Air Entrainment During Flame Aerosol Synthesis of Nanoparticles

• Published in: Aerosol science and technology Vol. 48; no. 11; pp. 1195 - 1206
• Main Authors: Waser, Oliver, Groehn, Arto J., Eggersdorfer, Maximilian L., Pratsinis, Sotiris E.
• Format: Journal Article
• Language: English
• Published: Colchester Taylor & Francis 02.11.2014; Taylor & Francis Ltd
• Subjects: Adsorption; Aerosols; Chemistry; Coagulation; Colloidal state and disperse state; COPPER OXIDE; CUPRIC OXIDE; Enclosure; Entrainment; Exact sciences and technology; FABRICATION; Fourier transforms; Gases; General and physical chemistry; Hoisting; PARTICLES; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Surface chemistry; Synthesis; TUBE; Tubes; Walls; Aerosols; Synthesis; Air; Nanoparticle; Flame
• ISSN: 0278-6826; 1521-7388
• DOI: 10.1080/02786826.2014.969800

Enclosed flames typically produce substantially larger particles than open flames under identical reactant flows and composition. The enclosure hinders air entrainment to the flame and reduces heat losses by radiation and convection, facilitating particle coagulation and coalescence. Here the effect of natural air entrainment on flame aerosol synthesis is investigated by lifting off the enclosing tube from the burner surface and utilizing tracer gas (Ne) analysis after calibration with forced air entrainment. That way the effect of air entrainment on product primary particle diameter and mobility size distribution dynamics is investigated by microscopy, scanning mobility particle sizing, and N 2 adsorption, while temperature is measured by Fourier-transform infrared spectroscopy. So air entrainment during flame spray pyrolysis is examined here for its versatility in scalable manufacture of an array of material compositions, while copper oxide (CuO) is used for its electro-chemical applications (e.g., battery electrodes). It is shown that natural air entrainment facilitates rapid gas-to-particle conversion and high process yields by minimizing vortex recirculation and particle deposition on the enclosing tube walls and burner surface. For example, the average primary particle diameter of CuO can be controlled from 42 to 10 nm and the yield from 40 to 90% by gradually lifting off the enclosing tube, resulting in up to 250 L/min natural air entrainment at the present CuO synthesis conditions. Copyright 2014 American Association for Aerosol Research