An electroassisted filtration technique has been employed to improve dewatering of a suspension of microfibrillated cellulose (MFC) produced via 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation. In addition, all-atom molecular dynamic (MD) simulations were performed to deepen the understanding of the complicated dewatering mechanism on a molecular level. Both the experimental and the simulation results implied that the dewatering rate was not only improved when electroassisted filtration was used but also found to be proportional to the strength of the electric field. A channeled dewatered structure was observed for these experiments and may have contributed to enhanced dewatering by providing high overall permeability. The MD simulations revealed that the electric field had a significant impact on the fibril movement, whereas the impact of pressure was limited. The simulations also suggested that the increased filtrate flow upon the application of an electric field was not only due to electroosmotic flow but also due to electrophoretic movement of the fibrils toward the anode that led to the release of water that had been trapped between the fibrils, allowing it to be pressed out together with the rest of the bulk water. This study shows that electroassisted filtration has the potential to improve the dewatering of TEMPO-MFC, and the MD simulations provide further insights into the dewatering mechanism.

Capillary forces between cellulose channels depend on the direction and magnitude of an applied electric field. An electric field applied parallel to a solid–liquid interface increases the capillary force while a perpendicular field reduces it.

Understanding how the solvent structure affects the stability of the dissolved state and the following precipitation is important for designing future dissolution-coagulation systems for cellulose processing. In this study, two morpholinium hydroxides with different alkyl chain lengths, namely N,N-dimethylmorpholinium hydroxide (NDMMOH(aq)) and N‑butyl‑N-methyl morpholinium hydroxide (BMMorOH(aq)), were studied and compared with the previously thoroughly investigated cellulose solvent benzyltriemethylammonium hydroxide (Triton B(aq)) which is well-known for its superior ability to stabilize the dissolved state. Cellulose solutions in each solvent were characterized by NMR, flow and frequency sweeps, while cellulose coagulation by CO₂(g) was followed by in situ FTIR, pH and temperature measurements. The coagulated systems were characterized by CP/MAS ¹³C NMR, flow, and frequency sweep measurements. Complementary molecular dynamic (MD) simulations were performed to gain a deeper insight into the observed gelation behavior. The intrinsic viscosity indicated more extended cellulose chains in the solvents with more hydrophobic moieties (Triton B and BMMorOH). Even though the course of coagulation did not show any significant differences during monitoring, both the properties of the obtained gels and the MD simulations indicated differences in formation and properties of the coagulated materials that could be related both to the choice of solvent and coagulant.