Salt crystallization pressure as a new method to obtain micro and nanocellulose

This work evaluated the crystallization pressure of sodium and magnesium sulphates as a tool to break down and defibrillate plant cell walls, aiming at a novel, environmentally friendly and low-cost methodology to obtain micro and nanofibrilated cellulose. Elephant grass leaves both in natura and delignified were soaked in Na2SO4 and MgSO4 solutions and oven-dried at 105 ± 3 °C to promote salt crystallization, while the damage resulted from the pressure exerted by the growing crystals within the cell walls was evaluated. Na2SO4 crystallization proved to be more effective to unpack and defibrillate cell walls in comparison to MgSO4. In addition, both salts had more noticeable effects in previously delignified samples than in in natura samples. Nanofibrillated cellulose was obtained by Na2SO4 action and after shearing fibres treated with an aqueous MgSO4 solution (30% w/v), glycerol and NaOH (5% w/v).