Agroindustry Residues as a Source for Cellulose Nanofibers Production

Abstract

Our study was motivated by the large amount of crop residues produced in Brazil, which represent underutilized waste biomass and a serious threat to the environment because of the landfilling. For example, even though the corn crop is not popular in Brazil, it is produced in the area of around 18-20 million hectares with an average production of 5-6 t ha-1. That is the reason to seek for the crop residues value-added applications as proposed in the present study. Four Brazilian crop waste biomass: orange bagasse, corn husks, sugarcane straw and coffee residues were used for cellulose nanofibers (CNF) production. CNFs were prepared using alkali treatment, followed by bleaching with sodium chlorite and extraction with oxalic acid. All steps were applied under moderate conditions of temperature and pressure, such as temperature of 120 °C and below, water solutions with chemicals’ concentrations lower that 10% and short sonication pulses. CNFs with diameters in the range 50-70 nm were obtained and products from orange bagasse and corn husks presented high crystallinity indexes (CI), 0.72 and 0.75, respectively. The highest CNF yield was obtained from corn husks (38.5%) followed by sugarcane straw (24.0% with CI of 0.69). CNFs obtained from coffee residues showed a CI value of 0.65 after two bleaching steps. Different CNF morphologies were obtained according to the raw material. The four-crop waste biomass can be considered as excellent starting materials for CNF production in the four-steps process that adds new value to agro-industrial waste and might bring great economical valorization to Brazilian crops production.

High-Resolution Magic-Angle Spinning NMR Spectroscopy for Evaluation of Cell Shielding by Virucidal Composites Based on Biogenic Silver Nanoparticles, Flexible Cellulose Nanofibers and Graphene Oxide

“…Hesperetin (2S)-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)-2,3-dihydrochromen-4-one (>95%) ( Supplementary Figure S1A ), silver(I) nitrate, sodium hydroxide, and hydrogen chloride were purchased from Sigma Aldrich (St. Louis, United States). The cellulose nanofibers were obtained from the orange peels by sequential extraction in a three-step process: 1) removal of pectin and hemicelluloses, 2) bleaching the cellulose with hydrogen peroxide, and 3) nanonization of cellulose using an ultrasound [ Mariño et al, 2021 ). Graphene oxide was prepared by the Hummers’ method ( Yu et al, 2016 ).…”

“…The manufacture comprised: 1) the preparation of cellulose nanofibers. Cellulose nanofibers were added to the aqueous solution of sodium hydroxide (NaOH, Sigma-Aldrich), 7% by mass, and sonicated, in an ice bath (4°C), using a 7 mm probe (diameter of the tip) at 70% amplitude and 90 W (Hielscher, Model UP400ST) with a pulse of 2 s ( Mariño et al, 2021 ). This mixture remained in the freezer for 1 h at 1.5°C; 2) Graphene oxide (GO) was suspended in deionized water by ultrasound for 10 min at room temperature (25°C); 3) AgNP@HST were added dropwise into the as-obtained GO suspension and sonicated for another 5 min or sprayed onto newly obtained GO@CNF after their mixture and filtration; 4) The suspensions of CNF and pristine GO or GO@AgNP@HST were mixed and filtered, leading to the manufacture of freestanding composites; and 5) GO@CNF papers decorated with AgNP@HST were obtained by vacuum filtration and 24 h drying at room temperature (25°C).…”

Optimization of microfibrillated cellulose isolation from cocoa pod husk via mild oxalic acid hydrolysis: A response surface methodology approach

“…However, strong acid hydrolysis leads to random rupture of crystalline regions, low yields, hazardous by-product generation, and equipment corrosion [ 4 ]. Organic acids (i.e., acetic, citric, oxalic) are worth exploring as substitutes for hydrolysis due to their ease of production, safety management, low cost, and environment-friendliness [ 5 ]. Oxalic acid is the simplest dicarboxylic acid and a natural product of plant metabolism.…”

Nanofibers from soybean hull insoluble polysaccharides as Pickering stabilizers in oil‐in‐water emulsions formulated under acidic conditions

“…Their structure provides them with unique properties, such as high tensile strengths, high thermal stability and high viscosity, and allows them to be widely used for food applications 3 . Chemical and mechanical treatments were successfully used for the isolation of nanofibers from agricultural residues, 4,5 including soybean hull 6 . Among mechanical treatments, high pressure homogenization (HPH) allows varying diameters of fibers to be obtained, according to the number of homogenization cycles and the pressure applied 2,7 …”