AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Measurement of Sub 3 nm Flame-generated Particles Using Boosted Butanol CPC 3776 and DEG CPC
GIRISH SHARMA, Mengda Wang, Michel Attoui, Pratim Biswas, Washington University in St Louis
Abstract Number: 558 Working Group: Instrumentation and Methods
Abstract Ultrafine laminar TSI CPC is widely used in aerosol science for the detection of particle greater than 3 nm. For the measurement of particles as small as 1 nm, di-ethylene glycol (DEG) booster is used to activate these particles, before they are detected by butanol based CPC. CPC does provide reduction in background noise as compared to electrometer, but suffers from polarity and chemistry dependent activation efficiencies.
In this work, the new half-mini DMA is used to classify particles as small as 1 nm with high resolution. Different types and sizes of ions/particles are generated in sub 3 nm range viz. four different types of tetra-alkyl ammonium bromide ions from electrospray set-up; titanium dioxide nanoparticles using flame aerosol reactor; and soot particle from McKenna burner to study the chemistry dependence of boosted butanol TSI CPC 3776, and TSI DEG CPC. First, the best operating conditions for the boosted CPC are selected which provides maximum signal with minimal noise ( < 10 #/cm3), and were found to be at saturator temperature 45 C, and condenser temperature of 10 C, with capillary flow rate of 70 sccm. These conditions were then set for the measurement of flame generated particles. It is found that negatively charged particles are more easily activated as compared to positively charged for all the particles. Moreover, the activation efficiency is found to be chemistry dependent for mobility size less than 1.8 nm, above which the chemistry dependence was negligible for butanol based CPC. The activation efficiency of different flame generated particles is also compared for DEG CPC.