Microfibrillated celluloses produced from kraft pulp of coffee parchment

The objective was to produce microfibrillated cellulose (MFC) and microfibrillated lignocellulose (MFLC) from waste materials, specifically coffee parchment. Additionally, the objective was to perform the characterization of the microcelluloses. Three MFCs were produced from kraft pulps (K#60, K#25, and Bleached), utilizing the conditions: pulp hydration and defibrillation using an ultra-refiner. The MFCs presented a chemical composition that is similar to the original pulps because they were produced through a purely mechanical process. It was obtained MFCs of highly viscous (5357 to 15,587 cP), even at very low consistencies (1.5%). The length of the samples ranged from 39 to 47 µm, and the measured diameters were 6820 nm (MFLC-K#60), 5600 nm (MFLC-K#25), and 5280 nm (MFC-Bleached). Due to these measurements, these materials were named microcelluloses. The crystallinity values were 52.5%, 58.8%, and 65.1% for the MFLC-K#60, MFLC-K#25, and MFC-Bleached samples, respectively. The thermogravimetric degradation curves were similar for the suspensions of MFC. The maximum degradation temperatures varied in the range of 322 to 339 °C. The infrared profiles of microfibrillated cellulose exhibited similar patterns, with distinct bands corresponding to the stretching and deformation of C-H, O–H, and C-O. The Zeta potential values obtained for MFLC-K#60, MFLC-K#25, and MFC-Bleached were − 19.8 mV, − 15.8 mV, and − 27.4 mV, respectively. The water retention values for MFLC-K#60, MFLC-K#25, and MFC-Bleached were 792, 849, and 1032%, respectively. The pulp fibers from the parchment proved to be a viable alternative for the production of MFLC and MFC, as they presented comparable properties to microcellulose produced from wood.