Superfund Research Program
Enhanced Recovery of Pharmaceutical Solvent driven by EPA Initiative
Project Leader: Sudipto Majumdar
Grant Number: R44ES022885
Funding Period: Phase II: March 2018 – May 2020
The U.S. Environmental Protection Agency (EPA) is establishing new safeguards for hazardous secondary materials with objectives to promote the economic, environmental, and public health benefits of recycling wastes, with an emphasis on several industrial sectors, including the pharmaceutical industry. On average, pharmaceutical manufacturers use at least 100 kg of solvents to make 1 kg of active pharmaceutical ingredient. EPA has determined that the environmental impacts from solvents used as manufacturing and processing aids could be significantly reduced if the product life of solvents used for these purposes were extended to more than a single use. By encouraging the safe recycling of wastes, EPA hopes to reduce the life cycle risk of these wastes. Many of the solvents of interest to the EPA form mixtures with water that are difficult and/or energy-intensive to separate with conventional separation technologies such as distillation. Energy-efficient, cost effective, and otherwise non-polluting alternative technologies would make solvent recycling more feasible. The net effect of the EPA proposed safeguards is that these will strongly incentivize pharmaceutical manufacturers to recycle process solvents. There are numerous needs in the pharmaceutical industry to use and recover high purity solvents. Key uses include high purity alcohol, the ability to develop low-cost dewatering of solvents, and a relatively gentle and simple process for dewatering solvents under mild conditions.
Compact Membrane Systems (CMS) proposes a novel membrane process that can lead to extremely high dewatering rates with high separation capabilities based on a family of chemically inert amorphous perfluoro membranes operating under a wide range (almost universal) of operating conditions. CMS's dewatering process is compatible with existing pharmaceutical solvent (PS) processing. Therefore, from a chemical stability standpoint, it can be operated with alcohols, organic acids, ketones, amines, and aprotic solvents, to name a few. Since the high flux of their membrane is based on its high free volume and perfluoro nature, there is little need for concern about chemical interaction with the species present, and the actual permeability does not change significantly with water activity. Therefore, CMS has a potentially universal and simple system that can work on a wide range of PS for a wide range of applications under varying water activity.
To enhance the potential for "universal" PS dehydration, CMS will develop membranes with enhanced water/solvent separation and a more resistant system, which equates to more resistant porous supports. CMS has recruited a number of key companies for supplying materials and subsequently marketing the final product. CMS has acquired the resources (people and facilities) to prepare perfluoro co-polymers which are not available elsewhere and which possess a new range of properties. Although the familiar monomer tetrafluoroethylene (TFE) is too hazardous for handling by a small company, a variety of other fluorinated monomers are safe to handle. Many co-polymers have now been prepared by CMS. By not using TFE in their synthesis, they eliminate potential explosions and contact with potential carcinogens. Also, they do not use PFOA/C8 surfactants as an additional precaution.
In this phase of the project, CMS is building a dehydration system and demonstrating dehydration of a number of solvents including methanol. Given their innovative success in the first phase of the project with porous supports and special perfluoropolymer membranes, these materials will be used whenever existing porous supports and membranes do not work well. While they have been very successful with special perfluoropolymer membranes for enhanced solvent dehydration, this work has been exclusively using small laboratory-scale membranes. This phase of the project focuses on scaling up the membrane size and demonstrating it on real systems (i.e., working with pharmaceutical companies and the EPA).