(4ds) Energy Efficient Carbon Capture from Wet Flue Gas Streams and Seawater

Greenhouse gas contributions to global climate change have generated interest in separating carbon dioxide (CO2) from wet flue gas streams. To address this challenge, absorption of CO2 via environmentally friendly, green solvents, has emerged as a useful technique. Solvent-based capture systems have emerged in the carbon capture space due to their reusability, high absorption capacities, and favorable economics. Compared to commercially available carbon capture processes that utilize ionic liquids and amine-based technologies, membrane-based carbon capture with diethyl sebacate (DS) is cheaper, energy efficient, and presents high capacity for industrial level carbon capture use. The use of DS as a solvent for pre- and post-combustion carbon capture has many advantages over other solvents such as high hydrophobicity, low viscosity, low vapor pressure, high CO2 solubility, high CO2 selectivity, and commercial availablility in larger quantities as compared to deep eutectic solvent, a common green solvent. Despite its advantageous properties, little research has investigated DS as a solvent for carbon capture. To absorb CO2 from flue gas streams, a scalable, energy-efficient, hollow fiber membrane (microporous polypropylene and polyvinylidene fluoride) contactor (HFMC)-based process was designed with low-cost and high surface area to provide high interfacial area for effective CO2 capture. Single gas measurements in this system demonstrated effective capture of CO2 while rejecting nitrogen. A purity of 95.3% CO2 was achieved using DS, with a permeate flux over one magnitude greater than deep eutectic solvent in this same system. Results from this work underscore the importance of utilizing green solvents in HFMC-based separation processes for effective carbon capture and provides a pathway toward practical deployment.

For the last 300 years, the ocean has functioned as a natural sink for CO2 and has absorbed approximately 30% of atmospheric CO2. This absorption of CO2 has reduced the pH of seawater to 8.1, coinciding with a 30% increase in acidity that negatively impacts marine wildlife. Once absorbed into seawater, CO2 primarily exists as bicarbonate ions. Direct ocean capture of CO2 has much potential in the carbon capture space when considering CO2 concentration is 140 times higher in the ocean compared to the atmosphere. Most CO2 seawater removal technologies being researched utilize electrochemical approaches that are energy-intensive and require expensive capital and operational costs. A scalable, cost-efficient process is needed to advance the direct ocean capture space and achieve net-negative carbon emissions. To bridge this gap, a scalable, energy-efficient, hollow fiber sorbent (microporous polyvinylidene fluoride (PVDF)) contactor-based process was designed with low-cost and high surface area to provide high interfacial area for effective CO2 capture from oceanic seawater. To effectively remove bicarbonate ions from seawater, PVDF hollow fibers are first functionalized with bicarbonate selective groups to effectively adsorb bicarbonate ions from solution and achieve this separation. To measure CO2 removal, a carbon dioxide ion selective electrode was utilized. Upon saturation of bicarbonate ions, a pH swing mechanism was employed to regenerate the hollow fibers by desorbing the ions back into solution, allowing for further adsorption. This regeneration process allows for repeated, recycled use of the contactor in a cost-friendly and energy-efficient manner. Results from this work underscore the importance of utilizing bicarbonate selective PVDF hollow fibers in HFMC-based separation processes for effective direct ocean carbon capture and provides a pathway toward practical deployment.

Research Interests

The synthesis of traditional polymeric materials requires the usage of petroleum-based precursors, creating a movement towards incorporating environmentally friendly, renewable biopolymers such as cellulose, chitosan, and lignin. Lignin, a byproduct of the paper mill industry, is the world’s second most abundant natural polymer (behind only cellulose) and while 50 million tons are produced yearly, most is burned as fuel. When properly recovered, this biopolymer presents opportunities to reduce the usage of petrochemicals in the fabrication of next-generation polymer composites and provides many other added benefits that include enhanced mechanical properties and biocompatibility. Additionally, lignin contains a high concentration of hydroxyl groups serving as potential sites for chemical functionalization and direct crosslinking.

My research interests after completing postdoctoral studies are to investigate ways of incorporating lignin into hollow fiber membranes for direct ocean capture. Much research has investigated lignin-based composite hollow fibers for various applications, but very little has investigated lignin-based hollow fibers for direct ocean capture. Lignin’s abundance of hydroxyl groups and rigid polymer structure make it an attractive biopolymer for direct ocean capture studies, a relatively new field of research. When considering my graduate work that heavily centered on lignin-based composites, along with my postdoctoral studies that are focused on hollow fiber membranes in the carbon capture space, I hope to combine these skillsets and grow an academic group in the direct ocean capture space.

Teaching Interests

I have served as a teaching assistant multiple times for the fluid dynamics course offered to undergraduate chemical engineering students at Clemson University. I have also served as a teaching assistant for unit operations and thermodynamics. As such, my teaching interests primarily lie in fluid dynamics and graduate-level transport phenomena.

I was born with sensorineural hearing loss and have navigated the lifelong challenge of hearing impairment. To effectively hear and communicate, I must wear hearing aids. The amount of deaf and hard of hearing people in the country is 3%, while even less (0.13-0.19%) represent pupils in STEM-based careers. One of my career aspirations is improving the educational experiences and resources for deaf and hard of hearing students and encouraging them to pursue advanced STEM degrees. I hope the successes of my research group as a tenured professor will inspire deaf and hard of hearing people, along with other underrepresented pupils, to pursue STEM-based career paths and get involved in carbon capture research.