The deposited dust provides a large surface for heterogeneous ozone uptake reactions in urban regions. Prior studies have barely considered the effect of the photothermal conversion of deposited dust and underlying surface on ozone uptake. In this study, Fe 2 O 3 , TiO 2 , α-Al 2 O 3 , and SiO 2 were selected as model mineral dusts (MDs) to evaluate the photothermal effect. With an irradiation intensity of 100 mW/cm 2 , the uptake coefficients of ozone by Fe 2 O 3 , TiO 2 , α-Al 2 O 3 , and SiO 2 were 2.4, 30, 2.72, and 2.83 times higher than those in a dark condition. For SiO 2 and α-Al 2 O 3 , the increase in the uptake coefficient was due to the temperature increase induced by photothermal conversion. For Fe 2 O 3 and TiO 2 , photoelectric and photothermal conversion simultaneously participated in ozone uptake reactions. At 70 °C, the contribution of thermal catalysis to ozone uptake over Fe 2 O 3 and TiO 2 was approximately 55.4 % and 55.0 %, respectively. The temperature increase induced by photothermal conversion also promoted MDs' activity for ozone uptake after removing the light source (after sunset). This work proves that the ozone uptake induced by the photothermal effect of deposited MDs and the underlying surface was the primary ozone elimination pathway in urban atmospheres.
Kun Xiong,Jiupeng Zhang,Yinzhang He,Junbo Li,Mingliang Zhang,Rui Li,Jianzhong Pei,Yuanyuan Li,Lei Lyu
Cracking in asphalt pavement may lead to structural distress while existing crack repair materials have significant shortcomings in terms of cost and construction efficiency. This study incorporates mineral powder into the polyurethane grouting materials to provide a more economical and durable solution for repairing cracks in asphalt pavement. The results of bonding and tensile tests show that excessive mineral powder may deteriorate the mechanical properties of polyurethane grouting materials, which is caused by the agglomeration of mineral powder observed by the microscale characterization. Characterization tests indicate that ultraviolet exposure results in the evolution of the chemical components and thermal stability of polyurethane grouting materials, subsequently causing the degeneration in the mechanical properties. The addition of mineral powders was found to increase the tensile strength of polyurethane grouting materials after Ultraviolet aging by 12 %, while the elongation at break measured in tensile tests remained essentially unchanged. The results of the splitting test, bending test, and immersion Marshall test prove the enhanced low-temperature property and moisture resistance of mineral powder-modified polyurethane grouting materials as compared to the styrene-butadiene-styrene emulsified asphalt. The economic analysis shows that this study presents a practical approach to cost-effective asphalt pavement crack repair, offering insights for enhancing the durability of asphalt pavements.
This study fabricated two composite anticorrosion coatings based on a waterborne epoxy resin matrix, incorporating TC4 alloy powder and TiO2 nanoparticles, respectively, with mineral powder hybridization to enhance performance and reduce material costs. Salt spray testing demonstrated that both systems maintained stability in corrosive environments for over 30 days. However, the TC4-based coating exhibited local edge warping on day 10, indicative of insufficient interfacial adhesion and structural instability. In contrast, the TiO2 composite coating retained structural integrity throughout the test period, demonstrating superior corrosion resistance. Characterization analyses (SEM, TEM, EDS, FTIR, UV–Vis) revealed that TiO2 particles achieved better dispersion and interfacial binding capacity, effectively minimizing pore formation and structural defects. The dense oxide layer on TiO2 surfaces amplified the “maze effect,” significantly inhibiting corrosive medium penetration. Cross-cut adhesion testing and impact resistance evaluation further confirmed the TiO2 system's advantages in interfacial bonding strength and mechanical robustness over the TC4 counterpart. Collectively, the TiO2–mineral hybrid coating demonstrates superior comprehensive protection properties and greater engineering application potential, offering a novel strategy for designing cost-effective, high-performance waterborne epoxy anticorrosion materials.
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