Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Room: Exhibit Hall
Iiana Robinson - Regis University
Co-Author(s): Reina Sandoval, Regis University, Denver, CO; Surendra Mahapatro, Regis University, Denver, CO
Hexavalent chromium is a known carcinogen. The EPA has a drinking water standard of 0.1 milligrams per liter (mg/l) or 100 parts per billion (ppb) for total chromium. Interestingly, chromium(III) is part of glucose tolerance factor (GTF) and Cr(III)-picolinate is a dietary supplement. The source of chromium(VI) drinking water is mainly from industrial use (chrome plating and leather tanning), and due to the complex geochemistry involving rocks containing chromite and solid manganese dioxide (MnO2. nH2O; Birnessite, a common manganese mineral). The express purpose of our study is to screen several renewable organic substrates that could potentially reduce hexavalent chromium to Cr(III) individually or in co-oxidation reactions with ethanol. This list includes oxalic, lactic, citric, malic, tartaric, gallic and tannic acid. We will report half-lives (t1/2) of first-order reactions under pseudo first-order conditions and discuss the transition state for the ter-molecular complex involving Cr(VI), ethanol and the hydroxy-acid. Reductive detoxification of hexavalent chromium requires reliable methods for the quantitative estimation of Cr(VI). We will examine the relative merits of all available methods including chromate (CrO42-, shows a λmax a 372 nm (4.8 x 103 M-1 cm-1), EPA protocol method 7196A involving 1,5-diphenylcarbazide and the green radical cation ABTS●. 1.Genesis of hexavalent chromium from natural sources in soil and groundwater Christopher Oze, Dennis K. Bird, and Scott Fendorf, PNAS, 2007 104 (16), 6544-6549. 2.Reduction behavior of chromium(VI) with oxalic acid in aqueous solution Hao Peng & Jing Guo ; Nature Scientific Reports volume 10, Article number: 17732 (2020)
Funder Acknowledgement(s): This research is supported by the Western Alliance to Expand Student Opportunities (WAESO) Louis Stokes Alliance for Minority Participation (LSAMP) National Science Foundation (NSF) Cooperative Agreement No. HRD-1619524.
Faculty Advisor: Surendra Mahapatro, firstname.lastname@example.org
Role: I researched background information and methods to detect hexavalent chromium in water. I also set up and conducted the tests with the different mixtures and on the machines.