【作者】 胡康博；

【导师】 王毅力；

【作者基本信息】 北京林业大学 ， 环境科学， 2011， 硕士

【摘要】 黄河是高含沙河流,其所含大量的泥沙对水体中的污染物具有一定的吸附作用。本研究选择鹊山水库沉沙条渠6个不同断面的泥沙沉积物为研究对象,分析其理化性质,揭示各特征参数间的内在相互关系；通过吸附-解吸实验(以沉积物B1和B2为例),分析泥沙沉积物吸附磷的动力学过程、吸附等温线、吸附影响因素、吸附可逆性及吸附前后的结构特征变化,并结合表面分析技术,探讨吸附磷的作用机理。研究结果表明：泥沙沉积物属于中性偏碱、低有机质含量、表面带有负电荷、絮凝能力较小且以粘粒、粉砂和细砂粒为主的颗粒,其理化参数间存在较好的相关性。颗粒的表面形貌复杂多样,孔尺寸分布不均一,表面孔隙主要处于中孔范围,属于具有较高填充能力的分形孔隙,其孔表面分形维数(Ds)约为2.67-2.89,且孔分布对Ds具有一定的贡献。此外,颗粒的复杂形貌对各元素的面分布有较强的影响,并导致了表面吸附位分布不均匀。泥沙沉积物对磷的吸附可以分为快速的物理、物化吸附(0-3h)和缓慢的化学吸附2个阶段,吸附过程符合准-二级动力学过程。吸附等温线不经过坐标原点,而是在浓度轴上存在一个交点使整个吸附等温线分为两部分——吸附段和解吸段,对应的吸附-解吸平衡磷浓度(EPC0)为0.038～0.049mg·L-1; Langmuir交叉吸附等温式比其它模型更适合描述黄河泥沙沉积物吸附磷的特征。该吸附过程为吸热过程,存在“固体浓度效应”,且颗粒粒度、溶液的pH、盐度、有机质含量等因素对该过程具有重要的影响。此外,泥沙沉积物对磷的吸附具有可逆性,所吸附的磷在一定条件下可以发生解吸。吸附磷后,颗粒的比表面积、孔体积、孔表面分形维数(Ds)均略有下降,而平均孔径略有增加,其中,孔隙体积在孔径1.5-30nm范围内变化较大。表面吸附磷的关键元素(Al、Fe、Ca)的分布存在异质性,导致磷主要吸附在颗粒表面的边脊、凹陷和突鞍等部位,占总量的96%以上更多还原

【Abstract】 As a high-silt river, a large number of silt particles in the Yellow River played an important role in the adsorption of water pollutants. In this thesis, the sediment samples were collected from 6 cross-sections through the desilting basin of Queshan reservoir, and the relationship among the characteristic parameters of their physicochemical properties was determined. The adsorption and desorption process of phosphate on sediment (B1 and B2) was conducted to analyze the corresponding dynamic process, isotherms, influence factors, reversibility and structural variation. Moreover, the adsorption mechanism was identified with some specific surface analysis techniques. The results listed as following:The neutral or slight alkaline sediment particles were mainly composed of clay, silt and fine sand, with very low content of organic matters and some negative charges on their surface, then low flocculating ability was observed among these sediment particles. There were good correlations existed among these physicochemical parameters characterizing these sediments. The surface of sediment particles showed complex morphology and heterogeneous pore size distribution, being mainly composed of mesopore. The pore surface fractal dimensions (Ds) of these sediment particles were 2.67-2.89, which implied a highly filling capability on the surface of these particles. The pore-size distribution also presented certain contribution to above Ds values. In addition, the complex surface morphology of these particles had strong influence on the surface element distribution, which could lead to the heterogeneity of surface adsorption sites.The adsorption process could be divided into two stages:a high-speed physical adsorption and physicochemical adsorption (0-3h) stage, slow-speed chemical sorption. A pseudo second-order reaction kinetic equation fitted above dynamic process. The curves of adsorption isotherms did not pass the origin of coordinates which was divided into two parts by the zero equilibrium P concentration (0.038-0.049mg-L-1). The Langmuir cross-axis-type adsorption model showed much better fitting results for above mentioned phosphate adsorption curves than other adsorption models. Moreover, phosphate adsorption onto sediment particles was an endothermic process, and showed a solid concentration effect, particle size of sediments, pH value, salinity and organic matter content of adsorption solution matrix had important influences on the above mentioned adsorption process. In addition, phosphate adsorption onto sediment particles had reversibility, and phosphate desorption could occurr under some specific conditions.Once phosphate was absorbed onto the sediment particles, their specific surface area, pore volume and pore distribution were slightly decreased, but average pore diameter was slightly increased. The change in pore volume within pore size of 1.5-30nm was significant. It was observed that lots of phosphate absorbed on the sediment surface of ridge, concave and saddle areas, which occupied more than 96% adsorption capacity. In addition, it can be deduced that Al, Fe, Ca hydrous oxides were a main component in phosphate adsorption.更多还原