Novel Electrohydraulic Technique of Cellulose Fiber Production from Industrial Hemp

The key stage of processing high-cellulose hemp raw materials is delignification-the removal of lignin and hemicelluloses to obtain strong cellulose fibers. This study experimentally demonstrated the effectiveness of using the electrohydraulic effect (EHE) to delignify high-cellulose hemp raw material, which can then be used as a base for composite materials. Hemp raw material, in the form of 50 mm-long straws, was placed in a water-filled chamber and exposed to a shock wave generated in the water by an electric discharge with an energy of 1.6 kJ at a voltage of 50 kV. The tensile strength of the treated fibers after combined processing (NaOH/EHE) and after EHE reached 262 MPa and 201 MPa, correspondingly, which are 5% and 37% higher than after chemical delignification in a NaOH medium (191 MPa). Cellulose materials obtained from cellulose fiber after EHE exhibit higher strength properties compared to materials based on cellulose obtained by delignification in a NaOH medium. Thus, the tensile strength (σ) of materials made from fibers after EHE was 4.37 MPa, after combined NaOH/EHE treatment 1.94 MPa, and after alkaline treatment 3.95 MPa. EHE reduced delignification time by 2-20 times compared to NaOH treatment and eliminates the need for an additional fiber separation procedure. The use of EHE is proposed as a highly cost-effective, technologically and environmentally sound solution for producing hemp fiber for use in biocomposites, woven, and non-woven materials.