Efficient extraction of Eucommia ulmoides gum by a deep eutectic solvent-organic solvent biphasic recyclable system

Eucommia ulmoides gum (EUG) with high purity was extracted directly from the Eucommia ulmoides pericarp using a biphasic solvent system consisting of deep eutectic solvent (DES) and petroleum ether. The addition of DES enabled the deconstruction of lignocellulose and the exposure of EUG, leading to the efficient dissolution of EUG in petroleum ether. The extraction rate of EUG was 22.986 %, and the purity of EUG was 98.01 %. The chemical structure of EUG was confirmed by FTIR and NMR characterization. XRD and DSC analysis reviewed the partial destruction of crystal structure and the decline of β-crystal phase of EUG during the extraction process. Moreover, the extracted EUG exhibited high tensile strength of 10.360 MPa, excellent elongation at break of 78.663 % ascribed to the unique crystallinity that enhanced the flexibility of molecular chains. In addition, the recycling performance of DES and petroleum ether was verified, and the recovery rate were up to 94.04 % and 82.60 %, respectively, indicating that this method is expected to replace the traditional pretreatment method for extracting EUG.