ICP-MS研究黄河三湖河口表层沉积物对Cd~(2+)和Cu~(2+)的吸附-解吸特性

为了研究黄河上游表层沉积物与Cd~(2+)和Cu~(2+)的相互作用机理,以黄河三湖河口表层沉积物(简称样品)为研究对象,采用电感耦合等离子体质谱(ICP-MS)技术,优化样品对Cd~(2+)和Cu~(2+)的吸附固液比、时间、pH等条件。并在此条件下研究了Cd~(2+)和Cu~(2+)在样品上的吸附特性和解吸特性。结果表明:两种金属的优化吸附条件不同,在各自优化吸附条件下,样品对Cu~(2+)和Cd~(2+)的平衡吸附量分别为0.88和0.13 mg·g~(-1);对两种金属的吸附动力学符合伪二级吸附动力学模型,且样品对Cu~(2+)的吸附速率大于对Cd~(2+)的吸附速率;吸附热力学拟合结果显示吸附过程符合Freundlich模型,对两种金属的吸附均属于优惠型吸附,且吸附过程属于吸热过程,可自发进行;解吸动力学研究表明,两个金属的解吸过程均符合Elovich方程,属于非均相扩散;在多离子竞争吸附-解吸实验中发现,样品对Cu~(2+)的吸附-解吸受到共存离子的影响更大。研究结果揭示了黄河三湖河口表层沉积物对Cd~(2+)和Cu~(2+)吸附和解吸的作用机理以及共存离子对吸附解吸特性的影响。对于分析重金属在水体与沉积物之间的作用机理、固液两相分布规律以及重金属迁移能力提供了理论依据,同时也为制定研究区域针对性的重金属防控措施具有一定指导意义。

Study on Adsorption and Desorption Characteristics of Cd2+ and Cu2+ on the Surface Sediments of Sanhuhekou of Yellow River by Using ICP-MS

In order to study the interaction mechanism between Cd2+,Cu2+ and surface sediments in the upper reaches of the Yellow River,the surface sediment of Sanhuhekou (YRSSM) was chosen as research object with inductively coupled plasma mass spectrometry (ICP-MS) as analysis method .The adsorption reaction condition such as liquid-solid ratio,reaction time and pH were optimized,and the adsorption and desorption characteristics of Cd2+ and Cu2+ onto the surface sediments under the optimized experimental conditions we re studied .The results showed that the adsorption capacity of Cu2+ was greater than that of Cd2+,the equilibrium absorption capacity were 088 and 013 mg·g-1 under each optimum experimental condition,respectively .The adsorptions of Cu2+ and Cd2+ were in accord with the pseudo-second-order kinetic,while adsorption rate of Cu2+ was also greater than that of Cd2+ .The adsorption thermodynamics data were in accordance with the Freundlich model and the fitting .Results showed that the adsorption process of Cu2+ and Cd2+ belonged to the preferential adsorption,and were endothermic and spontaneous processes .The desorption process showed that the Elovich equation were suitable for Cd2+ and Cu2+ and belonged to the heterogeneous diffusion .Multi-ions competitive adsorption and desorption experiments indicated that Cu2+ was influenced more by co-existing ion .The study revealed not only the mechanism of adsorption and desorption between Cd2+,Cu2+ and surface sediment in Sanhuhekou,but also the influence of coexisting ions on the adsorption and desorption characteristics .The results demonstrated that the distribution mechanism of heavy metals between solid-liquid phases,and provided a theoretical basis for the migration ability of heavy metals .It also had a guiding significance for establishing heavy metals preventive and control measures of the study area .