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Disposal of Waste MDI and Used MDI Storage Containers

Erin Dickison

Committed to Safe Handling, Storage and Disposal of Diisocyanates

Diisocyanate producers make safe handling, storing and disposing of diisocyanates an industry-wide priority. ACC member companies take great care when disposing of all waste materials—whether at their own sites or when assisting customers. Waste disposal is highly regulated at federal, state and local levels. Waste methylene diphenyl diisocyanate (MDI) handling is required to be in compliance with U.S. environmental laws and in accordance with the manufacturer’s Safety Data Sheet (SDS).

Disposal of Waste MDI

Hazardous waste regulations are developed and implemented by the U.S. Environmental Protection Agency (EPA) as directed by Congress in the Resource Conservation and Recovery Act of 1976 (RCRA). EPA defines hazardous waste in 40 CFR Part 261. A material is considered a hazardous waste if (1) it is a listed hazardous waste published by EPA in 40 CFR Part 261, Subpart D or (2) exhibits at least one of the four characteristics defined in 40 CFR 261, Subpart C. The four characteristics are ignitability, corrosivity, reactivity, and toxicity. For more information about the EPA rules for waste characterization and disposal, please refer to the following document available through the Center for the Polyurethanes Industry (CPI): Guidelines for the Responsible Disposal of Wastes and Containers from Polyurethane Processing.

MDI (CAS# 26447-40-5) is not a listed hazardous waste under RCRA nor does it exhibit any of the four characteristics defined in 40 CFR 261. Therefore, if discarded in its purchased form, MDI would not be a hazardous waste under the Federal statute.

The easiest and most convenient way to manage waste MDI is to react it with waste polyol to produce a low-quality foam, which can then be sold or used as a manufactured product. However, if the foam is to be disposed of, it must be done in full compliance with all federal, state and local regulations and requirements governing the disposal of such materials.

Federal and state requirements may differ on whether MDI and the foams produced by reacting waste MDI with waste polyol may be discarded or disposed of as non-hazardous wastes. Be sure, therefore, to check with the appropriate regulatory agencies before disposing of waste MDI or MDI-based polyurethane foams. Caution: The MDI/polyol reaction is exothermic, which may cause spontaneous combustion with the foam produced.

Another way to dispose of waste MDI is to react the material with a neutralization solution. To help minimize potential risks, users generally add the waste MDI slowly or in increments, under mechanical stirring, to the solution, which is contained in an open-top drum. Note: Be sure this process is conducted in a well-ventilated area or outdoors. Carbon dioxide gas will be produced in the process so providing standing time allows the gas to escape. For example, many companies will let the reacted material stand for 48-72 hours. Finally, the liquid is decanted and both the solid and liquid products disposed of in accordance with all relevant federal, state and local regulations. Again, since MDI is not a RCRA listed hazardous waste, such treatment does not require a federal permit. Although, according to federal regulations, the resulting product may be disposed of as a non-hazardous waste, it is important to check state and local regulations because they may be more stringent.

If you are considering alternative ways of disposal (i.e., reacting with a liquid decontamination solution[1], or reacting waste MDI with waste polyol) and have questions, contact your product supplier or manufacturer for guidance.

Disposal of Empty MDI Containers


When purchasing MDI or MDI products in 55-gallon steel drums, it is important to follow proper procedures and have an appropriate plan established for disposing of the drums once they are empty. Empty drums must be stored in a clean, dry, secure area until arrangements are made to dispose of them correctly. Even empty drums not properly managed can lead to many problems for the company responsible for their care. Empty MDI drums that have not been decontaminated with a neutralization solution will still contain a residue of MDI and must be handled with care.

A common method for disposal of empty drums is to contact a professional drum re-conditioner. A state by state listing of drum re-conditioners can be obtained from the Reusable Industrial Packaging Association. Providing a Safety Data Sheet (SDS) for the MDI product along with the drum helps ensure the re-conditioner will have information on the drum’s previous contents.

Drums may also be sent to a scrap dealer, an incinerator, or a landfill but may need to be decontaminated, then punctured or crushed to prevent reuse. Instructions can be obtained from the scrap dealer or incinerator company on how to prepare the drums for transport and refer to the manufacturer’s recommendations on how to decontaminate MDI drums as appropriate.

Because MDI is not a hazardous waste under RCRA, drums with MDI residue are not required to meet the RCRA-empty standards at 40 CFR 261.7. However, many companies choose to follow the federal procedure as a management practice. This means that all liquid waste within the drum has been removed from the drum by the generator using common practices such as pouring, pumping, and aspirating (no free liquid can remain inside the drum). For closed head drums with contents that cannot be poured, there can be no more than one inch of residue in the drum, or no more than 3 percent by net weight stuck to the bottom, top, and sides. Emptying a drum until it is “drip dry” is generally considered a practice commonly employed to remove material from this type of drum.

If the empty drums are sent to scrap metal recyclers or approved landfills, they may request that the drums be thoroughly decontaminated with a neutralizing solution prior to disposal. Contact your MDI supplier for information on recommended neutralization/decontamination solutions. After using a decontamination solution, carbon dioxide gas may be released during the neutralization process so often bungs are loosely applied to the drum until the drum can be destroyed. Crushing the empty MDI drums, after they are internally decontaminated prevents re-use.

In summary, there are three options available for disposing of steel drums that contained MDI. Disposal must be in compliance with all applicable federal, state, and local laws and regulations.

To help ensure proper disposal of drums, consider one of the options below:

  • a professional drum re-conditioner
  • a professional scrap metal recycler, or
  • an approved landfill that complies with all federal, state and local laws and regulations. In addition, it is important to understand whether the landfill has any special restrictions. For example, certain landfills have a ban on accepting recognizable drums and other containers over a certain size. In some cases, processors may be able to destroy the drums (i.e., using a drum crusher) and send them to a landfill. Still, sending empty drums to a landfill can pose long-term liability issues if the landfill is ever found to be contaminated. Careful diligence is warranted when using this procedure).

If requested to decontaminate an MDI drum and you have any questions, contact the product supplier or manufacturer for guidance.

WARNING: Empty drums should not be burned or cut open with a gas or electric torch, as toxic decomposition products may be liberated. It is also important to not allow a drum to be re-used for any purpose including storage of other liquid chemical products, trash burning, grill pits, or water collection.

In summary, companies that use 55-gallon drums should have a plan established on properly handling and disposing of drums once empty. All empty drums should be managed so they are stored in a specific location that is secure and protected from the weather until proper arrangements are made for disposal. Keeping MDI drums appropriately sealed, easily accessible, labeled, and frequently inspected helps ensure their integrity.

Intermediate Bulk Containers or IBC’s (commonly referred to as totes)

Polymeric MDI is also commonly packaged in IBC’s or totes. Totes are large plastic containers mounted within a metal cage assembly. Totes contain a much larger volume of MDI than drums (approximately 250 gallons of liquid product in a tote) and thus can be more convenient packaging method for many polyurethane processors. Tote manufacturers sponsor a tote recycling program. Typically, tote manufacturers do not require the tote to be cleaned or conditioned for return. Each tote comes with a return recycling ticket attached to the cage. Return totes in accordance with the manufacturer information on the recycling ticket. Warning: Empty totes may contain liquid or vapor residue, which may be dangerous. Empty totes may not be used for other purposes.

Pails (5-gallon plastic containers) and Small Sample Containers

MDI and MDI products may be shipped in 5-gallon pails (plastic containers) or sent to customers in 1-liter or 4-liter aluminum bullet containers. These types of containers are non-returnable and are not re-used for any other purpose. All precautions on the Safety Data Sheet (SDS) must be observed when handling and disposing of these containers. These containers should be decontaminated with an appropriate neutralization solution before disposal.

Resources on Disposal of MDI

CPI offers a variety of additional resources regarding health and safety information for diisocyanates and polyurethanes. Visit CPI’s Products, Resources and Document Library for a complete list of resources.

Government and Other Resources

Resources for Purchase

  • MDI and TDI: Safety, Health and the Environment: A Source Book and Practical Guide – by D. C. Allport (Editor), D. S. Gilbert (Editor), S. M. Outterside (Editor): MDI and TDI are polymer building blocks used in large quantities and have a variety of applications in industry. MDI and TDI are subject to stringent health and safety regulations. This book covers important topics concerning MDI and TDI and provides comprehensive coverage on the health and environmental science associated with these. Among these topics, neutralization, decontamination and disposal of DII wastes are covered extensively.

Legal notice: This document provides general guidance only; users must independently determine appropriate practice relative to their own circumstances and applicable law. Neither the American Chemistry Council (ACC), nor member companies of the Diisocyanates Panel make any warranty or representation, either express or implied, with respect to the accuracy or completeness of the information contained in this material; nor do ACC or the Panel member companies assume any liability or responsibility for any use, misuse or reliance on any information in the document. New information may be developed subsequent to publication that renders information contained herein incomplete or inaccurate. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED


[1] Refined Solution for Neutralization of Residues in Emptied Diisocyanate Drums – by West, R., Hugel, E. (2013), Paper presented at the CPI Polyurethane Technical Conference, Arizona, September 23-25, 2013

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