Enhancing the Oil Adsorption Properties of Cellulose Nanofiber Aerogels Through Chemical Modification

The primary objective of the study was to develop a method for enhancing the oil adsorption capacity of cellulose nanofibers (CNFs) by modifying their surface. To achieve this goal, aerogels were first dried in a freeze dryer, followed by surface hydrophobization of CNFs using hexadecyltrimethoxysilane (HDTMS) as the modifier. The optimal concentration of the HDTMS for enhancing the nanofiber's surface was determined by testing different concentrations ranging from 0 to 3 mL. The efficacy of the modifier was confirmed by FTIR, which showed the presence of functional groups and hydrogen bonding between CNFs and HDTMS. BET analysis revealed that high concentrations of HDTMS modifier increased the density and reduced the porosity of the aerogels. Moreover, the high concentration of the modifier improved the pressure resistance of the aerogels, with the highest pressure resistance observed for the sample modified with 2 mL of HDTMS. The oil adsorption capacity of the modified samples was also evaluated, and it was found that the highest oil adsorption capacity was observed for the adsorbent with 0.5 mL of the modifier. Conversely, the lowest adsorption rate was observed for the adsorbent with 3 mL of the modifier. Interestingly, it was observed that higher-viscosity oil was absorbed less effectively than lower-viscosity oil. SEM micrographs showed that increasing the amount of HDTMS modifier in the samples resulted in smaller existing pores, thicker pore walls, and a transition from hydrophilic to hydrophobic aerogels. Overall, the results suggest that the optimal concentration of HDTMS for enhancing the surface of the nanofibers is 2 mL, as this concentration provides the highest pressure resistance while still maintaining good oil adsorption capacity.