BENGALURU: To make water purification greener, Indian Institute of Science (IISc) scientists have developed a way to make faster evaporation techniques. The study was done by researchers from the Department of Chemical Engineering (CE), IISc.
At present, water purification, particularly for desalination, makes use of membrane distillation, which works by evaporating contaminated water. The vapour passes through a porous material. Due to the flexibility in heating water through renewable energy, the process of membrane distillation is preferred for water purification.
To bring down the use of energy for evaporation, IISc researchers have arrived at a combination of the perfect membrane and water solution, which precipitates evaporation compared with other combinations of membrane and water solution.
Researchers said they used nanoporous graphene, a material that is highly hydrophilic (incredibly water absorbent).
In particular, the type of graphene that they found was highly effective, at the ångström scale. One ångström is one ten-billionth of a metre. Working at that scale, the researchers used different solutions of water, including water mixed with potassium chloride, sodium chloride and lithium chloride, for membrane distillation. Experiments revealed that the fastest evaporation and water vapour absorption occurred with nanoporous graphene that was 4.53 ångström with a potassium chloride mixture.
The researchers could increase the rate of evaporation 35-fold. They said that this would reduce the energy requirement of the process.