Furfural degradation in a dilute acidic and saline solution in the presence of glucose

•Degradation of pure furfural in an acidic and saline solution is accurately modeled both using first- and second-order kinetics.•Furfural is degrading significantly faster when glucose is present in the reaction mixture.•The influence of glucose on furfural degradation is best incorporated by addition of a second-order reaction.•A Diels–Alder reaction is propounded for the second-order degradation of furfural.

A kinetic study has been performed on the degradation of furfural in a dilute acidic and saline solution with and without the presence of glucose. Experiments have been performed in a stirred batch reactor. The degradation of furfural alone was accurately predicted both using a first- and a second-order kinetic model. It was shown that furfural is degrading significantly faster when glucose is present in the reaction mixture. In the series with glucose present distinct second-order reaction kinetics were observed. From experiments with varying concentrations of glucose it turned out that an additional (second-order) reaction had to be added to the reaction mechanism in order to satisfactorily predict the experimental data. This additional reaction incorporated the initial glucose concentration as a constant in the Arrhenius expression for the reaction rate constant. Furthermore, it has been argued that this second-order reaction could well be a Diels–Alder reaction.

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