Non-covalent and covalent immobilization of Candida antarctica lipase B on chemically modified multiwalled carbon nanotubes for a green acylation process in supercritical CO2

•Efficient immobilization of Candida antarctica B lipase on modified MWCNTs.•Enzyme loading reaching as high as 21 wt.% for non-covalent immobilization.•Active O-acylation of geraniol into geranyl acetate by CAL-B in supercritical CO2.•Reaction regioselectivity unchanged through immobilization.•Development of a fully green enzymatic process.