The prospective applications of nanotechnology in agriculture demand a deep understanding of the interactions of engineering nanoparticles (ENPs) with other soil minerals. Clay mineral is a key component affecting soil properties and interactions of ENPs with clay minerals may therefore alter soil properties. In this study, charge-dependent interactions between kaolinite and cerium oxide nanoparticles (CeO2NPs) were investigated at the atomic level using several complementary surface characterization techniques. A strong affinity of positively charged and neutral CeO2NPs to the surface of kaolinite was observed, in contrast to the weak attachment for negatively charged CeO2NPs, indicating that the electrostatic interactions between CeO2NPs and kaolinite surface governed the interactions. The results also demonstrated a charge-dependent aggregation of CeO2NPs on the kaolinite surface, with the neutral CeO2NPs showed the most substantial aggregation. The attachment of CeO2NPs altered the surface charge density distribution on the surface of kaolinite, as indicated by the conversion from a relatively homogenously charged basal plane to a heterogeneously charged plate. The variation in surface charge property of kaolinite may significantly affect the interactions of clay minerals with surrounding macro- and micro-nutrients in soil pore water and subsequently influence their bioavailability to plants.

Attachment of cerium oxide nanoparticles with different surface charges to kaolinite: Macroscopic and microscopic variations in kaolinite surface properties

ACS Fall 2021

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