Academic journal article The Science Teacher

Safer Science

Academic journal article The Science Teacher

Safer Science

Article excerpt

Handling Hazardous Waste

High school science lab experiments and demonstrations often involve dangerous chemicals or produce hazardous waste products. Science teachers must know when they may be handling hazardous waste products and how these substances can be appropriately disposed.

Determining whether waste is hazardous can be difficult. One of the best resources (in addition to individual chemicals' Safety Data Sheets [SDS]) is the "Hazardous Wastes" page on the Lawrence Berkely National Laboratory website (see "On the web"). It notes that hazardous waste includes:

* flammable liquids, such as nonhalogenated solvents;

* corrosive liquids, such as strong acids and bases;

* solid oxidizers;

* wastes that contain heavy metals and halogenated organics; and

* greases and oils.

The website futher points out that the experimenter needs to have an understanding of the materials being used by

* knowing the hazardous properties of all chemicals used,

* understanding how the chemicals are used,

* understanding the nature of the reaction to determine whether hazardous chemicals were produced, and

* knowing whether the process converted hazardous chemicals to nonhazardous ones.

The U.S. Environmental Protection Agency (EPA) regulates hazardous waste management based on two general criteria: (1) characteristics of the waste and (2) waste on specific lists. Use these criteria to determine the proper storage, treatment, and disposal of various types of hazardous waste.

Waste materials are considered hazardous if they have one or more of the following four basic characteristics:

Ignitable: can create fires under certain conditions, are spontaneously combustible, or have a flash point below 60[degrees]C (140[degrees]F). Examples include ignitable liquids (e.g., acetone, methanol), ignitable compressed gases (e.g., propane), and oxidizers (e.g., hydrogen peroxide).

Corrosive: acids or bases (pH less than or equal to 2 or greater than or equal to 12.5, respectively) that can corroding metal containers. Examples of corrosive aqueous liquids include hydrochloric acid, nitric acid, and sodium hydroxide.

Reactive: unstable under "normal" conditions. …

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