Poly(ethylene terephthalate) powder (PET; 300 μm particle size) was pre-treated according to a previously reported method. PET (50 mg mL -1 ) was stirred in 2 mol L -1 KOH solution at 40 °C for 24 h, then filtered and the filtrate diluted to twice its volume with H2O, producing a hydrolysed PET solution containing ethylene glycol (25 mg mL -1 PETinitial; 4.2 mg mL -1 EGfinal) with a final KOH concentration of 1 mol L -1 .