电絮凝中铝的形态结构调控及电絮凝-超滤除氟研究

发布时间：2018-04-18 18:03

本文选题：电絮凝 + 铝形态　；参考：《河北工业大学》2015年硕士论文

【摘要】：电絮凝与膜分离是近几年广泛研究和应用的水处理技术。本文旨在从铝形态、絮体特性等进一步探讨电絮凝去除污染物的机理以及与膜分离技术的联用。本文通过电解铝板研究了电絮凝过程中铝形态的分布、电解过程中Al13的形成机制,并考察了pH值、电流密度、外加电压等对铝形态分布的影响,以及相应的絮体特性,并在此基础上进行了电絮凝去除天然有机物,电絮凝-超滤去除饮用水中氟的研究和相应的膜污染探讨。得出以下主要结论:(1)电絮凝过程中,特别是阴极表面OH-的不断生成与金属-溶液界面处不平衡的pH分布促进了Al3+离子的水解-聚合反应。随着电絮凝的进行,初始阶段以Ala为主要优势形态,逐渐转化为Alb为优势形态,继而Alc成为主要的铝形态。电絮凝过程能够原位产生Al13聚合物。(2)电絮凝过程中Al13形成的适宜pH范围为5-7。降低电流密度和电压有利于Al13形成。提高pH值、电流密度和极板电压能够加剧阳极溶出的铝离子的水解-聚合反应,导致Ala、Alb的相对含量显著减少,Alc的相对含量增加。(3)pH值与电流密度对多羟基聚合铝絮体特性有重要影响。随着电解的进行,酸性、中性条件下,pH值先升高继而趋于稳定;碱性条件下,pH先降低,2 min之后也变为先升高再趋于稳定。Zeta电位都有一个短暂的上升阶段,继而都开始下降,最后趋于稳定。增大电流密度,pH增加的更快,Zeta电位下降的更快。(4)pH值与电流密度对电絮凝去除天然有机物与浊度有重要影响。弱酸性下,电流密度在10 A/m2下,Zeta电位在10 min左右到达等电点附近,此时胶体、天然有机物的稳定性最低,最容易失稳聚集。粒径在10 min左右达到稳定,此时形成比较均匀、多孔隙、具有一定密实度的絮体团簇,絮体强度高,比表面积大,吸附能力强。(5)在连续流下EC-UF工艺除氟效果良好,在电流密度30 A/m2、水力停留时间20 min、初始pH值在6.0-7.0的最佳工艺条件下,氟的去除率达到80%以上。膜污染主要是由电解过程产生的铝絮凝剂与氟离子形成的颗粒物质导致。
[Abstract]:Electroflocculation and membrane separation are widely studied and applied water treatment technology in recent years.The aim of this paper is to discuss the mechanism of electroflocculation removal of pollutants and its combination with membrane separation technology from the aspects of aluminum morphology and flocculation characteristics.In this paper, the distribution of aluminum forms in electroflocculation process and the formation mechanism of Al13 in electrolysis process are studied. The effects of pH value, current density, applied voltage on aluminum speciation distribution and the corresponding flocs characteristics are also investigated.On this basis, the removal of natural organic matter by electroflocculation and the removal of fluoride from drinking water by electroflocculation-ultrafiltration were studied and the corresponding membrane fouling was discussed.The main conclusions are as follows: during electroflocculation, especially the unbalance pH distribution between the formation of OH- on cathode surface and the interface between metal and solution promotes the hydrolysis polymerization of Al3 ion.With the development of electroflocculation, Ala is the main dominant form in the initial stage, and gradually transformed into Alb as the dominant form, and then Alc becomes the main aluminum form.The suitable pH range of Al13 formation during electroflocculation is 5-7.The reduction of current density and voltage is beneficial to the formation of Al13.Increasing pH value, current density and plate voltage can accelerate the hydrolysis-polymerization reaction of anodic dissolved aluminum ions.As a result, the relative content of Ala Alb decreased significantly. The increase of the relative content of Alc. The pH value and the current density had important effects on the properties of polyhydroxyl polymerized aluminum floc.With the electrolysis, pH value increased first and then stabilized under neutral condition, and pH decreased at first for 2 min under alkaline condition, and then increased at first and then stabilized. Zeta potential increased for a short period and then began to decrease.Finally, it tends to stabilize.Increasing the current density and increasing the pH value of Zeta potential decrease faster. The pH value and current density have important influence on the removal of natural organic matter and turbidity by electroflocculation.When the current density is 10 A/m2, the Zeta potential reaches the isoelectric point at about 10 min, and the colloid has the lowest stability and the most easily unstable aggregation.The particle size is stable at about 10 min, and the flocs with uniform and porous size and certain density are formed. The flocs have high strength, large specific surface area and strong adsorption ability. The EC-UF process has a good effect on fluoride removal under continuous flow.Under the optimum conditions of current density 30 A / m 2, HRT 20 min, initial pH 6.0-7.0, the removal rate of fluorine is over 80%.Membrane fouling is mainly caused by aluminum flocculant produced by electrolysis and particulate matter formed by fluorine ion.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU991.2

【参考文献】