| A large amount of electroplating wastewater is generated in the electroplating production process.The composition of electroplating wastewater is complex,containing various types of heavy metal ions and hazardous waste(highly toxic substances,acids and alkalis),etc.If electroplating wastewater is directly discharged into the environment without treatment,a large amount of toxic and harmful Substances not only pollute the environment,but also cause great harm to the human body,directly affecting human health and safety.This article takes electroplating wastewater as a research object,compares the advantages and disadvantages of traditional electroplating wastewater treatment methods,and proposes a new method for treating electroplating wastewater by progressive static freezing method.The freezing method has the characteristics of wide range of raw water,no selectivity,no need to add external agents,and no secondary pollution.The application of the freezing method for the treatment of electroplating wastewater is simple,convenient to operate,and can reduce energy consumption.It has been developed for electroplating wastewater treatment.A new way.Based on the application of freezing separation theory,this paper takes copper acid,nickel plating,and chromium plating wastewater in the electroplating process as the experimental objects,and conducts progressive static freezing experimental research on the heavy metals Cu2+?Ni2+?Cr6+ in the wastewater.According to the characteristics of electroplating process and freezing method,the removal effect of heavy metal ions in electroplating wastewater,the freezing mechanism and the method of electroplating wastewater recycling are explored.By analyzing the economic benefits and resource co-ordination of freezing method for electroplating wastewater treatment,it provides electroplating enterprises wastewater treatment New technology approach and reference.The experimental research has achieved the following research results:1.Taking the simulated electroplating wastewater in the laboratory as the experimental object,study the effect of wastewater concentration,freezing temperature,freezing rate and solution PH value on the removal of heavy metal ions in electroplating wastewater.Experimental results show that the lower the mass concentration of wastewater,the higher the removal rate of heavy metal ions.When the mass concentration of Cu2+?Ni2+?Cr6+ in the wastewater solution is 0.1g / L,after the Cu2+?Ni2+?Cr6+ solution is frozen,the ion removal rate in the solution is more than 95%;when the mass concentration is> 0.1g / L ? 1g / L,as the mass concentration increases,the removal rate of heavy metal ions decreases rapidly;when the mass concentration is> 1g / L ? 2g / L,the concentration is about 4% ? 7% of the Cu2+?Ni2+?Cr6+ concentration in the plating bath solution,Which can not only meet the high removal effect,but also meet the current status of high concentration discharge of electroplating wastewater;when the concentration of Cu2+?Ni2+?Cr6+ in wastewater is greater than 2g / L ? 10 g / L,the removal rate of heavy metal ions is affected by the concentration factor No longer obvious.The lower the freezing temperature,the faster the freezing speed,but the removal efficiency of heavy metal ions is low.The optimal freezing temperature is-5?,which can not only ensure the freezing speed,but also ensure the removal efficiency of heavy metal ions.The removal rate of heavy metal ions decreases with the increase of the freezing rate.When the freezing rate is low,the removal rate of heavy metal ions is high.In order to balance the ion removal rate and the freezing rate,the optimal freezing rate is 70%.2.Analyze the freezing mechanism in the freezing process from a micro perspective,and explore the formation of crystal nuclei and the growth process of ice crystals in the freezing process.By observing the internal microstructure of ice crystals formed under different conditions through a microscope,the study found that the internal microstructure of ice crystals formed under different conditions is different.By changing the mass concentration of the solution,the purity of the ice crystals in the freezing process can be affected,and the freezing process can be affected by changing the freezing temperature.The size of medium ice crystals and changing the freezing rate can affect the growth of ice crystals during freezing,which in turn affects the removal of impurities in the solution.3.The freezing method is used to treat the actual electroplating wastewater.The solid ice and concentrated liquid are obtained by controlling the freezing rate.In the ice melt water after the solid ice is melted,under the optimal freezing conditions,the removal rate of heavy metal ions in the wastewater is more than 60%,so it can be used The method uses the ice melt water after the solid ice is melted to supplement the cleaning water of the primary wastewater tank,which can reduce the amount of cleaning water in the electroplating plant.After the concentrated solution is processed by freezing,the experiment proves that it can be used in the electroplating tank.Since the heavy metal reagents in the raw materials for preparing the plating solution are expensive,this method not only saves the cost of raw materials in the electroplating plant,but also reduces the heavy metal pollution caused by wastewater discharge,and achieves the goal of cleaner production. |
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