CHEE Seminar: Roberto Guzman
Monday, October 4, 2021 – 3:00 p.m.
Roberto Guzmán
CHEE professor
“Synthesis of Chelating Polymers and Their Application to Protein and Metal Ion Separations: Regenerable Adsorbents for Effective Removal of Arsenic from Aqueous Solutions”
Harshbarger Bldg., Room 206
ABSTRACT
The contamination of water, air and soils by heavy metal is one of our most important and challenging environmental issues. The current need for improved metal recovery technologies serves as a strong justification for exploratory research into approaches that may yield better new processes. In this presentation, Guzmán will describe his work with chelating-polymeric adsorbents for proteins (IMAC-Immobilized metal affinity chromatography) and metal ion separations. Emphasis will be placed in derivatives of polyethyleneimine (PEI)-polymer-chelates and their use as chelating hydrogels for metal ion separations. The complexation chelation chemistry of the adsorbents is used for the isolation of nucleophiles and metal fractionation. This specific property is used for the synthesis of regenerable arsenic adsorbents that after removal (adsorption) and desorption permits its efficient recovery and or disposal. The significance of this method is that there is no need for disposal of the adsorbent since this new media can be re-generated indefinitely without a decrease in their capacity or effectiveness. In this approach, the adsorbed arsenate ions are desorbed by decreasing the pH of the eluant solution and recovered in a highly concentrated form. The adsorbent column remains intact and can be regenerated and therefore there is no need to dispose of the media in a landfill. Once the column is re-equilibrated with iron at an appropriate pH (now as a regenerated adsorbent) it is ready again to start a new arsenic adsorption-desorption cycle. The mechanism of adsorption in this proposed case is the same mechanism involved in the adsorption of arsenic by iron-based oxide systems, the most common adsorption of arsenic technique used and recommended by the EPA, but in our scheme, the process of adsorption is reversible and thus the adsorbent regenerable.
BIO
Roberto Guzmán is a Chemical Engineering professor at the University of Arizona (since 1989). He received a Ph.D. in Chemical Engineering/Biotechnology from North Carolina State University (NCSU) where he continued as a postdoc for a year before joining the University of Arizona. He received an MSc in Chemical Engineering from the University of Illinois, Chicago and a B.S. in Chemical Engineering from the University of Guanajuato, Mexico. At present, his research emphasis is in biomolecular nanotechnology and synthesis of specific adsorbents for protein affinity purifications and metal ions recovery, synthesis of nanoparticles for drug delivery and theranostics, and the discovery and isolation of biomarkers from biological fluids. His research has strong bases in molecular recognition, affinity technology, and falls within the boundaries between synthetic chemistry, biology, medicine, polymer sciences, and engineering and incorporates both experimental and theoretical work analysis.