Development of Low Volume Substrate Based Particulate Matter Sampler

Abstract

Air pollution has arisen as a major concern in the present era due to its adverse impact on human health and surrounding environment. Among the six criteria pollutants, the atmospheric particulate matters have been considered as a challenge to ensure air quality in Bangladesh because the Air Quality Index (AQI) value for particulate matter (PM) is mostly ranges from caution to extremely unhealthy. However, air quality sampling and monitoring program in Bangladesh is very insignificant due to expensive PM sampler dealing with nano to micro scale parameters. This study focuses on the development of a low cost PM sampler which is low volume, multi-nozzle and substrate based. The design parameters such as nozzle number, nozzle diameter and nozzle to plate distance were determined from the dimensionless factor named stokes number ( ) introducing the Reynolds number (Re). The optimal nozzle configuration array was selected to avoid the effect of cross flow parameter upon the collection characteristics. The PM sampler operates at a flow rate of 5 L/min and consists of two different sets of circular nozzles designed for cut-off PM10 (Diameter of particle less than 10μm) and PM2.5 (Diameter of particle less than 2.5μm). The designed PM sampler was fabricated from the Fab-Lab of Khulna University of Engineering and Technology (KUET) using the silver metallic PLA filament which is light weight and corrosion resistant. Microscopic analysis of the substrate was performed to investigate cut-off performance. Gravimetric analysis was conducted to evaluate the field performance of the developed PM with a sensor based (light-scattering) reference sampler within the KUET campus. The loss of particle on this study was determined by counting the particle inside the sampler’s wall as well as the stagnant corner point of the inside of the PM sampler. A stage wise sharp cut-off was found for PM10 and PM2.5 of developed PM sampler. The average mass concentration of PM10 and PM2.5 was found as 108μg/m3 and 49μg/m3, respectively. The average mass concentration of PM10 and PM2.5 was found very close to the reference sampler. The average particle loss for the impactor nozzle and sampler body was found 12.0% which shows good agreement with previous studies. The obtained cross-flow parameter for the stage PM10 (0.20) and PM2.5 (0.29) were also satisfying the critical value (< 1.2). Overall, the PM sampler was developed as light-weight, easy to use, portable, low maintenance required, and low cost which can be implemented for PM monitoring in Bangladesh.