【作者】 张广鑫；

【导师】 董德明； 花修艺；

【作者基本信息】 吉林大学 ， 环境科学， 2007， 硕士

【摘要】 为了模拟水环境多相体系,研究不同固相物质对重金属的吸附规律,研制了模拟研究装置,利用装置研究了南湖和松花江多相共存体系中各固相物质对Pb和Cd的吸附热力学和动力学规律,考察不同pH下各固相物质对Pb和Cd吸附量的变化。结果发现,三种固相物质吸附Pb或Cd的能力各不同,且与单一体系中的规律不同,不同水体也表现出不同的规律。对于两个不同水体,pH对固相物质吸附Pb或Cd的影响相似。不同固相物质吸附Cd的量随pH的变化趋势相似,但吸附Pb的量随pH的变化趋势各不相同。各固相物质吸附Pb时达到吸附平衡的时间长于Cd。在本实验条件下,利用装置模拟多相体系中各固相物质吸附重金属的整个过程分为两种作用部分,即吸附作用部分和扩散作用部分。二者存在于吸附实验过程的始终,整个过程是二者共同作用的结果。更多还原

【Abstract】 Recently people are paying more attention to the existing configuration, transformation regulation and the environmental effects of the trace metal in the natural aquatic environment. Only few of the trace metals in the waters are in real soluble forms, most of them combine with varieties of organic or inorganic, living or unliving solid materials, especially on the surface of them, achieving correspondingly stable preparative equilibrium. These important solid materials in natural waters exit mostly in three forms: suspended solid, sediment and biofilm. With the water, they make up of the multi-compartment system which decides the trace metal behaviors in natural waters. Most studies select single kind of solid material, however, there are few comprehensive studies on the interaction of the coexisting solid materials themselves and the materials with the trace metals. In some studies, researchers have already made abundant survey on the three different solid materials, but the materials used in these experiments are all separated from each other in the single compartment system. To some extent these experiments can not simulate the multi-compartment system under natural condition, because the suspended solid, sediment and biofilm are existing together in the waters and they have relations and interaction inevitably. The distribution of the trace metals among the different materials in the system can be influenced due to the change of the condition from the mixed solid materials system to the single compartment system.In order to simulate the multi-compartment system, study the adsorption thermodynamics and kinetics regulations of all the different solid phases, and compare with the regulations at single compartment system, a new equipment is developed in this study and a series of simulation experiments are carried out. The equilibrium equipment is made of organic glass, and it is obturated and according with my design perfectly. The magnetic force mixer which is under the equilibrium equipment can stir the solution in five rooms with thesame strength simultaneously. The equipment is examined, the results show that the equilibrium of the acid and alkali is quick, but it is slow for the trace metal. We can conclude the equilibrium time of soluble materials is 4 days when the five rooms were continuous stirring and separated with membrane filters. The examining experiments for the solid material show that the solid materials could be mutually separated in their rooms to some extent.In this study I use the equipment for simulating the multi-compartment system, to compare the differences between the single compartment system and the multi-compartment system in the adsorption thermodynamics and kinetics regulations. Examine the influence of the pH on the trace metal distribution in the multi-compartment system. Compare the adsorption regulations between Pb and Cd. Simulate two multi-compartment systems in Nanhu Lake and Songhua River respectively and distinguish the similarities and differences in the trace metal distribution regulations.The results showed that adsorptions of Pb and Cd by the solid materials in two different waters are all fit to the Langmuir adsorption isotherm. For Pb adsorption capacities of each solid component in the Nanhu Lake multi-system, at lower equilibrium concentration they are in turns: sediment> suspended solid> biofilm. And adsorption capacities of suspended solid exceed that of the sediment with the equilibrium concentration ascending. For Cd adsorption capacities of each solid component in the Nanhu Lake multi-system, they are in turns: suspended solid> sediment> biofilm. The distribution regulation of Pb in Songhua River multi-system is different from that in Nanhu Lake: suspended solid > biofilm> sediment. And it is same for Cd between the two waters. The adsorptions capabilities for Pb are always higher than Cd.There are some differences in the adsorption capabilities between the single compartment system and multi-compartment system: The adsorption capability of the suspended solid for Pb or Cd in multi-system is higher than that in single compartment system, but the sediment and the biofilm act contrary. When in the multi-system, the adsorption predominance of thesediment and bioflim is replaced by the suspended solid. The suspended solid has the ability to obtain more metals in the competition with the biofilm. The reason and mechanism deserve further study.The influences of pH to the adsorption amounts of Pb or Cd in two different waters are similar. In the same water, the trends of adsorption amounts of Cd by the different solids influenced by pH are similar (the adsorption amounts go up with pH), it is probably caused by the weak influence to the relative competitive adsorption capabilities of each material. The trends of adsorption amounts of Pb by the three solids are different, and probably because the influences of pH to adsorptions of Pb by these materials are different: adsorption capability of suspended solid goes up with pH, but the sediment and the biofilm act contrary.For the adsorption of Pb, the adsorption equilibrium time for the sediment is about 30h, and for suspended solid and biofilm are 40h and 70h. For the adsorption of Cd, the equilibrium time are all about 20h. The simulated distribution process of the trace metals in the multi-compartment system is analyzed using the developed equipment under this experiment conditions: the whole process can be divided into two parts, quick reaction and slow reaction.The former one, taking place in each small room which contains solid materials, is a quick adsorption effect. The latter one is the diffusion and re-distribution process which takes place among the different rooms, and it is much slower because the blank equilibrium time of the soluble material among the rooms is long. The two effects exist all through this simulating process, and they are principal and subordinate by turns. The whole process is the result of the two effects together.更多还原