Presidential Green Chemistry Challenge: 1996 Small Business Award

Donlar Corporation (NanoChem Solutions, Inc., now Flexible Solutions)

Production and Use of Thermal Polyaspartic Acid

Innovation and Benefits: Donlar developed thermal polyaspartate (TPA), a nontoxic, environmentally safe, biodegradable polymer for use in agriculture, water treatment, and other industries. Donlar manufactures TPA using a highly efficient process that eliminates use of organic solvents, cuts waste, and uses less energy. TPA has been used successfully in a variety of applications, such as improving fertilizer uptake in plants, and improving the efficiency of oil and gas production.

Summary of Technology: Millions of pounds of anionic polymers are used each year in many industrial applications. Polyacrylic acid (PAC) is one important class of such polymers, but the disposal of PAC is problematic because it is not biodegradable. An economically viable, effective, and biodegradable alternative to PAC is thermal polyaspartate (TPA).

Donlar Corporation invented two highly efficient processes to manufacture TPA for which patents have either been granted or allowed. The first process involves a dry and solid polymerization converting aspartic acid to polysuccinimide. No organic solvents are involved during the conversion and the only byproduct is water. The process is extremely efficient—a yield of more than 97 percent of polysuccinimide is routinely achieved. The second step in this process, the base hydrolysis of polysuccinimide to polyaspartate, is also extremely efficient and waste-free.

The second TPA production process involves using a catalyst during the polymerization, which allows a lower heating temperature to be used. The resulting product has improvements in performance characteristics, lower color, and biodegradability. The catalyst can be recovered from the process, thus minimizing waste.

Independent toxicity studies of commercially produced TPA have been conducted using mammalian and environmental models. Results indicate that TPA is nontoxic and environmentally safe. TPA biodegradability has also been tested by an independent lab using established Organization for Economic Cooperation and Development (OECD) methodology. Results indicate that TPA meets OECD guidelines for Intrinsic Biodegradability. PAC cannot be classified as biodegradable when tested under these same conditions.

Many end-uses of TPA have been discovered, such as in agriculture to improve fertilizer or nutrient management. TPA increases the efficiency of plant nutrient uptake, thereby increasing crop yields while protecting the ecology of agricultural lands. TPA can also be used for water treatment, as well as in the detergent, oil, and gas industries.

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