电芬顿法处理络合铜镍电镀废水试验研究

发布时间：2018-07-26 11:19

【摘要】：电镀废水中络合态重金属是该类废水处理的重点,而络合态重金属有效去除的关键在于破络。目前,针对这类废水,往往采用芬顿氧化的方式破络,但该方法存在污泥产量大、停留时间长和药剂利用率低等问题。与传统芬顿法相比,电芬顿法具有H_2O_2和Fe~(2+)利用率高,产泥量小等优点,可以有效处理含络合态重金属的电镀废水,避免传统芬顿工艺存在不足。在电芬顿中电极材料的选择至关重要,虽然已有不少相关研究成果,但此类研究所得电极材料普遍存在制备困难、价格偏高等问题,难以实际应用。本课题将以市场易得、价格较低的铁、铝和石墨为研究对象,通过对比不同电极材料电芬顿法对含Ni-EDTA和Cu-EDTA废水的处理效果及处理成本,选择能用于实际工程的最优电极材料。在此基础上,通过小试试验及中试运行,确定该工艺适宜的工况参数。通过小试试验,考察以铁、铝、石墨为电极的电芬顿法处理络合铜镍废水的主要影响因素,并对三种电极材料在最优条件下的处理效果和处理成本进行综合比较。试验结果表明:三种电极材料电芬顿法对Ni-EDTA和Cu-EDTA模拟废水都有良好的去除效果。综合比选后,铁电极最优。铁电极电芬顿法在初始pH值为2.0,电流密度为20 mA/cm~2,过氧化氢投加量为6 mL/L·h时,Ni和Cu去除率达到了98.54%和99.8%,综合成本为12.75元/吨水。采用模拟废水,优化铁电极电芬顿法处理Cu/Ni-EDTA废水工艺参数并进行特性研究。试验结果表明:当电极间距为2 cm、电流密度为20 mA/cm~2,过氧化氢采用连续投加的方式,投加量为6 mL/L·h,重金属达到较好去除效果。Cl-的存在有利于电芬顿反应的进行,而柠檬酸和次磷酸盐对铁电极电芬顿法有抑制作用。铁电极电芬顿法处理Cu/Ni-EDTA模拟废水过程中,Ni和Cu的去除主要通过破络后絮凝沉淀以及金属离子与投加的OH-形成氢氧化物沉淀。同时,也有少量金属离子随着电流迁移到极板上吸附去除。对于实际废水,确定了不同络合态重金属浓度(2-30 mg/L)条件下,电芬顿工艺的主要工艺参数。在停留时间0.5-1 h,过氧化氢投加量3.4-8.5 mL/L·h,电流密度20-30 mA/cm~2运行状态下,电芬顿工艺可以实现Cu和Ni可实现稳定达标排放,对COD和TP也有一定去除效果。
[Abstract]:The complex heavy metal in electroplating wastewater is the key point in the treatment of this kind of wastewater, and the key to the effective removal of complex heavy metals lies in the breaking of the complex. At present, Fenton oxidation is often used to break the wastewater, but this method has many problems, such as high sludge yield, long residence time and low utilization rate of chemicals. Compared with the traditional Fenton method, the electric Fenton method has the advantages of high utilization ratio of H_2O_2 and Fe2, low sludge production and so on. It can effectively treat the electroplating wastewater containing complex heavy metals and avoid the shortcomings of the traditional Fenton process. The selection of electrode materials is very important in electric Fenton. Although there have been many related research results, the preparation of electrode materials is difficult and the price is too high to be applied in practice. In this paper, iron, aluminum and graphite, which are easily available in the market and low price, will be taken as the research object. By comparing the treatment effect and cost of different electrode materials for wastewater containing Ni-EDTA and Cu-EDTA, the optimal electrode materials which can be used in practical engineering will be selected. On the basis of this, the suitable operating condition parameters of the process are determined by small scale test and pilot-scale operation. The main factors affecting the treatment of copper and nickel complex wastewater by electric Fenton method with iron, aluminum and graphite as electrodes were investigated through a small scale experiment. The treatment efficiency and treatment cost of the three electrode materials under the optimum conditions were compared synthetically. The experimental results show that the three electrode materials, electric Fenton method, have a good removal effect on both Ni-EDTA and Cu-EDTA simulated wastewater. After comprehensive comparison, the iron electrode is optimal. When the initial pH value is 2.0, the current density is 20 Ma / cm ~ (-2) and the hydrogen peroxide dosage is 6 mL/L h, the removal rates of Ni and Cu are 98.54% and 99.8% respectively, and the comprehensive cost is 12.75 yuan / ton water. The process parameters and characteristics of Cu/Ni-EDTA wastewater were optimized by using simulated wastewater. The experimental results show that when the electrode spacing is 2 cm, the current density is 20 Ma / cm ~ (-2), the hydrogen peroxide is continuously added and the dosage is 6 mL/L / h, the existence of heavy metal to achieve a better removal effect. Citric acid and hypophosphate can inhibit the electric Fenton method of iron electrode. The removal of Ni and Cu in the treatment of Cu/Ni-EDTA simulated wastewater by ferroelectric Fenton method was mainly carried out by flocculation and precipitation of metal ions and hydroxide precipitation by adding OH-. At the same time, a small amount of metal ions moved to the plate with the current adsorption and removal. For the actual wastewater, the main process parameters of the electric Fenton process were determined under the conditions of different complex state heavy metal concentrations (2-30 mg/L). Under the conditions of residence time 0.5 ~ (-1) h, hydrogen peroxide dosage 3.4-8.5 mL/L / h, current density 20-30 mA/cm~2, Cu and Ni can be discharged stably, and COD and TP can be removed to some extent.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X781.1

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