A process for recovering polyester

Abstract

The present disclosure relates to a process for recovering a polyester component and products of a non-polyester component from an article containing a polyester blend. The polyester blend consists of a polyester component and a non-polyester component. Particularly, the polyester component of the present disclosure is polyethylene terephthalate and the non-polyester component is at least one selected from the group consisting of cotton and viscose. The process of the present disclosure includes hydrolyzing the article using at least one hydrolyzing agent having pH ranging from 7 to 14 to obtain a first mixture containing the polyester component, the non-polyester component, optionally, products of the non-polyester component and the hydrolyzing agent. This is followed by incubating the first mixture using at least one enzyme selected from the group consisting of cellulose and pectinase to further convert the non-polyester component into products of the non-polyester component thereby releasing the polyester component.

1 . A process for recovering, from an article comprising a polyester blend comprising a polyester component and a non-polyester component, the polyester component and products of the non-polyester component wherein said non-polyester component is at least one selected from the group consisting of cotton and viscose; said process comprising the following steps:
 i. hydrolyzing said article using at least one hydrolyzing agent having pH ranging from 7 to 14, to obtain a first mixture comprising said polyester component, said non-polyester component, optionally, products of said non-polyester component and said hydrolyzing agent; and   ii. incubating said first mixture with at least one enzyme selected from the group consisting of cellulase and pectinase to further convert said non-polyester component into products of said non-polyester component and release the polyester component.   
     
     
         2 . The process as claimed in  claim 1 , wherein said polyester component is polyethylene terephthalate (PET). 
     
     
         3 . The process as claimed in  claim 1 , wherein said step of hydrolyzing said article includes a pre-step of shredding said article. 
     
     
         4 . The process as claimed in  claim 1 , wherein said step of hydrolyzing said article is carried out at a temperature ranging from 90 to 160° C. for a time period ranging from 10 to 90 minutes and at a pressure ranging from 5 to 25 psi. 
     
     
         5 . The process as claimed in  claim 1 , wherein said step of hydrolyzing said article is carried out in an autoclave. 
     
     
         6 . The process as claimed in  claim 1 , wherein said hydrolyzing agent includes at least one alkali selected from the group consisting of sodium hydroxide, sodium carbonate, calcium hydroxide and calcium carbonate, having concentration ranging from 0.1 to 5%. 
     
     
         7 . The process as claimed in  claim 1 , wherein said step of hydrolyzing further comprises neutralizing said first mixture. 
     
     
         8 . The process as claimed in  claim 1 , wherein said step of incubating is carried out in the presence of a buffer having strength ranging from 30 to 70 mM and pH ranging from 4.5 to 7.0 for a period ranging from 20 to 50 hours at a temperature ranging from 40 to 60° C.; said buffer being sodium citrate. 
     
     
         9 . The process as claimed in  claim 1 , wherein said step of incubating includes stirring at a speed ranging from 150 to 250 rpm. 
     
     
         10 . The process as claimed in  claim 1 , wherein said enzyme is selected from the group consisting of cellulase and a combination of cellulase and pectinase and has a concentration ranging from 0.5 to 15 g/L. 
     
     
         11 . The process as claimed in  claim 1 , wherein said article is dyed article and said non-polyester component includes a dye.