Preparation of stable and regenerable ceramic-supported-polymeric composite nanofiltration membrane with high flux and heavy metal removal performance

Novel thin film composite nanofiltration membranes were prepared over ceramic substrate by interfacial polymerization (IP). Glutaraldehyde (GA) was used as crosslinker between aqueous phase monomer polyethyleneimine (PEI) and the ceramic surface in order to enhance the attachment between polyamide functional layer and ceramic substrate. PEI was further reacted with trimesoyl chloride (TMC) by IP technique to create denser crosslinked structure with lower pore size. The effect of GA crosslinking on IP of PEI and TMC was studied by varying the concentration of GA and PEI. Different coating approaches were explored to form stable and uniform functional layer over ceramic substrate. A series of composite membranes were fabricated and characterized using FESEM, EDX and XPS analyses. The membrane with optimum properties exhibited clean water permeability in the range of 20-32 Lm- 2h-1bar- 1 and highest rejection of 99.5 % for Cu(II), 99 % for Pb(II), 85 % for As(V) and 60 % for Cr(VI) from 5 mg/L aqueous solution. Finally, the robust ceramic substrate was regenerated by removal of the polymeric functional layer with 1000 mg/L & sdot;hr of free chlorine treatment followed by 1 min of ultrasonication at 33.3 KHz. Composite membrane prepared using the regenerated ceramic substrate showed similar flux and rejection properties compared to virgin membrane.