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Study on Influencing Factors of Photocatalytic Performance of Cds/Tio2 Nanocomposite Concrete

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Study on Influencing Factors of Photocatalytic Performance of Cds/Tio2 Nanocomposite Concrete Nanotechnology Reviews 2020; 9: 1160–1169 Research Article Kang He, Yu Chen*, and Mengjun Mei Study on influencing factors of photocatalytic performance of CdS/TiO2 nanocomposite concrete https://doi.org/10.1515/ntrev-2020-0074 received June 01, 2020; accepted September 02, 2020 1 Introduction Abstract: In this study, a high-energy ball mill was used Since the industrial revolution, fossil energy has become - to composite nano TiO2 and CdS, and three kinds of an indispensable energy source for human beings, but - nanocomposite photocatalysts TiO2, CdS/TiO2 R400, and the environmental pollution problems caused by it have - CdS/TiO2 R600 were prepared, which can respond to become more and more serious; on the other hand, with visible light. The photocatalytic concrete test block was the increase in the number of cars, the emissions of prepared by mixing the nanocomposite photocatalyst automobile exhausts have become larger and larger. and other masses with cement by incorporation method. Among them, nitrogen oxides (NOx) and SO2 seriously ff To study the e ect of the photocatalyst content on the affect the quality of urban air and threaten the health of photocatalytic performance of nanoconcrete, a total of urban residents. When academia discovered that water ( ) four catalyst contents 0, 2%, 5%, and 8% were set. The molecules on the surface of titanium dioxide electrode ff - ( ) e ects of high temperature treatment 400°C and would decompose under ultraviolet light, this new ff ( ) di erent light sources ultraviolet and visible light on material TiO attracted much attention. With the ffi 2 photocatalytic e ciency were also considered. The deepening of research, the concept of using nanocom- ffi - results show that the catalytic e ciency of CdS/TiO2 posite treat pollutants has been proposed and accepted R400 under two light sources is higher than that of the by many people [1,2]. TiO2 has the advantages of safety other two photocatalysts. Compared to ultraviolet light and non-toxicity, low price, high catalytic activity, and sources, the photocatalytic efficiency of CdS/TiO nano- 2 good stability. It is recognized as the best photocatalyst composite concrete under visible light is lower, and the and has a good application prospect in the field of efficiency is below 9%. The optimal amounts of CdS/TiO2 environmental pollution treatment. However, TiO2 has a nanocomposite photocatalyst under ultraviolet and wide bandgap (anatase phase 3.2 eV), which can only be visible light are 2% and 5%, respectively. The high- excited by ultraviolet light source, and the utilization temperature treatment can improve the photocatalytic rate of sunlight is only 3% to 5%, which greatly limits performance of CdS/TiO nanocomposite photocatalyst 2 the application of TiO under general conditions [3]. by 2% to 3%. 2 Therefore, by modifying TiO2, expanding its response range to sunlight, and improving the utilization rate of sunlight has become a research hotspot. There are many Keywords: photocatalytic concrete, nanocomposite, studies on the modification of TiO2 photocatalysts. In CdS/TiO2, degradation rate, visible light terms of semiconductor recombination, semiconductor materials with a more negative conduction band potential and smaller forbidden bandwidth than TiO2, such as CdS, PbS, CdSe, and Cu2O nanoparticles, are used for sensitization [4–8]. The semiconductor CdS has a bandgap of 2.42 eV and an excitation wavelength of * Corresponding author: Yu Chen, College of Civil Engineering, 495 nm or less, which has a good absorption effect on Fuzhou University, Fuzhou, 350116, China, sunlight. Through the synergistic effect of different e-mail: [email protected], tel: +86 18030219629 Kang He, Mengjun Mei: College of Civil Engineering, Fuzhou forbidden bandwidths between semiconductors, the University, Fuzhou, 350116, China light stability of the catalyst is enhanced, and the Open Access. © 2020 Kang He et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. Study on influencing factors of photocatalytic performance of CdS/TiO2 nanocomposite concrete 1161 recombination probability of photo-generated carriers is by TiO2 using a spectrophotometric method. The results reduced, so that the photocatalytic performance of the showed that the photocatalytic degradation rate of material is effectively improved [9]. The role of TiO2 rhodamine B by TiO2 was higher in acidic conditions phase composition, nanocrystalline sizes, carbon con- than in alkaline conditions. Yang et al. [25] prepared tent in its different forms in establishing static and silver and vanadium oxide co-doped TiO2 by a one-step dynamic magnetic response of our samples will be sol–gel solvothermal method in the presence of a discussed by Typek et al. [10]. Ruot et al. [11] used nano- triblock copolymer surfactant (P123). Song et al. [26] TiO2 cement paste and cement mortar to degrade prepared Cu and N co-doped TiO2 nanoparticles and rhodamine B. The results show that the type of cement studied the effects of different amounts of Cu and N has little effect on the photocatalytic performance. Shen doping on the photocatalytic activity of TiO2. Shen et al. et al. [12] covered the surface of the prepared concrete [27] prepared N and Ce co-doped TiO2 by sol–gel with tens of nanometers of C–S–H and TiO2 nanoparti- method. The co-doped TiO2 can photocatalytically cles. The results show that photocatalytic ultra-smooth degrade nitrobenzene under visible light. concrete surfaces can effectively degrade methylene blue Nanoconcrete as an effective combination of nano- (MB). Teh et al. [13] discovered through research that technology and traditional civil engineering has broa- higher specific surface area can promote the adsorption dened the application range of nanotechnology and of more reactant molecules to the catalyst surface, nanomaterials, and also solved many problems that thereby avoiding the recombination of photo-generated traditional concrete materials are difficult to solve. This electron–hole pairs. The low grain size increases the area has also produced a lot of research results in recent specific surface area of the catalyst and promotes the years [28–32]. Zhang et al. [33] evaluated the flexural photogenic support to turn to the surface of the catalyst strength and durability (carbonization resistance, pene- to enhance the interaction with the reactant molecules tration resistance, cracking resistance, freeze–thaw [14]. Wang et al. [15] prepared a concrete pavement with resistance) of nano-SiO2 cement-based composite mate- emulsified asphalt as the carrier and nano-TiO2 as a rials through experimental research. Tekin et al. [34,35] photocatalytic coating. The results showed that the studied the effects of WO3 and Bi2O3 additives on the nano-TiO2 content in the coating was 8% and the micron and nanometer scales on the radiation shielding 2 spraying amount was 400 g/m . The sidewalk NOx properties of hematite serpentine concrete (HSC).He degradation rate was the highest. Two asphalt emulsions et al. [36] replaced the traditional concrete in GFRP and one cement mortar are used in the right lane and concrete composite columns with a new type of emergency lane of highway sections. After comparison, nanoconcrete and carried out a series of experimental it was found that the asphalt emulsion-based substrate studies on the mechanical properties of this new type of still has a good NO degradation effect after 572 days [16]. composite column. Cheng et al. [37–41] added a certain Wang et al. [17–19] used photocatalytic degradation of amount of nano-siO2 to concrete to improve the phenol with anatase phase TiO2 with different grain sizes durability of concrete. Al-Swaidani [42] studied the to investigate the effect of grain size on the photo- efficiency of adding concrete binder to volcanic slag on catalytic performance of anatase phase TiO2. The results a nanometer scale. In recent years, a new method for show that when the grain size is increased from 6.6 to producing heterogeneous photocatalysts, a high-energy 26.6 nm, the photocatalytic degradation rate of TiO2 ball milling method, has been proposed. The high- nanoparticles in the anatase phase increases signifi- energy ball milling method is also called mechanochem- cantly. They believe that the increase in grain size of the ical method. The substance undergoes chemical changes anatase phase TiO2 can suppress the undesired hydro- or physical and chemical changes due to the action of quinone–benzoquinone redox reaction, thereby pro- mechanical forces. The method can realize a reaction moting the complete decomposition of phenol and that can occur only under chemical or high-temperature phenolic compounds. Saeli et al. [20–22] prepared a conditions under normal temperature conditions. In this lime mortar containing 5 wt% Ag-TiO2 and studied the paper, a high-energy ball mill was used to combine TiO2 removal activity of nitrous oxide (NOx) and volatile and CdS through mechanochemical action to make a organic compounds (VOC). The addition of dopants did CdS/TiO2 nanocomposite photocatalyst. Then, the nano- not significantly change the physical properties or curing composite CdS/TiO2 was replaced by cement by an of the lime mortar but showed excellent photocatalytic incorporation method, and the effects of different activity in sunlight. Chen et al. [23,24] studied the effect dosages (0, 2%, 5%, and 8%) on the photocatalytic of pH on the photocatalytic degradation of rhodamine B performance of concrete were studied. 1162 Kang He et al. 2 Testing process 2.3 Preparation of composite catalyst 2.1 Materials and instruments First, weigh 2 g CdS powder and 18 g TiO2 powder into a 500 mL corundum ball mill pot with a mass ratio of 1:9. The material of the ball in the tank is zirconium dioxide. The main instruments and consumables in this test The planetary ball mill is used for ball milling at a speed include QM-QX2L omnidirectional planetary ball mill; of 400 rpm for 2 h, as shown in Figure 1, and the powder UV-2600 ultraviolet visible spectrophotometer; TG16-WS was then weighed and ground with a rotating ball at a high-speed centrifuge; CJJ78-1 magnetic stirrer; SX-4-10 speed of 600 rpm for 2 h.
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