A research team led by Professor Tang Chuyang from the Department of Civil Engineering of the University of Hong Kong found that this membrane can quickly filter heavy metals such as lead (Pb), nickel (Ni), cadmium (Cd) and chromium (Cr) while eliminating E. coli and Bacillus subtilis While waiting for bacteria, the efficiency exceeds 99.9%. Membrane filters are easy to operate through a gravity-driven filtration process and can be reused after rinsing with vinegar.
The invention won a gold award at the 47th Geneva International Invention Exhibition earlier this year. It has obtained US and Chinese patents and is applying for another US patent. It is expected that technology transfer, licensing and commercialization will soon take place. The material is expected to be used in domestic water purifiers and portable water filter bottles. The project is funded by the Innovation and Technology Fund of the Hong Kong Government's Innovation and Technology Commission.
Since 2014, the research team has been working on developing an efficient membrane to rapidly filter contaminants and bacteria in water. The newly invented nanofiber membrane is manufactured by electrospinning technology, which uses electricity to spray a polymer solution onto nanofibers and stretch its diameter to 10 to 100 nanometers. Their different sizes enable nanofibers to handle a variety of target contaminants with different properties. These nanofibers are then woven into a nanofiber membrane.
This new nanofiber membrane provides an efficient, convenient and inexpensive solution for filtering heavy metals and bacteria in water. After filtration with this membrane, the concentration of heavy metals in drinking water was significantly lower than the threshold set by the World Health Organization (WHO). It also performs better than commercial water filters using activated carbon. In a feed solution of 50 μg / l (ppb) of lead (the safe level of lead in WHO's drinking water is 10 μg / l (ppb) or lower), the removal efficiency exceeds 99.9%. The same level of efficiency is achieved by removing nickel and other heavy metals (such as cadmium and chromium) commonly used in pipes and fittings. Bacteria such as E. coli and Bacillus subtilis are almost completely removed in this process.
Other conventional water treatment methods for removing heavy metals, such as reverse osmosis and distillation, consume energy. The nanofiber membrane does not require any electrical or energy input in its operation. It can be reused multiple times because the captured contaminants can be removed simply by rinsing the membrane in vinegar. Since the raw materials for the membrane are cheap, the price of this nanofiber membrane filter is expected to be 30% to 50% cheaper than similar products using carbon filters on the market.
Professor Tang said, "This nanofiber membrane was originally designed to address the urgent need for cleaning and drinking water after major natural disasters. After an earthquake or tsunami, there is often a lack of reliable sources of clean water or electricity, so you need some practical Disaster relief solution. Our filter is perfect: it provides safe drinking water in less than a minute. Simple and reliable, no electricity required. It is compact and fits easily in a pocket. The filter is also popular with travelers and adventures Great interest and attention of the people. "
Looking ahead, Professor Tang and his team are working to expand the capabilities of nanofiber membranes to filter a wider range of pollutants and achieve rapid water purification.