Characterization of mineralogy and surface zeta potential of atmospheric dust fall in northwest China

Abstract

The mineralogy characterization of dust fall in atmosphere is important in understanding and improving air quality. In this paper, dust fall samples were collected in the suburb of four areas of northwest China during April to May 2012. The size distribution, mineral phase and composition, morphology, and surface charge of dust fall were investigated, respectively, by particle size analyzer, X-ray powder diffraction spectrometer (XRD), scanning electron microscopy (SEM), and zeta potential analyzer. The average volume size of dust fall was from 59.17 to 62.88 μm, and the dust fall in Tuoketuo County of Inner Mongolia Autonomous Region had the finest particles (59.17 μm), while the number percentage of fine particulate matter (<1.0 μm) in dusts was about 88.36 % of total particles. The main minerals of dust fall samples are composed of quartz, calcilte, muscotive, albite, clinochlore, and gypsum. And four dust fall samples had the same main mineral phase. Minerals of surface soil were identified as an important source of atmospheric dust fall. The morphological of the atmospheric dust fall presented irregular square, sphere, agglomerate elongated particles, and granular aggregates. Zeta potentials of four dust fall samples were negative in tested pH range. Moreover, their zeta potentials decreased with increasing pH of the solution. The surface charge of dust fall was strongly affected by the quantity of carbonate minerals (calcite and dolomite) in samples. The simulated zeta potential result of multimineral dusts indicated that the magnitude and tendencies of dust’s zeta potential were dominated by the main mineral phase in dust fall.