【作者】 孙晓慧；

【导师】 沈学优；

【作者基本信息】 浙江大学 ， 环境科学， 2006， 硕士

【摘要】 膨润土是一种新型的环境吸附材料,在环境污染控制和修复中有很好的应用前景。本文评述了膨润土的结构、性质及有机膨润土的特性,重点总结了膨润土吸附处理水中有机物、重金属及其它污染物的研究现状及机理,展望了膨润土在废水处理领域的研究趋势。 本文研究了膨润土对复杂水体中表面活性剂的吸附。在此基础上,研究了“膨润土+表面活性剂”直接处理有机废水过程中表面活性剂的最经济适宜投加量及表面活性剂的二次污染问题。重点研究了膨润土的固定化技术,探讨最佳的合成条件及颗粒态膨润土吸附污染物的动力学、热力学特征及机理;从吸附效果、吸附后固液分离情况以及改性剂的脱附等方面,对粉末态膨润土(P-Bent)与颗粒态膨润土(G-Bent)进行定量比较。主要得到以下研究结论: (1)Na基膨润土对阳离子表面活性剂的吸附去除效果最好,对阴离子表面活性剂基本不吸附,而对非离子表面活性剂的吸附去除效果介于上述两者之间。SDBS在Ca基膨润土上的吸附损失机理主要为沉淀作用,损失量在SDBS平衡浓度为1.5CMC时达到极大值。CPC对膨润土吸附TX-100的影响:低浓度为增强作用,高浓度为抑制作用。SDBS能显著降低膨润土对TX-100的吸附量。NaCl的存在,能显著增强膨润土对CPC的吸附量,并可使膨润土对TX-100的去除率由56%提高到99%以上,且NaCl浓度与TX-100去除率成线性正相关。膨润土对CPC的吸附为放热过程,对TX-100的吸附为吸热过程。 (2)长碳链表面活性剂的存在,可使膨润土处理p-硝基苯酚的去除率提高2倍以上。表面活性剂在膨润土处理含p-硝基苯酚废水中的最经济适宜的投加量与膨润土阳离子交换容量(CEC)相当。与表面活性剂改性土相比,用相应浓度的“膨润土+表面活性剂”混合直接处理含p-硝基苯酚废水更为有效,并可以省略制土坏节,节约成本,且基本不会增加表面活性剂二次污染。 (3)采用包埋技术,用控制变量法,得出了制备颗粒态膨润土的最优化条件。在较高CEC载量(>0.5CEC)改性下G-Bent对重金属的去除效果明显好于P-Bent。在1.0～1.5CEC载量改性下,G-Bent对有机物的吸附去除率与P-Bent相当,都达到了90%以上,且不存在固液分离的问题,不需离心或过滤,基本解决了膨润土更多还原

【Abstract】 Bentonites, a new kind of environmental adsorption material, have been widely used in the environmental pollution control and remediation. In this dissertation, the structure and properties of bentonite and the character of organobentonite have been described. The study progress and mechanism of bentonites in treating organic pollutants, heavy metals and other pollutants in water have been mainly summarized, and the trend of its application in wastewater treatment have also been forecasted.The sorption of surfactants in complex system on bentonites has been firstly investigated. Based upon that, the most economical and fitting dosage of surfactant in the process of treating organic wastewater by "bentonite + surfactant" mixture system directly, and the problem of the secondary pollution of surfactant have been studied. Finally, the embed-immobilization technique of bentonite has been mainly investigated to find out the best conditions of preparation, the dynamic and thermodynamic characters and mechanism of adsorbing pollutants by granule bentonites. Granule bentonite (G-Bent) is compared with powder bentonite (P-Bent) in terms of adsorption efficiency, solid liquid separation facility and the desorption of modifier. The results list as follows:(1) the uptake of cationic surfactant on Na-bentonite is greater than that of nonionic Surfactant and anionic surfactant, and anionic surfactant showed hardly any adsorption. SDBS is adsorbed to Ca-bentonite mainly through precipitation interaction. It reaches a maximum at 1.5 Critical Micelle Concentration (CMC). Cetyl pyridinium chloride(CPC), in the low concerntration range, can enhance the uptake of TX-100 on bentonites, but inhibit the uptake when its concentration is high. The presence of SDBS can observably suppress the sorption of TX-100 on bentonites. The amount of CPC adsorbed on bentonite can be increased by NaCl. The removal rates of TX-100 can also be increased by NaCl from 56% to above 99% and is positively proportional to the concentration of NaCl. The sorption process of CPC on bentonite is exothermic reaction, while that of TX-100 is endothermic.(2) The removal rates of p-nitrophenol could be enhanced more than two times by quaternary ammonium cation surfactants with the long-chain alkyl . In treating waste water containing p-nitrophenol, the most economical dosage of surfactants correspondsto cation-exchange capacity (CEC) of bentonite. Compared with surfactant modified bentonite, "surfactant+bentonite" mixture of corresponding concentration is more effective in directly treating waster water containing p-nitrophenol and has advantages such as omitting the process of modifying bentonite, lower cost, and hardly no secondary pollution of surface active agent.(3) Using embed-immobilization technique, the optimal condition of bontonites’s immobilization is found by variable control. Heavy metal is better removed by G-Bent than P-Bent when CEC loading capacity is relative high (>0.5CEC). In the range of 1.0-1.5CEC loading capacity, the removal rate of organic matters by G-Bent is corresponding to P-Bent, both larger than 90%. Overcoming the primary difficulty in solid liquid separation encounterd in the treating wastewater, G-Bent occupies the advantages of the easy solid liquid separation and centrifuge elimination. Besides, G-Bent has no secondary pollution as little surfactants and PVA desorption. The sorption of p-naphthol on bentonites can be well described by the Langmuir and Freundlich model. At examined P-naphthol concentrations(0~1000mg/L), the removal rate of P-naphthol by G-Bent is corresponding to P-Bent. Not sensitive to temperature, Sorption process of P-naphthol to G-Bent is endothermic reaction. The driving force of sorption is the decreasing of AG° and the increasing of AS0. G-Bent modified with 1.0CEC-1.5CEC loading capacity can effectively adsorb organic contaminants several times.更多还原