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Handling , Storage and Disposal of Chemicals

Fuming acids and bases e.g. HCL, HNO₃  ,NH₄OH

Storage; Protect container against physical damage, Separatefrom metallicpowders,carbides,sulfides organic acids and combustibles and other oxidizing compounds e.g. Cl,Br, I etc. Provide good ventilation and away from direct sunlight

 Disposal; by diluting with a lot of water and flushing out or neutralization and flashing out

Flammable liquids e.g. acetone, petrol, diethyl ether

Storage:  Protect container against physical damage, outside storage is most preferable, store in cool well-ventilated room away from any sources of ignition and direct sunlight. Isolate from other combustible materials. Place switches outside the store and use vapor proof bulbs for lighting

Disposal: Place in shallow metal trays and place in an open area where they are left to evaporate or simply burn them by igniting them from a safe distance Light sensitive material e.g. silver bromide and hydrogen peroxide

Storage: Store in dark brown bottles with tightly fitting glass stoppers and place them in dark cupboards or dark rooms

(d)Poisonous chemicals e.g. arsenic, cyanides etc.

Storage: Store under lock and key and keep details of the people issued in a poison record book

Disposal: Burning in an incinerator or by burying

Deliquescent and hygroscopic chemicals e.g. NaOH,   KOH, phenols

Storage: Store in airtight containers. Do not store NaOH and KOH in glass-stoppered bottles  

Handling and preparation method: Use gloves. Dissolve NaOH and KOH little by little in large amount of water to avoid overheating.

Disposal: By dilution and flushing out or neutralization and flushing out.

Radioactive substances

Storage: Store in sealed lead container and placed in thick wood or concrete and kept in a locked cupboard situated away from the main building

Methods of handling: Use proper protective clothing’s, radiation indicators and gadgets e.g. pocket dosimeters and GM tubes. Regular medical checkup is important.

Disposal: Radioactive substances are usually collected in stores then periodically shipped to disposal centers.

Care should be taken not to dispose in normal waste disposal systems. They should be properly segregated and handled according to the recommendation by experts.

Oxidizing agents e.g. chlorates, permanganates and chromates

Storage: Should be kept away from combustible materials and in separate stores i.e. never keep both oxidizing and reducing agents together.

Disposal: They should be chemically converted into safe substances, which have low oxidation power by reacting them with sodium thiosulfate, and then Diluting and flushing out into the sewer system (dispose by reacting with any reducing agent).

Handling: Use protective clothing is when handling them.  Be extra careful when reacting them together.

Reducing agents e.g. alkali and alkaline earth metal ions

Storage: Should be kept away from combustible materials and in separate stores i.e. never keep both oxidizing and reducing agents together.

Disposal: They should also be safely reacted with substances that will destroy their reducing power e.g. sodium hypochlorite (dispose by reacting with any oxidizing agent).

Handling: Use protective clothing is when handling them.  Be extra careful when reacting them together.

Acids

Mineral acids, including phosphoric, hydrochloric, nitric, sulfuric, and perchloric acid can be stored in a cabinet designed for Corrosive Acids. These non-metallic cabinets have no internal metallic parts, acid resistant coating and a cabinet floor constructed to be able to contain spillage.

Volatile acids, such as oleum or fuming nitric acid, should be stored either in an acid cabinet or in a vented cabinet, such as the fume hood base, particularly after they have been opened.  Concentrated mineral acids can be very reactive, even with each other.

Concentrated acids can even react vigorously with dilute solutions of the same acid, if mixed together rapidly. For example, concentrated sulfuric acid mixed quickly with one molar sulfuric acid will generate a lot of heat. Different concentrated acids should be stored apart. If stored within the same cabinet, plastic trays, tubs or buckets work well to keep different acids apart within the cabinet. Acetic acid is an organic acid and should be stored separately from mineral acids.  Since it is also flammable, it is best stored with other flammable liquids. Picric Acid can form explosive salts with many metals, or by itself when dry. Perchloric Acid is an extremely powerful oxidizer and must be kept away from all organic materials, including wood. 

Alkali and alkaline earth metals compounds e.g. Na, K, and Li, Ca, Mg etc.

Handling: Use protective clothing.  Dissolve small amounts in water at a time to reduce heat produce.

Preparing Sodium Hydroxide Solution

A great amount of heat is liberated when sodium hydroxide and water are mixed. The temperature of the solution may rise very rapidly. In fact, the temperature may rise so fast that the solution may boil and possibly spatter a hot, caustic solution. Immerse the flask or beaker in an ice–water bath to control the solution temperature. In addition, pay special attention to the condition of the beaker or flask, you use to prepare these solutions. If you use a glass vessel, it must be borosilicate glass and it must be free of any scratches, chips or breaks. Inspect the vessel carefully before use. Add ingredients slowly with continuous stirring.

Storage: Never store alkali metals in ground stoppered bottles because they attack glass. Store under paraffin and never expose them to air. Ca and Mg can be store in ordinary closed containers.

Disposal: Dissolve in enough alcohol and leave them to stand until bubbles cease to appear, add water and dispose into the sink with running tap water. Cal and Mg can be disposed by letting them react with cold water then flushed through the sink.

Explosive chemicals e.g. picric acid and related compounds e.g. bouin‘s solution

Storage: Dry picric acid is very explosive, it react with metals to form explosive metal picrates, which are highly sensitive to detonation. It explodes in the air and cause fire. Should be stored under water in ground neck glass stoppered bottles. Avoid friction, shock or sudden heating which can initiate an explosion. There containers should not have metal caps since it vigorously react with it.

Disposal: only trained personnel (e.g. bomb squad) are allowed to dispose picric since it is very explosive. Apply physical shock other chemicals e.g. peroxides and ether are also shock sensitive, therefore can be disposed in the same way, and then transported to safe disposal area.

Phosphorous

Handling: Use gloves and chemical resistant apron.

Storage: Highly reactive and flammable also poisonous. Reacts with air under controlled conditions to phosphoric acid and can spontaneously ignite in air where it is converted to phosphorous pentoxide .its therefore stored under water.

Disposal: Small quantities can be disposed by allowing them to ignite in air in a controlled condition or letting it to react with 0.5 M H2SO4 and KBr while stirring. Then add sodium metabisulfate and flush out.

Hydrofluoric acid

Storage: Attacks glass hence they are stored in polythene bags or plastic containers.    Disposal: Neutralization or dilution and flushing into the sewer.

Noncombustible organic solvents

Storage: store safely in closed containers

Disposal: Dissolve in flammable solvent e.g. alcohol or benzene and place the solution in an open pan and burn them with due care.

Mercury metal                                                                                   

Disposal: Only disposed off by returning to the supplier for recycling. It should never be disposed off by burring, burning or flushing through drainage system.

Heavy metals and their salts e.g. lead antimony, cadmium, chromium, cobalt and nickel

Storage:  Are very soluble in water, extremely toxic and accumulates in the body tissue.

Disposal: They must be first converted into stable insoluble salts by reacting them with sulfide or silicate ions then they can be buried in approved landfills for disposal of hazardous waste.

Halogenated solvents

They are volatile, insoluble in water and cannot be burnt except in high temperature incinerators

Disposal: Pour a shallow layer of the substance   into the pan and place it under efficient fume hood in appropriate outdoor site then allow the material to simply evaporate.

Inorganic sulfides:

They release highly toxic hydrogen sulfide gas on treatment with an acid

Disposal: They should first be oxidized into sulfates using hypochlorite as an oxidizing agent, which forms a more stable salt. These can then be flushed through the sink.

Inorganic and organic peroxides

They are strong oxidizing agents, flammable and explosive, sensitive to heat, friction or contact with combustible materials. They are stored in dark. Sodium peroxide is stored in sealed containers to avoid reaction with air.

Disposal: Hydrogen peroxide is destroyed by reducing with sodium metabisulfite or diluting it with water and flushing out. Organic peroxides  e.g. benzyl peroxide are reacted with bases which will cleave  between the two joined oxygen atoms and form sodium benzoate which are insoluble in water and less harmful.

Unstable Chemicals

Ethers and some ketones and olefins may form peroxides when exposed to air or light. Since they may have been packaged in an air atmosphere, peroxides can form even if the container has not been opened.

Some chemicals, such as dinitroglycerine and germane, are shock-sensitive, meaning that they can rapidly decompose or explode when struck, vibrated or otherwise agitated. These compounds become more shock-sensitive with age.

For any potentially unstable chemical:

• Write on the label the date that the container was received and the date that it was opened.
• Discard containers within 6 months of opening them.
• Discard unopened containers after one year, unless an inhibitor was added.

Volatile hydrocarbonse.g. alcohols, ketones and esters

They have low toxicity but very flammable

Disposal: Remove any source of ignition and place on a shallow pan in a fume hood and allow natural air to pass through it to evaporate.

Non-volatile hydrocarbons

They are non-flammable and easily converted to less toxic materials

Disposal: Disposed by licensed hazardous waste company and by burning.

Silver compounds

They are very expensive but can be recovered after use by dissolving the silver ions in the solution with NaOH and heating. Then adding sucrose. The sucrose will hydrolyze in a strong base to   the monosacharides i.e. fructose and glucose which will reduce silver ions to silver metal which will form as gray precipitated

Disposal: Disposed by precipitation into an insoluble silver chloride using NaCl and disposed in a landfill.

Microbiological cultures

Handling: Use protective clothing and sterilized equipment’s.

Storage: Never keep in food refrigerators or mix with other instruments used for mouth pipetting.

Disposal: Sterilize instruments in autoclave or dispose them by incineration.

 Carcasses

Handling: Use sterilized equipment’s and wear protective clothing.

Storage: Keep in specimen bottles, special polythene bags and under a suitable preservative e.g. formalin.

Disposal: can be disposed by Burying, burning or incineration.

Designated Areas

Any area where particularly hazardous substances, including carcinogens, acutely toxic chemicals and reproductive toxins, are stored or used must be posted as a Designated Area. These materials should be stored separately from other chemicals, as space permits

Segregation of Incompatible Chemicals 

Incompatible chemicals should not be stored together. Storing chemicals alphabetically, without regard to compatibility, can increase the risk of a hazardous reaction, especially in the event of container breakage.

There are several possible storage plans for segregation. In general, dry reagents, liquids and compressed gases should be stored separately, then by hazard class, then alphabetically (if desired).

Segregate dry reagents as follows:

1. Oxidizing salts
2. Flammable solids
3. Water-reactive solids
4. All other solids

Segregate liquids as follows:

1. Acids– Separate mineral acids (hydrochloric, sulfuric) from organic acids (picric, acetic)
2. Bases
3. Oxidizers
4. Flammable or combustible liquids
5. All other liquids

Segregate compressed gases as follows:

• Toxic gases
• Flammable gases
• Oxidizing and inert gases