In a significant breakthrough to solve fresh water deficiency in different parts of the world, scientists from the Indian Institute of Technology Bombay have developed a new material that can facilitate water desalination.
Scientists Professor Swatantra Pratap Singh and Aiswarya CL have developed dual ghostly superhydrophobic laser induced graphene (DSLIG), which deals with several shortcomings of earlier evaporation and has the potential for large applications.
While the water is abundant on the ground, only about 3% of it is fresh water, and even in less than 0.05% is easily accessible. The removal of salt (desalination) of seawater and brackish water is considered one of the solutions for solving this problem, and scientists are working to develop more efficient and faster desalination techniques. However, the brine (concentrated salt solution) of desalination is a big problem in inland places and the industry is looking for zero liquid discharge.
Scientists have stated that solar -based desalination methods are considered desirable because of their reduced carbon footprint. However, factors such as intensity fluctuations and the availability of sunlight and reduced light absorption levels significantly affect the efficiency and consistency of desalination techniques based on solar energy.
Mr. Singh explained that in recent years systems of evaporation of interiphases have appeared as a promising approach. A key part of these systems is a evaporator made of materials that can absorb solar energy and warm up. The evaporator, located on the water surface, lags behind the solar heat on the thin layer of water on the surface of the evaporator than the heating of the entire volume. This localized heating minimizes heat loss and increases the efficiency of the desalination process.
Despite this advantage, however, problems with traditional solar desalination techniques are also influenced by intermediate vapors.
“Sunlight fluctuations cause temperature changes on the evaporator surface. On cloudy days, the performance of the intermediate system is stopped due to lack of solar energy.
Another major challenge with the evaporation systems of intermediate evaporation is the storage of salt crystals on the surface of the evaporator. The storage of salt on the surface prevents water from contacting the evaporator, and then its efficiency decreases over time. The aim of this research is to solve both these problems. In addition to solar heating, DSLIG vapors can also be heated by electricity (known as Joule Heating), said Mr. Singh.
By combining solar and electric heating, the material is protected from fluctuating the availability of sunlight. If there is less or no sunlight, electricity can be used to heat the evaporator and maintain similar temperatures, which ensures consistent performance. In addition, the DSlig has a superhydrophobic property, which means it repels water as lotus leaves.
Due to the characteristics of their surfaces, the superhydrophobic materials reduce the contact surface between the water droplets and the surface of the material, so that the droplets roll them instead of wetting.
“In desalination applications, the superhydrophobic nature of the DSLIG helps to prevent salt dissolved in water from gluing to the surface of the evaporator, maintaining efficiency over time. The primary goal of our work was to create a superhydrophobic surface, exposing a lotus effect that is able to function with solar and joule,” Mr. Singh explained.
Scientists have made a dslig by coating a layer of polymer called polyvinylidene fluoride (PVDF) on one side of a thin layer of another polymer league, poly (ether sulfon) (dog). Grafen was then engraved on the polymer side of the PVDF material using laser engraving technology. “The material derives its name from the fact that it has two different sides consisting of two polymers and used production technology. The dog does not forgive water, but it is necessary to prevent easy evaporation. It contributed to hydrophobic characteristics necessary for effective evaporation processes,” said the professor.
Laboratory tests show that DSlig not only shows the behavior similar to lotus leaves, prevents salt storage and excellent efficiency for desalination in electrical and solar heating, but is also very effective in the treatment of extremely concentrated salt solutions. As a result, it is an ideal candidate for the treatment of salt water discharges from other desalination outlets and industrial waste water.
Scientists have also shown that DSLIG performance improves when more vaporizers are stacked. While low carbon footprint, low toxicity and cost efficiency make DSLIG a potential candidate for extensive sustainable application of desalination and cleaning of industrial waste water. Mr. Singh said that further testing in the field is required before this extensive application.
“One of the main obstacles faced by the team in ensuring and testing the industrial readiness of this technology is the lack of funding. Meanwhile, we are looking forward to the development of other such superhydrophobic materials that can also use solar and electricity with even greater efficiency,” added Mr. Singh.
Published – April 17 2025 07:49 IS
