Characterizing nanoparticle aerosols is crucial for understanding their behavior during generation, evolution, and deposition. Among the various methods available for generating these aerosols, electrical heating of metallic wires stands out as the simplest and most widely used technique, particularly for metallic particles. The aerosols generated through this method are used for calibrating nanosizers and conducting specialized experiments to validate theoretical models. Additionally, these nanoparticles, generated at high number concentrations (>106 cm−3), have been shown to demonstrate fascinating features such as fractal shapes, a sharp peaking profile, and sporadic oscillations in the concentration profile. These properties find applications in characterizing aerosol sources by determining their number emission rates and in validating aerosol models related to nucleation and coagulation processes. Managing air quality effectively requires efficient mechanisms to mitigate airborne particles. Alongside conventional filtration-based techniques, charging-based methods are also employed. Unipolar ionizers, for example, are commonly used in small, enclosed environments. However, the efficiency of aerosol removal is size-dependent, with nanoparticles presenting a particular challenge due to their lower charging efficiencies. This limitation hinders the overall efficacy of charging-based mitigation strategies. To enhance efficiency, it is crucial to identify the most sensitive parameters influencing charging-based particle removal. Two key factors that define the charge characteristics of an ionizer are “charge concentration” and “aerosol current”. Experimental studies using single and multi-array ionizers have provided valuable insights into these parameters. Such investigations allow for better optimization of particle charging, ultimately improving removal efficacy, particularly in the nanoscale size range. Recent advancements in nanoparticle scavenging include the use of electrohydrodynamic atomizers, which enhance cleaning efficiency by charging nanodroplets. This innovative approach may provide an alternative to conventional electrostatic precipitators in industrial applications. Another promising development is the incorporation of CNTs into filtration systems. Because of their high surface-to-volume ratio, CNTs offer excellent air-cleaning capabilities, provided that pressure drops are effectively managed. The production of CNTs in reactors is influenced by the properties of precursors in the aerosol phase. Controlling the characteristics of nucleated particles is key to improving reactor throughput and optimizing CNT production. In this chapter, we have outlined the processes of generating and characterizing nanoparticles, emphasizing their role in refining applications for air quality management. These advancements underscore the importance of tailoring nanoparticle behavior for enhanced environmental and industrial outcomes.

Characterizing Nanoparticle Aerosols for Better Air Quality Management

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发表日期：

2025年

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Manish Joshi,
B. K. Sapra,
D. K. Aswal

摘要

Characterizing nanoparticle aerosols is crucial for understanding their behavior during generation, evolution, and deposition. Among the various methods available for generating these aerosols, electrical heating of metallic wires stands out as the simplest and most widely used technique, particularly for metallic particles. The aerosols generated through this method are used for calibrating nanosizers and conducting specialized experiments to validate theoretical models. Additionally, these nanoparticles, generated at high number concentrations (>106 cm−3), have been shown to demonstrate fascinating features such as fractal shapes, a sharp peaking profile, and sporadic oscillations in the concentration profile. These properties find applications in characterizing aerosol sources by determining their number emission rates and in validating aerosol models related to nucleation and coagulation processes. Managing air quality effectively requires efficient mechanisms to mitigate airborne particles. Alongside conventional filtration-based techniques, charging-based methods are also employed. Unipolar ionizers, for example, are commonly used in small, enclosed environments. However, the efficiency of aerosol removal is size-dependent, with nanoparticles presenting a particular challenge due to their lower charging efficiencies. This limitation hinders the overall efficacy of charging-based mitigation strategies. To enhance efficiency, it is crucial to identify the most sensitive parameters influencing charging-based particle removal. Two key factors that define the charge characteristics of an ionizer are “charge concentration” and “aerosol current”. Experimental studies using single and multi-array ionizers have provided valuable insights into these parameters. Such investigations allow for better optimization of particle charging, ultimately improving removal efficacy, particularly in the nanoscale size range. Recent advancements in nanoparticle scavenging include the use of electrohydrodynamic atomizers, which enhance cleaning efficiency by charging nanodroplets. This innovative approach may provide an alternative to conventional electrostatic precipitators in industrial applications. Another promising development is the incorporation of CNTs into filtration systems. Because of their high surface-to-volume ratio, CNTs offer excellent air-cleaning capabilities, provided that pressure drops are effectively managed. The production of CNTs in reactors is influenced by the properties of precursors in the aerosol phase. Controlling the characteristics of nucleated particles is key to improving reactor throughput and optimizing CNT production. In this chapter, we have outlined the processes of generating and characterizing nanoparticles, emphasizing their role in refining applications for air quality management. These advancements underscore the importance of tailoring nanoparticle behavior for enhanced environmental and industrial outcomes.