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Monday, March 27, 2023

Sodium ethoxide as an environmentally benign and cost-effective catalyst for chemical depolymerization of post-consumer PET waste

Polyethylene terephthalate (PET) waste is mounting up within the surroundings attributable to its poor biodegradability and low recycling charge. Glycolysis is a promising chemical recycling method to transform PET into its monomer bis(2-hydroxyethyl)terephthalate (BHET). Right here we current our work on the glycolytic depolymerization of post-consumer PET waste utilizing sodium ethoxide (EtONa) as a low-cost catalyst. As a way to optimize the response by way of PET conversion and BHET yield, response floor methodology (RSM) based mostly on the Field-Behnken design was utilized for the response temperature (160-190 oC), the molar ratio of PET: EtONa (50-150), the molar ratio of ethylene glycol to PET (EG: PET) (3-7), the response time (2-6 h) and the PET particle measurement (0.25-1 mm). Based mostly on the experimental outcomes, regression fashions as a operate of serious course of parameters had been obtained and evaluated by evaluation of variance (ANOVA) to foretell the depolymerization efficiency of EtONa. By additional optimization and increasing the parameter house past the preliminary higher limits, excessive PET conversion (98%) and remoted yield of BHET (76%) had been achieved. Underneath related circumstances the depolymerization efficiency was in comparison with different broadly studied catalysts, corresponding to zinc acetate (PET conversion 97%, BHET yield 75%) and cobalt acetate (PET conversion 93%, BHET yield 70%). BHET precipitation with out water can also be demonstrated and proven that EG and catalyst recycling is feasible no less than for five recycled runs with persistent conversion. Therefore, EtONa is a really promising low-cost catalyst for PET depolymerization that has potential feasibility for a large-scale course of.

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