【作者】 郭志强；

【导师】 徐进章；

【作者基本信息】 兰州大学 ， 粒子物理与原子核物理， 2012， 博士

【摘要】 60C0是一种比较常见的放射性核素,在工业、农业、医学等方面有广泛的应用。60Co可以放出很强的伽玛射线,导致脱发、再生性障碍贫血症和白血病等疾病。因此,去除水体中的放射性核素60Co对水资源的保护和人类的健康具有重要意义。本文采用宏观静态吸附法研究放射性核素60Co在高岭石、蒙脱石、针铁矿、氧化钛和鸡蛋壳衍生物上的吸附行为,着重考察不同环境条件(接触时间、pH值、离子强度、温度、竞争离子和腐殖酸)对放射性核素60Co在以上几种材料上吸附的影响,并通过动力学、热力学研究以及模型拟合阐明60Co的吸附机理。研究结果表明：60Co在高岭石和蒙脱石这两种粘土上的吸附受pH、离子强度和竞争离子的影响很大。在低pH下,60Co在两种粘土上的吸附随离子强度的增大而减小；在高pH下,60Co在两种粘土上的吸附不受离子强度的影响。在同一pH下,60Co在两种粘土上的吸附顺序表现为：Li+>Na+>K+,说明竞争离子可以改变粘土表面的性质,从而影响粘土对60Co的吸附。在低pH下,富里酸的存在促进了60Co在两种粘土上的吸附；在高pH下,富里酸对60Co在两种粘土上的吸附起抑制作用。在低pH下,60C0在两种粘土上的吸附主要通过离子交换和外层络合共同作用实现；在高pH下,60Co在两种粘土上的吸附主要通过内层络合作用实现。离子强度对60Co在二氧化钛和针铁矿两种氧化物上吸附的影响效果不同。在低pH下,60Co在针铁矿上的吸附随离子强度的增大而减小；在高pH下,60Co在针铁矿上的吸附不受离子强度的影响。然而,在任何pH下,60Co在二氧化钛上的吸附都不受离子强度的影响。在低pH下,富里酸的存在促进了60Co在两种氧化物上的吸附；在高pH下,富里酸的存在抑制了60Co在两种氧化物上的吸附。60Co在针铁矿和二氧化钛上的吸附机理不同：在针铁矿上的吸附主要通过离子交换和表而络合共同作用实现；在二氧化钛上的吸附主要通过内层络合作用实现。pH、离子强度和竞争离子对60Co在羟基磷灰石上吸附的影响与在两种粘土上的情况相似。但是,富里酸对60Co在羟基磷灰石上吸附的影响与在以上几种材料上的情况不同：在低pH下,富里酸的存在抑制了60Co在羟基磷灰石上的吸附；在高pH下,富里酸对60Co在羟基磷灰石上的吸附没有影响。在低pH下,60Co在羟基磷灰石上的吸附主要通过离子交换和外层络合共同作用实现；在高pH下,60Co在羟基磷灰石上的吸附主要通过内层络合作用实现。高岭石、蒙脱石、针铁矿、二氧化钛和鸡蛋壳衍生物均价格低廉,对放射性核素60Co都有较强的吸附能力,在处理放射性核素60co污染废水领域有广阔的实际应用前景。更多还原

【Abstract】 60Co, one of the most common radionuclides, is widely utilized in industrial, agriculture and medical applications.60Co is characterized by emission of high gamma energy which can cause alopecia, reproducibility obstacle of anemia and leukemia. Therefore, the removal of60Co from wastewater is of great significance for human health and environment protection.This work contributes to the sorptions of60Co on kaolinite, montmorillonite, goethite, titanium dioxide and eggshell derivative as a function of contact time, pH, ionic strength, temperature and foreign ions in the absence and presence of humic acid using a batch technique. Sorption mechanisms of60Co on materials above are determined through the dynamics data, thermodynamics research and model fitting. The results show that:The effects of pH, ionic strength and foreign ions on sorptions of60Co on kaolinite and montmorillonite are obvious. The sorptions of60Co on the two clays above decrease with increasing ionic strength at low pH values. However, the sorptions of60Co on the two clays above are independent of ionic strength at high pH values. The sorptions of60Co on the two clays above under the same pH values are in the following sequence:Li+>Na+>K+, indicating that the cations can alter the surface properties of the two clays and thus influence the sorptions of60Co. The presence of FA enhances60Co sorptions on the two clays above at low pH, but suppresses60Co sorptions at high pH. Outer-sphere surface complexation and/or ion exchange are the main mechanisms of60Co sorptions on the two clays above at low pH values, whereas inner-sphere surface complexation is the main adsorption mechanism at high pH values.The effects of ionic strength on sorptions of60Co on goethite and titanium dioxide are different. The sorption of60Co on goethite decreases with increasing ionic strength at low pH values, and is independent of ionic strength at high pH values. However, the sorption of60Co on titanium dioxide is independent of ionic strength at any pH values. The presence of FA enhances60Co sorptions on goethite and titanium dioxide at low pH values, but reduces60Co sorptions at high pH values. The sorption mechanisms of60Co on goethite and titanium dioxide are different. Surface complexation and/or ion exchange are the main mechanisms of60Co sorption on goethite, whereas inner-sphere surface complexation is the single sorption mechanism of60Co sorption on titanium dioxide.The effects of pH, ionic strength and foreign ions on sorption of60Co on hydroxyapatite are similar to that on the two clays above. However, the effect of FA on sorption of60Co on hydroxyapatite is different from that on other materials above. The presence of FA suppresses60Co sorption on hydroxyapatite at low pH, but has no effect on60Co sorption at high pH. Outer-sphere surface complexation and/or ion exchange are the main mechanisms of60Co sorption on hydroxyapatite at low pH values, whereas inner-sphere surface complexation is the main sorption mechanism at high pH values.Kaolinite, montmorillonite, goethite, titanium dioxide and eggshell derivative can be used to remove60Co from wastewater on a large scale, due to their low cost and better sorption capacity of60Co.更多还原