Pretreatment method for cotton textile waste fibers.

Abstract

A mechanical and decolorizing pretreatment of cotton-containing textiles (such as "waste" feedstock in terms of end-of-life textiles) is disclosed that can be used to produce sugars without the use of harsh pretreatment conditions.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This is an international application under the Patent Cooperation Treaty, which claims priority to U.S. Provisional Patent Application No. 63 / 287,355, filed December 8, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] The present disclosure relates to a process for producing sugars from cotton-containing textiles. [Background technology]

[0003] The U.S. Environmental Protection Agency (EPA) estimates that 3.2 million tons of textile waste and landfill waste were incinerated in the United States in 2018, and landfills received 11.3 million tons of textile waste. EPA “Textiles: Material-Specific Data” EPA Website (2021). If disposed of in landfills, these textiles contribute to the release of greenhouse gases (e.g., methane) as they decompose. Furthermore, the decomposition process of synthetic fibers (e.g., polyester) can take hundreds of years. If textile waste is incinerated, toxic gases can be released, especially from more complex blends. BBC Website “Why Clothes are so hard to recycle.” (July 12, 2020).

[0004] Textile waste accounts for 3% of the global waste market share. 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. It is the 10th most generated waste after food, paper, plastic, and glass waste. The decomposition time of cotton fabric is approximately 50-77% in 90 days. Li, Frey, and Browning, “Biodegradability study on cotton and polyester fabrics,” J. Eng. Fiber. Fabr., vol. 5, no. 4, pp. 42-53, 2010.

[0005] There is a need in the art for methods to process textile waste into sugars and other value-added products. Summary of the Invention

[0006] In one embodiment, the method of pretreating a cotton-containing textile material may include refining the cotton-containing textile material in a PFI mill for about 2,000 to 20,000 revolutions.

[0007] In one embodiment, a method of pretreating a cotton-containing textile material may include bleaching the cotton-containing textile material and refining the cotton-containing textile material in a PFI mill for about 2,000 to 20,000 revolutions.

[0008] The method may further include additional pretreatment. The additional pretreatment may include mechanical, chemical, enzymatic pretreatment, or a combination thereof. The method may further include shredding the cotton-containing textile material, cutting the cotton-containing textile material, and grinding the cotton-containing textile material prior to refining the cotton-containing textile material in the PFI mill.

[0009] In one embodiment, a method of treating a cotton-containing textile material may include (a) shredding the cotton-containing textile material, (b) cutting the cotton-containing textile material, (c) grinding the cotton-containing textile material, (d) refining the cotton-containing textile material in a PFI mill for about 2,000 to 20,000 revolutions, and (e) subjecting the pretreated cotton-containing textile material to hydrolysis to produce a hydrolysate. In one embodiment, the method may further include decolorizing the cotton-containing textile material after cutting and grinding but prior to refining.

[0010] In one embodiment, a method of treating a cotton-containing textile material may include (a) shredding the cotton-containing textile material; (b) cutting the cotton-containing textile material; (c) grinding the cotton-containing textile material; (d) decolorizing the cotton-containing textile material; (e) refining the cotton-containing textile material in a PFI mill for about 2,000 to 20,000 revolutions; and (f) subjecting the pretreated cotton-containing textile material to hydrolysis to produce a hydrolysate.

[0011] In one embodiment, the decolorizing step may include bleaching. Bleaching may include treatment with ozone, sodium hypochlorite, hydrogen peroxide, Fenton's reagent, or combinations thereof. The hydrogen peroxide may range from about 1.0% to about 8.0% (w / w). The hydrogen peroxide may range from about 2.0% to 6.0%, 4.0% to 8.0%, 5.0% to 7% (w / w).

[0012] In one embodiment, bleaching may further include 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).

[0013] In one embodiment, the method comprises: 2+ The method may further include adding Cu. 2+may be added in the range of 100 ppm to 250 ppm. The range may be about 120 ppm to 170 ppm. The amount may 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, 1 ppm, 130ppm, 131ppm, 132ppm, 133ppm, 134ppm, 135ppm, 136ppm, 137ppm, 138ppm, 139ppm, 140ppm, 141ppm, 142ppm, 143ppm, 144 ppm, 145ppm, 146ppm, 147ppm, 148ppm, 149ppm, 150ppm, 151ppm, 152ppm, 153ppm, 154ppm, 155ppm, 156ppm, 157ppm, 158ppm, 159p pm, 160ppm, 161ppm, 162ppm, 163ppm, 164ppm, 165ppm, 166ppm, 167ppm, 168ppm, 169ppm, 170ppm, 171ppm, 172ppm, 173ppm, 174p pm, 175ppm, 176ppm, 177pm, 178ppm, 179ppm, 180ppm, 181ppm, 182ppm, 183ppm, 184ppm, 185ppm, 186ppm, 187ppm, 188ppm, 189ppm , 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] In one embodiment, the method comprises: 2+ The method may further include adding Fe. 2+may be added in the range of 100 ppm to 250 ppm. The range may be about 120 ppm to 170 ppm. The amount may 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, 1 ppm, 130ppm, 131ppm, 132ppm, 133ppm, 134ppm, 135ppm, 136ppm, 137ppm, 138ppm, 139ppm, 140ppm, 141ppm, 142ppm, 143ppm, 144 ppm, 145ppm, 146ppm, 147ppm, 148ppm, 149ppm, 150ppm, 151ppm, 152ppm, 153ppm, 154ppm, 155ppm, 156ppm, 157ppm, 158ppm, 159p pm, 160ppm, 161ppm, 162ppm, 163ppm, 164ppm, 165ppm, 166ppm, 167ppm, 168ppm, 169ppm, 170ppm, 171ppm, 172ppm, 173ppm, 174p pm, 175ppm, 176ppm, 177pm, 178ppm, 179ppm, 180ppm, 181ppm, 182ppm, 183ppm, 184ppm, 185ppm, 186ppm, 187ppm, 188ppm, 189ppm , 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.

[0015] In one embodiment, bleaching may be carried out at a temperature range of 60° C. to 120° C. The temperature may range from about 80° C. to 100° C. Bleaching may be carried out at a temperature of about 100° C. to 110° C., 90° C. to 100° C., 90° C. to 110° C., or 95° C. to 120° C. The temperature may be about 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, 116°C, 117°C, 118°C, 119°C, or 120°C.

[0016] In one embodiment, bleaching may occur for a period of time ranging from 60 minutes to 120 minutes. The period of time may range from about 80 minutes to 110 minutes. The period of time may range from about 80 minutes to 90 minutes, 90 minutes to 100 minutes, 95 minutes to 120 minutes, or 110 minutes to 120 minutes. The time may be about 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.

[0017] In one embodiment, bleaching may be performed at a pH between about pH 7 and pH 11. Bleaching may be performed at a pH greater than pH 10. Bleaching may be performed at about pH 11. Bleaching may be performed at about pH 11.5. Bleaching may be performed at about pH 11.75. Bleaching may be performed at about pH 12.

[0018] In one embodiment, a solvent may be added to the cotton-containing textile material prior to refining in the PFI mill. The solvent may be water.

[0019] In one embodiment, the method may further comprise enzymatic hydrolysis of the pretreated cotton-containing textile material to produce a hydrolysate.

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

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

[0022] In one embodiment, the method may further include bleaching the cotton-containing textile material.

[0023] In one embodiment, mechanical pretreatment may include chopping, cutting, grinding, refining, and combinations thereof.

[0024] In one embodiment, the method may further include adding a solvent to the cotton-containing textile material during the mechanical pretreatment. The solvent may be water. The solvent may be added before refining, during refining, or both before and during refining. The solvent may be added in an amount of about 1:0.01 to 1:30 weight to weight of mechanically pretreated cotton-containing textile:solvent. The amount of solvent added to the cotton-containing textile may be about 1:0.1 to 1:20, 1:0.1 to 1:10, 1:0.1 to 1:5, or 1:0.1 to 1:0.5 weight to weight of mechanically pretreated cotton-containing textile:solvent. The amount of solvent added to the cotton-containing fabric may be about 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 weight to weight of mechanically pretreated cotton-containing fabric:solvent. The amount of solvent added to the cotton-containing fabric may be 1:0.2 weight to weight of mechanically pretreated cotton-containing fabric:solvent.

[0025] In one embodiment, the mechanical pretreatment may be performed at a temperature of about 0° C. to 50° C. The mechanical pretreatment may be performed at a temperature of about 10° C. to 40° C. The mechanical pretreatment may be performed at a temperature of about 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. The mechanical pretreatment may be performed at a temperature of about 25° C.

[0026] In one embodiment, the mechanically pretreated cotton-containing textile material may comprise about 1% to 50% by weight of fines. The mechanically pretreated cotton-containing textile material may comprise about 1% to 20% by weight of fines, 25% to 50% by weight of fines, 10% to 30% by weight of fines, 30% to 50% by weight of fines, or 15% to 35% by weight of fines. The mechanically pretreated cotton-containing textile material may contain 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% fines.

[0027] In one embodiment, the fiber length LWL (mm) of the mechanically pretreated cotton-containing textile material may be about 0.1 mm to 2.00 mm. The fiber length LWL (mm) of the mechanically pretreated cotton-containing textile material may be 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.

[0028] In one embodiment, the level of purification may be about 2,000-20,000 PFI rotations. The level of purification may be about 2,000-10,000 PFI rotations, 5,000-15,000 PFI rotations, 5,000-20,000 PFI rotations, or 10,000-20,000 PFI rotations. The level of purification may be about 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 rotations.

[0029] In one embodiment, the Canadian Standard Freeness (CSF) of the mechanically pretreated cotton-containing textile material may be between about 100 and 900 CSF milliliters. The Canadian Standard Freeness (CSF) of the mechanically pretreated cotton-containing textile material may be between about 100 and 900 CSF milliliters, between 200 and 400 CSF milliliters, between 400 and 600 CSF milliliters. The level of refinement may be between about 100 and 900 CSF milliliters.

[0030] In one embodiment, the mechanically pretreated cotton-containing fabric may be in the form of a powder, the powder having an average particle size of about 0.10 mm to about 2.0 mm.

[0031] In one embodiment, a Wiley Mill may be used for the cutting process.

[0032] In one embodiment, a mechanical pretreatment may be carried out prior to bleaching of the cotton textile material.

[0033] In one embodiment, the hydrolysis may comprise enzymatic hydrolysis comprising the addition of at least one hydrolytic enzyme.

[0034] In one embodiment, the enzymatic hydrolysis may include an additional combination of cellulase and β-glucosidase.

[0035] In one embodiment, the hydrolysate may comprise sugars, which may be glucans, xylans, arabinans, mannans, galactans, glucose, sucrose, hexoses, or combinations thereof.

[0036] In one embodiment, the enzymatic hydrolysis may be carried out at a temperature of about 20° C. to 75° C. The enzymatic hydrolysis may be carried out at a temperature of about 40° C. to 75° C., about 45° C. to 75° C., 50° C. to 75° C., about 55° C. to 75° C., 60° C. to 75° C., or about 65° C. to 75° C. The enzymatic hydrolysis may 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.

[0037] In one embodiment, the enzymatic hydrolysis may be carried out at a pH of about pH=4.5 to pH=8.5. The enzymatic hydrolysis may be carried out at a pH of 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.

[0038] In one embodiment, the enzymatic hydrolysis may be carried out for about 1 hour to 300 hours. The enzymatic hydrolysis may be carried out for about 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. The enzymatic hydrolysis may be carried out for about 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. The enzymatic hydrolysis may be carried out for about 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, 180, or 192 hours.

[0039] In one embodiment, the amount of enzyme used in the enzymatic hydrolysis may be about 1 FPU to 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.

[0040] In one embodiment, the amount of enzyme used in the enzymatic hydrolysis may be about 0.01% to 10% enzyme / ingredient (w / w), optionally about 0.02% to 0.05% enzyme / cotton (w / w).

[0041] In one embodiment, the enzymatic hydrolysis efficiency may be at least 50%, at least 60%, at least 65%, or at least 70%.

[0042] In one embodiment, the 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.

[0043] In one embodiment, the method may further include filtering the hydrolysis product to produce a permeate and a retentate, where the permeate may comprise the hydrolysate and the retentate may comprise the residue.

[0044] In one embodiment, the method may further comprise subjecting the hydrolysate to fermentation, oxidation, reduction, or hydrogenation to produce an end product.

[0045] In one embodiment, the method may further comprise subjecting the hydrolysate to fermentation.

[0046] In one embodiment, the end products produced by fermentation include alcohols, sugar alcohols, acids, fatty acids, gases, amino acids, chemicals, and mixtures thereof. The sugar alcohols may include sorbitol, xylitol, ethylene glycol, glycerol, erythritol, threitol, arabitol, ribitol, mannitol, galactitol, fucitol, iditol, inositol, volemitol, isomalt, lactitol, and mixtures thereof. The alcohols may include ethanol, butanol, methanol, propanol, and mixtures thereof. The acids may include 2,5-furandicarboxylic acid, itaconic acid, levulinic acid, succinic acid, lactic acid, malic acid, citric acid, acrylic acid, fumaric acid, hydroxypropionic acid, acrylic acid, and mixtures thereof. The 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 gases may include methane, ethane, CO, CO2, and H2, or mixtures thereof.

[0047] In one embodiment, the enzymatic hydrolysis and fermentation may occur simultaneously.

[0048] In one embodiment, the enzymatic hydrolysis and fermentation may be carried out separately.

[0049] In one embodiment, the method may not include pretreatment steps requiring neutralization from the use of acid or base, recovery of any solvents, or rinsing steps required from pretreatment requiring removal of components prior to hydrolysis and / or fermentation.

[0050] In one embodiment, the method may not include a step that requires the use of an acid.

[0051] In one embodiment, the mechanical pretreatment may be substantially free of the use of chemicals.

[0052] In one embodiment, a system for producing sugars from cotton-containing textile materials may include a shredding means, a cutting means, a grinding means, a refining means, and an enzymatic hydrolysis reactor, all mechanically coupled together in series. [Brief description of the drawings]

[0053] [Figure 1] Figure 1 shows cotton fibers after mechanical refining: (A) chopped, (B) Wiley Mill, (C) PFI 2500 rpm, (D) PFI 5,000 rpm, (E) PFI 10,000 rpm, and (F) PFI 20,000 rpm. Fiber length LWL (mm) and percentage of weighted fiber fines are included below. [Diagram 2] Figure 2 shows the enzymatic hydrolysis (50°C, pH=5.2, 6 FPU) of cotton textile waste for 96 and 192 hours compared to no refining. Cotton conversion (%) is shown on the left x-axis and the percentage of fines on the right x-axis. The level of refining in PFI was measured in (turns). Finally, the energy consumption per ton of cotton corresponding to each level of refining is shown at the bottom. For example, 900 KWh is required to refine 1 ton of cotton with 5,000 PFI turns. [Diagram 3] Figure 3 shows the cotton conversion (%) as a function of purification, as measured by PFI rotation. Enzymatic hydrolysis was carried out at 50°C, pH = 5.2, 5 FPU for 48, 72, 96, or 192 hours. The efficiency of cotton conversion, measured in percent (%) based on the initial mass of cotton, increased with increasing PFI rotation. [Figure 4] Figure 4 shows the cotton conversion (%) as a function of purification, measured by reaction time. The enzymatic hydrolysis was carried out at 50°C, pH = 5.2, and 5 FPU. The efficiency of cotton conversion, measured in percent (%) based on the initial mass of cotton, increased with increasing reaction time. [Diagram 5]Figure 5 shows cotton conversion (%) as a function of purification, as measured by PFI turnover. Enzymatic hydrolysis was carried out at 50°C, pH = 5.2, with 5 FPU (4.4% g enzyme / gOD cotton) or 6 FPU (5.1% g enzyme / gOD cotton) for 96 hours. Experiments were performed in duplicate. The efficiency of cotton conversion, measured in percent (%) based on the initial mass of cotton, increased with increasing PFI turnover, with 6 FPU producing approximately 6% more cotton conversion than 5 FPU. [Figure 6] Figure 6 shows cotton conversion (%) as a function of purification, as measured by PFI turnover. Enzymatic hydrolysis was carried out at 50°C, pH = 5.2, with 5 FPU (4.4% g enzyme / gOD cotton) or 6 FPU (5.1% g enzyme / gOD cotton) for 192 hours. Experiments were performed in duplicate. The efficiency of cotton conversion, measured in percent (%) based on the initial mass of cotton, increased with increasing PFI turnover. Both reactions carried out with 5 or 6 FPU reached 92% cotton conversion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] The disclosed process, which includes mechanical pretreatment with a PFI mill to refine the cotton-containing fabric, obtains high sugar yields from the cotton-containing fabric.

[0055] Cotton textile waste from textiles has been found to be a promising biomass for the production of bioethanol as a renewable fuel source. According to the present disclosure, cotton textiles (such as "trash" feedstock in terms of end-of-life cotton textiles) can be used to produce sugars without the same type of harsh pretreatment used for other biomass such as corn, grass feedstocks, or wood. Cotton is known to have a high degree of crystallinity (compared to such other biomass), which makes it very difficult to obtain very high yields of sugars from cotton. The inventors have surprisingly discovered that, despite having a higher degree of crystallinity, cotton in the form of cotton textiles can be used to obtain high yields of sugars using the methods described herein.

[0056] The methods described herein provide more efficient pretreatment of waste-containing cotton fabrics, with the cotton fibers produced by the pretreatment having shorter fiber lengths, a greater weight percent of fines, and more disrupted cellulosic fibers, leading to unexpected improvements in the processing of the waste-containing pretreated cotton fabrics into sugars and downstream processing into chemicals.

[0057] definition Below, definitions are provided of some of the terms frequently used herein to characterize the present invention. These terms have, in each instance of their use, their respective defined and preferred meanings in the remainder of the specification.

[0058] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the content clearly dictates otherwise.

[0059] As used herein, "fines" refers broadly to fibers small enough to pass through a mesh screen having a perforation diameter of 76 μm and also contribute to the final properties of the product. Fischer et al. "Pulp Fines - Characterization, Sheet Formation, and Comparison to Microfibrillated Cellulose" Polymers 9(366): 2017.

[0060] As used herein, "fiber length LWL" refers broadly to pulp terms related to the average length-weighted 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.

[0061] As used herein, "filter paper cellulase activity (FPU)" refers broadly to the amount of enzyme that will produce 2.0 mg of released sugars from 50 mg of filter paper (Whatman No. 1) within 1 hour.

[0062] As used herein, "cotton-containing fabric" refers broadly to any fabric that contains cotton fibers.

[0063] As used herein, "woven cotton" or "recycled woven cotton" refers broadly to collected raw materials (e.g., clothing at the end of its useful life, fabric offcuts from the clothing industry, lint) that are waste and whose cotton content is essentially composed of greater than 90% cellulose (which can be converted to sugars).

[0064] As used herein, "Canadian Standard Freeness (CSF)" refers broadly to cotton-containing textile materials that have been mechanically pretreated. Canadian Standard Freeness (CSF) is directly related to the intensity of mechanical refining. It provides a measure of the rate at which a dilute suspension of pulp (e.g., cotton fibers) is dewatered under specific conditions. The rate of dewatering varies inversely with the level of refining.

[0065] Textile Waste and Processing Current methods for converting cellulosic textile waste into bio-based building blocks are few and are based on acid or alkaline chemical use with yields of 40-90% under very aggressive conditions (high chemical charge). These proposed routes are capital investment intensive and involve high conversion costs mainly related to high chemical use, and subsequent problems related to chemical recovery, resulting in 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 feasible bio-based building blocks could represent an important contribution to the cotton and recycling waste business. Abbati De Assis et al., “Risk management consideration in the bioeconomy,” Biofuels, Bioprod. Biorefining (2017)11: 549-566.

[0066] Cotton has not been considered a high-value biomass feedstock due to the intense pre-processing required to obtain sugars from cotton biomass (e.g., plants, petioles, cotton weaving waste). In addition, cotton typically has a higher degree of crystallinity than other sources of cellulose, making bioconversion even more difficult. OJ Rojas, Cellulose Chemistry and Properties : Fibers, Nanocelluloses and Advanced Materials. 2016. However, cotton in the form of textiles is already processed to 90%+ pure cellulose (and subsequently glucose) and is essentially a free feedstock for bioprocessing at the end of the consumer product's life. In addition to the economic benefits, environmental benefits are obtained when utilizing end-of-life cotton clothing instead of cultivated biomass for use as a feedstock.

[0067] For the production of sugars from cotton fabric, the use of exotic solvents, high levels of acid, or high levels of caustic at low temperatures presents a barrier to commercialization. These processes are not commercially viable due to the cost and additional materials required to neutralize the high levels of acid or caustic, the cost of the solvent plus recovery and recycling of the solvent, and maintaining temperatures near freezing for the caustic. In addition to neutralizing the acid or caustic, the neutralized components require additional rinsing.

[0068] Cellulose has been used as a feedstock for ethanol and glucose production via enzymatic hydrolysis and fermentation. Different pretreatment methods have been used to hinder the action of hemicellulose and lignin on enzymatic hydrolysis and thus make the cellulose available to enzymes. In the case of cotton textile waste, the cellulose is more available for enzymatic hydrolysis because the content of hemicellulose and lignin residues is very low. Therefore, other issues (e.g., cellulose crystallinity, degree of polymerization and fiber size, as well as porosity) must be addressed to increase the yield of glucose and ethanol production.

[0069] Enzymatic hydrolysis processes have been used to break down cellulose into glucose. However, in cotton textile waste, unless the fibers are subjected to some form of pretreatment, the conversion of cellulose to glucose is slow due to the high degree of crystallinity and small pore size, which creates challenges in the availability of cellulose molecules to react with enzymes. Chandra et al., “Substrate pretreatment: The key to effective enzymatic hydrolysis of lignocellulosics?,” Adv. Biochem. Eng. Biotechnol.(2007) 108: 67-93. The availability of cellulose for enzymatic hydrolysis of cotton waste material is a factor that increases the yield of glucose and ethanol production. The physicochemical properties that affect the yield of glucose in the enzymatic hydrolysis of cellulose include the specific surface area and the cellulose crystallinity and degree of polymerization.

[0070] The methods described herein efficiently break down cellulose structure, allowing access for enzymes during cellulose hydrolysis (saccharification) to produce sugars (e.g., glucose). No harsh pretreatment is required. The inventors have found that treating unrefined cotton-containing textiles results in low cellulose conversion. The mechanical refining methods described herein result in delamination, and microfibrillation of cotton fibers in a PFI mill at 5,000 rpm results in greater cellulose conversion, without the use of any chemicals. For example, using a PFI mill at 10,000 rpm resulted in 84% conversion using (5 FPU of enzyme) and 90% conversion using (6 FPU of enzyme). [Units of filter paper cellulase activity].

[0071] cotton-containing fabric Cellulose is a natural polymer consisting of linear chains of hundreds to thousands of D-glucose units linked by β-(1,4)-glycosidic bonds. The cellulose content varies depending on the biomass source. Among the natural fibers containing cellulose, cotton is the biomass that contains the highest percentage of cellulose, and its lignin content is almost zero, which offers advantages in processing. Bajpai, “Pretreatment of Lignocellulosic Biomass,” Springer, Singapore, (2016) pages 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.

[0072] Cotton fibers have a primary wall, a secondary wall, and a central core or lumen. The width of a cotton fiber varies between 12-20 μm in width. The average degree of polymerization of cotton ranges from 9,000-15,000 and the average crystallinity is 73, both of these values ​​are very high compared to other lignocellulosic materials such as wood pulp (DP=600-1,500 and crystallinity=35) and viscose rayon (DP=250-450 and crystallinity=60). OJ Rojas, Cellulose Chemistry and Properties: Fibers, Nanocelluloses and Advanced Materials. 2016.

[0073] The typical composition of raw cotton fiber is shown in Table 1. Cotton contains approximately 90% or more cellulose. The non-cellulosic components of cotton include proteins, amino acids, and nitrogen-containing compounds, which are primarily found in the epidermis and lumen. [Table 1] Heinze et al, Cellulose Chemistry and Properties : Fibers , Nanocelluloses and Advanced Materials, vol. 271. Springer International Publishing, 2016.

[0074] The cotton-containing fabrics treated by the methods described herein can include any cotton, cotton blend garments, including but not limited to cotton-polyester blend garments, or mixtures thereof.

[0075] Mechanical Pretreatment Mechanical pretreatment of cotton-containing textiles may include mechanical processes to break down the cotton-containing textiles, including but not limited to grinding, shredding, cutting, milling, refining, shearing, or garnetting. Mechanical pretreatment effectively physically breaks down the textile into smaller components, increases the surface area of ​​the textile components, reduces the crystallinity of the textile, or a combination thereof, aiding in subsequent hydrolysis.

[0076] Commonly used equipment for fiber size reduction includes mills, extruders, and fibrillators. The effectiveness of mechanical treatment is achieved mainly due to the high shear forces generated in the grinding and milling process. Different size fiber fractions accumulate in the largest particles (>0.1-2 mm), while fines increase with the intensity of shear stress during processing. Disc milling, which produces more microfibrillation and delamination of fibers, has proven to be more effective in enhancing cellulose hydrolysis than hammer milling. Grinding, crushing, and refining require high energy inputs, which are costly and detrimental to widespread applications. Hendriks and G. Zeeman, “Pretreatments to enhance the digestibility of lignocellulosic biomass,” Bioresour. Technol., vol. 100, no. 1, pp. 10-18, Jan. 2009.

[0077] Mechanical refining action consists of three mechanisms that change fiber structure and morphology: shearing (reduction in fiber length), shearing (fibrillation of the fiber surface), and compression (delamination of the fiber layers). The mechanisms occur simultaneously but at different relative levels depending on the refining technique.

[0078] The reduction in fiber length occurs due to the cutting action of the refiner plate as the two refining bars pass each other. Microfibrillation is generally an external effect, involving the peeling off of smaller fiber fragments from the main fiber mass due to shear forces. Finally, delamination is generally an internal effect resulting from the repeated compression and decompression of the fibers as they are squeezed between the bars and grooves of the refiner plate. The level of refining can be about 5,000 to 20,000 PFI revolutions.

[0079] The effect of mechanical refining on fiber properties may maximize fiber responsiveness to enzymatic hydrolysis with lower energy consumption. Microscopic image analysis shows that refining induces cell separation, surface fibrillation, internal delamination, and the generation of fines. Collectively, these changes may contribute to an increase in accessible surface area and higher yields of enzymatic hydrolysis of cellulose (10-30% increase in conversion).

[0080] Mechanical pretreatment may include disrupting the cotton-containing textile material by shredding, cutting, grinding, and then refining. Exemplary equipment includes ball mills or PFI mills for grinding, Wiley Mills for cutting, and refiners such as PFI refiners, single disc refiners, double disc refiners, and twin disc refiners.

[0081] A preferred mechanical pretreatment method involves refining in a PFI mill, optionally at about 5,000 to 20,000 PFI revolutions. The inventors have surprisingly discovered that the use of a PFI mill to refine cotton-containing textiles produces pretreated materials containing finer, smaller, more disrupted cellulose, resulting in unexpected improvements in results. For example, cotton-containing textiles may be milled in a PFI mill at about 5,000 PFI revolutions, 6,000 revolutions, 7,000 revolutions, 8,000 revolutions, 9,000 revolutions, 10,000 revolutions, 11,000 revolutions, 12,000 revolutions, 13,000 revolutions, 14,000 revolutions, 15,000 revolutions, 16,000 revolutions, 17,000 revolutions, 18,000 revolutions, 19,000 revolutions, or 20,000 revolutions. The cotton-containing fabric may be milled in a PFI mill at about 5,000 PFI rpm to 20,000 rpm, 5,000 rpm to 10,000 rpm, 7,500 rpm to 15,000 rpm, 7,000 rpm to 10,000 rpm, 10,000 rpm to 20,000 rpm, 15,000 rpm to 20,000 rpm, or 17,500 rpm to 20,000 rpm.

[0082] The PFI mill is a machine developed by Papirindustriens Forskningsinstitut-The Norwegian Pulp and Paper Research Institute. It is known in the art as the PFI mill. The PFI mill is a beater characterized by high reproducibility and is used to study the relationship between the beating degree of pulp and its physical properties. This machine may be used in the preparation stage of papermaking. Beating mechanism: a constant load is applied to the pulp circulating between a stainless steel roll and a cylindrical mill house, rotating with a constant difference in circumferential speed, applying mechanical effects such as shear and compression, thereby performing beating by frictional forces between the fibers. The number of revolutions is read on a counter. Beating degree is evaluated with a freeness tester. The results of refining are measured, compared and standardized by a property related to dewatering, also known as freeness, for which a quantitative measure is used, in particular the Canadian Standard Freeness. See description number 0027. See also TAPPI (2000) Laboratory Beating of Pulp (PFI Mill Method). T 248 sp-00.

[0083] Mechanical pretreatment, including grinding in a PFI mill, refines the cotton-containing fabric and opens up the cotton fibers, allowing better access to the enzymes during hydrolysis. In addition, the inventors used HPLC analysis to provide better analysis of the results and to better develop the method.

[0084] The mechanical pretreatment may include grinding the cotton-containing fabric into a powder, optionally using a PFI mill, the powder having an average particle size of about 0.10 mm to about 2.0 mm. The average particle size of the powder may be about 0.15 mm to about 1.60 mm. The average particle size of the powder may be about 0.20 mm to about 1.5 mm. The average particle size of the powder may be less than about 2.0 mm. The average particle size of the powder may be less than about 1.70 mm. For example, the average particle size of the powder 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.

[0085] The inventors have discovered that the mechanical refining action of the PFI mill has resulted in unexpected improvements in the pretreatment of cotton-containing textiles. The PFI mechanical refining action consists of three mechanisms that significantly alter fiber structure and morphology: shearing (reduction in fiber length), shearing (fibrillation of the fiber surface), and compression (delamination of fiber layers). These mechanisms occur simultaneously but at different relative levels depending on the refining technology. Chen et al. (2013) Bioresour.Technol. 147: 401-408; Park et al. (2016) Bioresour.Technol. 199: 59-67. Fiber length reduction occurs due to the shearing action of the refiner plates as the two refiner bars pass each other. Excessive fiber shearing results in the generation of fines. Microfibrillation is generally an external effect, involving the detachment of smaller fiber fragments from the main fiber mass due to shear forces. Finally, delamination is generally an internal effect resulting from repeated compression and decompression of the fibers as they are squeezed between the bars and grooves of the refiner plates. Corbett et al. (2020) Biotechnol. Bioeng. 117: 924-932; De Assis et al. (2018) Biotechnol. Biofuels 11. The forces involved in mechanical refining are described, for example, by Gharehkani et al. (2015) Carbohydr. Polym. 115: 785-803.

[0086] The method of the present disclosure may also be used on cotton-containing fabrics that have already been mechanically pretreated. The cotton-containing fabric may be ground, chopped, cut, sheared, garnetted, or a combination thereof. The cotton-containing fabric may be in the form of a powder.

[0087] The mechanical pretreatment may further include adding a solvent to the cotton-containing fabric before, during, or both before and during the pretreatment. The solvent may be water. The amount of solvent added to the cotton-containing fabric may be about 1:0.01 to 1:30 weight / weight ratio with the mechanically pretreated 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 about 1:0.1 to 1:20, 1:0.1 to 1:10, 1:0.1 to 1:5, or 1:0.1 to 1:0.5. The amount of solvent added to the cotton-containing fabric may be about 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, a PFI may be run at about 5% solids (w / w) and 95% water (w / w), which may be expressed as 1:20 fabric:solvent (water).

[0088] The mechanical pretreatment may be carried out at a temperature of about 0°C to 100°C.

[0089] The inventors have surprisingly discovered that in the pretreatment of cotton-containing fabrics, it is not necessary to use chemicals to achieve very high cotton conversion rates. For example, previous studies have used caustic chemicals, high heat consumption and enzyme consumption to achieve cotton conversion. [Table 2]

[0090] In summary, previous studies have relied on high temperatures, large amounts of enzymes, harsh chemicals, and mixtures thereof to achieve cotton conversion. In contrast, the methods described herein do not rely on high temperatures, large amounts of enzymes, harsh chemicals, and mixtures thereof to achieve cotton conversion. For example, the inventors obtained 84% conversion or 90% conversion, respectively, following grinding in a Wiley mill, purification in a PFI mill at 10,000 rpm, and hydrolysis for 96 hours with 5 FPU or 6 FPU. (5FPU = 4.4% g enzyme / g cotton and 6FPU = 5.1% g enzyme / g cotton).

[0091] For example, cotton-containing textiles may be shredded, cut, and ground, then water is added and refined in a PFI mill at about 5,000 to 20,000 rpm. Following this, the pretreated cotton-containing textile material is subjected to hydrolysis using, for example, either 5FPU or 6FPU. This results in greater than 80% conversion of the cotton fibers, and the only chemicals used are acetic acid or citric acid during the enzymatic hydrolysis step for pH control. No chemicals are used in the mechanical pretreatment step. The only solvent used in the mechanical pretreatment step is water.

[0092] bleaching If the cotton-containing fabric is a color other than bleached cotton, dyed or printed, or has finishes applied to it, such as, but not limited to, softeners, durable press resins, moisture / moisture resistant finishes, scratch resistant finishes, antibacterial finishes, or flame retardant finishes, the enzymatic hydrolysis performance is reduced. See Buschle-Diller & Traore (1998). Influence of direct and reactive dyes on the enzymatic hydrolysis of cotton. Textile Research Journal, 68(3), 185-192.

[0093] The cotton-containing textile may then be decolorized to remove dyes or finishes prior to pretreatment, hydrolysis, and / or saccharification. Dyed or finished cotton-containing textile may be subjected to a decolorization process to remove dyes and or finishes that may interfere with enzymatic hydrolysis. The inventors have surprisingly discovered that the decolorization methods described herein allow for decolorization without downstream interference with the enzymes used for hydrolysis and saccharification. For example, decolorization using the methods described herein increased yields from about 40% to about 80% to 90%. For example, cotton-containing textile may be decolorized after cutting and grinding but before mechanical refining.

[0094] The bleaching treatment may include removing all or a portion of the dye or exposing the cellulose of the cotton-containing fabric to a hydrolyzing material. The bleaching method may include using at least one bleaching compound. The bleaching compound may be ozone, sodium hypochlorite, hydrogen peroxide, Fenton's reagent, or a combination thereof.

[0095] The bleaching compound may be hydrogen peroxide. The cotton-containing material may be bleached with hydrogen peroxide in the range of about 1.0% to about 8.0%, optionally in the range of about 2.0% to 6.0%. The hydrogen peroxide may be combined with sodium hydroxide, which may be in the range of 1.0% to about 6.0%, optionally in the range of 2.0% to 4.0%. The hydrogen and sodium peroxide may be combined with sodium hydroxide in the range of 100 ppm to 250 ppm, optionally in the range of 120 ppm to 170 ppm Fe. 2+ and Cu 2+ In the process, the cotton content, measured by percentage (%) from the total mixture, can range from 1% to 20%.

[0096] The bleaching temperature is preferably in the range of 60° C. to 120° C., optionally in the range of 80° C. to 100° C., for a time in the range of 60 minutes to 120 minutes, optionally in the range of 80 minutes to 110 minutes, and at a pH range preferably above 10. For example, the pH range may be about 9 to 11.

[0097] The bleaching compound may be ozone. 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. The cotton-containing material is bleached with ozone in the range of about 1.0% to about 20.0% by weight, optionally in the range of about 2.0% to 10.0% by weight, at a flow rate in the range of about 0.1 L / min to 20 L / min, optionally in the range of about 0.5 L / min to 10 L / min, or optionally in the range of about 1 L / min to 5 L / min. 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 bleaching time ranges from about 1 minute to 60 minutes, optionally from 10 minutes to 30 minutes. 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. The ozone bleaching is preferably in the pH range of 2 to 11, optionally in the range of 3 to 11. The pH may be 3, 7, or 11. In the process, the cotton content, measured by percent (%) from the total mixture, may range from 1 to 30%.

[0098] In one embodiment, neutralization is performed after bleach pretreatment. Neutralization is performed with sulfuric acid up to pH 7. A washing process with water is then carried out at room temperature.

[0099] Acid Pretreatment / Cooling / Neutralization The cotton-containing fabric may optionally be subjected to an acid pretreatment. The acid pretreatment of 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, in contrast to strong acids, weak acids are acids that are known not to completely dissociate in water. 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 from about 0.01M to about 0.5M, optionally from about 0.10M to about 0.25M, and optionally from about 0.15M to about 0.20M.

[0100] The at least one acid is added to the powder in a liquor ratio ranging from about 2:1 to about 12:1, optionally from about 4:1 to about 10:1, optionally about 6:1.

[0101] Optionally, step (c) does not include the addition of a base, i.e., no base is used to pretreat the cotton-containing fabric. In one embodiment, step (c) does not include a rinsing step required from a pretreatment requiring neutralization from the use of strong acids or bases, recovery of any solvents or pretreatment aids, or pretreatment requiring removal of components prior to hydrolysis and / or fermentation.

[0102] The elevated temperature in step (c) may range from about 115°C to about 210°C, optionally from about 121°C to about 137°C, optionally from about 126°C to about 132°F, optionally about 130°C. The heating time in step (c) ranges from about 0.5 to about 5 hours, optionally from about 1 to about 3 hours, optionally about 2 hours. Optionally, an agitator may be added to the slurry to enhance internal mixing of the slurry. Due to the acid pretreatment, the resulting slurry has a much lower viscosity.

[0103] Step (c) may include cooling the slurry to a temperature in the range of about 48°C to about 71°C, optionally to a temperature in the range of about 54°C to about 65°C, optionally to a temperature of about 60°C.

[0104] Step (e) may include adding at least one base to the slurry from (c) and optionally stirring the slurry. The at least one base may include a strong base. Examples of strong bases 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 base used in step (e) may include sodium hydroxide. The concentration of sodium hydroxide may range from 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 the phosphoric acid to form sodium phosphate in situ. The slurry is then optionally stirred for 1 to 120 minutes at a temperature ranging from about 48° C. to about 70° C., optionally at a temperature ranging from about 55° C. to about 65° C., optionally at a temperature of about 60° C.

[0105] 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 optionally agitating the slurry. The at least one additional acid used in step (e) may include 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 do not completely dissociate in water. The at least one additional acid used in step (e) may include citric acid.

[0106] The citric acid from step (e) may form a buffer with the sodium phosphate from step (d). The citric acid and sodium phosphate buffer is known as McIlvaine's buffer.

[0107] The concentration of the at least one acid in step (e) is from about 0.001M to about 1.0M, optionally from about 0.010M to about 0.1M, optionally from about 0.025M to about 0.050M.

[0108] Saccharification The pretreated material may be subjected to enzymatic hydrolysis to produce sugars (saccharification). For example, the pretreated material may be subjected to separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), or direct microbial conversion (DMC). Wyman et al. (1992) Biomass and Bioenergy 3(5f): 301-307.

[0109] Sugars produced by the methods described herein include, but are not limited to, glucans, xylans, arabinans, mannans, galactans, glucose, sucrose, hexoses, and combinations thereof. Enzymatic hydrolysis may include incubation with a cellulase composition that includes one or more enzymes that hydrolyze the cellulosic material. Cellulase enzymes include, but are not limited to, endocellulases, exocellulases, cellobiases, oxidized cellulases, and endoglucanases. Other enzymes that may be used include, but are not limited to, cellobiohydrolases, beta-glycosidases, and combinations thereof. Hydrolysis may further include filtration, whereby the hydrolysate is fermented and saccharified to produce ethanol. Alternatively, if filtration does not occur, hydrolysis may include fermenting and saccharifying the slurry to form ethanol.

[0110] The same process may include fermenting and saccharifying the hydrolysate, or when the process includes fermenting and saccharifying a slurry, the previous step may further include combining the hydrolytic enzyme with yeast.

[0111] Saccharification may include 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 optionally agitating the slurry. The enzymatic hydrolysis may be performed utilizing a mixed combination of at least one cellulase and β-glucosidase. The enzyme mixture may include hemicellulase, cellulase, endo-glucanase, exo-glucanase, and 1-.beta.-glucosidase. The cellulase may be cellobiohydrolase, endocellulase, exocellulase, cellobiase, endo-beta-1,4-glucanase, beta-1,4-glucanase, or a mixture thereof.

[0112] After the hydrolysis mixture is added to the pretreated cotton material, hydrolysis occurs for about 24 to about 240 hours, optionally for about 48 to 216 hours. Hydrolysis can occur for about 24 to 36 hours, 24 to 144 hours, 24 to 168 hours, or 48 to 216 hours. Hydrolysis occurs at 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, 109, 109, 102, 104, 105, 106, 107, 108, 109, 109, 109, 102, 103, 104 6, 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, 12 3, 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, 169, 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 may occur over a period of several hours.

[0113] The temperature during hydrolysis may range from about 20° C. to about 60° C., optionally from about 40° C. to about 55° C., optionally about 48° C. The temperature during hydrolysis may be about 30° C., around which temperatures saccharification and fermentation may occur simultaneously.

[0114] The pH of the enzyme solution during hydrolysis can be controlled with an acid or base or both for pH control. The pH during hydrolysis can be selected by the skilled artisan and can be 3.0 to 10.0, optionally in the range of about 4.0 to about 8.0, optionally in the range of about 4.5 to about 6.5. The pH can be in the range of up to 3 pH units, or up to 5 pH units. The optimum pH 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. The pH can be about 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, the pH can be about 5.2.

[0115] The hydrolysis time is 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 10 to 120 hours.

[0116] Enzyme activity should be measured as 1 FPU to 540 FPU / g cotton. Developed by IUPAC, FPU is a standard way of expressing enzyme dosage and is the ability to convert 50 g of cellulose filter paper to 2.0 mg of glucose in 60 minutes. Adney, B. and Baker, J. “Measurements of Cellulase Activities,” NREL Laboratory Technical Report NREL / TP-510-42628, 2008.

[0117] The weight ratio ISE of the amount of enzyme and cotton is 0.01%~10.0%.

[0118] Hydrolysis efficiency can be determined in a manner known to those skilled in the art. Exemplary analytical methods include cotton residue, HPLC, and RIDA® Cube. In one embodiment, 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%.

[0119] The methods described herein do not include pretreatment steps requiring neutralization from the use of strong acids or bases, recovery of any solvents or pretreatment aids, or rinsing steps required from pretreatment required to remove components prior to hydrolysis and / or fermentation.

[0120] Filtration and drying After the hydrolysis step, the slurry may be filtered to produce a retentate (cotton residue) and a permeate (hydrolysate containing sugars). This filtration may be performed by any conventional means known to those skilled in the art, such as those described in U.S. Pat. No. 9,540,665, which is incorporated herein by reference. The cotton residue is then dried, for example, in an oven, and optionally weighed after drying. The cotton residue is dried in an oven at a temperature ranging from about 48° C. to about 82° C., optionally ranging from about 60° C. to about 76° C., optionally about 70° C. The drying time may optionally be at least about 2 hours, optionally ranging from about 4 to about 48 hours, optionally ranging from about 10 to about 24 hours, optionally at least about 16 hours.

[0121] After drying, the conversion rate (or hydrolysis efficiency) can be calculated. For example, after drying, the cotton residue can be weighed at time=0 minutes and time≧15 minutes. The conversion rate is then calculated based on the amount of cotton added and the weight of the residue at time≧15 minutes. In one embodiment, HPLC and RIDA® Cube are analytical methods that can be used to measure the glucose concentration of the solution to calculate the hydrolysis efficiency.

[0122] In another embodiment, the cellulose conversion efficiency is calculated. The amount of cellulose in the garment is pre-determined by acid incineration. Then, HPLC is carried out to quantify the glucose in the hydrolysis sample. The determined glucose is compared with the theoretical amount of glucose in the sample based on the following formula: Cellulose conversion (%) = % of cellulose converted to glucose / % of initial cellulose in the system * 100 (1) Cellulose conversion (%) = (% of glucose by HPLC) * 0.9 / [(% of cotton in initial system) * cellulose content of cotton] * 100 (2) During the ceremony: % of cellulose converted to glucose = (% of glucose by HPLC) * 0.9 (3) Initial % cellulose in system = (% cotton in initial system) * cellulose content of cotton (4) (4)* The cellulose content of cotton is determined by compositional analysis using TAPPI and NREL standard methods.

[0123] Conversion of sugars to end products The sugars produced by the methods described herein may be further subjected to biochemical processing (e.g., fermentation) to produce an end product. For example, the sugars produced by the methods described herein may be contacted with a microorganism in a fermentation process to produce an end product. The sugars produced by the methods described herein may be contacted with an enzyme or mixture of enzymes in a fermentation process to produce an end product. End products produced by fermentation may include, but are not limited to, alcohol, acid (including fatty acids), gas, amino acids, chemicals, and mixtures thereof.

[0124] Alcohols that may be produced include, but are not limited to, ethanol, butanol, methanol, propanol, and mixtures thereof.

[0125] Acids that may be produced include, but are not limited to, 2,5-furandicarboxylic acid, itaconic acid, levulinic acid, succinic acid, lactic acid, malic acid, citric acid, acrylic acid, fumaric acid, hydroxypropionic acid, acrylic acid, and mixtures thereof.

[0126] 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, polyhydroxyalkanoates, 1,3-propanediol, or mixtures thereof.

[0127] Gases that may be produced include, but are not limited to, methane, ethane, CO, CO2, H2, or mixtures thereof. EXAMPLES

[0128] Example 1 Enzymatic hydrolysis of cotton fabrics. Cotton fabric was shredded, ground, and then mechanically refined in a PFI mill at 5,000, 10,000, or 20,000 rpm. Controls were used without refinement. The pretreated cotton fabric was then enzymatically hydrolyzed at 50°C, pH=5.2, and enzyme loading up to 5 PFU / g cotton.

[0129] FPU is a standard way of expressing enzyme dosage and is the ability to convert 50 g of cellulose filter paper to 2.0 mg of glucose in 60 minutes. Adney, B. and Baker, J. “Measurements of Cellulase Activities,” NREL Laboratory Technical Report NREL / TP-510-42628, 2008.

[0130] The inventors observed a surprising improvement in the efficiency of cotton conversion (e.g., fiber converted to sugars) with increasing intensity of PFI pretreatment. Stronger PFI pretreatment resulted in shorter fiber lengths and an increase in the weight percent of fines. The inventors found a 60% increase in yield, from 28% without refining (control) to 90% with PFI pretreatment at 10,000 rpm. Figure 2. This demonstrates that PFI pretreatment leads to an unexpected improvement in cotton fabric hydrolysis. See also Figures 3-6. Enzymatic hydrolysis experiments were performed with different residence times (24, 48, and 96 hours). In all cases, PFI mechanical refining highly improved cotton conversion.

[0131] Enzymatic hydrolysis experiments were carried out at different enzyme loadings, e.g., 4, 5, and 6 FPU / gram of OD.

[0132] The enzymatic hydrolysis experiments were carried out at 5% cotton content (eg, 5% concentration, or 5% (w / w) solids content).

[0133] All publications (e.g., non-patent literature), patents, published patent applications, and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All such publications (e.g., non-patent literature), patents, published patent applications, and patent applications are herein incorporated by reference to the same extent as if each individual publication, patent, published patent application, or patent application was specifically and individually indicated to be incorporated by reference.

Claims

1. 1. A method for pretreating a cotton-containing textile material, comprising refining the cotton-containing textile material in a PFI mill for about 2,000 to 20,000 revolutions; A process that does not include pretreatment steps requiring neutralization from the use of acids or bases, recovery of any solvents, or rinsing steps required from pretreatments requiring removal of components prior to hydrolysis and / or fermentation.

2. 10. The method of claim 1, wherein the method further comprises a pretreatment comprising mechanical, chemical, enzymatic pretreatment, or a combination thereof.

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

4. The method of claim 2, wherein the mechanically pretreated cotton-containing textile material comprises about 1% to 50% by weight of fines.

5. 3. The method of claim 2, wherein the mechanically pretreated cotton-containing textile material has a fiber length LWL (mm) of about 0.1 mm to 2.00 mm.

6. 3. The method of claim 2, wherein the mechanically pretreated cotton-containing textile material has a Canadian Standard Freeness (CSF) of about 100 to 900 CSF milliliters.

7. 3. The method of claim 2, wherein the mechanically pretreated cotton-containing fabric is in the form of a powder.

8. 3. The method of claim 2, wherein a Wiley Mill is used in the cutting step.

9. 3. The method of claim 2, wherein the mechanical pretreatment is carried out before bleaching the cotton-containing textile material.

10. 10. The method of claim 1, further comprising shredding the cotton-containing textile material, cutting the cotton-containing textile material, and grinding the cotton-containing textile material prior to refining the cotton-containing textile material in a PFI mill.

11. 10. The method of claim 1, wherein a solvent is added to the cotton-containing textile material prior to refining in a PFI mill.

12. The method of claim 11 , wherein the solvent is water.

13. 12. The method of claim 11, wherein the solvent is added before, during, or both before and during purification.

14. 10. The method of claim 1, wherein the method further comprises enzymatic hydrolysis of the pretreated cotton-containing textile material to produce a hydrolysate.

15. The method of claim 1 , wherein the method further comprises bleaching the cotton-containing textile material.

16. 16. The method of claim 15, wherein the decolorizing step comprises bleaching.

17. The method comprises: ２＋ 10. The method of claim 1, further comprising adding:

18. The method comprises: ２＋ 10. The method of claim 1, further comprising adding:

19. 10. The method of claim 1, wherein the level of purification is about 2,000 to 20,000 PFI revolutions.

20. 10. The method of claim 1, wherein the method further comprises subjecting the pretreated cotton-containing textile material to hydrolysis to produce a hydrolysate.

21. 21. The method of claim 20, wherein the hydrolysis comprises enzymatic hydrolysis comprising the addition of at least one hydrolytic enzyme.

22. 22. The method of claim 21, wherein the enzymatic hydrolysis comprises an additional combination of cellulase and β-glucosidase.

23. 21. The method of claim 20, wherein the method further comprises subjecting the hydrolysate to fermentation to produce an end product.

24. 24. The method of claim 23, wherein the end products produced by fermentation include alcohols, sugar alcohols, acids, fatty acids, gases, amino acids, chemicals, and mixtures thereof.

25. The method of claim 1 , wherein the method does not include a step requiring the use of an acid.

26. The method of claim 1, wherein the cotton-containing fabric comprises cotton, cotton blend garments, cotton-polyester blend garments, or mixtures thereof.

27. 1. A method for treating a cotton-containing textile material, comprising: (a) shredding the cotton-containing textile material; (b) cutting the cotton-containing textile material; (c) comminuting the cotton-containing textile material; and (d) refining the cotton-containing textile material in a PFI mill for about 2,000 to 20,000 revolutions; (e) subjecting the pretreated cotton-containing textile material to hydrolysis to produce a hydrolysate; A process that does not include pretreatment steps requiring neutralization from the use of acids or bases, recovery of any solvents, or rinsing steps required from pretreatments requiring removal of components prior to hydrolysis and / or fermentation.

28. 28. The method of claim 27, wherein the cotton-containing fabric comprises cotton, cotton blend garments, cotton-polyester blend garments, or mixtures thereof.

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