Particle size distribution in yellow-brown soil: Fractionation and characterization

Utilizing sieving,sedimentation,centrifugation and cross-flow filtration(CFF),the particle size in yellow-brown soil was sequentially fractionated into five scales including fine sand(50~250μm),silt(5~50μm),coarse clay(1~5μm),fine clay(0.1~1μm),and nanocolloids(0.1μm).Laser granulometry,transmission electron microscopy(TEM),and x-ray diffraction(XRD) were used to characterize these particles with different size.Results showed that the determined size of each particle was well consistent with the theoretical fractionation scale,indicating the availability and reasonableness of the fractionation method.TEM test displayed that nanocolloids were uniformly spherical with size range of 20~40 nm and good dispersion and distribution,but presented a few large granular aggregates.