Hydrolysis of poly(lactic acid) into calcium lactate using ionic liquid [Bmim][OAc] for chemical recycling

Hydrolysis of poly(lactic acid) (PLA) to calcium lactate was studied using an ionic liquid catalyst, 1-butyl-3-methylimidazolium acetate [Bmim][OAc], to develop a chemical recycling process for waste PLA. The influences of experimental parameters, such as reaction time, reaction temperature, [Bmim][OAc] dosage and water dosage on the hydrolysis results of PLA were examined. A study on reusability of the ionic liquid showed that it could be reused up to 7 times with no noticeable decrease in the hydrolysis conversion of PLA and the yield of calcium lactate. A mechanism of PLA hydrolysis in [Bmim][OAc] was proposed. In addition, the kinetics of this reaction was investigated. The results demonstrated that the hydrolysis process was a first-order kinetic reaction in the presence of [Bmim][OAc] and the activation energy is 133.9 kJ/mol.