Novel multilevel dispersion strategy produces high-efficiency membrane for bioethanol recovery

The purification of bioethanol from fermentation broths is a critical step in renewable fuel production. Pervaporation has emerged as a sustainable and highly efficient method for bioethanol extraction. In this process, mixed matrix membranes containing specialized nanofillers can selectively separate ethanol from water. However, the performance of these membranes is often limited by the agglomeration of nanofillers within the polymer matrix, which blocks transport pathways and reduces efficiency.

Researchers from Beijing University of Chemical Technology and Xinjiang University have now developed an innovative strategy to overcome this limitation. As reported in a study published on July 1, 2025, in Frontiers of Chemical Science and Engineering, they propose a multilevel dispersion strategy integrating in situ confined growth with ultrasonic spraying and rotational shear technology to suppress graphdiyne agglomeration.

The key advancement is the multilevel dispersion approach. Triphenylamine-based graphdiyne particles are first in situ synthesized within the PDMS solution to avoid agglomeration during drying. Subsequently, ultrasonic cavitation disrupts interparticle agglomerations for further dispersion. Then, the droplets are sprayed in an atomized state, and the particles are dispersed within the small droplets. Finally, the particles are deposited with the droplets onto the surface of the high-speed rotating base membrane under the action of shear force.

This synergistic combination of dispersion techniques significantly reduces nanofiller agglomeration in the polymer matrix. The particle agglomeration scale in the polydimethylsiloxane matrix can be effectively reduced from about 660 nm to about 291 nm. With an optimal loading of 2.5 wt% TPNGDY, the membrane achieved the reported high performance. A 96-hour continuous pervaporation test indicated the robust stability of the membrane.

The high performance is attributed to the uniformly dispersed TPNGDY particles endowed with a nanoscale pore distribution, which led to the construction of a fast mass transfer channel for ethanol. The membrane achieved a synergistic enhancement of permeation flux and separation factor, effectively overcoming the trade-off effect.

This work provides valuable insights into the development of efficient bioethanol recovery technologies and advances the development of sustainable technologies for molecular separation processes.