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| Size effects of Lou soil colloids on the adsorption properties of ammonium，phosphate，and potassium |
| Received:October 26, 2023 |
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| KeyWord:soil colloidal fractions from Lou soil;nanoparticles;particle diameter;nutrients;adsorption |
| Author Name | Affiliation | E-mail | | LI Xin | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | DING Wei | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | YAN Yuyang | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | XU Chenyang | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China
State Key Laboratory of Plant Nutrition and Agro-Environment, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Yangling 712100, China | xuchenyang@nwafu.edu.cn | | DU Wei | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China
State Key Laboratory of Plant Nutrition and Agro-Environment, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Yangling 712100, China | | | HU Feinan | State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China
Institute of Soil and Water Conservation, Chinese Academy of Sciences, Ministry of Water Resources, Yangling 712100, China | | | GENG Zengchao | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China
State Key Laboratory of Plant Nutrition and Agro-Environment, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Yangling 712100, China | |
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| Abstract: |
| This study was conducted to investigate the size effects of Lou soil colloids on the adsorption behaviors and mechanisms of nitrogen, phosphorus, and potassium. The colloidal fractions of Lou soil with diameters of <2 000, <1 000, <500, <200 nm, and <100 nm were extracted using high-speed centrifugation, and their particle size distribution, element contents, and zeta potentials were determined. The adsorption behaviors of ammonium（NH4+）, phosphate（PO43-）, and potassium（K+）were assessed through batch adsorption experiments. The results showed that the particle size distributions of coarse soil colloids with diameters of <2 000 nm and <1 000 nm exhibited a bimodal distribution, whereas the fine soil colloids with diameters of <500, <200 nm, and <100 nm had a unimodal distribution. As the mean particle diameter decreased, increases in the total carbon and organic carbon contents for all soil colloidal fractions were observed. Furthermore, the absolute values of zeta potential increased at higher pH levels, accompanied by increases in charge density and charge variability with increasing particle diameter. The adsorption processes of NH4+、PO43-, and K+ by Lou soil colloids of different diameters conformed to pseudo-first-order dynamics and the Freundlich model. This suggests that the adsorption process is characterized by physical diffusion and multi-molecular layer adsorption. Furthermore, the size of the colloids significantly influenced the adsorption behaviors of NH4+、PO43-, and K+. Notably, the highest adsorption capacity was observed in the coarse soil colloidal particles（<2 000 nm）, indicating that differences in nutrient adsorption among Lou soil colloids are primarily regulated by variations in charge density. |
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