Academician Hou Li'an: water environment management urgently needs "membrane" technology

    New materials online, September 26: on September 25, Hou Lian, academician of Chinese Academy of engineering, delivered a speech entitled "new membrane separation materials help the continuous improvement of water environment quality" at the "2020 China new materials capital technology conference".

    "Green water and beautiful scenery is Jinshan Yinshan". Under the guidance of general secretary Xi Jinping's "two mountains" theory, after 15 years of development, the water quality of our country has improved significantly. During this year's NPC and CPPCC sessions, Huang Runqiu, Minister of the Ministry of ecological environment, once again stressed that in terms of establishing the strategic commitment of ecological environment protection, ecological environment departments should be firm in three aspects.

    The increasing popularity of green development and sustainable concept puts forward higher performance requirements for membrane materials used in environmental protection engineering, which not only requires energy saving and high efficiency, but also has the advantages of high flux, long life and strong anti pollution performance. Academician Hou Li'an has a positive attitude towards this, he said: "the development of materials science has greatly promoted the progress of membrane materials, and the new membrane technology meets the policy requirements of" clean production, energy conservation and emission reduction "in China, and has a role in promoting national policies."

    Entering the period of rapid growth, new materials have new breakthroughs

   Membrane separation technology is regarded as one of the most valuable landmark achievements in the 21st century. It is the key technical means to solve the global energy crisis, environmental crisis and other major problems,

    After two stages of initial development and initial scale, the development of membrane industry in China has entered a period of rapid growth. The engineering application scale of reverse osmosis, ultrafiltration, microfiltration and other membrane technologies in the fields of energy and power, non-ferrous metallurgy, seawater desalination, water treatment, wastewater reuse, medicine and food has expanded rapidly.

    Relevant data show that from 2011 to 2018, the average annual growth rate of China's membrane industry will remain above 24%. In 2018 alone, the market scale of China's membrane industry will reach 190 billion yuan, and the output value is expected to be close to 360 billion yuan by 2024.

    The prosperity of membrane material industry depends on the close demand of downstream application fields, and water environment treatment is one of the major application fields.

    Water resources development, standard discharge, reclaimed water reuse and emergency disposal are the main application fields of traditional membrane technology. In addition, drinking water purification, seawater desalination and reclaimed water recovery are also important application stages of membrane technology.

   Although the traditional polymer separation membrane has many kinds, various treatment objects and wide range of applications, it is developing rapidly at present, but there are still two bottlenecks in the application of water environment treatment.

    First, with the increasingly high requirements of modern production teams in enterprises, conventional membrane materials can not effectively solve the technical problems of filtration in high temperature, high pressure and corrosive environment, so many industries and enterprises encounter development bottlenecks.

    Second, in the application process, the improvement of the permeability and selectivity of the membrane always has the "seesaw effect". At the same time, if it is used for a long time, it will not only shorten the service life of the membrane, affect the separation performance of the membrane, increase the operation cost, but also prone to concentration polarization and membrane pollution.

     Three challenges to be solved: the emergence of new materials and new technologies

   With the rapid development of science and technology, new materials and new technologies are constantly emerging. The breakthrough of membrane industry development is to improve the innovation consciousness and innovation ability of membrane industry, and to solve the bottleneck problem of membrane industry by using modern science and technology.

    Academician Hou Li'an believes that "new membrane materials are the key to the development of current membrane technology". Based on graphene, metal organic framework materials, organic covalent framework materials, carbon nanotubes, molecular sieves, hydrotalcite like and other new separation membranes, ultra-thin separation layers with nano channels can be constructed, showing far more permeability than traditional polymer membranes, which is expected to break through the gap between permeability and selectivity The limitation effect of the model. It is necessary to develop new membrane materials with high selectivity and permeability for water treatment.

    "The design of new membrane structures and functions based on different material systems, such as polymer materials, inorganic materials, composite materials and nano materials, is a research hotspot at present, and also the key to further in-depth research and application development of membrane separation technology," he further said

    In terms of membrane technology, it is the pursuit of current membrane science research to innovate new membrane separation technology with multi process coupling and suitable for unconventional environment. It is necessary to accelerate the development of membrane chemical reactor, vibrating membrane, forward osmosis, membrane electrochemical coupling, photochemical oxidation membrane method and other new processes.

    Of course, the research and development of new materials and technologies inevitably encounter challenges. "Separation mechanism, biosafety and efficient integration are the main challenges for the development of new membrane technology," academician Hou Li'an said.

    Encourage membrane technology innovation to improve water environment quality

   Only by constantly breaking through the technical bottleneck can we help improve the comprehensive national strength.

   The research of membrane technology in China started late, and the influence of national brand membrane products needs to be improved. We should increase the investment in membrane technology research, encourage technological innovation, and promote the continuous progress of membrane science.

   Aquaporin, graphene, carbon nanotubes and other foreign scientists have won awards for their technology, and Chinese scientists have achieved technological breakthroughs by relying on the spirit of scientific research, and gradually transformed into landing products. However, there is still room for improvement in the research of permeability, pollution resistance, mechanism, and other aspects, and the development of new membrane materials such as organic covalent framework membrane, metal organic framework membrane, etc The same is true of research.

   Taking Turing pattern structure separation membrane as an example, academician Hou Li'an pointed out the upgrading route of membrane material performance. He proposed: "based on Turing's" reaction diffusion "control theory, improve the traditional interface polymerization membrane preparation method, obtain the separation membrane with pattern structure on the surface, improve the effective permeability area of the separation membrane, so as to improve the permeability of the membrane."

    New membrane process is another content that academician Hou Lian repeatedly emphasized to upgrade. He pointed out that the technical level of forward osmosis, membrane filtration coupled with advanced oxidation and other processes in China still needs to be strengthened.

    At the same time, academician Hou Li'an also called for strengthening the research on the ecological safety of nano materials. In this regard, the United States has been active for a long time. Since 2005, the proportion of annual investment in nanotechnology in the field of environment, health and safety has increased from less than 3% in 2005 to 7% in 2017, and the total investment has exceeded US $1 billion.

    In addition to strengthening the research and utilization of materials and technologies, academician Hou Li'an believes that in the process of using new membrane materials to promote the improvement of water environment quality in China, we should strengthen the research on membrane separation mechanism, strengthen the optimization and integration of new membrane process, enhance the power guarantee of membrane process, improve the laws and standards related to membrane technology, pay attention to waste disposal in membrane process, and face the future The establishment of a new "smart water plant" can not be ignored.

    In particular, the world has entered the era of big data. Based on the comprehensive utilization of big data and the breakthrough of all membrane combined process technology, the development of forward-looking "smart water plant" will help to improve the utilization efficiency and security level of water resources. Moreover, the "smart water plant" can achieve the goals of flexible membrane treatment process, intelligent management and multi-level water quality. It can become a truly social and mutually beneficial urban infrastructure and help to ensure urban water safety.

    As for how to start with membrane materials to strengthen ecological and environmental protection, academician Hou Li'an summed up: "to give full play to the function of new membrane technology in environmental quality improvement, we should start with scientific research investment, material development, technological innovation, process research and development, laws and standards, and promote environmental quality improvement."