Cellulose is a naturally abundant polymer with intrinsic resistance against a wide range of organic solvents and is therefore an attractive polymer for membrane separations in these solvents. Cellulose membranes can be formed by phase inversion, which requires a homogeneous starting solution of cellulose in a suitable solvent such as an ionic liquid. Alternatively, a more soluble cellulose derivative, such as cellulose acetate, can be formed into a membrane and then converted back into cellulose. This approach is quite attractive as many conventional solvents can be used for forming the membranes, and a wide range of morphologies can be obtained. By varying the solvent composition during cellulose acetate precursor membrane formation, the separation performance of cellulose membranes formed by their alkaline hydrolysis can be varied from ultrafiltration to nanofiltration range. Upon conversion to cellulose, the permeance and rejection of large-pore, small-pore, and dense membranes change in different directions. Loose ultrafiltration membranes’ rejection increases and permeance decreases, while denser membranes’ rejection decreases and permeance increases¹. This is attributed to partial degradation of cellulose chains in alkaline medium, which in turn would affect transport through the pores as well as the membrane matrix, the former being dominant for ultrafiltration and the latter for nanofiltration. Prominent applications of ultrafiltration in organic solvents or water-organic solvent mixtures lie in continuous polymer and nanoparticle synthesis² and treatment of waste process streams contaminated with polymers³. Performance of cellulose membranes in concentration and solvent exchange of nanoparticle suspensions in polar protic and aprotic solvents and the effect of particle-solvent, membrane-solvent and solvent-solvent interactions will be demonstrated².

References

(1) Tekin, F. S.; Çulfaz-Emecen, P. Z. Controlling Cellulose Membrane Performance via Solvent Choice during Precursor Membrane Formation. ACS Appl. Polym. Mater. 2023, 5 (3), 2185–2194. https://doi.org/https://doi.org/10.1021/acsapm.2c02185.

(2) Özçelik, F. Cellulose Ultrafiltration Membranes for Separation of Nanoparticles from Organic Solvents, Middle East Technical University, 2023. https://hdl.handle.net/11511/105936.

(3) Savaş-Alkan, A.; Çulfaz-Emecen, P. Z. Solvent Recovery from Photolithography Wastes Using Cellulose Ultrafiltration Membranes. J. Memb. Sci. 2022, 647. https://doi.org/10.1016/j.memsci.2022.120261.