Through extensive and consistent doctoral research, Rahmah, a recipient of the Master’s-to-Doctoral Education Program for Outstanding Bachelor’s Graduates (PMDSU) scholarship, successfully compiled and analyzed a comprehensive database of zeolite membranes demonstrating exceptionally high CO2 separation performance. Their performance significantly exceeds that of polymer membranes, which have served as the global benchmark for decades.

The culmination of this research is the “Rahmah Upper Bound,” a new performance boundary developed from the renowned Robeson Upper Bound. For more than three decades, the Robeson Upper Bound has been regarded as a “natural barrier” limiting membrane performance because of the trade-off between permeability and selectivity. The Rahmah Upper Bound represents the first major crack in that barrier.

Supported by extensive data, the new boundary clearly demonstrates that the fundamental limit once considered nearly impossible to surpass can, in fact, be shifted through the design of zeolite-based membrane materials.

This discovery is more than an incremental improvement. It provides a new reference for the global membrane research community in reassessing the long-established understanding of performance trade-offs in gas separation membranes. In other words, the Rahmah Upper Bound changes how researchers worldwide map the potential of membrane materials while opening up a design space that was previously considered inaccessible.

The research has been published in a top-tier international journal and has received 83 citations to date, reflecting its considerable influence within the global scientific community. These citations demonstrate that the Rahmah Upper Bound is regarded not only as theoretically significant but also as a practical reference for research on CO2 separation and capture, low-carbon technologies, and climate change mitigation strategies.

This achievement demonstrates that Indonesian doctoral researchers are capable of standing alongside their international counterparts and even providing new direction within global scientific discourse. It also highlights the effectiveness of the PMDSU program in developing outstanding researchers while strengthening the position of ITB and Indonesia as important contributors to the advancement of membrane science and technology worldwide.

Rahmah’s closed doctoral examination, entitled “A Green Approach to the Synthesis of CHA Zeolite Membranes: A Study of the Trapped-Gel Method for Carbon Capture Processes,” was held on Friday, January 9, 2026, at ITB Ganesha Campus.

The supervisory team consisted of Prof. Ir. I Gede Wenten, M.Sc., Ph.D.; Prof. Dr. Ing. Ir. Danu Ariono; and Dr. Ir. Khoiruddin, S.T., M.T.

The publication on the upper bound is available at: https://doi.org/10.1016/j.jece.2022.108707