Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2006
Publication Date: 6/15/2007
Citation: Bissey, L.L., Smith, J.L., Watts, R.J. 2007.Soil organic matter-hydrogen peroxide dynamics in the treatment of contaminated soils and groundwater using catalyzed h2o2 propagations (modified fenton’s reagent). Water Research 40:2477-2484. Interpretive Summary: In soils that are contaminated with chemicals such as oil or fuel, remediation can include catalyzed H2O2 propagation (CHP) reactions which use H2O2 to oxidize the oil or fuel. Native soil organic matter interferes with these reactions such that they become less efficient and more costly. Our objective was to determine what fraction of soil organic matter interferes with the remediation reaction the most so as to be able to predict from soil to soil if the catalyzed H2O2 propagation (CHP) reaction will be useful, efficient and cost effective. We found that the soil organic carbon from the smallest fraction of soil (<53 um) affected the remediation reactions the most and that the overall efficiency of the reactions was pH dependent. Practitioners of soil remediation can use this information to design systems of chemical remediation that can be used efficiently from soil to soil.
Technical Abstract: The effect of different pools of soil organic matter (SOM) on catalyzed H2O2 propagations (CHP) reactions is largely unknown. This study was conducted to determine the effect of CHP reactions on various pools of SOM, and to determine the effect of SOM on CHP remediation. The effect of CHP reactions on SOM was determined by exposing a Palouse silt loam soil to six different CHP treatments and determining carbon content in two soil size fractions after reactions reached completion. Information on the oxidizing species was determined by adding a hydroxyl radical scavenger to select CHP reactions. The effect of SOM on CHP remediation was determined by measuring hydrogen peroxide degradation rates and hydroxyl radical probe degradation rates using soils of varying organic carbon content. In low pH systems, the loss of soil organic carbon was 30-60% after treatment, while loss in natural (pH= 5.6) and pH 7systems is minimal to none. The loss of soil organic carbon occurred predominantly in the NPOM (non-particulate organic matter) fraction (<53 'm fraction). When the hydroxyl radical scavenger isopropanol was used in CHP systems, the loss of organic carbon was not statistically different ('= 0.05) from that in parallel systems without the scavenger. Hydrogen peroxide decomposition rates in CHP systems were not affected by soil organic carbon content in pH 3 systems; however, hydrogen peroxide decomposition rates increased in natural pH systems when soil organic carbon was not present. Similarly, hydroxyl radical production in CHP systems was not affected by soil organic carbon in pH 3 systems, but was lower in natural pH systems when soil organic matter was not present. The destruction of SOM by CHP reactions and the effect of SOM on CHP remediation were found to be largely pH dependent.