (d). This citric acid and sodium phosphate buffer solution is known as McIlvaine buffer.

[0111] The concentration of at least one acid in step (e) is between about 0.001 M and about 1.0 M, or as needed between about 0.010 M and about 0.1 M, or as needed between about 0.025 M and about 0.050 M. Glycation

[0112] Pretreated materials can be subjected to enzymatic hydrolysis to produce sugars (saccharification). For example, pretreated materials can undergo separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), or direct microbial conversion (DMC). Wyman et al. (1992) Biomass and Bioenergy 3(5):301-307.

[0113] Sugars produced by the methods described herein include, but are not limited to, dextran, xylan, arabinogalactan, mannan, galactan, glucose, sucrose, hexose, and combinations thereof. Enzymatic hydrolysis may involve incubation with a cellulase complex comprising one or more enzymes that hydrolyze fibrous materials. Cellulases include, but are not limited to, endonucleases, exonucleases, cellulases, oxidative cellulases, and endoglucanases. Other enzymes that may be used include, but are not limited to, cellulolytic enzymes, β-glucosidases, and combinations thereof. Hydrolysis may further include filtration, wherein the hydrolysate is fermented and saccharified to produce ethanol. Alternatively, if filtration does not occur, hydrolysis may involve fermenting and saccharifying the slurry to form ethanol.

[0114] The same steps may include fermentation and saccharification of the hydrolysate, or when the steps include fermentation and saccharification of the slurry, the preceding steps may further include a combination of hydrolytic enzymes and yeast.

[0115] Saccharification may involve adding at least one hydrolytic enzyme, such as at least one cellulase, to the pretreated cotton material to initiate enzymatic hydrolysis of the pretreated cotton material to form a slurry, and stirring the slurry as needed. Enzymatic hydrolysis may be carried out using a mixture of at least one cellulase and a β-glucosidase. The enzyme mixture may include hemicellulase, cellulase, endoglucanase, exoglucanase, and 1-β-glucosidase. The cellulase may be a cellulolytic enzyme, endocellulase, exocellulase, cellobiase, endoβ-1,4-glucanase, β-1,4-glucosidase, or a mixture thereof.

[0116] After the hydrolyzed mixture is added to the pretreated cotton material, hydrolysis takes approximately 24 to 240 hours, or as needed, approximately 48 to 216 hours. Hydrolysis can take approximately 24 to 36 hours, 24 to 144 hours, 24 to 168 hours, or 48 to 216 hours. Hydrolysis can occur over the following time periods: approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63. 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 1 69, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, or 216 hours. The slurry can be stirred.

[0117] The temperature during hydrolysis can range from about 20°C to about 60°C, or as needed from about 40°C to about 55°C, or as needed about 48°C. The temperature during hydrolysis can also be about 30°C, at which saccharification and fermentation can occur simultaneously.

[0118] The pH of the enzyme solution during hydrolysis can be controlled by acid or base, or both. The pH during hydrolysis can be selected by someone skilled in the technique and can be between approximately 3.0 and 10.0, or as needed, between approximately 4.0 and approximately 8.0, or as needed, between approximately 4.5 and approximately 6.5. The pH range can be up to 3 pH units or up to 5 pH units. Optimal pH values ​​can be within the limits of pH 3.0 to 9.0, 3.5 to 8.5, 4.0 to 8.0, or 4.0 to 7.5. pH values ​​can be approximately 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, or 6.5. For example, a pH value of approximately 5.2 is possible.

[0119] The hydrolysis time is approximately 6 hours or more, 10 hours or more, 12 hours or more, 14 hours or more, 16 hours or more, 18 hours or more, 20 hours or more, 30 hours or more, 40 hours or more, 50 hours or more, 60 hours or more, 70 hours or more, 80 hours or more, 90 hours or more, 100 hours or more, 110 hours or more, 120 hours or more, 130 hours or more, 140 hours or more, 150 hours or more, 160 hours or more, 170 hours or more, 180 hours or more, 190 hours or more, or 200 hours or more. The hydrolysis time is between 10 and 120 hours.

[0120] Enzyme activity should be measured between 1 FPU and 540 FPU / g cotton. Developed by IUPAC, FPU is the standard method for expressing enzyme dosage and its ability to convert 50g of cellulose filter paper into 2.0 mg of glucose within 60 minutes. Adney, B. and Baker, J., "Measurements of Cellulase Activities", NREL Laboratory Technical Report NREL / TP-510-42628, 2008.

[0121] The amount of enzyme-to-cotton weight ratio (ISE) is between 0.01% and 10.0%.

[0122] Hydrolysis efficiency can be determined in a manner known to one of those skilled in the art. Exemplary hydrolysis methods include cotton residue, HPLC, and RIDA® Cube. In one embodiment, the hydrolysis efficiency is determined using the RIDA® Cube method. The hydrolysis efficiency is at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 51%, at least about 52%, at least about 53%, at least about 54%, at least about 55%, at least about 56%, at least about 57%, at least about 58%, at least about 59%, at least about 60%, at least about 61%, at least about 62%, at least about 63%, at least about 64%, at least about 65%, at least about 66%, at least about 67%, at least about 68%, at least about 69%, at least about 70%, at least about 71%, at least about 72%, at least about 73%, at least about 74%, at least about 75%, at least about 76%, at least about 77%, at least about 78%, at least about 79%, or at least about 80%.

[0123] The methods described herein may not include pretreatment steps requiring neutralization with strong acids or bases, recovery of any solvents or pretreatment acids, or rinsing steps required by a pretreatment that necessitates the removal of components prior to hydrolysis and / or fermentation. Filtration and drying

[0124] Following the hydrolysis step, the slurry may be filtered to produce a residue (cotton residue) and a permeate (hydrolysate containing sugar). This filtration may be performed by any known means to those skilled in the art, such as those described in U.S. Patent No. 9,540,665, which is incorporated herein by reference. The cotton residue is then dried, for example, in an oven and, if necessary, weighed after drying. The cotton residue is dried in the oven at a temperature ranging from about 48°C to about 82°C, if necessary, from about 60°C to about 76°C, and if necessary, from about 70°C. The drying time may be about 2 hours, if necessary, ranging from about 4 hours to about 48 hours, if necessary, ranging from about 10 hours to about 24 hours, and if necessary, at least about 16 hours.

[0125] After drying, the conversion rate (or hydrolysis efficiency) can be calculated. For example, after drying, the cotton residue can be weighed at a time of 0 minutes to a time of ≥15 minutes. The conversion rate is then calculated based on the amount of cotton added and the weight of the residue at a time of ≥15 minutes. In one embodiment, HPLC and RIDA® Cube are analytical methods that can be used to measure the cellulose concentration in the solution to calculate the hydrolysis efficiency.

[0126] In another embodiment, the cellulose conversion efficiency is calculated. The amount of cellulose in the clothing is pre-determined by acid burn-off. HPLC is then performed to quantify the cellulose in the hydrolyzed sample. The determined cellulose is compared with the theoretical amount of cellulose in the sample based on the following equation: Cellulose conversion rate (%) = % cellulose converted to glucose / % initial cellulose in the system * 100 (1) Cellulose conversion rate (%) = (% glucose in HPLC) * 0.9 / [(% cotton in the initial system) * cellulose content in cotton] * 100 (2) in: % of cellulose converted to glucose = (% glucose in HPLC) * 0.9 (3) %Initial cellulose in the system = (%Initial cotton in the system) * Cellulose content in the cotton (4) * (4) *The cellulose content in cotton was determined by composite analysis using the TAPPI and NREL standard methods. Convert sugar into end products

[0127] Sugars produced by the methods described herein may undergo further biological processing (e.g., fermentation) to produce end products. For example, sugars produced by the methods described herein may be contacted with microorganisms during a fermentation process to produce end products. Sugars produced by the methods described herein may be contacted with enzymes or mixtures of enzymes during a fermentation process to produce end products. End products produced by fermentation may include, but are not limited to, alcohols, acids (including fatty acids), gases, amino acids, chemicals, and mixtures thereof.

[0128] The alcohols that can be produced include, but are not limited to, ethanol, butanol, methanol, propanol and mixtures thereof.

[0129] The acids that can be produced include, but are not limited to, 2,5-furandicarboxylic acid, itaconic acid, acetylpropionic acid, succinic acid, lactic acid, malic acid, citric acid, acrylic acid, fumaric acid, hydroxypropionic acid, acrylic acid, and mixtures thereof.

[0130] The chemicals that may be produced include, but are not limited to, glycerol, 3-hydropropionic acid, 2,5-dimethylfuran (DMF), 5-hydroxymethylfurfural (HMF), furfural, aldehydes, amines, terephthalic acid, hexamethylenediamine, isoprene, polyhydroxy fatty acid esters, 1,3-propanediol, or mixtures thereof.

[0131] The gases that may be produced include, but are not limited to, methane, ethane, CO, CO2, H2, or mixtures thereof. [Example] [Example] [1] Enzymatic hydrolysis of cotton fabrics [, , ]

[0132] The cotton fabric is cut, shredded, and then mechanically refined using a PFI refiner at 5,000, 10,000, or 20,000 rpm. Controls are used for non-refining. The pretreated cotton fabric then undergoes enzymatic hydrolysis at 50°C, pH 5.2, and an enzyme loading of up to 5 PFU / g cotton.

[0133] FPU is the standard method for expressing enzyme dosage and its ability to convert 50g of cellulose filter paper into 2.0 mg of glucose within 60 minutes. Adney, B. and Baker, J., "Measurements of Cellulase Activities", NREL Laboratory Technical Report NREL / TP-510-42628, 2008.

[0134] The inventors have observed a satisfactory improvement in the efficiency of cotton conversion (e.g., conversion to sugar fibers) with increased intensity of PFI pretreatment. Stronger PFI pretreatment results in shorter fiber lengths and a percentage increase in fineness by weight. The inventors found a 28% increase in yield compared to 60% of the 90% yield of PFI pretreatment at 10,000 rpm under unrefined (controlled) conditions. (Figure 2). This demonstrates that PFI pretreatment causes an unexpected improvement in cotton fabric hydrolysis. (See also Figures 3 through 6). Enzymatic hydrolysis experiments were performed with different residence times (24 hours, 48 ​​hours, and 96 hours). Under all conditions, mechanical PFI refining significantly improved cotton conversion.

[0135] Enzymatic hydrolysis experiments were performed at different enzyme concentrations, such as 4, 5, and 6 FPU / OD weights.

[0136] Enzymatic hydrolysis experiments were conducted at a cotton content of 5% (e.g., 5% uniformity or 5% (w / w) solids content).

[0137] All publications (e.g., non-patent documents), patents, patent application publications, and patent applications referred to in this specification indicate the skill level of those skilled in the art to which this invention relates. All such publications (e.g., non-patent documents), patents, patent application publications, and patent applications are incorporated herein by reference to the same extent, as each individual publication, patent, patent application publication, or patent application is specifically and individually indicated to be incorporated by application.

[0138] none

[0139] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A method for pretreating cotton-containing fabric material, the method comprising the steps of refining the cotton-containing fabric material in a PFI refiner at a speed between 2,000 and 20,000 revolutions, wherein the method does not include: a pretreatment step requiring neutralization due to the use of an acid or alkali, recovery of any solvent, or a rinsing step required for a pretreatment requiring the removal of components prior to hydrolysis and / or fermentation.

2. The method as described in claim 1, wherein the method further comprises a pretreatment comprising mechanical pretreatment, chemical enzyme pretreatment, or a combination thereof.

3. The method as described in claim 2, wherein the mechanical pretreatment is substantially free of the use of chemicals.

4. The method as described in claim 2, wherein the mechanically pretreated cotton fabric material contains between 1% and 50% fine particles by weight.

5. The method as described in claim 2, wherein the fiber length LWL (mm) of the cotton-containing fabric material undergoing mechanical pretreatment is between 0.1 mm and 2.00 mm.

6. The method as described in claim 2, wherein the Canadian Standard Freeness (CSF) of the cotton-containing fabric material undergoing mechanical pretreatment is between 100 and 900 CSF ml.

7. The method as described in claim 2, wherein the cotton-containing fabric material undergoing mechanical pretreatment is in the form of a powder.

8. The method as described in claim 2, wherein a Willy grinder is used for a cutting step.

9. The method as described in claim 2, wherein the mechanical pretreatment is performed before the decolorization of the cotton-containing fabric material.

10. The method as claimed in claim 1, wherein the method further comprises the steps of: shredding the cotton-containing fabric, cutting the cotton-containing fabric, and pulping the cotton-containing fabric before refining it in the PFI refiner.

11. The method as described in claim 1, wherein a solvent is added to the cotton-containing fabric material before refining in the PFI refiner, during refining in the PFI refiner, or both before and during refining in the PFI refiner.

12. The method as described in claim 11, wherein the solvent is water.

13. The method as claimed in claim 1, wherein the method further comprises the step of: enzymatically hydrolyzing the pretreated cotton-containing fabric material to produce a hydrolysate.

14. The method as described in claim 1, wherein the method further comprises the step of: decolorizing the cotton-containing fabric material.

15. The method as described in claim 14, wherein the decolorization step includes a bleaching step.

16. The method as described in claim 1, wherein the method further comprises the step of adding Cu2+.

17. The method as described in Request 1, wherein the method further comprises the step of adding Fe2+.

18. The method as claimed in claim 1, wherein the method further comprises the step of: subjecting the pretreated cotton-containing fabric material to hydrolysis to produce a hydrolysate.

19. The method as described in claim 18, wherein the hydrolysis comprises enzymatic hydrolysis, the enzymatic hydrolysis comprising the addition of at least one hydrolytic enzyme.

20. The method as described in claim 19, wherein the enzymatic hydrolysis comprises adding a combination of a cellulase and a β-glucosidase.

21. The method as described in claim 18, wherein the method further comprises the step of subjecting the hydrolysate to fermentation to produce a terminal product.

22. The method as described in claim 21, wherein the end product produced by the fermentation step comprises alcohols, sugar alcohols, acids, fatty acids, gases, amino acids, chemicals, and mixtures thereof.

23. The method as described in claim 1, wherein the method does not include a step requiring the use of an acid.

24. The method as described in claim 1, wherein the cotton-containing fabric material comprises cotton, cotton blend garments, cotton-polyester blend garments, or mixtures thereof.

25. A method for processing cotton-containing fabric material, the method comprising the steps of: (a) shredding the cotton-containing fabric material; (b) cutting the cotton-containing fabric material; (c) pulping the cotton-containing fabric material; (d) refining the cotton-containing fabric material in a PFI refiner at a speed between 2,000 and 20,000 revolutions; and (e) subjecting the cotton-containing fabric material to hydrolysis to produce a hydrolysate, wherein the method does not include: a pretreatment step requiring neutralization due to the use of an acid or alkali, recovery of any solvent, or a rinsing step required for a pretreatment requiring removal of components prior to hydrolysis and / or fermentation.

26. The method as described in claim 25, wherein the cotton-containing fabric material comprises cotton, cotton blend garments, cotton-polyester blend garments, or mixtures thereof.

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