Safety Note #11: Procedures for the Disposal of Excess and Waste Chemicals

Chemical Research Safety Note #11
Professor Rick L. Danheiser and the Chemistry Department Safety Committee
Friday, July 14, 1995

Procedures for the Disposal of Excess and Waste Chemicals

All members of the Department have a responsibility to give proper attention to the disposal of the excess and waste chemicals involved in their research. Chemicals must be disposed of in ways that avoid harm to people and the environment. The methods of disposal must comply with the relevant local, state, and federal laws including, in some cases, the Resource Conservation and Recovery Act ("RCRA") of 1977 which is administered by the Environmental Protection Agency.

Consideration of the means of disposal of chemical wastes should be part of the planning of all experiments before they are carried out. The cost of disposing of excess and waste chemicals has become extremely expensive, and can even exceed the original cost of purchasing the chemical! As a rough guide, the cost of disposal for a typical container is approximately $10. Whenever practical, order the minimum amount of material possible in order to avoid the accumulation of large stocks of "excess chemicals" which will not be needed in future research. Such collections of "excess chemicals" frequently constitute safety hazards, since many substances decompose upon long storage and occasionally their containers become damaged or degrade. In addition, the disposal of significant quantities of excess chemicals ultimately presents a very significant financial burden to faculty research accounts.

Specific Procedures for Disposal of Excess and Waste Chemicals

This section presents specific procedures for arranging for the disposal of the most common classes of excess and waste chemicals. Although many such chemicals can be removed from your laboratory without prior treatment, in some cases it is advisable to convert a substance into a less hazardous one prior to disposal. It is the responsibility of the individual researcher and the faculty supervisor to evaluate the properties of the excess and waste chemicals resulting from their work, and to determine when special handling procedures are needed outside the general guidelines outlined below. The MIT Safety Office (Don Batson, ext. 3-4736) should be consulted for assistance in planning the disposal of such hazardous compounds. Detailed procedures for the laboratory destruction of a number of hazardous chemicals can be found in Chapter 7 of Prudent Practices in the Laboratory: Handling and Disposal of Chemicals (National Academy Press, 1995). Each research group should have a copy of this authoritative reference which is also available in the Department's Library of Laboratory Safety (18-383). See Melissa Manolis (18-390) if your group needs a copy of this book.

Disposal of excess and waste chemicals is arranged by calling the MIT Safety Office (ext. 3-4736) which will send an employee to pick up and transport the materials to the special storage area maintained by the Safety Office. The waste chemicals must be prepared for pickup by storing them in break-resistant containers (metal, plastic, or plastic-coated glass), or in breakable containers enclosed within "approved secondary containers" (i.e. large rubber, metal, or plastic bottle carriers with carrying handles). Each container must have attached to it a "Red Tag" identifying the type of waste and the hazards associated with it. Red Tags can be obtained from the Safety Office (E19-207). When the waste material is picked up, a packing list must be filled out providing information concerning the quantity and identity of the chemical and any hazards associated with it (flammable, toxic, water reactive, etc.).

Liquid Organic Chemicals

The local regulations that govern the MIT sewer system expressly prohibit the discharge of organic solvents into the system. No liquid organic chemicals should be disposed of "down the drain", and this rule applies to all solvents whether or not they are miscible with water. Rotary evaporators should always be equipped with effective cooling condensers to trap solvent vapors. Excess and waste liquid organic chemicals should be stored in appropriate containers as outlined above and sent to the Safety Office Waste Chemicals Storage Area (WCSA). Compatible mixtures of liquid organic compounds can be stored in one container provided that the Red Tag indicates the relative proportion of each component. Halogenated compounds (e.g. chloroform) should be segregated in separate containers from other organic compounds. Note that chlorinated solvents form explosive mixtures with certain other compounds (e.g. with some amines, with acetone in the presence of base, etc.). Ethereal solvents (diethyl ether, THF, dioxane, DME, etc.) should be stored in glass containers and diluted with water. Prolonged storage of ethers should be avoided since they can form explosive peroxides upon standing.

Aqueous Solutions

Aqueous solutions of acids and bases in the pH range 5-9 can be disposed of by pouring them down the drain provided that they do not contain toxic contaminants such as certain heavy metal salts. Consult Chapter 7 of Prudent Practices in the Laboratory: Handling and Disposal of Chemicals for a discussion of the toxicity hazards of various inorganic salts. Concentrated acids and alkalis should be neutralized and then disposed of down the drain.

Solid Inorganic and Organic Chemicals

Excess and waste solid chemicals can often be sent to the Waste Chemical Storage Area (WCSA) in their original containers. Compatible solids can be stored in one container provided that the Red Tag indicates the relative proportion of each component. Certain classes of solid waste chemicals require special handling. Toxic solid wastes can be sent to the WCSA in properly labeled, tightly sealed containers. Contact the Environmental Medical Service (ext. 3-2596) for advice on the handling and packaging of toxic waste chemicals (information on the properties and toxicity of organic and inorganic chemicals can also be obtained from the references in the Chemistry Department Library of Laboratory Safety, 18-383). Alkali metals such as sodium and potassium should be stored under mineral oil in tightly sealed containers and sent to the WCSA for disposal. Other pyrophoric metals and compounds such as magnesium, LAH, and NaH should be stored in tightly sealed metal containers and may be sent to the WCSA for disposal. Waste mercury should be stored in bottles or jars and sent to the WCSA; broken thermometers that contain mercury should be placed in jars and also sent to the WCSA. Consult Chemical Research Safety Note #4 for procedures for handling mercury.

Unknown Waste Chemicals

The MIT Safety Office will not accept unknown chemicals for transport to the WCSA. This is due to the fact that our outside contractors are prohibited from accepting unidentified materials for disposal. It is the responsibility of the research group generating the material to determine the chemical identity of the unknown waste; in some cases this may require paying for the services of an outside analytical laboratory. Once the composition of the waste material is known, it can then be disposed of according to the procedures outlined above.

Gas Cylinders

Gas cylinders are not sent to the WCSA for disposal. Excess and empty "returnable" gas cylinders as well as small "lecture-bottle-type" cylinders are picked up by BOC Gases (at MIT, ext. 3-4761). BOC will accept cylinders produced by the following companies: BOC (Airco), Matheson, Scott, Wesco, Middlesex Welding, Northeast Air Gas, MedTech, Spectra, and M. G. Products. For additional information on the disposal of gas cylinders, call BOC at the above number.

Whenever possible, avoid purchasing chemicals in non-returnable lecture bottles. The disposal of these cylinders has become extremely expensive, generally costing $1000 or more. Check with the Safety Office before ordering gases in lecture bottles other than those offered by the vendors listed above to determine what the company's return policy is. For gases purchased in lecture bottles from companies other than those listed above, it is recommended that you save the original shipping crate, warning labels, valve covers, etc. so that your cylinders can be returned to the vendor in accordance with the Department of Transportation's regulations and the vendor's procedure. All researchers are required to have their empty cylinders returned to the vendor before leaving MIT.

The disposal of several other categories of excess and waste materials are governed by special regulations which will be the subject of future Chemical Research Safety Notes. Materials of this type include (contact the indicated office for information on disposal):

Controlled Drugs (contact Marc Jones, ext. 3-1802)

Radioactive Materials (contact Radiation Protection Office, ext. 3-2180)

Biological Wastes (Contact Biohazards Office, ext. 3-1740)

Polychlorinated Biphenyls (PCBs) (Contact Safety Office, ext. 3-4736)

Chemistry Department Summer '95 Cleanup

Special arrangements have been made with the Safety Office for the exchange and disposal of excess chemicals within the Department. Every research group should schedule a general laboratory cleanup prior to the last week of July. As part of this cleanup, lab stockrooms should be carefully inspected and old and unneeded chemicals should be separated for disposal. During the week of July 31, these chemicals can be delivered for disposal to Room 18-124. The following rules will govern the Excess Chemical Exchange and Disposal Operation:

  1. Chemicals will be accepted in Room 18-124 between the hours of 1 and 4 PM only on July 31-August 3.
  2. Group Safety Coordinators must accompany the chemicals when they are brought to Room 18-124.
  3. Only chemicals in original, labeled commercial containers will be accepted; these containers must also have their original caps (no septa!). Bottles should contain at least 1/4 of their original contents. Lecture bottles and gas cylinders cannot be accepted. Pyrophoric reagent solutions (e.g. butyllithium, DIBAL, LAH solutions) and waste mercury will not be accepted. We also cannot accept radioactive materials and biohazardous materials.
  4. Chemicals must be transported to Room 18-124 using appropriate secondary containers.
  5. It is not necessary to provide an inventory of the excess chemicals presented for disposal. However, the Safety Committee personnel staffing the room will maintain a record of the number of containers submitted by each group; please come prepared with this figure.
  6. The chemicals listed below cannot be accepted since the Safety Office temporarily does not have an outside contractor that will accept these specific compounds for disposal.
    • Ammonium vanadate
    • Arsenic, arsenic(III) oxide, arsenic(V) oxide, orthoarsenic acid
    • Beryllium, cadmium
    • Calcium chromate
    • Cyanogen bromide
    • Dichlorophenylarsine, diethylarsine
    • Hydroxydimethylarsine oxide (cacodylic acid)
    • Lead tetraacetate, lead subacetate, lead phosphate, tetraethyl lead
    • Nickel carbonyl
    • Osmium tetroxide
    • Phenylmercuric acetate
    • Selenium, selenourea, selenious acid, selenium sulfide
    • Thallium acetate, carbonate, chloride, nitrate, oxide, selenite, and sulfate
    • Vanadium trioxide, tetroxide, and pentoxide

During the first week of August, each group in the Department will have an opportunity to examine the excess chemicals collected and select compounds they have use for in their research. Copies of the schedule for this chemical exchange operation will be available on Friday, August 4. Only Group Safety Coordinators will be authorized to "sign-out" chemicals, and each research group will be assigned a specific time slot to examine the excess chemical collection.

The Excess Chemical Exchange and Disposal Operation has been arranged to facilitate the redistribution of chemicals within the Department so as to reduce the need to purchase chemicals which are already available (but not needed) in other laboratories. This operation should also serve to reduce collections of excess chemicals which (as discussed above) can constitute safety hazards and which also can present a very significant financial burden to individual group research accounts. Through a "one-time-only" arrangement, the Safety Office will assume the expense of disposing of the unclaimed, excess chemicals collected in this operation.