Research Highlights

Bug sieve

doi:10.1038/nindia.2009.314 Published online 24 October 2009

Researchers have invented a delicate alumina-based membrane that can purify water by removing Escherichia coli, the smallest water-borne bacteria1.

The researchers prepared a very thin disc-type ceramic membrane made of pure alumina by tape-casting process for microfiltration application. They smeared an ultrafiltration layer on top of the microfiltration layer made of alumina sol. Sophisticated imaging technique showed the gradual change of sol particle to nano-crystalline particles of 5-10 nm.

The researchers tested the usefulness of the membrane for biochemical application by measuring their ability to purify water in terms of bacterial count of E.coli.

It was observed that some of the microfiltration membranes (with an average pore size of 0.12 micrometre) were capable of separating bacteria and some of them (pore size 0.49 and 0.68 micrometre) were capable of removing all bacteria after application of ultrafiltration layer.


  1. Das, N. et al. Ceramic membrane by tape casting and sol–gel coating for microfiltration and ultrafiltration application. J. Phys. Chem. Solid. 70, 1395-1400 (2009) | Article |