Kinetics of poly(3-hydroxybutyrate) hydrolysis using acidic functionalized ionic liquid as catalyst

- HSO3-functionalized ionic liquid can catalyze hydrolysis of PHB under moderate conditions.
- The reaction was carried out in absence of any other traditional acid or base catalyst.
- The ionic liquid can be reused 6 times without obvious decrease in reaction results.
- An environmentally friendly strategy was provided for hydrolysis of PHB waste.
- The reaction was a first-order kinetic one and activation energy was 171.1 kJ/mol.

Hydrolysis of poly(3-hydroxybutyrate) (PHB) was studied using acidic functionalized ionic liquid 1-methyl-3-(3-sulfopropyl)-immidazolium hydrogen sulfate ([HSO3-pmim][HSO4]) as catalyst. The influences of experimental parameters, such as reaction temperature, reaction time, the amount of catalyst and mole ratio of water to PHB were investigated. Under the conditions of reaction temperature 160 °C, reaction time 4.0 h, m([HSO3-pmim][HSO4]):m(PHB) = 0.06:1 and n(H2O):n(PHB) = 7:1, the conversion of PHB was over 98%. The ionic liquid could be reused up to 6 times without apparent decrease in the conversion of PHB. In addition, the kinetics of the reaction was investigated, the result indicated that hydrolysis of PHB in [HSO3-pmim][HSO4] was a first-order kinetic reaction and the activation energy was 171.1 kJ/mol.

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