Methods for the decomposition of contaminated plastic waste
This invention relates to the field of contaminated plastic waste decomposition. More specifically, the invention comprises methods and systems to decompose contaminated plastic waste and transform it into value-added products.
1. A system for the decomposition of polyethylene, comprising:
a reactor configured to carry out a reaction of polyethylene with an oxidizing agent to produce a reaction product and a reaction gas;
an absorption unit configured to recover the oxidizing agent from the reaction gas, and return the oxidizing agent to the reactor; and
a separation unit configured to separate the reaction product from the oxidizing agent,
wherein the oxidizing agent is aqueous nitric acid (HNO 3 ), wherein the reaction product comprises at least one of C 8 -C 20 dicarboxylic acid substituted with a single nitro group, or the salts or esters thereof.
2. The system of claim 1 , wherein the separation unit comprises an evaporator.
3. The system of claim 2 , wherein the evaporator comprises one or more of a wiped-film evaporator, a falling-film evaporator, a forced-circulation evaporator, or a flash evaporator.
4. The system of claim 1 , wherein the separation unit further comprises an oxidizing agent harvester.
5. The system of claim 4 , wherein the oxidizing agent harvester is selected from the group of a chromatography column, a crystallizer, a liquid-liquid extractor, and Nutsche filter dryer.
6. The system of claim 1 , wherein the separation unit further comprises a dryer.
7. The system of claim 1 , wherein the reactor comprises a stirred tank reactor.
8. The system of claim 1 , wherein the reactor comprises a chopping blade configured to blend and breakdown the polyethylene.
9. The system of claim 1 , wherein the reactor comprises a screw conveyor configured to convey the polyethylene into or through the reactor.
10. The system of claim 1 , wherein the separation unit is configured to recycle the separated oxidizing agent to the reactor.
11. The system of claim 1 , further comprising a distillation unit configured to concentrate the oxidizing agent prior to recycling the oxidizing agent to the reactor from the absorption unit.
12. The system of claim 1 , further comprising a condenser for condensing the reaction gas from the reactor.
13. The system of claim 1 , wherein the absorption unit is an absorption column.
14. The system of claim 1 , wherein the polyethylene and the oxidizing agent are reacted at a temperature of about 60° C. to about 200° C. in the reactor.
15. The system of claim 1 , wherein the reaction product comprises succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, and at least one of C 8 -C 20 dicarboxylic acid substituted with a single nitro group, or the salts or esters thereof.