GW Alum Leads Undergraduate Research Group to Unlock the Vast Resources of Lithium in the World Ocean

Robert Pellenbarg, Ph.D., recounts success in the Chemical Enterprise from undergraduate days at GW to receipt of a patent on the oceanic lithium work

 

The Chemistry universe at GWU in the early 1970s centered on Corcoran Hall.  Over 4 years, I attended lecture classes, lab sessions, conducted independent research, and joined the occasional invited presentation in the Hall.  Appended Samson Hall housed Faculty offices, and the Department library in a single 2^nd floor room.  Lab classes on the 4^th floor of Corcoran were often the challenge of doing much with little time.  Indeed, this tightness occasionally demanded use of various ‘breakage cards’ to replace glassware ‘lost in the shuffle’.  However, come Spring, the lab space was glorious with the tall windows of the lab thrown open to the balmy air of the season.

 Four years on campus presented a B.Sc. in Chemistry as an open door to the future.  I completed graduate work in Chemical Oceanography at the University of Miami (FL), and the University of Delaware.  At Delaware, my research focused on trace metal cycling in a salt marsh.  This work was very successful, and led to a research paper in Science, complete with a marsh related cover picture on the issue containing the paper.  A National Research Council fellowship supported a Post Doc appointment at the Naval Research Laboratory in Washington, DC.  I joined the Ocean Sciences Division at NRL, until Ocean Sciences was dissolved, then transferred to the Chemistry Division.  I worked at NRL for some 25 years, working, officially, on mostly classified research which could not be published in the open literature.  Therefore, I focused on extending my Post-Doc work, and expanded it as publishable in the open literature.  Indeed, one paper reported on environmental silicones for the first time.  Silicones were to be very important later in my career.

While at NRL, there was opportunity for travel.  Bermuda, Chile, Peru, Brazil, Argentina, Spain, the Azores, Alaska, Hawaii, Canary Islands, California and other destinations all left memorable marks on my official, burgundy colored Passport.  The Ocean Sciences Division made extensive use of USNS HAYES, a twin hull oceanographic platform.  Indeed, there was nothing quite like rousing from bed at 0300 (3AM) to commence work at an oceanographic station.  None the less, time at sea was always a welcome change of venue.        

 After a career at the Naval Research Laboratory, I relocated west for a change of venue.  I was honored to teach for 12 years at College of the Desert in Palm Desert, CA.  The COD Community College offered a rather unique opportunity for STEM students.  Specifically, the MESA program (Math, Engineering, Science Achievement) at COD provided a venue of support, and challenge, for STEM students at the College.

One aspect of the MESA effort was the annual Winter Session (~ 4 weeks duration) where MESA students engage in independent research projects.  The students self - assembled into small teams.  The teams are required to research a chosen project, design a solution, prosecute the design, and prepare a poster as an internal report presenting results.  All aspects of the effort MUST wrap up in 4 weeks.  No pressure!

One team chose to investigate the potential interactions of alkali metal ions with certain cyclosiloxanes.  Silicones redux!  This project was of interest because structurally, cyclosiloxanes resemble crown ethers which bond to alkali metal ions, e.g. K⁺.  To prepare for the team’s Winter’s tasking, I had procured chloride salts of lithium, potassium, rubidium and cesium.  Several small - ring cyclosiloxanes were also made available.

The approach to the effort relied on the ‘flame test’ as an assay for examining potential interactions.  Solutions of alkali metal ions were mixed with various cyclosiloxanes;  after a period of interaction, the upper siloxane phase (liquid siloxanes do not mix with water) was proofed via the low tech, but highly specific flame test.  The mix of Li⁺(aq) and a single cyclosiloxane gave an eye - popping result.  Specifically, once a bit of the upper cyclosiloxane layer, after contact with an underlying Li⁺ solution, was placed in a Bunsen burner flame, first an orange color (probably ubiquitous Na⁺ contamination) appeared as the siloxane flamed off, then a ruby flash popped as residual Li⁺ vaporized off a nichrome loop.  Li⁺ has a bright emission spectrum centered in the red.  Very, very interesting result, to say the least.

  The MESA effort at COD supports interested students to pursue research at nearby California State University, San Bernardino, over the Summer.   So, the siloxane effort, and I as Mentor, migrated to CSUSB to utilize the resources of the Department of Chemistry and Biochemistry there one Summer.  Our team examined the Li⁺ / siloxane interactions with NMR, FTIR, flame AA / emission mode, and SPARTAN molecular modeling software.  Eureka (!):  hints and suspicions from COD were firmly confirmed at CSUSB. Further, to clearly demonstrate the specificity of the siloxane / Li⁺ interaction, we studied the interaction in a seawater (hint:  all alkali metal ions present here!) matrix.  We used seawater from a local aquarium shop, and demonstrated clearly that the siloxane of interest would selectively sequester only Li⁺ from seawater.  Thus, we now had access to the vast amount of lithium in the world ocean!

Clearly, our Summer’s research had produced a significant result.  In fact, CSUSB applied for and received a patent for the outcome of the work of a superb, focused team of undergraduate STEM students.  Indeed, it had been a privilege, honor, and, yes, a challenge, to Mentor these, and many other STEM students, over the years.  Clearly, my firm foundation in Chemistry from 4 years at GWU has served me well.

Reference:  US Patent 11,279,626 B2;  Pellenbarg, et al.