The preparation and properties of marine diesel oil-in-water (o/w) emulsion stabilized by bifunctionalized cellulose nanocrystals (But-CNCs) were investigated. Bifunctional ButCNCs containing both carboxylic and n-butylamino groups were obtained using partial, sequential periodate-chlorite oxidation and reductive amination, followed by a homogenization treatment to liberate individualized nanocrystals with amphiphilic characteristics. The fabricated But-CNC suspensions were optically transparent, and the nanocrystals that were isolated were rod-like, with lengths ranging between 35-120 nm and with lateral dimensions varying from 2-4 nm. Bifunctionalized CNCs at low concentrations (up to 0.45 wt %) were investigated as possible surface-active stabilizers in o/w emulsions.In particular, their ability to enhance the emulsification of marine diesel oil in an aqueous environment was addressed in order to evaluate their potential to be used as "green" oil spill response agents. But-CNCs at 0.1wt % concentration in dispersion reduced the oil particle size from 50 µm to 9-16 µm, and the stability against coalescence was improved in emulsions where bifunctionalized CNCs were used compared to plain o/w emulsion.In addition, the influence of But-CNC dosage and emulsion salinity (0-5% NaCl by weight) was investigated. The background salt concentration only had a minor effect on droplet size, and the stabilization effect was still apparent, with high electrolyte concentration. These results demonstrate the potential of bifunctionalized cellulose (with surface-active groups attached) to act as a nanoparticle emulsifier in oil-water emulsions, thus enabling its utilization in oil-destruction activities.

14There is an urgent global need to develop novel types of environmentally safe dispersing chemicals from renewable 15 resources in order to reduce the environmental impact of oil spills. For this goal, cellulose, the most abundant natural 16 polymeric source, is a promising green, nontoxic alternative that could replace the current synthetic surfactants. In this 17 study, cellulose nanocrystals (CNC) synthesized using a deep eutectic solvent (DES) and two commercially available 18 cellulose nanocrystals were used as marine diesel oil-water Pickering emulsion stabilizers. In particular, oil in water 19(o/w) emulsion formation and stability of emulsified oil during storing were addressed using a laser diffraction particle 20 size analyzer, image analysis, and oil emulsion volume examination. The particle size of the o/w reference without 21CNCs after dispersing was over 50µm and coalescence occurred only a few minutes after the emulsifying mixing 22 procedure. All three investigated CNCs were effective stabilizers for the o/w system (oil droplets size under 10µm) by 23 preventing the oil droplet coalescence over time (6 weeks) and resulting in a stable creaming layer. The CNCs prepared 24 using green DES systems boasted performance comparable to that of commercial CNCs, and they showed effectiveness 25 at 0.1% dispersant dosage. 26

In this experiment, the influence of the morphology and surface characteristics of cellulosic nanoparticles (i.e., cellulose nanocrystals [CNCs] and cellulose nanofibers [CNFs]) on oil-in-water (o/w) emulsion stabilization was studied using non-modified or functionalized nanoparticles obtained following deep eutectic solvent (DES) pre-treatments. The effect of the oil-to-water ratio (5, 10, and 20 wt.-% (weight percent) of oil), the type of nanoparticle, and the concentration of the particles (0.05–0.2 wt.-%) on the oil-droplet size (using laser diffractometry), o/w emulsion stability (via analytical centrifugation), and stabilization mechanisms (using field emission scanning electron microscopy with the model compound—i.e., polymerized styrene in water emulsions) were examined. All the cellulosic nanoparticles studied decreased the oil droplet size in emulsion (sizes varied from 22.5 µm to 8.9 µm, depending on the nanoparticle used). Efficient o/w emulsion stabilization against coalescence and an oil droplet-stabilizing web-like structure were obtained only, however, with surface-functionalized CNFs, which had a moderate hydrophilicity level. CNFs without surface functionalization did not prevent either the coalescence or the creaming of emulsions, probably due to the natural hydrophobicity of the nanoparticles and their instability in water. Moderately hydrophilic CNCs, on the other hand, distributed evenly and displayed good interaction with both dispersion phases. The rigid structure of CNCs meant, however, that voluminous web structures were not formed on the surface of oil droplets; they formed in flat, uniform layers instead. Consequently, emulsion stability was lower with CNCs, when compared with surface-functionalized CNFs. Tunable cellulose nanoparticles can be used in several applications such as in enhanced marine oil response.

Cellulose nanocrystals (CNCs) with amphiphilic features were used in oil drop stabilization in diesel oil-in-water (o/w) emulsion. The functionalized CNCs were synthesized from a lignin-rich reject cellulose source from the pulp and paper industry, i.e., the non-bleached fines fractions of carton pulp. Partial periodate-chlorite oxidation, which was followed by reductive butylamination, was used to obtain surface-modified amphiphilic CNCs. All studied CNCs prevented droplet coalescence by stabilizing oil droplets in the emulsion thus resulting in stable o/w Pickering-like emulsions. CNCs from the fines fractions at concentrations 0.05-0.1% (weight by weight, w/w) provided high stability against creaming (i.e., phase separation), and they did not de-emulsify at low temperatures since the oil droplet size remained small at +5 °C at a 0.05% (w/w) CNC concentration. Salinity improved the stability against creaming with the reference chemical pulp CNC, but negatively affected the emulsion creaming rate for CNCs that had a higher level of lignin. However, the nonbleached fines fraction of the pulp may provide one potential and cost-effective raw material source for the development of a novel bio-based chemical.