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    Home > A new kind of defluorination material -- starch like fiber membrane covered with zirconia

    A new kind of defluorination material -- starch like fiber membrane covered with zirconia

    • Last Update: 2019-02-26
    • Source: Internet
    • Author: User
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    Fluorine is one of the essential trace elements in human body, but it has two sides in everything Excessive intake of fluorine will lead to various diseases such as dental fluorosis and osteofluorosis In China, the concentration of fluoride in drinking water is standard, and its maximum concentration shall not exceed 1.0 mg / L However, according to relevant surveys, more than 70 million people in China are drinking water with excessive fluorine content With the rapid development of industry, more and more people will be affected by fluorine pollution Therefore, in order to reduce and prevent the occurrence of fluorosis, scholars have invented a variety of methods to remove fluorine, including precipitation, adsorption, electrocoagulation, physical transfer, ion exchange and so on Figure 1 Preparation process of starch like fiber coated with zirconia nanoparticles (image source: angel Chem Int ed.) recently, Professor Zhang Qingrui of Yanshan University and Professor Raffaele mezzenga of Federal Institute of technology of Zurich, Switzerland, jointly reported a membrane material that can effectively remove fluoride ions from water It is found that the starch like fiber has a high affinity for charged zirconium Based on this characteristic, the author prepared small-sized zirconia (ZrO2) nanoparticles (Figure 1) on the surface of starch like fiber, and combined them with activated carbon to prepare a composite membrane (CAF Zr) which can remove fluorine ions from water This achievement was published in German Applied Chemistry (DOI: 10.1002 / anie 201901596) under the title of "selective and efficient removal of fluoride from water by in situ engineered ammoid fabrics ZrO 2 hybrid members" Figure 2 Morphology characterization of starch like fiber covered by zirconia nanoparticles (picture source: angelw Chem Int ed.) composite membrane is roughly divided into three steps First, β - lactoglobulin monomer is heated at 90 ℃ for 5 h, at this time, β - lactoglobulin will be transformed into amyloid fiber with length of about 3-4 μ m and width of about 5 nm (Fig 2) After that, the author dissolves zirconia dichloride (ZrOCl2) in the aqueous solution containing starch like fiber Depending on the high affinity of amino group and Zr (IV) ion on protein, the zirconium ion in the solution will be loaded on the starch like fiber Then adjust the solution to acid (pH = 3.5-4.0) to obtain ZrO2 nanoparticles with a size of about 7 nm (Fig 2) )The diameter of the fiber also increased to 13-18 nm Finally, the composite membrane caf-zr can be obtained by mixing the starch like fiber solution covered with activated carbon and ZrO2 nanoparticles and filtering them Figure 3 The removal ability of materials to water ions at different concentrations (left) and the removal ability of materials to fluorine ions (right) (picture source: angelw Chem Int ed.) after obtaining composite membrane materials, the author started to study their removal ability to fluorine ions Drinking water contains not only fluorine ions, but also chloride ions, sulfate ions, nitrate ions and other ions, and the concentration is high Therefore, the author first used the commercially available ion exchange resin ira-900 as a comparison to study the selective removal ability of the composite membrane for fluorine ions (left in Figure 3) The results show that the removal ability of ira-900 to fluoride is similar to caf-zr when the concentration of other ions is low, but with the increase of concentration of other ions, the latter still maintains a high removal ability, while ira-900 is almost inactivated Then, the author studied the removal ability of caf-zr and several reference materials to fluorine ions under different concentrations and acid conditions (right in Figure 3) The results showed that caf-zr showed the best removal effect under various concentrations and acid conditions Fig 4 Removal ability of caf-zr to fluoride ion in actual drinking water (picture source: angelw Chem Int ed.) Finally, the author studied the removal ability of caf-zr to fluoride ion with actual drinking water as sample The results showed that the removal efficiency of fluoride reached 99.5%, and the maximum removal amount of fluoride reached 1750 kg / M 2 Full text author: Raffaele mezzenga, Qingrui Zhang, sreenath bolisetty, Yiping Cao, Stephan handschin, Jozef adamcik and Qiuming Peng.
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