Study Of Technique And Equipment On Treatment Of Low Concentration Wastewater Containing Copper Ion By Electrosorption

The heavy metal wastewater is one of the main types of industrial wastewater, which endangers ecological environment and human health heavily, of which wastewater containing copper ion is spotlighted for its heavy pollution and high recovery value. Currently wastewater containing copper ion is mainly disposed by chemical, physiochemical and biological ways, among which electrosorption shows unique advantages over others due to its wide range of application, low energy consumption, easy access to regeneration and automation. Electrosorption, enriches copper ion on the plate surface through electrostatic force, thus realizing the separation of copper ion and water.In this paper, simulated wastewater containing copper ion of different concentration and p H is disposed using electrosorption equipment under flow between mode. The appropriate concentration and initial p H of the wastewater are established as follows: copper ion concentration 25 mg/L, initial p H 5. Then the structural and operating parameters of the electrosorption equipment are preliminarily optimized as follows: plate distance 4 mm, work voltage 1.8 V, influent flow 10 m L/min, reflux ratio 100. Under the optimized conditions, the absorption capacity per unit mass of carbon felt reaches 7.78 mg/g, the removal rate 64.04%, and energy consumption 1.5 k Wh/t respectively. After the electrosorptive process under the optimized conditions, the plates are regenerated by changing the polarity or being rinsed by sulfuric acid solution of 1 M. The results shows the Cu²⁺ concentration in the regenerated water reaches 27.42 mg/L, similar to the influent concentration, doing little good to enriching the copper ion. By contrast, after being rinsed by sulfuric acid, the concentration of effluent copper ion reaches 55 mg/L, and the concentration times reached 2.2, which indicates a fair condensing effect.Aiming at the shortcomings of flow between mode, flow through mode is introduced to optimize the structural and operating parameters of the electrosorption equipment, the optimized conditions are as follows: plate distance 4 mm, work voltage 1.8 V, reflux ratio 100. Under the optimized conditions, the absorption capacity per unit mass of carbon felt reaches 9.93 mg/g, the removal rate 97.5%, and energy consumption 0.44 k Wh/t respectively. Also, the plates are tentatively regenerated by changing the polarity of the plates but in vain. Then the plates are regenerated by being rinsed with sulfuric acid solution of 1 mol/L. After 6 cycles of regeneration, the effect of copper removal was not decreased obviously. In this way, the costs of copper removal by electrolysis are reduced while the recycle of copper and purification of water is achieved at the same time.Finally, the copper removing mechanism in the electrosorption equipment is preliminarily studied. The red substance occurring on the negative plate observed in the experiments are characterized in terms of its morphology and composition by XPS, SEM, EDS. The substance is identified as copper, indicating a compound effect of electrosorption and electrodeposition in copper removal of wastewater.