In a laboratory at Wuhan University of Science and Technology on April 2nd, Professor Zhou Zhihui shared with Science China that they have hit another milestone in overseas markets. Out of eight bids submitted this year, this marks the seventh successful one.
Over the past two decades, Zhou Zhihui and his team have traversed the path from researching membrane separation technology to developing membrane products and then to innovating membrane-based recycling systems. Today, not only has he popularized permeable gasification membranes nationwide with a market share of 70%, but he has also made significant strides in international markets. Behind the successful technology transfer lies Zhou's relentless pursuit of targets and continuous efforts in tackling challenges.
Professor Zhou Zhihui of Wuhan University of Science and Technology. Photo by Cheng Yu
Thin Membranes, Not to be Underestimated
Walking into Zhou Zhihui's laboratory, there are several metal trays on the table. Inside the trays, more than a dozen tubes resembling white chalk catch the eye. These tubes are coated with his developed permeable gasification membranes—nanometer-scale pores that are invisible to the naked eye and untouchable by hand.
"Solutions pass through these membranes, with large molecules being retained while small ones pass through, thereby achieving separation, purification, or concentration of the solution," Zhou Zhihui explains. Membrane separation technology is an efficient and energy-saving new separation technology. Some experts have pointed out that whoever masters membrane technology will master the chemical industry.
Twenty years ago, while pursuing his master's degree, Zhou Zhihui followed his mentor to conduct research in chemical enterprises. In the steam-filled production workshop, dozens of tanks were undergoing solution separation. This distillation separation had to be conducted at high temperatures, which not only consumed a lot of energy and resulted in low purity, but also polluted the environment and posed risks of fire and explosion.
At that time, foreign teams were already working on membrane separation technology. Zhou Zhihui became the first in his mentor's team to research permeable gasification membranes for his doctoral studies. He conducted a large amount of basic research in the laboratory and published a series of papers before coming to work at Wuhan University of Science and Technology.
Should he continue researching the seemingly insignificant membranes, or should he pursue other glamorous work? While hesitating, a high-tech solvent purification company in Wuhan noticed his papers and sought him out. According to the company's needs, he spent six months developing a 6-square-meter membrane. After the company used it, product quality improved, production costs decreased, and environmental pollution reduced, achieving satisfactory results.
At that time, China was advocating and practicing the concept of "green mountains and clear waters are golden and silver mountains," which strengthened his determination to focus on researching environmentally friendly membrane separation technology.
However, his first major project encountered troubles.
A pharmaceutical company in Wuhan needed 50 square meters of membrane and supporting equipment, with a one-month delivery requirement. Zhou Zhihui found a partner responsible for developing the equipment, while he himself focused on developing the membrane. Every day, he and his team could only produce 1 to 2 square meters of membrane. In order to meet the delivery deadline, he worked almost tirelessly, his eyes becoming red from lack of sleep.
Unexpectedly, problems kept arising after the company used the membranes. Zhou Zhihui visited the site and initially thought it was due to inadequate sealing between the membrane and the equipment. After solving the sealing problem, the membrane kept breaking. He took the broken membranes back to the laboratory for inspection and found "it was not a problem with the membrane." He returned to the site and found rust in the tanks containing the solution. After replacing the tanks with stainless steel ones, the use of the membranes finally returned to normal. He spent nearly half a year visiting this company every week, eventually solving the problem.
Through this ordeal, Zhou Zhihui realized that not only did he need to develop good membranes, but he also needed well-designed supporting equipment. He couldn't find relevant information online, so with the support of the university, he rented a workshop and started industrial research and development.
Using Membranes to Reduce Carbon Emissions
In order to produce ideal equipment, Zhou Zhihui self-studied mechanical and automation technologies, repeatedly visited companies, and sought advice from technical workers. After drawing up the blueprints, he communicated with equipment factories and technicians, adjusting parameters repeatedly. It took half a year to make the first piece of equipment, which he learned to operate himself before teaching the workers and then finally handing it over to the company.
The membrane tubes produced in the laboratory are generally 10 to 12 centimeters long, only the size of a piece of chalk, and have excellent separation effects. However, the membrane tubes required for continuous production in companies need to be at least 80 centimeters long, or even longer. How to ensure the uniform distribution and continuous density of membrane pores?
The thickness of the membrane is only 1/200 of a hair's width. The pore size of the membrane is in the nanometer range. For example, the diameter of ethanol molecules in alcohol is 0.42 nanometers, while the diameter of other molecules is 0.5 nanometers. The pore size of the membrane needs to be between 0.42 and 0.5 nanometers. Such a pore size needs to be magnified 300,000 times to be visible. The difficulty of membrane development can be imagined.
After repeated design and experimentation, they developed a series of new technologies, realizing the low-carbon synthesis and stable continuous production of membranes. Laboratory tests showed that alcohol was intercepted by the membrane, impurities passed through the membrane and were gasified, resulting in high-purity alcohol. The entire process is energy-saving, safe, and environmentally friendly.
However, what is cultivated in the laboratory are "greenhouse flowers," while industrialization requires "wild grass" due to the complexity of the environment. How to make membranes and equipment resistant to acid, alkali, and strong adsorption? Zhou Zhihui led his team to visit companies, collected various influencing factors on-site, and continuously adjusted designs and parameters back in the laboratory.
After more than ten years of research and development, they finally overcame a series of difficulties and achieved industrial application, becoming the pioneers in China to promote the industrialization of permeable gasification membranes.
An enterprise calculated that after using permeable gasification membranes, operating costs were reduced by at least 80%. The cost could be recouped in as quickly as two months or as slowly as half a year, while also achieving the effect of "using membranes to reduce carbon emissions."
How to encourage more companies to adopt this technology? Different industries and enterprises have different requirements for membrane pores and equipment. The way of dealing with different regions and bosses also varies. Zhou Zhihui's experience is: "Start with quality. If companies require 80 points, we should deliver at least 90 points."
With excellent capabilities and a good reputation, they gradually expanded into the market in Hubei province. Enterprises in Jingzhou, Yichang, Xiangyang, Shiyan, and other places in Hubei province are using more and more of their products, with more than 60 companies becoming their "clients."
In 2020, the country clearly proposed the "dual-carbon" goal. Zhou Zhihui increased market promotion efforts, and by 2023, their products were selling in over 90% of provinces in China, being used by more than 300 companies, and leading in sales nationwide.
"Chinese Membranes," Going Global
It is understood that membrane applications are very wide-ranging, with more than 90% of daily necessities requiring them. For example, pure water needs to remove impurities; alcohol needs to increase ethanol concentration; medicines need to screen for required compounds; chips need to refine high-purity solutions... Using membrane separation technology and membrane circulation equipment not only allows for precise separation of useful liquids but also enables the recycling of wastewater and exhaust gas for reuse, achieving nearly "zero" emissions.
The more membranes are used, the less carbon emissions there will be." Zhou Zhihui is pushing for the industrialization of membranes while researching applications for a wider range of scenarios, striving to encourage more enterprises to adopt this technology.
He told Science China Press that the widespread application of membrane technology is still insufficient. Currently, over 90% of separation processes in the market still rely on distillation, which is energy-intensive. Using membranes is an important step towards energy conservation and will help drive the transformation and upgrading of industries such as chemicals, pharmaceuticals, electronics, and new energy.
Last year, following the strategy of "developing one generation, producing one generation, and reserving one generation," he divided the team into three groups with the aim of developing "mixed membranes" – a type of membrane that can be used for the separation of any solution.
Zhou Zhihui often tells his students and colleagues, "Let's speed things up." With a series of innovations in key technologies, Zhou Zhihui quickly led the team to build over 600 sets of complete equipment for pervaporation membranes. Each unit can process over 100,000 tons of solvent per year. Over the past two years, they have generated an additional economic benefit of 1.088 billion CNY for various enterprises and reduced carbon dioxide emissions by 221,000 tons.
In 2023, membrane-related projects at Wuhan University of Technology won the first prize for scientific and technological progress in Hubei Province and received orders from companies in the United States, India, and other countries. A thin layer of "Chinese membrane" has thus stepped out of the country and onto the world stage.
