Scharlab - AMCO Instruments, SRL

www.scharlab.comThe wise choiceDisposal of laboratory wasteNeutralization of laboratory residuesSpecial precautions have to be taken since many chemical reactions can be very violent. All work has to be executed byqualified personnel, following the basic safety rules and always under a fume cupboard. The method chosen to neutralizethe chemical in question must at all events be tried out first on a small scale, to see if there are any unforeseen problems.To facilitate the disposal of small quantities, each product has been assigned a “Disposal number”. This number refers tothe particular paragraph set out below. The Container stipulated for collecting that chemical will be a Container listed inthe previous page.1. Organic halogen-free solvents: Container no. V.Small quantities of halogen-free solvents may be collectedand disposed of together with halogen solvents.Be sure to test for absence of peroxides, before handingover to the waste disposal company.2. Organic halogen solvents: Container no. VI.3. Relatively non-reactive organic reagents should be collectedin Container no. V. If halogen, they should be placedin Container no. VI. For solid residues use Container no. I.10. Organic peroxides can be detected in aqueous solutions andorganic solvents with the aid of test-kits and removed, percolatingthrough liquid chromatography grade aluminum oxide.Organic residues: Container no. V or no. VI.Aqueous solutions: Container no. VII.11. Acid halides should be added drop wise to an excess ofmethanol, in order to convert them to the correspondingmethyl esters. A few drops of hydrochloric acid can beadded to accelerate the reaction.Neutralize with sodium hydroxide solution: Container no. VI.Disposal of laboratory waste4. Aqueous solutions of organic acids should be carefullyneutralized with sodium hydrogen carbonate or sodiumhydroxide: Container no. VII. Aromatic carboxylic acids shouldbe precipitated with dilute hydrochloric acid and filtered off.Precipitate: Container no. I. Filtrate: Container no. VII.5. Organic bases and amines in solution: Container no. V or no. VI.To prevent unpleasant odours (fume cupboard), we recommendcareful neutralization with dilute hydrochloric acid or sulfuric acid.6. Nitriles and mercaptans should be oxidized by stirringfor several hours (preferably overnight) with sodiumhypochlorite solution. Any excess oxidant should beneutralized with sodium thiosulfate.Organic phase: Container no. V or no. VI respectively.Aqueous phase: Container no. VII.12. Inorganic acids and anhydrides thereof should first bediluted or hydrolyzed by stirring carefully into ice-water,then neutralized (gloves, fume cupboard) with sodiumhydroxide solution: Container no. VII.Fuming sulfuric acid should be carefully stirred a dropat a time into 40% sulfuric acid. Have plenty of ice onhand for cooling. When sufficiently cool, treat the highlyconcentrated sulfuric acid as above.Acid gases (hydrogen bromide, hydrogen chloride andhydrogen iodide, chlorine, phosgene, sulfur dioxide)should be bubbled into dilute sodium hydroxide solutionand treated as under Inorganic acids above.13. Inorganic bases should be diluted if necessary, by carefullystirring them into ice-water, then neutralized (gloves, fumecup board) with hydrochloric acid: Container no. VII.7. Water-soluble aldehydes should be converted to bisulfiteadducts using a concentrated aqueous sodium hydrogensulfite solution: Container no. V or no. VI.8. Hydrolysis-sensitive organo-metallic compounds, whichare generally dissolved in an organic solvent, should becarefully stirred drop wise into n-butanol using a fumecupboard with the front screen closed. Any flammablegas formed should be fed via a tube directly into theextractor tubing. When gas development has ceased,continue stirring for one hour and add an excess of water.Organic phase: Container no. V.Aqueous phase: Container no. VII.9. Alkyl sulfates are carcinogenic. Take special care to avoidinhalation and skin contact. To deactivate alkyl sulfates,add drop wise (from a dropping funnel) to concentratedice-cool ammonia solution, under vigorous stirring:Container no. VII (adjust pH previously to 6-8).36414. Inorganic salts: Container no. II.Neutral solutions of these salts: Container no. VII.15. Solutions and solids containing heavy metals: Container no.III. Stir Raney nickel in the form of an aqueous suspensioninto hydrochloric acid until dissolved: Container no. III.Neither Raney nickel nor filter residues should be allowedto dry out, otherwise they will spontaneously ignite in air.16. Highly toxic thallium salts and aqueous solutions of thesemust be handled with great caution; take special care toavoid skin contact: Container no. III.Thallium salts in aqueous solution can be treated with sodiumhydroxide to precipitate out thallium (lll) oxide for reuse.17. Inorganic selenium compounds are toxic and must behandled with caution: Container no. III.Elemental selenium can be recovered by first oxidizingthe salts in aqueous solution with concentrated nitricScharlab The Lab Sourcing Group