Extraction of Cellulose Micro-Whiskers from Rice Husk: A Greener Approach.

Herein, we report a greener, total chlorine free, ultrasonic physicochemical process of extraction and purification of cellulose micro-whiskers from rice husk. The initial step involves the treatment of the rice husk with a concentrated aqueous alkali solution for the duration of 6 h at 80 °C in round bottom flask in order to completely dissolve lignin and silica. After alkali pretreatment, the product obtained was thoroughly washed with distilled water, filtered and dried. The dried product was subjected to mechanical treatment followed by a bleaching process. A sonolytic technique was applied for the bleaching of rice husk using Na2O2/H2O2 as a chlorine-free bleaching agent. The detailed mechanism for the ultrasonic physicochemical bleaching of extracted cellulose from rice husk was also proposed. Extracted and bleached cellulose was characterized for morphological, compositional and thermal properties through different characterization techniques.