【摘要】 通过电位滴定试验,证明了5种颗粒物的表面存在着一定量的OH-受体,其表面位浓度(Hs)在0.1219~0.3134mmo·.L-1之间,表面位密度(DOH)在0.8586~2.1305个·nm-2之间,且不同采样点的颗粒物,其表面位浓度和表面位密度差别很大.所采集的5种颗粒物的孔结构接近平行板狭缝,孔尺寸分布不是均一的,平均孔径分布范围较宽(1.8~76nm);BET比表面积为9.5669~34.5605m·2g-1,累积脱附孔体积为0.01729~0.06711cm3·g-1,BJH脱附平均孔径为5.6768~7.7388nm,处于中孔范围,且平均孔径均大于其PSD峰值对应的孔径.通过分形FHH方程模拟N2吸附和脱附等温线数据计算出这些颗粒物的孔表面分形维数Ds比较接近(2.68~2.82之间),但它们的分形标度区间不同.另外,采用热力学模型和分形FHH理论计算出的表面分形维数的差异主要归因于这些样品孔尺寸分布的不均一性.更多还原

【Abstract】 Titration was used to study the surface acid-based properties of particles from river and its bank at 0.05 mol·L -1 concentrations of supporting electrolyte CaCl₂. The results showed that there were some hydroxide acceptors on the surface of the particles, and the surface site concentrations（H_s） were 0.1219⁰.3134 mmol·L -1 , specific surface sites（D OH ） were 0.8586².1305sites·nm -2 as well. The difference of surface acid-based properties was found among these particles taken from different sampling sites. Nitrogen absorption-desorption isotherms were obtained on different samples, and their data points were used to analyze the pore structure and fractal properties of the obtained solids. The slit-shaped pores were determined from isotherms, and all the pore size distributions （PSD）, with wide range （1.8⁷6nm）, are not uniform. Other microstructure parameters of these particles are following: 9.5669³4.5605 m2·g -1 of BET specific surface area, 0.01729⁰.06711 cm3·g -1 of BJH cumulative desorption volume and 5.6768⁷.7388nm of BJH desorption average pore diameter within the range of mesopores. The average pore diameter was larger than that corresponding to the peak value of pore size distribution（PSD）. The self-similar and rough surface was observed on these particles, and the pore surface fractal dimensions D_s of the particles using fractal FHH theory were between 2.68 and 2.82. The agreement between the D_s values and disagreement between fractal scale ranges from N₂ absorption data and ones from desorption data were also found. Furthermore, the differences between the calculated pore surface D_s values from fractal FHH theory and thermodynamic model were attributed to non-uniform pore size distribution of these particles.更多还原