1, chromium-containing wastewater treatment mainly from chromic acid wastewater, potassium dichromate titration wastewater analysis of chromium-containing wastewater produced by the experiments of the treatment: first of all, in the acidic conditions of chromium-containing wastewater in the addition of people in the waste of iron filings, FeS04 or sulfide, sulfite, and other reductants, will be a strong toxicity of the Cr0 'reductions of ten into a Less toxic Cr", and then add waste lye or sodium hydroxide, calcium hydroxide, quicklime, etc., adjust the solution pH to 7 or so, so that CrI1 into a low-toxicity Cr (OH) precipitation, separated from the precipitation can be directly discharged after the clear liquid slag after dehydration and drying can be comprehensively utilized, or with the roasting method of treatment, treatment of chromium slag can be mixed with cement, curing can be landfilled sub-surface.
2, lead, bismuth waste treatment
Complex titration method for continuous determination of Bi and Pb in the mixture is an important experiment in quantitative analysis, but also lead, bismuth waste is the main source of liquid, the experiment produced by the waste liquid if the direct discharge of the environment and the human body is very harmful, but also a waste of valuable resources. In this regard, the following methods can be used to treat the waste liquid first, and then directly recovered and recycled.
(I) the concentration of lead, bismuth continuous determination of the waste liquid, each time to take 2500mL in 3000mL beaker, in the electric furnace heating to near boiling after taking down, in the stirring while hot to add 2mol / L Na, S solution to the waste liquid PH value of 12.
5 a 13.0, stirring fully after the precipitation (can also be stirred twice), due to the existence of solution of Due to the presence of strong electrolytes such as hexamethylenetetramine salt and Na in the solution, the sulfide will precipitate very quickly, and the upper layer of the clear liquid is purplish-red, which is the color of dimethylphenol orange indicator under alkaline conditions.
(2) After pouring off the clear liquid of the kernel layer, and then each time with about 1500mL of tap water to pouring method to wash the sulfide precipitation produced 3 times, and then a small amount of deionized water to wash 2 times, and then finally make the volume of sulfide precipitation and water in about 1500mL, to be fully washed by the water, and then add a person with a concentrated HNO, 14mL, heating until the black sulfide is completely dissolved, and then heating Boil for 2min, drive off the nitrogen oxides, cooled and filtered, and finally the filtrate can be diluted to 830mL It is worth noting that the method of regeneration of the mixed solution acidity is exactly in the EDTA titration of Bi's required pH.7 a 1.. Within the range, so do not have to use sodium hydroxide neutralization, directly available for the next time to do experiments when reused, and the method of lead, the secret recovery rate of 99% or more, is a kind of protection of the environment, a good way to save resources.
3: Mercury-containing waste treatment method
This method is mainly derived from the determination of iron content of iron ore pretreatment agent SnC1 a HgC1: the reaction process, generally used:
(1) chemical cohesion and precipitation method: mercury-containing waste solution with NaoH to adjust the pH value of the solution to 8-10, add an excess of iron sulfide or sodium sulfide, so that the generation of mercuric sulfide Precipitation, and then add a certain amount of ferrous sulfate as a flocculant, will be suspended in the water is difficult to precipitate mercury sulfide particles adsorption and *** with precipitation, and then static, separation or centrifugal filtration, the clear liquid can be directly discharged into the sewer, the residue of satin-fired method of recycling or made into mercury salts again
(2) amalgam extraction method: in the mercury wastewater solution, add people with zinc or aluminum chips, so that the mercury in the waste liquid is very easy to be zinc or aluminum replacement At the same time, mercury can 'j generate zinc amalgam or aluminum amalgam, so that the wastewater to achieve purification. Electrolysis can also be used to remove impurities with mercury amalgam, and then vacuum distillation method to obtain high-purity request.
4, containing arsenic waste treatment
Add lime in the arsenic waste, adjust and control the pH value of 8 or so, calcium arsenate and calcium arsenite precipitation can be generated, there is a Fe "presence can also be precipitated together, to be separated from precipitation, filtrate can be discharged directly into the sewer, the residue can be used as slag treatment
5, containing cyanide waste treatment
(1) if the CN-content is small, the CN-content is small, the CN-content is small, and then vacuum distillation method to obtain high purity. (1) If the CN-content is small, it is appropriate to use KMn0, oxidation method, that is, in the waste liquid add NaOH, adjust the pH value to 10 or more, and then add 3% KMn0, . Make CN oxidative decomposition;
(2) If the CN content is high, alkaline chlorination method can be used that is, add NaOH in the waste liquid, adjust the pH value to 10 or more, add sodium hypochlorite to make CN oxidative decomposition.