《Enhanced Adsorptivity of Hexavalent Chromium in Aqueous Solutions Using CTS@nZVI Modified Wheat Straw-Derived Porous Carbon》

  • 来源专题:现代化工
  • 编译者: 武春亮
  • 发布时间:2024-06-05
  • Through the XRD characterization of the three materials, a distinctive diffraction peak appears near 20°, as illustrated in
    Figure 3
    c. Comparison with the PDF card, the characteristic peak suggested the presence of certain carbon material composition in the three materials [
    31
    ]. The introduction of nZVI and CTS did not alter the structure and composition of the original biological carbon. No significant deviation was observed in the characteristic peaks of nZV-WSPC and CTS@nZVI-WSPC, indicating a minimal difference in their crystal structure. This is attributed to the fact that CTS acts as a natural polymer polysaccharide, with characteristic diffraction peaks predominantly occurring at 10–20°. The appearance of this characteristic peak is a result of intermolecular or intramolecular hydrogen bonds stemming from the presence of -OH and -NH
    2
    functional groups in CTS [
    32
    ,
    33
    ]. Many salts or oxides tend to disperse on the carrier surface to form monolayers and submonolayers. In the case where the loading amount is below a certain threshold, a monolayer dispersion state is maintained, and the active component cannot be detected by X-ray. From the XRD profile, it is evident that nZVI was successfully synthesized in both composites. The diffraction peaks are located at 30.27°, 35.68°, 44.5°, 57.4°, and 63.25°, corresponding to different forms of iron (Fe), with the peaks at 44.5° and 63.25° specifically indicating the presence of nano-zero-valent iron, as reported in various literature sources [
    34
    ]. Moreover, the diffraction peaks of CTS@nZVI-WSPC at 2θ = 29.9°, 40.17°, and 55.08° align well with the ferric oxide standard card, which appears after the adsorption reaction [
    35
    ,
    36
    ]. The characteristic peak band at 35.19° represents the formation of ferric oxide, suggesting that the composite may undergo oxidation after the reduction by iron particles, which is consistent with the XPS analysis results. The comprehensive analysis showed that the introduction of nZVI and chitosan did not alter the carbon structure of the raw wheat straw. After the reaction, the material’s structure remained largely unchanged, retaining a stable morphology.
  • 原文来源:https://www.mdpi.com/2079-4991/14/11/973
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    • 来源专题:现代化工
    • 编译者:武春亮
    • 发布时间:2024-06-05
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  • 《Key Technologies of Terahertz Wave Modified New Materials Initiated in China》

    • 来源专题:宁夏重点产业科技信息服务
    • 编译者:刘 悦
    • 发布时间:2025-06-05
    • Recently, good news came from Zhumeng Jiuzhou Technology Co., Ltd., located in Beijing. After more than 10 years of intensive research and repeated experiments by the company, an energy support device (waveguide cabin) that can generate terahertz waves and empower a variety of materials through waveguide effect and molecular synchronous resonance technology has been successfully launched. And formally began to serve the chemical industry and new materials and other fields, marking a major breakthrough in the industrial application of terahertz technology, which is the first domestic invention and is also in the leading position in the world. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; It is reported that terahertz (THz) waves refer to electromagnetic waves with frequencies ranging from 0.1 to 10 THz (wavelengths ranging from 30 to 3000 μm). The terahertz (THz) wave band can cover the characteristic spectrum of semiconductors, plasmas, organisms and biological macromolecules. The use of this frequency band can deepen and expand human understanding of some basic scientific issues in physics, chemistry, astronomy, informatics and life sciences. THz technology can be widely used in radar, remote sensing, homeland security and anti-terrorism, high-security data communication and transmission, atmosphere and environmental monitoring, real-time biological information extraction, medical diagnosis and other fields. Therefore, the research of THz technology has great application value for the national economy and national security. & lt; br & lt; span style = "height: 6px; display: block;" & gt; & lt;/span & gt; THz is the last virgin land in the electromagnetic spectrum. It is favored by all countries because of its unique advantages and wide application value. In 2004, the U.S. government rated THz technology as one of the "Top Ten Technologies to Change the Future World", and almost all important national laboratories are studying THz technology; Japan listed THz technology as the first of the "Top Ten Key Strategic Objectives of National Pillars", and carried out research and development with the strength of the whole country; European countries also use EU funds to organize large-scale THz research projects involving multi-disciplines across countries; the Russian National Academy of Sciences has also established the Terahertz Research Institute to actively carry out THz technology research in conjunction with universities. Therefore, THz technology has become one of the most important emerging disciplines in this century. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; In November 2005, the Chinese government held a special "Fragrant Hill Science and Technology Conference" to discuss the development direction of THz industry in China, and formulated the development plan of THz technology in China. At present, many research institutes in China are carrying out relevant research in the field of terahertz. & lt; br & lt; span style = "height: 6px; display: block;" & lt;/span & lt; According to Lv Tao, Technical Director of Dream Building Jiuzhou Company, as a scientific and technological enterprise specializing in high-tech research and development and promotion. Relying on the high-quality scientific research resources in Beijing, the company has actively cooperated with relevant universities and other scientific research institutions to create key technologies for terahertz industrial applications. Firstly, the technology was successfully applied to the field of high temperature calcination, and terahertz wave pretreatment was used to promote sintering densification. This technology can not only reduce the energy consumption of ceramic tile sintering by about 8%, but also greatly improve the strength of ceramic tile (without reducing the performance of the premise, can reduce the thickness of ceramic tile by 20%, to achieve cost reduction and efficiency, the effect is remarkable. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; In silicon steel sheet, magnesium oxide powder is mainly used for insulation coating, high temperature annealing separator and improving magnetic properties. After terahertz technology modification, the performance of insulation coating can be significantly improved. Nhancing the quarantine effect of the high-temperature annealing, enhancing the quarantine effect of the high-temperature annealing, optimizing the magnetic performance and improving the mechanical performance. Through the modification, the particle distribution and the surface activity of the magnesium oxide powder can be optimized, so that a more uniform and compact insulating coating is formed on the surface of the silicon steel sheet, the insulating performance of the silicon steel sheet is improved, the electric leakage phenomenon is reduced, and the eddy current loss is reduced. The adhesive force and the high temperature resistance of the coating are improved; the particle size of the magnesium oxide powder is refined, and the dispersibility of the magnesium oxide powder is improved, so that the silicon steel sheet is more effectively prevented from being adhered in the high temperature annealing process. The surface quality of the silicon steel sheet after annealing is improved, the surface chemical property of the magnesium oxide powder is optimized, and the silicon steel sheet is promoted to form a more ideal magnetic domain structure in the annealing process. But also can significantly reduce iron loss, save energy, protect environment, and improve the efficiency of a motor and a transformer; the activity of the magnesium oxide powder is improved, and the bonding force between the magnesium oxide powder and a silicon steel sheet matrix is enhanced, so that the mechanical strength of the silicon steel sheet is improved; and the corrosion resistance of the silicon steel sheet is enhanced. The denser insulating coating can effectively prevent the contact between the external corrosive medium and the silicon steel substrate, further improve the chemical stability of the magnesium oxide, more effectively resist the corrosion of acid, alkali and other corrosive media, and protect the silicon steel substrate from being damaged. & lt; br & lt; span style = "height: 6px; display: block;" & lt;/span & lt; The modified magnesium oxide powder can also improve the insulation performance and surface quality of the silicon steel sheet to meet the strict requirements of high-end electronic products on material performance. The modified magnesium oxide powder can improve the mechanical strength and high temperature resistance of the silicon steel sheet and prolong the service life of equipment. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; Compared with the traditional bamboo charcoal board before the terahertz wave energizing, the bamboo charcoal board made by the terahertz wave energizing bamboo charcoal powder has significant improvement in physical properties, chemical activity and functionality. Before energization, the specific surface area of conventional bamboo charcoal powder is about 300-500 m 2/G, the pore structure is mainly micropores, the pore size distribution is uneven, and the adsorption efficiency is limited. After terahertz wave activation, the specific surface area of bamboo charcoal can be increased to 600-800 m 2/G, or even higher. The terahertz wave promotes the expansion of micropores to mesopores/macropores, forming a hierarchical pore structure and enhancing the adsorption capacity of macromolecular pollutants such as formaldehyde and VOCs. The adsorption rate is increased by 30% -50%, and the saturated adsorption capacity is increased by more than 20%. & lt; br & lt; span style = "height: 6px; display: block;" & gt; & lt;/span & gt; In terms of mechanical properties, the bending strength of ordinary bamboo charcoal board is about 15-25MPa before energizing. The wear resistance is general, and it is easy to cause brittleness due to loose internal structure. After the energization, the bending strength is improved to 30-40MPa, and the terahertz wave optimizes the dispersion and the interface binding force of the carbon powder. The wear resistance is improved by 20-30%, the agglomeration of the carbon powder is reduced due to the terahertz wave treatment, and the bonding density with the matrix material is enhanced. & lt; br & lt; span style = "height: 6px; display: block;" & gt; & lt;/span & gt; In terms of antibacterial and mildew-proof performance, before energization, it relies on the weak antibacterial property of bamboo charcoal itself (mainly physical adsorption, no active sterilization ability). The mildewproof grade is Grade II standard of GB/T 35601-2017. After being energized, the terahertz wave excites the functional groups (such as carboxyl and hydroxyl) on the surface of the carbon powder to enhance the interaction with the microbial cell membrane, and the antibacterial rate can reach more than 90% (such as Escherichia coli and Staphylococcus aureus). The mildew-proof grade can be upgraded to grade I (long-acting bacteriostasis). < br > span style = "height: 6px; display: block;" Far infrared and negative ion release. Before energization, the far infrared emissivity is about 0.7-0.8 at room temperature. The amount of negative ions released is 500-1000/cm 3. After energization, the far-infrared emissivity is increased to 0.85-0.95, the carbon lattice vibration mode is controlled by terahertz wave, and the release amount of negative ions can reach 2000-3000/cm 3. < br > < span style = "height: 6px; display: block;" >/span > Thermal stability and flame retardancy, the thermal decomposition temperature is about 300-350 ℃ before energization. Oxygen Index (LOI) is 22-24 (flammable). After energization, the thermal decomposition temperature is increased to more than 400 deg C (the terahertz wave promotes the degree of graphitization). The oxygen index can reach 28-30 flame retardant level, which is more suitable for high temperature or fire protection requirements. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; Lu Tao said that at present, Zhumeng Jiuzhou Company, together with relevant chemical and new material enterprises, has successfully carried out industrial application experiments of enabling modification of bio-based and inorganic chemical products such as bamboo charcoal board, silicon steel and magnesium oxide in Zhejiang and Hebei provinces, and achieved good results, with a number of performance indicators significantly improved. Terahertz technology can also be used to modify titanium dioxide, silicon dioxide, calcium carbonate, coatings, sodium humate, potassium humate and other chemical products to improve product quality. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; By optimizing the electromagnetic characteristics and surface structure, the terahertz wave modified titanium dioxide is significantly superior to traditional products in high-frequency communication, weather resistance and dispersibility, especially suitable for 6G technology and high-end industrial fields. Its technological breakthroughs not only improve material performance, but also provide innovative solutions for multi-scenario applications. Lu Tao added. & lt;br& gt;& lt;span style="height:6px;display:block;"& gt;& lt;/span& gt; Terahertz wave has a certain thermal effect, which can break and recombine some chemical bonds on the surface of silica, thus changing the chemical structure and the distribution of active sites on the surface, and increasing the number and activity of active groups on the surface. The electric field component of the THz wave can also interact with the charge distribution on the silica surface, affecting the distribution and migration of the surface charge. The resonance effect increases the vibration amplitude of molecules or lattices, resulting in minor changes in the internal structure, such as the adjustment of pore structure, the change of surface roughness, etc., thus increasing the specific surface area and improving its performance in catalysis and other fields. At the same time, the energy of THz wave can also induce defects in silicon dioxide, such as oxygen vacancies. Change the electronic structure of silicon dioxide to make it more chemically active. Oxygen vacancies and other defects can be used as adsorption sites to enhance the adsorption capacity of reactant molecules, and also contribute to the transfer and transfer of electrons, thus promoting the catalytic reaction.