Magnetically assisted commercially attractive chemo-enzymatic route for the production of 5-hydroxymethylfurfural from inulin

Biomass has recently been extensively exploited as an attractive alternative to the scarce fossil fuels and has been widely used for the production of fine chemicals. The present work defines an integrated approach for high yield of 5-hydroxymethylfurfural (HMF) from inulin via a two-step process. Initially, insolubilization of inulinase from Aspergillus niger on chitosan-coated magnetic nanoparticles (cMNP) was achieved, and under optimal conditions, hydrolysis of 5% inulin by immobilized inulinase (2.5 U/mg) led to fructose release of 35.8 g/L at pH 6.0 and temperature 60 °C in 3 h. Subsequently, the fructose was dehydrated to HMF in the presence of TiO₂-magnetic silica spheres (TiO₂-MSS). Upon optimizing the process parameters, HMF yield of 96.58% was achieved with 15% fructose in 15 min at 140 °C with a TiO₂-MSS load of 10% (w/w). Concerning the operational stability of the immobilized biocatalyst/catalyst, the immobilized inulinase was recycled up to 10 cycles of inulin hydrolysis with 9.2 g/L of fructose released at the 10th cycle. TiO₂-MSS also showed high operational stability and were recycled up to 10 cycles of HMF production with 5.4 g/L of HMF produced at 10th cycle. The mass balance for inulin to HMF was performed which showed the efficiency of the process.