Copper Complexation by Dissolved Organic Matter in arid Soils: A Voltametric Study

A voltammetric method was used to estimate the complexing capacity of water extracts from both desert soils sampled at the root zone of creosote and salt cedar plants, and in soils from interspace or background regions where no vegetative influence was apparent. The copper complexing capacity of water extracts of these desert soils was influenced by contact time and pH. In soils from the root zones of creosote and salt cedar plant, copper complexation capacities at pH 8 were from 5 µM to 60 µM after five min contact periods, while 18 h contact periods yielded copper complexation capacities of 40 µM–80 µM. Soils with no vegetative influence had copper complexing capacities of less the 2 µM. The copper complexing capacities of these soils are well correlated with the concentration of organic carbon in the water extract (r2 = 0.86). The abundance of soluble organic matter in the root zone of desert shrubs has the potential to control the solution speciation of Cu2+. The formation of soluble complexes should also have an important influence on the plant uptake and transport of copper, as well as other heavy metals in the root zones of desert shrubs and beyond

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix: Quarterly Report January-March 2003

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of radioactive iodine. This proposal will develop and examine the use of Fullerene Containing Carbon (FCC) compounds as potential sorbents for iodine release from the reprocessing of nuclear fuel. This work will also include the development of bench-scale testing capabilities at UNLV to allow the testing of the FCC material in a simulated process off-gas environment. This experimental capability will also be used to test other potential sorption materials and processes, such as natural organic matter (NOM) and other promising alternatives. This work will also examine the development of a process to convert the sorbed iodine into a ceramic material with the potential for use as either a transmutation target or as a waste form in a partitioning and sequestration strategy. Bench scale experimental apparatus and methodologies to simulate Iodine entrainment in the vapor phase released from the head end of the PUREX process (the 4M nitric acid dissolution of spent nuclear fuel) will be developed, along with procedures to test the sequestration of Iodine from the vapor mixture. Long term performance/suitability of FCC and NOM will be tested for sequestration of iodine released by nuclear fuel reprocessing. FCC-bearing materials will be prepared and evaluated under laboratory conditions by KRI-KIRSI. Simulated process evaluations will be done on the FCC bearing materials, NOM, and other matrices suggested by the collaborators at UNLV. Conversion of the sequestered iodine to a ceramic-like material will be examined by the KRI-KIRSI team. Recovery of the Iodine from the sequestering matrices will also be examined (by both teams)

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix: Quaterly Report September-December 2003

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of radioactive iodine. This proposal will develop and examine the use of Fullerene Containing Carbon (FCC) compounds as potential sorbents for iodine release from the reprocessing of nuclear fuel. This work will also include the development of bench-scale testing capabilities at UNLV to allow the testing of the FCC material in a simulated process off-gas environment. This experimental capability will also be used to test other potential sorption materials and processes, such as natural organic matter (NOM) and other promising alternatives. This work will also examine the development of a process to convert the sorbed iodine into a ceramic material with the potential for use as either a transmutation target or as a waste form in a partitioning and sequestration strategy. Bench scale experimental apparatus and methodologies to simulate iodine entrainment in the vapor phase released from the head end of the PUREX process (the 4M nitric acid dissolution of spent nuclear fuel) will be developed, along with procedures to test the sequestration of iodine from the vapor mixture. Long term performance/suitability of FCC and NOM will be tested for sequestration of iodine released by nuclear fuel reprocessing. FCC-bearing materials will be prepared and evaluated under laboratory conditions by KRI-KIRSI. Simulated process evaluations will be done on the FCC bearing materials, NOM, and other matrices suggested by the collaborators at UNLV. Conversion of the sequestered iodine to a ceramic-like material will be examined by the KRI-KIRSI team. Recovery of the iodine from the sequestering matrices will also be examined (by both teams)

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix: Quaterly Report January-March 2006

Project Highlights: • Established that iodide can be oxidized by MnO2 to I2 at pHs of 4-8 and moderate temperature. • Demonstrated that p-hydroxybenzoic acid can be iodinated by MnO2 and KI at pHs of 2-8. • Established that humic acids can be iodinated by MnO2 and iodide at room temperature in pH range of 4-8

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix: Quarterly Report August-September 2004

During first year of the project we were able to demonstrate iodine sorption by a sphagnum peat and Ca(OH)2 mixture. We decided to explore varying the ratio of Ca(OH)2 to sphagnum on the retention of iodine in both the iodine generator experiments and the fuel rod simulator experiments. We also constructed a device for simulating the dissolution of fuel rods. Early experiments were impacted by sorption of iodine onto various components of the sorption train. We have eliminated or minimized iodine sorption by the system components. We retested both FCC and the sphagnum using this device. In these experiments a known quantity of iodine (3 – 6 mg) is placed into the system and nitric acid is added. The system is sparged with nitrogen through trap materials and through bisulfite filled impingers. These experiments were conducted with very small quantities of sorbent (0.02 g) so that breakthrough could be observed in a reasonable amount of time. With larger amounts of material (~0.5 g) breakthrough was not observed under these conditions. We have conducted additional fuel rod simulation experiments on FCC and NOM to examine the effect of NOx

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix: Quaterly Report October-December 2004

We have conducted a large number of experiments to determine the possible reaction of iodate with sphagnum peat moss. These experiments indicate that the natural organic material reacts with iodate resulting in the formation of organically bound iodine and/or iodide in solution. In the last quarter, we have conducted a number of experiments at various pHs and several temperatures (70oC, 60oC and 40oC). The reaction of iodate with peat follows pseudo first-order kinetics, although the reaction rate does appear to decrease significantly with reaction time. As noted in a previous report organically bound iodine appears to go through a maximum with reaction time indicating that it is eventually released into the solution as iodide. The stability of the organo-iodine intermediate appears to be a function of pH and temperature, as is the reaction rate of iodate with peat

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of radioactive iodine. This proposal will develop and examine the use of Fullerene Containing Carbon (FCC) compounds as potential sorbents for iodine release from the reprocessing of nuclear fuel. This work will also include the development of bench-scale testing capabilities at UNLV to allow the testing of the FCC material in a simulated process off-gas environment. This experimental capability will also be used to test other potential sorbtion materials and processes, such as natural organic matter (NOM) and other promising alternatives. This work will also examine the development of a process to convert the sorbed iodine into a ceramic material with the potential for use as either a transmutation target or as a waste form in a partitioning and sequestration strategy

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Organic Matrix: Quarterly Report September-December 2002

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of radioactive iodine. This proposal will develop and examine the use of Fullerene Containing Carbon (FCC) compounds as potential sorbents for iodine release from the reprocessing of nuclear fuel. This work will also include the development of bench-scale testing capabilities at UNLV to allow the testing of the FCC material in a simulated process off-gas environment. This experimental capability will also be used to test other potential sorbtion materials and processes, such as natural organic matter (NOM) and other promising alternatives. This work will also examine the development of a process to convert the sorbed iodine into a ceramic material with the potential for use as either a transmutation target or as a waste form in a partitioning and sequestration strategy. Bench scale experimental apparatus and methodologies to simulate iodine entrainment in the vapor phase released from the head end of the PUREX process (the 4M nitric acid dissolution of spent nuclear fuel) will be developed, along with procedures to test the sequestration of Iodine from the vapor mixture. Long term performance/suitability of FCC and NOM will be tested for sequestration of iodine released by nuclear fuel reprocessing. FCC-bearing materials will be prepared and evaluated under laboratory conditions by KRI-KIRSI. Simulated process evaluations will be done on the FCC bearing materials, NOM, and other matrices suggested by the collaborators at UNLV. Conversion of the sequestered iodine to a ceramic-like material will be examined by the KRI-KIRSI team. Recovery of the Iodine from the sequestering matrices will also be examined (by both teams)

Oxalic, glyoxalic and pyruvic acids in eastern Pacific Ocean waters

A sensitive high performance liquid chromatographic (HPLC) technique has been used to determine the concentration and distribution of several α-keto acids and oxalic acid in seawater samples from a station (28°29′N, 128°38′W) in the eastern Pacific Ocean. Glyoxalic, pyruvic and oxalic acids were found to be present. Although the pyruvic acid profile at this station was in general featureless, the profiles for glyoxalic and oxalic acids showed variations which could be attributed to both primary production and heterotropic activity. Surface waters were found to have a combined concentration of glyoxalic and oxalic acids of ∼300 to 400 nm/liter which makes these two compounds some of the more abundant organic constituents of surface ocean waters

Immobilization of Fission Iodine by Reaction with a Fullerene Containing Carbon Compound and Insoluble Natural Matrix

Observations related to the oxidation of iodide to iodine (I2) or hypoiodic acid (HIO) by MnO2 were continued. The formation of triiodide presumable involves the adsorption of iodide onto the MnO2 surface (perhaps displacing a surface hydroxyl group). The iodide should be subsequently oxidized and released back into solution as IOH or I2, which rapidly forms I3 -. The kinetic data has been modeled as a first order process. First order rate constants have been obtained for the formation of iodine in the presence of MnO2. The increase in iodide oxidation rates with MnO2 concentration is evident in the data. The reaction rate increases with iodide concentration although the dependence is not first order (an order of 1.4 appear to fit the data). The oxidation rate also increases with temperature and has a apparent activation energy of 16.2 kJ/mol