Most of the waste gases, liquids and residues produced during the experiment are harmful and must be treated before discharge.
(1) Waste gas treatment adopted by laboratory design companies
A small amount of toxic gas can be removed from the air by exhaust equipment and diluted by the air. When the gas volume is large, it must be treated and discharged first. Acidic gases such as nitric oxide and sulfur dioxide are absorbed by alkali solution. Combustible organic waste liquid can be completely combusted with oxygen in the combustion furnace.
(2) Treatment of Waste Liquid Containing Phenol, Cyanide, Mercury, Chromium and Arsenic
Laboratory Design Company
Low concentration of phenol wastewater combined with sodium hypochlorite or bleaching agent will oxidize phenol to carbon dioxide and water. High concentration phenolic wastewater was recovered by heavy distillation with butyl acetate as extractant.
Cyanide-containing waste liquor was mixed with sodium hydroxide solution and pH10 solution, then 3% potassium permanganate was added for CN-oxidation decomposition. Alkali chlorination treatment was carried out for the waste liquor with high content of CN-by adding sodium hypochlorite to decompose CN-above pH10.
The wastewater containing mercury salt was adjusted to pH 8-10, excessive sodium sulfide was added to precipitate mercury sulfide, and co-precipitator ferrous sulfate was added. The obtained iron sulfide adsorbs suspended mercury sulfide particles in water, coprecipitates, discharges the purified liquid, and the residue is recovered by roasting or made into mercury salt.
铬酸洗液无效，加入高锰酸钾粉末氧化浓缩冷却后，用砂芯漏斗过滤器清除自由基氧化后再使用。减少废物与废铁屑洗剂残留的Cr (IV) Cr(Ⅲ),然后使用废物碱中和沉淀成低铬(OH) 3。
Chromic acid pickling solution is ineffective. Potassium permanganate powder is added to oxidize and concentrate to cool, then free radical is removed by sand core funnel filter and then used. Reduce the residual chromium (IV) and chromium (III) in waste and scrap iron lotion, then neutralize and precipitate to low chromium (OH) 3 with waste alkali.
Calcium oxide was added into arsenic-containing waste liquor and the pH value was adjusted to 8 to form calcium arsenate and calcium arsenite precipitation. Or adjust the pH above 10, add sodium sulfide and arsenic reaction to form refractory, low toxic sulfide precipitation.
The pH value of the waste liquor containing lead and cadmium was adjusted to 8-10 by using hydrated lime to precipitate Pb(OH)2 and Cd(OH)2 from Pb 2+ and Cd 2+. Ferrous sulfate was added as co-precipitator.
(3) Recovery of organic solvents
Waste ether solution was washed once with water, neutralized, rinsed to purple with 0.5% potassium permanganate, then rinsed with water, rinsed with 0.5%~1% ammonium ferrous sulfate solution, removed peroxide, rinsed with water, dried with calcium chloride, filtered, fractionated and collected fractions at 33.5~34.5 C.
Ethyl acetate waste liquor is washed several times with water, and then rinsed several times with sodium thiosulfate dilute solution to fade it. Then rinse with water several times, distill, dehydrate with anhydrous potassium carbonate, stand for several days, filter distillation, collect 76 ~ 77 C fraction.
Waste liquids such as chloroform, ethanol and carbon tetrachloride can be treated by reagent cleaning. Finally, the distillates near the boiling point were collected by distillation to obtain reusable solvents. The method can be found in the relevant information.
(4) Destruction of Wastes
Solid waste in the experiment can not be placed at will to avoid accidents. Hazardous waste that can release toxic gases or spontaneously ignite can not be thrown into the waste bin and discharged into the waste water pipeline. Chemical wastes insoluble in water are not allowed to be thrown into wastewater pipes. They must be incinerated or chemically treated in appropriate places to produce harmless substances. Broken glass and other sharp, angular waste can not be thrown into the wastebasket, must be collected and treated in special bins.