Direct conversion of citrus peel waste into hydroxymethylfurfural in ionic liquid by mediation of fluorinated metal catalysts

A new green technology was developed using citrus peel waste to produce hydroxymethylfurfual (HMF). FT-IR analysis of the waste showed 4 characteristic vibration modes (CH, CO, COH, and CO/COO^?), contributing to sugars. XRD and FESEM elucidated that the waste and its hydrolysate consist of highly amorphous clusters. HCl increased HMF yield by 1.4-fold. CrF₃ increased its yield by 1.7-fold. At 0.2 of the stoichiometric ratio value, HMF yield was highest. The highest HMF yield was achieved in the reaction mixture of 4 g OMIM]Cl, 1 mL ethyl acetate, 0.1 g CrF₃, 5 mL 0.3 M HCl, and 0.5 g biomass.