The effect of ultrasonic waves on alpha-cellulose extraction from wheat bran to prepare alpha-cellulose nanofibers

In this research, alpha-cellulose was extracted from wheat bran using the chemical-mechanical procedure (Soxhlet – Ultrasonic waves). The chemical method involves lipid and wax removal with the prepared solvent (toluene-ethanol) and two-stage bleaching with a sodium chloride solution. The mechanical stage was performed with the aid of an ultrasonic device to remove holocellulose (cellulose + hemicellulose). The alpha-cellulose was prepared for the first time at three initial times for 10 min, 30 min and 60 min. FTIR, DSC and XRD tested the effect of ultrasonic waves on the purification of the alpha-cellulose extracted from the wheat bran. The alpha-cellulose powder was dissolved in TFA and TFA/MC (trifluoroacetic acid/methylene chloride) solvents. The viscosity behavior of the solutions was determined using viscosity measurement. The diameter distribution of the nanofibers was checked by scanning electron microscope (SEM) and ImageJ software. FTIR spectra showed that holocellulose was removed mainly during alkali treatment under ultrasonic waves. The DSC results indicated a decrease in the peaks' position of the alpha-cellulose extracted from the wheat bran. The XRD results demonstrated that the degree of crystallinity of the alpha-cellulose obtained from wheat bran was 78%. In assessing the diameter distribution, the nanofiber layer obtained from alpha-cellulose extracted from the wheat bran dissolved in the TFA/MC had a diameter of about 56 nm, and the nanofiber layer obtained from alpha-cellulose dissolved in the TFA had a diameter of about 37 nm.