Electron Microscopy: An Important Tool for Preparation and Characterization of Asymmetric Ceramic-Polymer Composite Nanofiltration Membrane

Membrane technology has emerged as an important tool in sustainable management of water and energy owing to its high efficiency and low footprint. Ceramic polymer composite membranes are an emerging category which tends to combine the merits of both pure ceramic and polymeric membranes. The present work elucidates the role of electron microscopy in preparation and characterization of novel ceramic-supported-polymeric asymmetric composite membrane developed by successive pore size reduction of commercial macroporous ceramic support. In each step of preparation process, formation of a layer (ceramic intermediate layers and polymeric functional layer) with conforming properties was evaluated and its morphology was studied in details with the help of Field Emission Scanning Electron Microscopy (FESEM) analysis. An amine-functionalized composite membrane was developed using polyethyleneimine as functional layer material over modified alumina-based ceramic substrate. The membrane was found to exhibit a water permeability of 3.9-3.1 L m-2 h-1 bar-1 and a low molecular weight cut-off (< 2000) suggesting its nanofiltration nature toward contaminant rejection. The membrane demonstrated a maximum removal of 93.5% of Crystal Violet dye from 25 mg/l aqueous solution at 4 bar pressure. The excellent stability of the membrane in high-pressure application suggests its potential use in other nanofiltration application.