Electroplating equipment Chemical treatment method of
The chemical method of electroplating solution treatment is to dissolve harmful chemicals into non-toxic and pollution-free by means of redox reaction or neutralization precipitation reaction.
1. Precipitation method
(1) Neutralization precipitation method. Alkali is added to the sewage containing metal cadmium to carry out neutralization reaction, and the metal cadmium is transformed into the hydrogen oxygen precipitation mode of insoluble water, which can be separated from many aspects. Neutralization sedimentation method is convenient to use and is a commonly used sewage treatment method.
(2) Sulfide precipitation method. After sulfide is added to the sewage, the metal cadmium positive ion will be converted into sulfide precipitation, so as to remove it. Compared with the neutralization precipitation method, the sulfide precipitation method has the following advantages: the solubility of heavy metal sulfides is lower than that of hydroxides, reflecting that the PH value is between 7 and 9. The settled sewage generally does not need to be neutralized, and the settled sewage generally does not need to be neutralized, so the actual effect is strong. The disadvantage of the sulfide precipitation method is that the sulfide precipitation particles are small, which is easy to form colloidal solution. The sulfide precipitation remains in the water and will be converted into vapor when encountering acid, which will cause pollution.
2. Air oxidation method.
The harmful chemicals in electroplating wastewater are oxidized into non-toxic or low harmful substances after being added into the air, which is suitable for solving the problem of CN - in electroplating wastewater Fe2+. Mn2+cheap positive ions and various organic compounds causing saturation, taste and taste, as well as pathogenic microorganisms. For example, when treating cyanide containing sewage, at least positive cyanide ions are usually oxidized in the air under the standard conditions of alkalinity, so that cyanate is converted into low toxic cyanate Zero discharge of electroplating wastewater It can further dissolve non-toxic carbon dioxide and nitrogen.
3. Organic chemical reduction.
In the treatment of electroplating wastewater by organic reduction method, the typical type Z is the treatment of chromium containing wastewater. Use FeS04.NaHS03.Na2S03.S02 or copper powder and other methods to convert Cr (Ⅳ) into Cr (III), and then add NaOH or lime milk to precipitate for separation. Its advantages are simple machines and tools, less project investment and large sludge production, but it avoids pollution caused by sediment deposition.
4. Neutralization method
Adjust the acidity and alkalinity of electroplating wastewater to make it weakly acidic or close to weakly acidic or pH acid-base that is suitable for the next step. The key is to solve the acid pickling and passivation wastewater in the plating plant.
