Much of the world continues to face a significant drought caused by the climate crisis, which has increased extreme weather events such as heatwaves over the past year. However, water purification technology has emerged as a great ally in combating this situation.
The latest innovation in this field comes from Hong Kong, where an invention that purifies water 10 times faster, using up to 80% less energy, has been created.
A team of researchers, led by Professor Chuyang Tang, a professor in the Department of Civil Engineering at the Faculty of Engineering of the University of Hong Kong (HKU), has developed a novel nanofiltration membrane that uses natural silk, a sustainable, strong, and biodegradable material.
This innovative technology could completely transform the process of purifying and treating water, a resource that is becoming increasingly scarce.
Advances in nanofiltration with natural silk
Nanofiltration membranes are not new; they are widely used in applications such as treating industrial wastewater or filtering water in households.
These membranes remove a wide range of contaminants, including heavy metals, organic molecules, and microorganisms, while allowing the passage of water and beneficial mineral ions such as calcium and magnesium, essential for human health. However, they present a problem that this innovative membrane solves.
Nanofiltration is a process in which a fluid is passed through a semi-permeable membrane at a certain pressure, separating molecules based on their size.
Current methods require extremely high pressures, up to 10 bar, which entails high energy costs and the need for bulky equipment. This is where Professor Tang and his team’s innovation comes into play.
Innovation and energy efficiency
The team has created a silk nanofiltration membrane with a wrinkle-free rejection layer, capable of purifying water at a much lower pressure. This is achieved by using a partial vacuum of less than 1 bar instead of high pressure.
This approach drastically reduces energy consumption and simplifies the necessary equipment, solving the three main issues of conventional nanofiltration membranes.
During testing, the natural silk model achieved a water flow rate of 56.8 liters per square meter per hour at a vacuum pressure of less than 1 bar, allowing the passage of beneficial minerals and rejecting 99% of organic contaminants from the water.
The researchers also noted that the silk membrane rejected perfluorinated compounds (PFAS), known as “forever chemicals,” found in numerous consumer products and that have raised global concern due to their toxicity and persistence in the environment.
A revolution in water purification
“Our new silk-based membrane is revolutionary. It can filter water almost ten times faster than conventional commercial nanofiltration membranes, while effectively removing harmful contaminants. And it can do so using only a slight vacuum suction, without intense pressure,” stated Professor Chuyang Tang.
The researchers have obtained a patent for this technology, which has been published in the scientific journal Nature Communications.
This new invention is not only highly efficient but also offers sustainability advantages. According to its creators, this “ultra-permeable membrane” reduces energy consumption by approximately 80% compared to conventional nanofiltration systems. Additionally, the use of silk as the main material provides unique properties to this device.
“Silk is an amazing material: resilient, flexible, and eco-friendly. We have leveraged its unique properties to push the boundaries of water purification,” explained Bowen GAN, the lead author of the article and a doctoral student supervised by Professor Tang.
Being biodegradable and environmentally friendly, this membrane is a more sustainable alternative to address the growing global demand for clean water and access to drinking water, especially in areas with limited resources.
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