环境化学
王毅力,刘杰,杜白雨,石宝友,王东升.颗粒物表面酸碱特性与孔表面分形的研究[J].环境科学学报,2007,27(1):106-113
颗粒物表面酸碱特性与孔表面分形的研究
- Study on the surface acid-base properties and pore surface fractal of particles
- 基金项目：国家自然科学基金资助项目(No.20407004,50578012);霍英东青年教师基金资助项目(No.91078);北京市重点学科资助(No.XK100220555)
- 作者
- 单位
- 王毅力
- 北京林业大学资源与环境学院环境科学学科, 省部共建森林培育与保护教育部重点实验室, 北京 100083
- 刘杰
- 北京林业大学资源与环境学院环境科学学科, 省部共建森林培育与保护教育部重点实验室, 北京 100083
- 杜白雨
- 北京林业大学资源与环境学院环境科学学科, 省部共建森林培育与保护教育部重点实验室, 北京 100083
- 石宝友
- 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085
- 王东升
- 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085
- 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9.5669～34.5605m2·g-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.
- 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（Hs） were 0.1219～0.3134 mmol·L-1, specific surface sites（DOH ） were 0.8586～2.1305sites·nm-2as 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 （1.8～76nm）, are not uniform. Other microstructure parameters of these particles are following: 9.5669～34.5605 m2·g-1 of BETspecific surface area, 0.01729～0.06711 cm3·g-1 of BJHcumulative desorption volume and 5.6768～7.7388nm of BJHdesorption 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 Ds of the particles using fractal FHHtheory were between2.68 and 2.82. The agreement between the Ds 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 Ds values from fractal FHHtheory and thermodynamic model were attributed to non-uniform pore size distribution of these particles.
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