Zeolitic imidazolate framework membranes for gas and water purification

Abstract

Zeolitic imidazolate frameworks (ZIF) have a flexible structure, controllable pore size, and thus adjustable properties, which make them effective materials for membrane separation. They have been used as a pure membrane in about 55% of cases, and as a structure modifier of mixed matrix membranes in other cases. ZIF-based membranes have been applied in pervaporation, nanofiltration, reverse osmosis and gas separation processes. This manuscript reviews the role of ZIF in promoting the membrane performance. A new performance parameter is defined based on permeability and selectivity, in order to compare the results of published reports. Findings show that the presence of ZIF in mixed matrix membranes improves the performances of pervaporation by 70%, nanofiltration by 211%, and reverse osmosis by 30%. ZIF also improved 11 times the membrane performance in gas separation, compared to the raw membrane. © 2019, Springer Nature Switzerland AG.