Preparation and characterization of cellulose nanocrystals using soluble grade cellulose from acid hydrolysis of huizache (Acacia farnesiana L. Willd.)

Abstract

High purity cellulose nanocrystals (NCCs) were obtained through the generation of various nanoparticle suspensions from different hydrolysis conditions of soluble grade cellulose (α-cellulose) prepared from huizache wood (Acacia farnesiana L. Willd.). These NCCs exhibited different surface morphologies and properties. Hydrolysis was carried out using both sulfuric and hydrochloric acids, while the methodology was based on 23 factorial designs of experiments. The obtained nanocrystals were characterized for particle size distribution, morphology, size of the NCCs, residual surface charge of the nanoparticles, and chemical composition using various experimental techniques. The two acid hydrolysis procedures produced NCCs suspensions that exhibited a unimodal or bimodal pattern of the Gaussian type, but differed in their properties. Average NCCs particle size obtained by hydrolysis with different concentrations (60 to 65%), at different temperatures (45 to 55 oC) and treatment times (45 to 65 mins) with H2SO4 acid and HCl acid were approximately 100 to 260 nm and between 75 nm to 512 nm, respectively, indicating influence of concentration and treatment time with both acids. Also, residual load analysis of sulphate groups in the NCCs suspensions in producing NCCs by H2SO4 hydrolysis revealed a minimum load of 39 mmol/kg and a maximum of 505 mmol/kg of NCCs.

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“…The hydrolysis product was then dialyzed at pH 5.5, replacing the water every 12 h. Next, the suspension was filtered through 2, 1.5, and 1 µm filters and stored at 4 °C until use. The residual concentration of sulfate groups on the CNC-S surface (mmol/kg) was measured by conductometric titration as depicted for CNCs from huizache wood [ 38 ].…”

“…Polymers 2023, 15, x FOR PEER REVIEW 5 of 25 sulfate groups on the CNC-S surface (mmol/kg) was measured by conductometric titration as depicted for CNCs from huizache wood [38].…”