Director, Material Science
John Freim has a B.S. in Chemical Engineering from the University of Illinois and a Doctorate in Materials Science from the University of California at San Diego. He has 30 years of experience in the research, development, and manufacturing of engineered materials. At REGENESIS®, Dr. Freim's focus is developing and manufacturing advanced materials used for in-situ environmental remediation. These include colloidal iron product AquaZVI and MicroZVI, colloidal activated carbon (PlumeStop) along with remediation products under development. Dr. Freim has served as principal investigator for over 20 research and development programs and is the author of 8 patents.
Advancements in Chemical Reduction Strategies Using Colloidal Sulfidated Zero Valent Iron
Sulfidated zero-valent iron (SZVI) is a powerful electrochemical reductant that provides accelerated reactivity and favorable reaction pathways with chlorinated ethenes and ethanes. A key feature of sulfidated iron is a unique structure with a metallic iron core and an iron sulfide surface. This configuration prevents the reaction between iron and water that is undesirable because it can prematurely consume iron and produce a passivating hydroxide surface layer. In addition to its use as a stand-alone amendment, SZVI can provide synergistic benefits when applied with other remediation approaches. We describe experiments showing the beneficial effects of using a combination of colloidal SZVI, organic bioremediation amendments, and dechlorinating microbes. Also described are experiments showing the benefits of combining SZVI and colloidal activated carbon adsorbents. Compared to stand alone strategies each approach provided accelerated reactivity with fewer and shorter-lived daughter products.