Tae-Hyun Bae

Amine‐Appended Hierarchical Ca‐A Zeolite for Enhancing CO2/CH4 Selectivity of Mixed‐Matrix Membranes

An amine-appended hierarchical Ca-A zeolite that can selectively capture CO2 was synthesized and incorporated into inexpensive membrane polymers, in particular polyethylene oxide and Matrimid, to design mixed-matrix membranes with high CO2 /CH4 selectivities. Binary mixture permeation testing reveals that amine-appended mesoporous Ca-A is highly effective in improving CO2 /CH4 selectivity of polymeric membranes. In particular, the CO2 /CH4 selectivity of the polyethylene oxide membrane increases from 15 to 23 by incorporating 20 wt % amine-appended Ca-A zeolite. Furthermore, the formation of filler/polymer interfacial defects, which is typically found in glassy polymer-zeolite pairs, is inhibited owing to the interaction between the amine groups on the external surface of zeolites and polymer chains. Our results suggest that the amine-appended hierarchial Ca-A, which was utilized in membrane fabrication for the first time, is a good filler material for fabricating a CO2 -selective mixed-matrix membrane with defect-free morphology.

Membrane-based technologies for post-treatment of anaerobic effluents

Anaerobic digestion-based processes for converting wastewater into clean water and energy are attracting ever-growing industrial interest. However, apart from the microbial digestion step, current technologies require further progress from an integrated process point of view, including post-treatment steps. Anaerobic effluents normally undergo extensive post-treatment steps to meet stringent discharge standards, while valuable nutrients are rarely recovered. Additionally, a significant portion of the produced methane remains inevitably dissolved in the effluent, which is eventually released into the environment, causing economic loss and global warming concerns. To address these issues, several membrane-based technologies show significant promise. Here, we review current progress in membrane-based recovery of dissolved methane and nutrients, highlighting opportunities where membrane-based technologies can improve the post-treatment of anaerobic effluents. Lastly, we also share our perspectives for promising research directions and how to secure the competitiveness of membrane-based technologies for anaerobic wastewater treatment processes, focusing on current challenges for membrane development, biofouling mitigation strategies, and small-scale to large-scale implementation.