电催化氧化处理脱硫废水COD的试验研究

Experimental study on COD treatment of desulphurization wastewater by electrocatalytic oxidation

燃煤电厂脱硫废水成分复杂,COD来源主要为亚硫酸盐和连二硫酸盐等还原性无机物。此外,脱硫废水中的Cl^(-)浓度很高,在降解COD时会形成较大干扰。电催化氧化法在工业废水处理中的应用较多,但较少应用于脱硫废水。尝试采用钌铱、铂金、掺硼金刚石(BDD)这3种不同材料作为阳极极板,电催化氧化处理脱硫废水COD。首先筛选出最佳极板材料,再用单因素实验方法确定响应面分析实验条件,采用BBD(Box-Behnken Design)法设计实验并分析极板间距、电压、反应时间的交互影响作用,最后研究SO_(4)^(2-)和Cl^(-)对电催化氧化处理脱硫废水COD的影响。结果表明,BDD极板对于脱硫废水的电催化氧化性最强,最佳反应条件:极板间距为1.52 cm,电压为25 V,反应时间为40 min。此时COD去除率最高,为87.1%。适当质量浓度的SO_(4)^(2-)和Cl^(-)在溶液中可起到促进氧化的作用,但当SO_(4)^(2-)和Cl^(-)分别超过8000 mg/L和5000 mg/L时会抑制COD的去除效果。

Desulphurization wastewater from coal-fired power plants is complicated in composition.The main chemical oxygen demand(COD)are from reductive inorganic substances such as sulfites and dithionate.In addition,the content of chloride ions in desulfurization wastewater is very high,which can affect COD removal of desulfurization wastewater,so it is difficult to degrade the COD of desulfurization wastewater.Electrocatalytic oxidation is widely used in industrial wastewater treatment,but rarely used in desulfurization wastewater.In this study,three different materials including ruthenium-iridium,platinum and boron-doped diamond(BDD)were used as anode plates to treat COD from desulphurization wastewater by electrocatalytic oxidation.Firstly,the optimal plate material was selected,and then the response surface analysis experimental conditions were determined by single factor experiment method.BBD(Box-Behnken Design)method was used to design experiments and analyze the interaction between plate spacing,voltage and reaction time.Finally,the influence of sulfate radical and chloride ion on electrocatalytic oxidation treatment of COD in desulfurization wastewater was experimentally studied.The results showed that BDD electrode had the strongest electrocatalytic oxidation for desulfurization wastewater,and the best reaction conditions were as follows:plate spacing 1.52 cm,voltage 25 V,reaction time 40 min.Under these conditions,the COD removal rate was the highest,which was 87.1%.Appropriate concentration of sulfate and chloride ions can promote oxidation in the solution,but when the concentration of sulfate and chloride ions exceed 8000 mg/L and 5000 mg/L,respectively,the removal effect of COD was inhibited.