网板式超重力电化学反应器处理电镀废水的研究

发布时间：2018-03-03 01:18

本文选题：电氧化　切入点：电镀废水　出处：《浙江工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：电镀废水作为一种典型的重金属废水,其产生量大、危害性强的特点,对环境造成日益严重的污染。其中金属络合物性质稳定、毒性强,难以通过沉淀法直接去除。电化学氧化可对重金属络合物进行有效破络合处理,并能有效改善废水的可生化性。但仍存在电化学反应的传质问题,限制了电氧化的处理效率和电流效率。本文引入超重力概念,设计了一种新型的网板式超重力电化学反应器(RMDE-HER),强化电氧化反应过程。通过电极旋转产生离心力,促进电极表面液膜快速更新,强化电氧化传质过程,提高处理效率和电流效率,降低能耗;避免了普通平板电极中电流密度分布不均匀的问题。以含Cu、Ni和Cr金属络合物的实际电镀废水为实验对象,重点考察了电流密度、旋转电极转速和溶液pH值等宏观工艺参数对RMDE-HER处理效率的影响。研究结果表明:增大电流密度能提高破络合率,但当其超过10 mA·cm-2时,将明显降低破络合负荷提高能耗。破络合率随着旋转电极转速增加而增加,但当转速从200 rpm增至400rpm时,传质效果未继续增强甚至有削弱的趋势。在pH=3.0-12.6范围内具有较好的破络合效果,酸性或碱性条件均促进破络合作用,均比中性条件下破络合效果好。由于酸性溶液抑制了析氧副反应,而碱性条件促进生成·OH、·HO2等活性基团。Cu金属络合物的去除遵循一级反应动力学模型,在pH=11.0时反应速率最快,其反应速率常数为-0.0448 min-1。在最佳工艺条件电流密度为10 mA·cm-2、旋转电极转速为200 rpm和pH=11.0条件下,电解90 min后,Cu、Ni和Cr金属络合物破络合率分别达到98.09%、95.57%和96.10%,其对应破络合的电能消耗分别是106.04 k W·h·kg-1、518.29 kW·h·kg-1和938.12 kW·h·kg-1。另外,RMDE-HER可有效改善难生物降解废水的可生化性;考察了电流密度和转速对实际废水的CODCr和B/C比值的影响。在最佳工艺条件电流密度为10 mA·cm-2和旋转电极转速为200 rpm下,电解90min后,废水的B/C比值从0.20提高至0.48,也可有效降低CODCr;具有较好的改善废水的可生化性的效果。
[Abstract]:Electroplating wastewater, as a typical heavy metal wastewater, has the characteristics of large amount of production and strong harmfulness, which causes increasingly serious pollution to the environment. It is difficult to remove the complex directly by precipitation. Electrochemical oxidation can effectively break the complex of heavy metals and improve the biodegradability of wastewater. However, the mass transfer problem of electrochemical reaction still exists. The treatment efficiency and current efficiency of electrooxidation are limited. In this paper, the concept of hypergravity is introduced and a new type of grid plate type high gravity electrochemical reactor is designed to enhance the electrooxidation process. The centrifugal force is generated by rotating the electrode. Promote the rapid renewal of the liquid film on the electrode surface, strengthen the mass transfer process of electrooxidation, improve the treatment efficiency and current efficiency, reduce energy consumption; The problem of uneven distribution of current density in common plate electrode was avoided. The actual electroplating wastewater containing Cu Ni and Cr metal complex was used as the experimental object, and the current density was mainly investigated. The effects of rotating electrode speed and pH value of solution on the treatment efficiency of RMDE-HER were studied. The results show that increasing the current density can increase the breaking complexing rate, but when the current density is higher than 10 Ma 路cm-2, The breaking complexation rate increased with the increase of rotating speed of the rotating electrode, but when the rotational speed increased from 200 rpm to 400rpm, The effect of mass transfer has not been further enhanced or even weakened. In the range of pH=3.0-12.6, the effect of breaking complexation is better, and the acid or basic conditions promote the breaking of complexation. Because acidic solution inhibited the side effects of oxygen evolution, while alkaline conditions promoted the removal of 路OH, 路HO2 and other active groups. The removal rate of Cu metal complexes followed the first-order reaction kinetic model, and the reaction rate was the fastest at pH=11.0. The reaction rate constant is -0.0448 min-1. Under the optimum conditions, the current density is 10 Ma 路cm ~ (-2), the rotating speed of the rotating electrode is 200 rpm and pH=11.0. After 90 min electrolysis, the breaking complexation rate of Cu Ni and Cr metal complexes reached 98.09% and 96.1057%, respectively, and the electric energy consumption corresponding to breaking the complex was 106.04 kW 路h 路kg-1U 518.29 kW 路h 路kg-1 and 938.12 kW 路h 路kg-1.In addition, RMDE-HER could effectively improve the biodegradability of refractory wastewater. The effects of current density and rotating speed on the ratio of CODCr to B / C of wastewater were investigated. Under the optimum conditions of current density of 10 Ma 路cm-2 and rotating electrode speed of 200 rpm, electrolysis was performed for 90 minutes. The increase of the ratio of B / C of wastewater from 0.20 to 0.48 can also effectively reduce the COD _ (Cr), and has a better effect of improving the biodegradability of wastewater.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X781.1

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