The researchers from the Indian Institute of Technology, Guwahati,(IIT-G) have developed two membranes that can separate oil and water. A IIT-G spokesman said the membranes — super-water repellent in air, and super oil-repellent in water — could separate complex mixtures of oil and water. The oil-water separation membranes could also be used in oil spill management.
The research, by Uttam Manna, Assistant Professor, Department of Chemistry, IIT-G, and his team, comprising Avijit Das, Dibyangana Parbat and Arpita Shome, has recently been published in ACS Sustainable Chemistry & Engineering.
The team also developed a prototype of oil-water separation device, to collect the separated oil and water in different containers.
“The oil-water separation is relevant because in many sectors, like mining, textiles, food and petrochemicals, massive volumes of oily wastewater is produced, which must be treated before being discharged,” said Manna.
“In recent times, material scientists have taken cues from nature to develop oil-water separator. The lotus leaf, for example, is water repellent and does not get soggy. The body surface of fish, on the other hand, repels oil to survive in polluted waters,” he said.
Scientists have studied the surface structures of lotus leaves and fish scales to understand superhydrophobicity (super-water repellence) and superoleophobicity (super-oil repellence), to replicate them for oil-water separation applications.
Manna and his team also developed a system of ‘super liquid repellent’ materials, by combining the lotus leaf superhydrophobicity and fish scale superoleophobicity. Layer-by-layer deposition technique was used to obtain alternating layers of ‘chemically reactive polymeric nano-complex’ and ‘amino graphene oxide nanosheets’ on a stretchable and fibrous substrate.
“These systems allow continuous, parallel and selective separation of oil-water mixtures, irrespective of surface tension, density, and viscosity of the oil phase and chemical complexity in the water phase”, Manna said explaining the design of the device.