Colloidal Substances in Soil

Investigation of Physico-Chemical Features of Soil Colloids

There is abundant evidence that the surface properties of colloidal particles can deviate significantly from those displayed by their macroscopic counterparts. To predict the chemical and physical properties of colloids in soil, they can be characterized by conventional analytical methods, such as SEM, X-ray diffraction, elemental analysis, surface area determination, total organic carbon analysis, Fourier transform infrared and nuclear magnetic resonance spectroscopy. Many advanced instrumental techniques have also been used to characterize soil nanoparticles, including X-ray photoelectron, X-ray absorption and X-ray absorption fine structure spectroscopy, and scanning transmission X-ray microscopy.

Fig.1 Colloids and colloid-related metals in soil.^[3]

Classification of Soil Colloids

The colloids in the soil are small in size and interact with each other, so the isolation yield is low. The separation mechanism of colloids is related to particle size, shape and surface area. Colloid fractionation techniques include split-thin flow fractionation(SPLIFF), flow field-flow fractionation (FIFFF), sedimentation field-flow fractionation(SdFFF), and cross-flow filtration(CFF, also called tangential flow filtration(TFF)). It has been found that colloidal particles can be successfully separated from soil by a combination of sieving, sedimentation, centrifugation and cross-flow filtration.

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• Alfa Chemistry has research strength in the characterization and separation of soil colloids, and can solve various problems in research for customers.
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References

1. XueYan L, et al. Effects of Ionic Strength and pH on Colloid Release from Different Soils. Journal of Agro-Environment Science, 2014.
2. Benny K. G, et al. Nanoparticles in the Soil Environment. Elements, 2008.
3. Xia B, et al. Occurrence and fate of colloids and colloid-associated metals in a mining-impacted agricultural soil upon prolonged flooding. Journal of Hazardous Materials, 2018.

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