Enhancing the deposition of secondary organic aerosol by negative air ionizer

In this study, we investigated the effectiveness of a high-efficient NAI on the deposition of the SOA generated from the ozonolysis of d-limonene in a test chamber under controlled ventilation rate and relative humidity. Our experiments showed that compared to other effects including the gravity, particle eddy diffusion, and Brownian diffusion, the effect of negative air ion is the most dominate one on the deposition of SOA particle onto the wall surface in the near-wall region. The tested NAI can efficiently enhance the deposition of the SOA with the effective cleaning rate (ECR) ranging from 2.84±0.15 to 5.35±0.22 m³ h^-1 with a low ozone production of 1.36±0.12 μg h^-1. The relative high performance of the NAI was relevant to its high air ion production rate and elevated electric field strength (> 10¹¹ ions m^-3 and > 3 kV m^-1 at 30 cm away from the ionizer).