Antibacterial membranes for purifying water
doi:10.1038/nindia.2014.128 Published online 24 September 2014
Researchers have developed porous, antibacterial membranes from graphene oxide film and the common plastic polyethylene1. These membranes are promising for purifying water contaminated with disease-causing bacteria.
The researchers used a technique called melt mixing to synthesize two membranes: one made from modified graphene oxide and polyethylene and the other from modified graphene oxide, maleated polyethylene and polyethylene. They then created microscopic pores in the membranes by mixing the membranes with polyethylene oxide, which they later rinsed out using water.
The researchers tested the efficiencies of the membranes to filter harmful bacteria such as Escherichia coli from contaminated water and compared them with that of a control membrane made from polyethylene and polyethylene oxide. They performed the experiments by dipping the membranes in phosphate buffer solutions containing the bacteria.
They found that the membranes with graphene oxide filtered bacteria more efficiently than the control membrane. The membrane containing modified graphene oxide and polyethylene exhibited the highest efficiency for filtering bacteria.
The researchers found dead bacteria on the graphene-oxide-based membranes. They attributed the antibacterial properties of the membranes to modified graphene oxide, which probably ruptured the membranes of bacterial cells by generating reactive oxygen species. The pore sizes of the graphene-oxide-based membranes are between 0.5 and 0.7 micrometres, enough to remove bacteria and colloids bigger than 1 micrometre.
“Given their small sizes, the membranes could potentially be used to increase the efficiency of a water purification technique that employs reverse osmosis system,” says Suryasarathi Bose, a senior author of the study.
The authors of this work are from: Center for Nano Science and Engineering, Department of Chemical Engineering and Department of Materials Engineering, Indian Institute of Science and Polymer Science Diagnostic Center, Steer Engineering Pvt. Ltd, Bangalore, India.