Efficient extraction of cellulose nanocrystals from waste Calotropis gigantea fiber by SO42-/TiO2 nano-solid superacid catalyst combined with ball milling exfoliation

摘要

Cellulose nanocrystals (CNC) was successfully extracted from natural Calotropis gigantea fiber (CGF) by a combined ball milling defibrillation and SO42-/TiO2 nano-solid superacid catalyst-assisted method. In the extraction process, natural Calotropis gigantea fibers were defibrillated layer by layer, subsequently, catalysis degraded by nano-solid superacid catalysis. The new extraction method avoids large amounts of acid pollution. The yield of CNC obtained from Calotropis gigantea fiber was 55.37 %. Rod-like CNC with an average length of 242.06 nm and width of 8.80 nm was obtained. The aspect ratio of the CNC (the length:width) was 27.5 times. The green method avoids the use of large amounts of sulfuric acid. The ball milling defibrillation combined with SO42-/TiO2 nano-solid superacid catalyst-assisted provides an efficient and sustainable manner to make full use of natural Calotropis gigantea fiber resources.