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). [ABSTRACT FROM AUTHOR]