Treatment Of Dyestuff Wastewater With Copper-plating Iron Chips Intensive Inner Electrolysis- Photocatalysis Combined Process

The composition of dyestuff wastewater is complicated. Its chromaticity is high; COD is high and hard to be degraded by biochemical treatment. That is why it causes serious pollution to the environment. In this dissertation, a combined process of copper-plating iron chips intensive inner electrolysis - photocatalysis was used to treat dyestuff wastewater. The main contents and results were presented as follows:1. Compared with iron chips, the effects of the dyestuff wastewater by copper-plating iron chips intensive inner electrolysis - photocatalysis was studied by static experiments. The affecting factors of treatment were also studied. The results were as follows: (1) compared with iron chips, copper-plating iron chips magnified the potential difference between anode (Fe) and cathode (promoter), so that more organic compounds could be reduced. As a result, the degradation of dyestuff was accelerated. (2) Because of photochemical characteristic of Fe(Ⅲ)-OH complex system which was produced from inner electrolysis and Cu2O which was the component of the plating zone, the decoloration ratio and the COD removal ratio of dyestuff wastewater could be promoted by sunlight. Reacting 30 min, the decoloration ratio was over 95% and the COD removal ratio was increased about 10%-20%. (3) Increasing the reaction time, the quantity of copper-plating iron chips and the oscillation rate could intensify the removal effects of dyestuff wastewater. But the effects would be unnoticeable when the quantity of these factors exceeded the specific quantity. (4) When pH value was cut down, the hydrogen potential difference between anode and cathode can be magnified. No matter used copper-plating iron chips or iron chips, reducing the pH value could intensify the removal ratio of dyestuff. Compared with traditional iron inner electrolysis, the decoloration ratio and COD removal ratio of dyestuff wastewater whose pH value was from 6.0-9.0 were also high, when the wastewater was treated by copper-plating iron chips. For example, decoloration ratio of reactive turquoise blue and reactive yellow was over 95%, when their pH value was about 9.0. (5) When iron chips were plated with copper, constructions and characteristics of their surface were changed. So the limit about the gain size was shrinking, and the phenomenon about agglomeration and rust was ameliorated. In addition, copper-plating iron chips could be used more times than iron chips.2. The flow-equipment was made by our own. The factors such as residence time and quantity of aerating affecting the treatment effect of reactive black, the wastewater of YinHai Corporation and the mixed dyestuff wastewater were studied. We also studied the running stabilization of the flow-equipment. The results were as follows: (1) the decoloration ratio and COD removal ratio of these three kinds of dyestuff wastewater were increased with the increment of residence time and the quantity of aerating. But the treatment effects of these three wastewater improved inconspicuousness when the residence time and quantity of aerating exceeded specific quantity. (2) Using the flow-equipment to treat the mixed dyestuff wastewater, the removal ratio of the wastewater did not reduce so much after 30 days. The decoloration ratio was from 96.2% to 92.2% and the COD removal ratio was from 87.5% to 84.4%.3. Modern analysis methods were used to characterize the surface of copper-plating iron chips. (1) Scanning electron microscopy (SEM) was employed to explore the changes between iron chips surface and copper-plating iron chips surface, and the changes on copper-plating iron chips surface in the process treating dyestuff wastewater. Although iron surface was clean, copper-plating iron chips surface was different with iron surface. After reaction, there were things whose shapes liked grape generated from copper-plating iron chips surface. (2) X-ray diffraction (XRD) was used to explore the component of plating zone. The plating zone of copper-plating iron chips was mainly composed of copper and oxides of copper.4. The mechanism of copper-plating iron chips intensive inner electrolysis -photocatalysis in treatment of dyestuff wastewater was researched. Hydroxyl radical(·OH) was determinated in the process of inner electrolysis by fluorimetry. The oxidation value of·OH was so high that it can degrade dyestuff more effectively. It also contented oxido-reduction of hydrogen, reducing action of iron, electric field action, complexation-concrete action of iron, and the photochemical characteristic of Fe(Ⅲ)-OH and Cu2O.