Comparison of Treatments by Mercerization and Plasma Glow Discharge on Residues of the Amazon Chestnut Shell (Bertholletia Excelsa)

The chestnut shell from the Amazon region shared between Colombia, Brazil, and Perú is an abundant residue of the walnut used for obtaining food and cosmetic products. This residue is not yet usable due to the lack of knowledge of its properties and the environmental impact generated by its treatment through methods such as mercerization. This work presents the results of the characterization of Amazon chestnut shell residues treated by two methods, mercerization with NaOH solution and intense plasma discharge (Glow Discharge Plasma), in a reactor with argon gas in a 0,3-bar vacuum and discharge conditions of 80 mA and 600 s. The microstructural, morphological, topographic, and nanomechanical changes of the chestnut residues without treatment and with the two proposed treatments were evaluated by means of the µRaman, scanning electron microscopy, and atomic force microscopy techniques. The results showed the effectiveness of the plasma method over the mercerization method at obtaining more crystalline cellulose structures due to the reduction of hemicellulose, lignin, and the aqueous phase of walnut shell waste.