引黄水库沉沙条渠沉积物的表面理化及分形特征研究

Surface Physicochemical and Fractal Characteristics of Sediments in Desilting Basin from Yellow River Diversion Reservoir

研究了引黄水库沉沙条渠泥沙沉积物的表面微观形貌和孔表面分形特征.采集了引黄供水鹊山水库沉沙条渠6个泥沙沉积物样品,对其粒径、形貌、孔隙结构、表面元素分布及分形特征进行分析,目的是考察由不同模型计算的颗粒孔表面分形维数和标度空间存在差异的原因,探讨这些颗粒表面微观形貌对其表面元素分布的影响.结果表明,泥沙沉积物颗粒的平均粒径约为18～83μm,主要以黏粒、粉砂和细砂粒为主;表面形貌和孔隙分布复杂多样,其BET比表面积约为8.248～31.60m2/g,孔隙尺寸分布范围较宽(1.870～60.78 nm),平均孔径约为3.977～7.850 nm.采用热力学模型和分形FHH模型计算出的孔表面分形维数Ds约为2.67～2.89,标度空间一般在数nm到数十nm,但不同模型计算所得结果存在一定的差异,其主要原因是泥沙沉积物颗粒的孔尺寸分布不均一.基于孔尺寸分布数据计算的Ds约为2.12～2.60,其与分形FHH模型计算出的对应结果越接近,孔分布对Ds的贡献越大.此外,颗粒的复杂表面形貌对各元素分布有较强的影响,这是颗粒表面形貌的高度不均一性导致表面吸附位分布不均的结果.

Surface morphology and pore surface fractal characteristics of the sediment in the desilting basin of Queshan Reservoir were studied.Six sediment samples were collected and particle size,morphology,pore structure and fractal characteristics,surface elements distribution were analyzed as well.The objectives of this study were to investigate the reason for the differences among the pore surface fractal dimensions and fractal scales on the basis of different models,and discuss the effect of surface morphology of these sediment particles on their surface elements distribution.The results showed that these sediment particles with average diameter of 18-83 μm were mainly composed of clay,silt and fine sand.Their complex surface morphology and pore size distribution were reflected by wide range of the BET surface area（8.248-31.60 m^2/g）,average pore diameter（3.977-7.850 nm） and pore-size distribution（1.870-60.78 nm）.Although the pore surface fractal dimensions（Ds）,based on fractal FHH or thermodynamic models,were 2.67-2.89,and their fractal scales generally ranged from several nanometers to tens of nanometers,the differences were still observed in Ds values calculated from above two models because of inhomogeneity in surface pore size distribution.Therefore,the Ds based on pore-size distribution were 2.12-2.60,these values close to Ds calculated from fractal FHH models revealed that pore-size distribution could contribute significantly to Ds calculation.In addition,the heterogeneous surface adsorption sites of these sediment particles caused by much complex surface morphology had strong influence on the each element distribution on the particle surface.