**3. Results**

#### *3.1. Properties of Dispersions*

#### 3.1.1. Product Concentration and Ion Content

The yield was measured gravimetrically. The gross yield of nanoparticles was corrected for the ion mass, determined by ion chromatography. Sulfuric acid hydrolysis followed by basic neutralization and successive centrifugation led to a gross yield of 41.4 ± 0.8 wt % of CNC from cotton linters. A gross yield of 32.2 ± 0.7 wt % of SNP was achieved from corn starch.

Redundant H2O and excess ions were mostly removed during precipitation and redispersion. The relative nanoparticle concentrations in the hydrolyzed products were 53.6 ± 1.0 g kg−<sup>1</sup> of product and 125.2 ± 2.6 g kg−<sup>1</sup> of product for cellulose and starch, respectively. The concentration of Na+ of 4.3 ± 0.1 mmol g−<sup>1</sup> of CNC and 1.0 ± 0.3 mmol g−<sup>1</sup> of SNP, and the concentration of SO4 <sup>2</sup><sup>−</sup> of 2.3 ± 0.1 mmol g−<sup>1</sup> of CNC and 0.6 ± 0.0 mmol g−<sup>1</sup> of SNP, respectively, indicate an excess of free sulfate ions in both hydrolyzed products. This finding is confirmed by the acidic pH of 2.07 and 2.71 after centrifugation for CNC and SNP, respectively. No other ions were detected, pointing at the purity of the raw materials. Thereby, more than 99.8% of the ionic residuals were removed during the washing step.

#### 3.1.2. Particle Size

Both cellulose and starch feed stocks had a bimodal particle size distribution with a volume-weighted mean equivalent diameter of 50.1 ± 0.4 μm and 7.7 ± 0.0 μm, respectively, while the spans were 5.16 ± 0.1 μm and 1.1 ± 0.0 μm. After the sulfuric acid treatment, microscale hydrolyzed residues or agglomerates due to high salt concentrations with a diameter of 7.4 ± 0.1 μm and 4.3 ± 0.0 μm for cellulose and starch, respectively, were still present. The spans corresponding to the mean diameters were 2.7 ± 0.1 μm and 1.9 ± 0.0 μm, respectively.

The apparent mean size of the nanoparticles was 113.4 ± 0.6 nm for cellulose and 248.7 ± 15.7 nm for starch. Accordingly, the polydispersity indices were 0.225 ± 0.007 and 0.369 ± 0.015. Thus, both nanoscale and microscale particles coexist in the hydrolyzed product [49]. An overview of the dispersion properties and the nanoparticle sizes of CNC and SNP is given in Table 2.


**Table 2.** Properties of nanoparticle dispersions as prepared from cotton linters and corn starch.
