Biobased dimethyl isosorbide as an efficient solvent for alkaline hydrolysis of waste polyethylene terephthalate to terephthalic acid

Recycling spent polyesters, a widely used type of plastic, is highly important for a circular economy but remains a great challenge. Herein, biomass-derived dimethyl isosorbide (DMI) was developed as an emerging solvent for recycling waste polyethylene terephthalate (PET). DMI showed a good ability to rapidly dissolve PET in 10 min at 170 & DEG;C to obtain a solubility of 0.3 gPET gDMI-1, originating from the matched Hansen solubility parameters between PET and DMI. Moreover, the dissolved PET in DMI could be regenerated with a PET degradation ratio of only 2.9% using water as an anti-solvent. More importantly, DMI-based solvents were highly effective for alkaline (KOH) hydrolysis of PET to generate terephthalic acid (TPA). In a solvent composed of DMI and ethylene glycol (EG) with a volume ratio of 6 : 4, complete conversion of PET could be achieved in 30 min at 100 & DEG;C, and the yield of TPA was nearly quantitative (99.6%). Systematic investigation revealed that the good performance of DMI/EG mixed solvents resulted from the formation of hydrogen-bonding interactions between DMI and EG. The renewability and good performance for PET recycling confirmed the great potential of DMI in practical applications of recycling waste plastics. Biobased DMI showed good ability to rapidly dissolve PET with a solubility of 0.3 gPET gDMI-1 at 170 & DEG;C in 10 min and DMI-based solvents were highly effective for alkaline hydrolysis of PET to generate TPA with a yield of 99.6% at 100 & DEG;C in 30 min.