Cellulose Nanostructures Obtained from Waste Paper Industry: A Comparison of Acid and Mechanical Isolation Methods

The paper industry primary waste is usually deposited in landfills or incinerated. This material has a high content of lignocellulosic components, which could be converted to cellulose nanostructures (CNS). This study aimed to compare compositional (Fourier transform infrared spectroscopy), thermal (thermogravimetric analysis), morphological (scanning electron microscopy) and dimensional (dynamic light scattering and atomic force microscopy) properties of CNS obtained through chemical and mechanical isolation processes. The FTIR results showed similar chemical bonding for both nanostructures, which indicated presence of cellulose and lignin. Their average size was 170 nm and 209 nm for chemical and mechanical processes, respectively. The morphology of SEM images showed a compact structure and the chemical isolation presents smaller CNS agglomeration than mechanical. TGA results showed higher thermal stability for CNS-chemical than CNS-mechanical samples and AFM images indicate the CNS morphologies, which showed nanoroads for CNS-chemical and nanoneedles for CNS-mechanical.