天然石英砂的表面络合模型研究

天然泥沙颗粒表面特性复杂,其与营养物质及重金属之间的相互作用,是研究天然水体水环境效应的关键科学问题之一.本文以石英砂为例,在考虑天然泥沙表面形貌引起的电荷非均匀分布的基础上,建立了统计意义上的表面电荷分布-表面电位数学关系,并修正表面络合模型,对表面络合常数采用更合理的静电力校正,模拟营养物质及重金属在天然泥沙颗粒表面的吸附-解吸关系.同时,表面滴定实验及吸附实验数据被用来进行模型验证.结果表明,泥沙颗粒的吸附特性受pH值、水相平衡浓度和背景离子强度等影响,考虑颗粒表面电荷非均匀分布的修正模型,更接近天然泥沙的吸附特性,相比传统表面络合模型,能够更好地模拟吸附结果.

Surface complexation model for quartz sand particles

The interaction between sediment and pollutants, such as nutrients and heavy metals, is one of the key issues related to the effects of water environment. This paper modified the surface complexation model with quartz sand as an example, considering the non-uniform distribution of surface charge. The surface morphology and charge distribution were observed using the electrical force microscope and the statistics of micro-morphology and surface charge distribution were obtained. Through the potential calculation, a statistical relationship between surface charge distribution and surface potential was established. The surface complexation model was then modified using a more reasonable correction of electrostatic factor, including the effects of non-uniform charge distribution. Data from titration experiment and adsorption experiment were used for the model validation. Results show that the adsorption characteristics of sediment particles are influenced by pH, equilibrium concentration, and ionic strength. The modified surface complexation model can better simulate the adsorption of pollutants on sediment particles.