08/18/2023
By Danielle Fretwell

The Francis College of Engineering, Department of Energy Engineering - Renewable, invites you to attend a Doctoral Dissertation Proposal defense by Christian Ayafor on: Sustainable Processes for Waste Plastic Upcycling and the Use of Safer Solvents.

Candidate Name: Christian Ayafor
Degree: Doctoral
Defense Date: Aug. 23, 2023
Time: 11 a.m. to 1 p.m.
Location: Perry 415

Committee:

Advisor: Hsi-Wu Wong, Ph.D., Associate Professor, Chemical Engineering, University of Massachusetts Lowell

Committee Members

  • Dongming Xie, Ph.D., Associate Professor, Chemical Engineering, University of Massachusetts Lowell
  • Margaret Sobkowicz-Kline, Ph.D., Professor, Plastics Engineering, University of Massachusetts Lowell
  • Gregory Morose, Sc.D., Research Manager, Toxics Use Reduction Institute

Brief Abstract:

The preservation of the environment for current and future generations entails applying sustainability principles to evolving innovative processes for meeting up with the ever-growing population and its demand. Sustainable measures contribute to nurturing prosperity, enhancing community resiliency, and safeguarding the environment. In this Ph.D. dissertation, two research topics are specifically explored: (1) enzymatic depolymerization of poly(ethylene terephthalate) (PET) via in-situ product removal and (2) safer solvents for active pharmaceutical ingredient purification using column chromatography. The overarching goal of the dissertation is to obtain enabled knowledge for the development of sustainable processes that help reduce non-benign substances to the environment, such as plastic waste and harmful solvents.

The first research topic aims at developing novel strategies to recycle poly(ethylene terephthalate) (PET), a common single-use plastic and a major contributor to plastic waste. PET upcycling through enzymatic depolymerization has drawn significant interest, but the lack of robust enzymes in acidic environments remains a challenge. This study investigates in-situ product removal (ISPR) of acidic products from enzymatic PET depolymerization via a membrane reactor, focusing on the ICCG variant of leaf branch compost cutinase. The results thus far provide valuable insights for future ISPR developments, addressing the pressing need for more sustainable solutions towards plastic recycling and environmental conservation. Future work to further advance our ISPR technologies is also discussed.

The second research topic aims to identify safer solvents for use in column chromatography, a technique widely used in pharmaceutical manufacturing for the purification of active pharmaceutical ingredients (APIs). This technique mainly employs a blend of dichloromethane (DCM) and methanol (MeOH) as the solvent of choice, thereby exposing workers of this sector to the health and safety risks caused by these harmful solvents and making this sector one of the major contributors to chlorinated solvent waste. In this study, the performance of safer solvent blends in column chromatography is compared against that of DCM/MeOH in terms of purification of ibuprofen and acetaminophen as model APIs, with caffeine used as a model impurity. Overall, the safer solvent blends were found to provide a better economic potential (higher API recovery and lower silica gel required) compared to DCM/MeOH in addition to health, safety, and environmental benefits (improved safer ratings and lower E factor). This work addresses the safety concerns in pharmaceutical manufacturing by providing a probable solution to replace the DCM/MeOH blend used in the pharmaceutical industry.