Application Of Ionic Liquids In Waste Textiles Recycling

Recycling waste textiles is one of the great challenges today. In this work, a new type of green solvent, ionic liquids [Amim]Cl, was implemented to recycle waste cotton and cotton/PET blend textiles.1. The regenerated cellulose membranes with excellent performance, smooth and dense surface were successfully prepared from waste cotton textiles. The tensile strength reached 149 MPa; light transmittance was above 85%; the onset temperatures of degradation in air and in nitrogen were about 310℃ and 330℃, respectively. The polymerization degree of cellulose had not changed in the process of dissolving. The dissolution process was mild and no chemical reactions happened. By filtration-rotary evaporation method, the recycling efficiency of recycling the solvent [Amim]Cl was greater than 99%. The regenerated cellulose membranes prepared in recovered [Amim]Cl solvent could still keep transparent and smooth. After the dissolution, the polymerization degree of cellulose had not altered as well. The tensile strength of the regenerated cellulose membrane retained 136 MPa.2. The waste cotton/PET blended textile was dissolved and separated by [Amim]Cl. The dissolution-separation process of cellulose/PET blend was observed by polarizing microscope with a hot stage. The results showed that [Amim]Cl had no effect on PET after 7 hours at 120℃. It proved that pure cellulose and pure PET have been acquired according to the data of ATR (Attenuated Total Reflection). The recovery rates of cotton and PET were 58% and 93%, respectively. The tensile strength of the regenerated cellulose membrane was 55 MPa; its light transmittance was 80.2%; the onset temperatures of degradation in air and in nitrogen were about 308℃,347℃, respectively. The recycled PET had the same melting point and thermal stability as commercial PET.3. The cellulose/PET composite membranes with uniform morphology were prepared from both pre-treated waste cotton textile and recycled PET. The quality ratio of cellulose to PET was selected 100:0-100:20. It was noted that, the light transmittance and the mechanical properties changed regularly with the variation of PET content in the composite membranes. The composite membrane had the highest light transmittance and tensile strength when the ratio of cellulose/PET is 100:5, and largest elongation at break when the ratio of cellulose/PET was 100:10. In air, the onset temperature of degradation decreased at first and then increased with the increment of PET content in the composite membranes; in nitrogen atmosphere, the onset temperature of degradation of the composite membrane (Cellulose/PET ratio,100:20) was 8℃ higher than the pure cellulose membrane and reached 344℃. Furthermore, the hydrophilic property of the composite membranes dropped at first and then rose with the application of PET content. The maximum contact angle with water for the composite membrane was 50.0° when the ratio of cellulose/PET was 100:5, which was 29.0° higher than that of pure cellulose membrane.