Rice straw cellulose nanofibrils from the optimal 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation/blending process carrying 1.17 mmol/g surface carboxyls were protonated to varying charged (COO^-Na⁺) and uncharged (COOH) surfaces. Reducing the electrostatic repulsion of surface charges by protonation with hydrochloric acid from 11 to 45 and 100% surface carboxylic acid most prominently reduced the aerogel densities from 8.0 to 6.6 and 5.2 mg/cm³ while increasing the mostly open cell pore volumes from 125 to 152 and 196 mL/g. Irrespective of charge levels, all aerogels were amphiphilic, super-absorptive, stable at pH 2 for up to 30 days, and resilient for up to 10 repetitive squeezing-absorption cycles. While these aerogels exhibited density-dependent dry [11.3 to 1.5 kPa/(mg/cm³)] and reduced wet [3.3 to 1.4 kPa/(mg/cm³)] moduli, the absorption of organic liquids stiffened the saturated aerogels. These data support protonation as a critical yet simple approach toward precise control of aerogels' dry and wet properties.

With downward pressure on the value of almond hulls (AHs), the major byproduct from the largest tree nut crop globally, the streamlined production of several grades of cellulose nanofibrils (CNFs) toward novel aerogels with concurrent sugar extraction was introduced to synergistically drive these products toward commercial adoption. Hot water extraction produced 50% lignocellulose (LC) with equal water-soluble sugars from AH of a soft-shell variety. Aqueous NaOH and NaClO2/KOH treatments isolated ca. 15% alkali cellulose and 12% cellulose, respectively. Coupled 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation and blending yielded 88, 91, and 95% LC micro-/nanofibrils (LCMNFs), alkali cellulose nanofibrils (ACNFs), and cellulose nanofibrils (CNFs) with, respectively, 0.76, 1.02, and 0.84 mmol/g surface carboxyls in a similar 4:1 width-to-thickness aspect ratio and ultrahigh length-to-thickness aspect ratios (800-1900). The LCMNF aerogel was mostly wet-resilient, wet-stable, and dry/wet shape-recoverable, whereas the most charged ACNFs gave the stiffest aerogel [31.6 kPa/(mg/cm3)].