Pore Engineering of MFI Zeolite Membranes: Enhancing Water Flux and Ion Rejection Using Polyacrylamide as a Secondary Template

R. Shahbaz and M. J. Vaezi

Abstract
A mesoporous MFI zeolite membrane was synthesized using polyacrylamide as a secondary template to separate nickel, chromium, and nitrate ions from water. Various analytical methods were employed to characterize the zeolite powders and membranes. Subsequently, tests were conducted to evaluate water permeation and the rejection of heavy metals and nitrate ions. The incorporation of 0.03 kg kg–1 polyacrylamide resulted in a 90 % mesostructure in the MFI zeolite. Higher amounts of polymer had no positive effect on the mesoporous structure. The membrane demonstrated a high water flux (22 L m–2 h–1) with 99 % nickel and 93 % chromium rejection, and effective nitrate rejection (up to 34 %). Increasing the total dissolved solids from 1 to 1000 µA A–1 led to a 50 % increase in water flux. Additionally, raising the pressure by 2 bar resulted in an 80 % increase in the water flux and 15 % improvement in nitrate rejection.

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Keywords
MFI zeolite membrane, secondary template, polyacrylamide, mesoporous structure, ion rejection