【作者】 张同钦；

【导师】 杜茂安；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2011， 硕士

【摘要】 近年来,随着我国工业的迅速发展,大量未经达标处理的重金属废水排入水体,造成了严重的重金属污染问题。重金属污染的综合治理及重金属的毒性评价成为当前环境治理中的重中之重。本文采用废弃的普洱茶作为一种新型吸附材料,以重金属Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺为研究对象,利用静态吸附实验,从影响因素、吸附等温线、吸附动力学、材料表面表征分析等方面对废弃茶叶对Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺的吸附性能进行了研究。并进一步考察了Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺在废弃茶叶表面的竞争吸附行为。最后,以大型蚤为试验生物,通过Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺对大型蚤的急性毒性试验,对这四种重金属的毒性程度进行了评价。实验结果表明,pH对吸附效果影响最大,对Cr⁶⁺吸附的最佳pH为2.0,对Cu²⁺、Pb²⁺、Zn²⁺吸附的最佳pH为5.0⁶.0。吸附反应速率非常快,5¹0min就可达到平衡吸附量的80⁹0%。对Cr⁶⁺的吸附为吸热反应,对Cu²⁺、Zn²⁺、Pb²⁺的吸附为放热反应。废弃茶叶对Cr⁶⁺、Cu²⁺、Zn²⁺的吸附能够较好的符合Langmuir方程,而对Pb²⁺的吸附则较好的符合Freundlich方程。拟二级动力学模型能够很好的描述Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺在废弃茶叶上吸附动力学。对废弃茶叶表面Zeta电位分析表明,废弃茶叶的pHZPC=3.8±0.1。FTIR光谱分析表明,茶叶表面存在着羧基、氨基等丰富的官能团,保证了废弃茶叶对重金属离子良好的吸附效果。废弃茶叶表面的SEM图表明,废弃茶叶的表面有着丰富的孔隙结构。吸附的Cr⁶⁺和Pb²⁺在表面形成了一层致密状的物质,而吸附的Cu²⁺和Zn²⁺只在表面形成一些颗粒状物质,从而验证了废弃茶叶对Cr⁶⁺和Pb²⁺有较高的吸附量,而对Cu²⁺和Zn²⁺的吸附量则相对较低。竞争吸附实验表明,Pb²⁺、Cu²⁺、Zn²⁺之间均呈现明显的拮抗吸附作用。其竞争能力排序为Pb²⁺>Cu²⁺>Zn²⁺,符合按重金属离子的电负性排列顺序。Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺对大型蚤的急性毒性试验表明,四种重金属离子对大型蚤的毒性大小顺序为:Cu²⁺>Cr⁶⁺>Pb²⁺>Zn²⁺。Cu²⁺属于剧毒物质,Cr⁶⁺属于高毒性物质,Pb²⁺和Zn²⁺属于中毒物质。Cr⁶⁺、Cu²⁺、Zn²⁺、Pb²⁺四种重金属离子的安全质量浓度分别为0.041mg/L、0.0033mg/L、0.66mg/L、0.21mg/L。实验证明,利用废弃茶叶吸附技术能够有效去除废水中的重金属,在小规模重金属废水的应急处理方面有着很好的应用前景。更多还原

【Abstract】 In recent years, amount of heavy metal wastewater which didn’t reach the discharging standard has been discharged with the rapid development of industry and caused serious heavy metal pollution. So, controlling heavy metal contamination and toxicity assessment of heavy metals have been a top priority in the environmental management.The paper which took waste Puer tea as a new type of adsorption material and Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺ as research subject researched the adsorbability of waste Puer tea. Through static adsorption experiment, following several aspects have been studied, including affecting factors, adsorption isotherms, adsorption kinetics and surface characteristics. Futhermore, competive adsorption among Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺ on the surface of waste Puer tea has been investigated. At last, the paper took Daphnia magna as experimental organism and acute toxicity of Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺ on Daphnia magna has been observed for toxicity assessment.Results showed that pH was the most important factor on heavy metal adsorption and the optimum pH for Cr⁶⁺ and Cu²⁺, Zn²⁺, Pb²⁺ were 2.0 and 5.0⁶.0, respectively. The adsorption rate was so fast that the adsorption amount could be up to 80%⁹0% of the equilibrium adsorption capacity in 5¹0min. The adsorption of Cr⁶⁺ onto waste tea is endothermal reaction, but the adsorption of Cu²⁺, Zn²⁺, Pb²⁺ onto waste tea was exothermic reaction. Isotherm experiments revealed that the adsorption of Cr⁶⁺, Cu²⁺, and Zn²⁺ was fitted very well to the Langmuir isotherm model. But for Pb²⁺, the adsorption data better followed the Freundlich isotherm model. Based on the coef?cient of determination R2, the adsorption kinetics of Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺ better followed Richie’s pseudo-second order rate equation. Through the determination of Zeta-potential of waste tea, the pHZPC of waste tea was 3.8±0.1. The FTIR spectra of waste tea indicated the existence of carboxyl and amino groups etc on the surface of waste tea, which was the reason of good adsorption capability for heavy metals. The surface structure of waste tea was investigated by means of SEM, showing that well-developed pore structure existed on the surface of waste tea. Densely packed matters could be found on the surface of waste tea through SEM when Cr⁶⁺ and Pb²⁺ adsorbed, but only granular materials could be discovered when Cu²⁺ and Zn²⁺ adsorbed. The results demonstrated high adsorption capacity for Cr⁶⁺ and Pb²⁺ and low adsorption capacity for Cu²⁺ and Zn²⁺. Through the competitive adsorption experiment on the surface of waste tea, obvious Pb²⁺-Cu²⁺ antagonism, Pb²⁺-Zn²⁺ antagonism and Cu²⁺-Zn²⁺ antagonism could be observed in the competition system.The adsorption order was Pb²⁺>Cu²⁺>Zn²⁺, which was fitted to the order arranged according to electronegativity.The acute toxicity test of Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺ on Daphnia magna suggested that the acute toxicity order was Cu²⁺>Cr⁶⁺>Pb²⁺>Zn²⁺. Cu²⁺ was a kind of extremely toxic substance and Cr⁶⁺ belonged to highly toxic substance. The toxicity grade of Pb²⁺ and Zn²⁺ belonged to medium toxicity. The research also showed that the safe concentration of Cr⁶⁺, Cu²⁺, Zn²⁺, Pb²⁺ were 0.041 mg/L, 0.0033 mg/L, 0.66 mg/L, 0.21 mg/L, respectively.Based on above research, we can see that the waste tea adsorption technique can remove heavy metal ions in industry wastewater effectively. The new adsorption technology will show a broad application prospect in the emergency treatment of little-scale heavy metal wastewater.更多还原