【作者】 黄瑾辉；

【导师】 曾光明； 黄国和；

【作者基本信息】 湖南大学 ， 环境工程， 2007， 博士

【摘要】 胶团强化超滤法是一种将表面活性剂技术和超滤技术结合的新型、高效的重金属废水治理方法。本文展开了胶团强化超滤法处理含镉废水的机理与应用基础研究,研究中以十二烷基硫酸钠(SDS)为表面活性剂,采用聚醚砜中空纤维超滤膜处理含镉废水,系统地研究了分离过程的各控制因素的影响,优化了分离过程条件,并通过考察动力学、热力学与吸附规律,结合微观检测,分析了胶团强化超滤的作用机制。研究中(1)从镉污染现状、含镉废水治理技术现状、超滤和表面活性剂技术在环境保护中的应用现状以及胶团强化超滤技术的现有成果出发,提出研究的背景和目的;(2)进行了废水水质环境下表面活性剂SDS临界胶团浓度和胶团特性变化规律的研究,采用三种非离子型表面活性剂与SDS的复配,有效地降低临界胶团浓度;(3)对含镉废水进行了胶团强化超滤,实现Cd2+截留率97%以上,研究发现SDS胶团与Cd2+的吸附过程遵循二级动力学规律,符合Langmuir吸附等温方程,属于自发的吸热过程,吸附作用力主要为相反电性的吸引;(4)对含镉、含锌、含铅废水以及混合体系进行胶团强化超滤,研究发现SDS胶团对二价重金属离子的吸附作用为Pb2+>Cd2+>Zn2+,当溶液中多种二价重金属离子存在时,各离子之间存在与SDS胶团的竞争吸附,竞争能力为Pb2+>Zn2+>Cd2+;(5)建立起基于超滤膜污染层性质的渗透通量模型,揭示了胶团强化超滤过程中的控制参数、膜装置参数与渗透通量的关系,该模型可有效的预测横向流胶团强化超滤稳态时的渗透通量变化规律,实验验证误差率在4.77%～12.85%;(6)进行了基于非离子型表面活性剂与离子型表面活性剂复配胶团的强化超滤,显著地减少了SDS的用量,降低渗透液中SDS的残留量;(7)采用微孔泡沫气浮深度处理胶团强化超滤渗透液,出水中Cd2+达到《污水综合排放标准》中一类污染物最高浓度允许限值的要求。研究结果表明,胶团强化超滤法可以高效、快速的处理含镉废水,与微孔泡沫气浮联用后可以实现Cd2+的达标排放,研究中将胶团强化超滤与微孔泡沫气浮联用,仅通过微气泡即同时实现含镉废水中Cd2+和表面活性剂的深度处理,并将胶团强化超滤和微孔泡沫气浮工艺联用改进作为减少表面活性剂用量的重要手段;建立起基于超滤膜污染层性质的渗透通量模型,克服了凝胶层阻力和膜阻力在实际应用中不易测定的缺点;采用微观检测方法推断胶团和重金属离子结合作用类型,从微观上检测胶团强化超滤过程中胶团与重金属离子的吸附机理。以上研究针对胶团强化超滤处理含镉废水过程中胶团的聚集自组装控制、胶团与重金属作用机制等关键问题进行了探讨,为实现胶团强化超滤在重金属工业废水治理中的应用和推广奠定基础,具有较好的理论意义和实际应用前景。更多还原

【Abstract】 Micellar-Enhanced Ultrafiltration (MEUF) is a powerful treatment process developed recently to remove heavy metals from wastewater, which combines ultrafiltration with surfactant technology. This study focuses on mechanisms and application of cadmium-containing wastewater treatment with MEUF. Sodium dodecyl sulfate (SDS) was applied as the surfactant and polysulfone hollow fibre was adopted as the ultrafiltration membrane. Influences of operation factors on separation process were systemically investigated. Conditions of separation process were optimized. In addition, mechanisms of MEUF were analyzed by dynamics, energetics, adsorption rules, as well as microcosmic detection.(1) Cadmium pollution, cadmium-containing wastewater treatment technology, application of ultrafiltration and surfactant technology in environment protection, along with current research of MEUF technology were reviewed, and purpose of this investigation were put forword. (2) Variety rules of critical micelle concentration and micelle characteristic of SDS in the wastewater was studied. Mixing nonionic surfactant with SDS efficiently decreases the critical micelle concentration. (3) Retention rate of Cd2+ is above 97% by cadmium-containing wastewater treatment with MEUF. Adsorption process of Cd2+ on SDS micelle follows the law of second-order kinetics, and accords with Langmuir Isotherm. Adsorption is a spontaneous endothermic process, in which adsorption force is principally the attraction of opposite electric charge. (4) MEUF was applied to treat cadmium-containing wastewater, zinc-containing wastewater, plumbum-containing wastewater and mixed wastewater. Results show that the sequence of adsorption of bivalence heavy metal ions to SDS micelle is Pb2+>Cd2+>Zn2+. With the wastewater containing a variety of bivalence heavy metal ions, competitive adsorption to SDS exists among various ions, and the sequence of competitive adsorption is Pb2+>Zn2+>Cd2+. (5) Permeation flux model based on membrane fouling characters was set up. Relationships between permeation flux und operation parameters and membrane parameters were described. Moreover, this model can exactly forecast variety rule of permeation flux by MEUF and the error is 4.77%~12.85% compared with experiments. (6) MEUF with the mixture of nonionic surfactant and SDS was experimented. Dosage of SDS reduces obviously and residue of SDS in permeation decreases. (7) Permeation by MEUF was advanced treated by MFF (Micropore Foam Flotation), and Cd2+ in effluent meets the requirement of the highest concentration limit of the first category contaminants in“Integrated Wastewater Discharge Standard”.The Study shows that cadmium-containing wastewater is efficiently and quickly purified with MEUF, and Cd2+ can meet the requirement of the wastewater discharge standard with the combination of MEUF and MFF. Advanced removal of cadmium ions and surfactant from wastewater is simultaneously achieved with tiny air bubble. Moreover, the combination of MEUF and MFF was adopted to reduce the surfactant dosage. Permeation flux model based on membrane fouling was set up, which can overcome the problem of difficulty by measuring the resistance of gelatin layer and membrane in application. Microcosmic detection was used to analyze the interaction between micelle and heavy metal ions for the first time and to detect the adsorption mechanisms between micelle and heavy metal ions on microcosmic level.Above study discusses the key technology of aggregation and self-assembly control of micelle, interaction mechanisms between micelle and heavy metal ions in cadmium-containing wastewater treatment by MEUF. The study provides foundation for application and popularization of heavy metal-containing wastewater treatment by MEUF.更多还原