Treating Metals in Acid Mine Drainage Using Slow-Release Hydrogen Peroxide A thesis presented to the faculty of the College of Arts and Sciences of Ohio University In partial fulfillment of the requirements for the degree Master of Science Samuel A. Miller August 2015 © 2015 Samuel A. Miller. All Rights Reserved. 2 This thesis titled Treating Metals in Acid Mine Drainage Using Slow-Release Hydrogen Peroxide by SAMUEL A. MILLER has been approved for the Department of Geological Sciences and the College of Arts and Sciences by Eung Seok Lee Associate Professor of Geological Sciences Robert Frank Dean, College of Arts and Sciences 3 ABSTRACT MILLER, SAMUEL A., M.S., August 2015, Geological Sciences Treating Metals in Acid Mine Drainage Using Slow-Release Hydrogen Peroxide Director of Thesis: Eung Seok Lee Metal concentrations from acid mine drainage (AMD) pose a significant threat to aquatic systems worldwide as a result of past and current mining operations. This study tested the efficacy of using slow-release hydrogen peroxide (SR-HP) to oxidize and remove ferrous iron (Fe2+) from AMD. Fenton’s reagent forms from a mixture of 2+ hydrogen peroxide (H2O2) and Fe available from AMD, creating an advanced oxidation process. Twenty-eight SR-HP forms were developed by dispersing sodium percarbonate (Na2CO3 1.5H2O2) salts in a polymeric matrix. The SR-HP forms released H2O2 in flowing water at a peak release rate of 0.05 – 52.1 mg min-1 during the initial hour and -1 continued to release H2O2 at a lower, stable release rate (0.02 – 1.5 mg min ) from a period of days to weeks depending on salt : binding agent mixing ratios. Oxidant : resin mixing ratios in addition to surface area were primary factors impacting the release profiles from the laboratory column leaching tests. Proof-of-concept iron removal tests indicate that SR-HP forms can efficiently remove Fe2+ from AMD within one minute. +2 2+ Ideal [Fe ]/[H2O2] ratios for >80% Fe removal clustered around 2, with decreasing Fe2+ removal as the ratio increases. A small-scale field test demonstrated the efficacy of SR-HP at oxidizing Fe2+. Ferrous iron concentrations were reduced by 80% within the first hour of treatment. These results suggest feasibility of using SR-HP to treat oxidizable metals in AMD water. Further development of SR-HP forms with higher 4 release rates, longer durations, stronger binder, and improved reproducibility could be possible. 5 DEDICATION To my parents and grandparents 6 ACKNOWLEDGEMENTS I would like to thank The Korean Institute of Geoscience and Mineral Resources (KIGAM), Ohio Department of Natural Resources – Division of Mineral Resources, and the Monday Creek Restoration Project for funding this project, sample analysis, and aiding in selection of potential proof-of-concept tests. I would like to thank my advisor Dr. Eung Seok Lee for giving me this opportunity and providing me with insight along the way. I would also like to thank fellow graduate students who have been willing to listen to my concerns and offer thoughtful advice. 7 TABLE OF CONTENTS Page Abstract ………………………………………………………………………………...…3 Acknowledgements ……………………………………………………………………….6 List of Tables……………………………………………………………………………...9 List of Figures……………………………………………………………………………10 Chapter 1: Introduction…………………………………………………………………..13 1.1 Formation of AMD…………………………………………..…………………..16 1.2 Advanced Oxidation Reactions…………………………………………………..18 1.2.1 Fenton’s Reagent…………………………………………………………..19 1.3 Slow Release Systems……………………………………………………………20 1.4 Study Site………………………………………………………………………...22 1.5 Study Objectives…………………………………………………………………26 Chapter 2: Materials and Methods……………………………………………………….28 2.1 Material…………………………………………………………………………..28 2.2 Field Measurements……………………………………………………………...28 2.3 Designing Slow Release Forms………………………………………………….29 2.4 Estimating Release Rate: Column Leaching Tests………………………………30 2.4.1 Determination of Hydrogen Peroxide Concentration ……………………..32 2.4.2 Determination of Ferrous Iron Concentration ……………………………..33 2.5 Proof-of-Concept Ferrous Iron Removal Tests…………………………………..35 2.6 Small-scale Field Application Test………………………………………………35 Chapter 3: Results and Discussion……………………………………………………….37 3.1 Study Site………………………………………………………………………...37 8 3.1.1 Baseline Chemical Sampling………………………………………………38 3.2 Characterizing Slow Release Systems…………………………………….……..40 3.2.1 Slow Release Form Dimensions…………………………………………...40 3.2.2 Column Release Tests……………………………………………………...41 3.2.3 Oxidant Release Efficiency / Recovery Rate………………………………62 3.3 Proof-of-Concept Iron Removal Tests…………………………………………...64 3.4 Small-scale Field Application Test………………………………………………67 Chapter 4: Conclusion…………………………………………………………………....84 References………………………………………………………………………………..86 Appendix A: H2O2 fluxes from 6 SR-HP column tests over two weeks…………………90 +2 Appendix B: Weight of sodium percarbonate (kg/day) necessary for a [Fe ]/[H2O2] 2:1 for different Fe2+ concentrations (mg L-1) and discharges (L s-1)……………………..…91 9 LIST OF TABLES Page Table 1-1. Redox potential of common oxidants ………………………………………..18 Table 1-2. Historic water chemistry and discharge measurements at study site BH00690…………………….....…………………………………….…………………..26 Table 3-1. Historic discharge and chemical parameter measurements at BH00690 (http://watersheddata.com) ……………………..………..…………..…….…………….38 Table 3-2. Aqueous chemistry data for BH006900 sampled on 6/10/2014….……….….39 Table 3-3. Properties of slow-release forms made with sodium percarbonate and casting resin……………………………….….……………………………………………..……40 Table 3-4. P-values from two-sided T-tests performed between first order decay constants between SR-HP 23-28…………………….…….……………………………….……….62 Table 3-5: Properties of SR-HP forms used in field removal demonstration…….……...65 Table 3-6: Percentage of dissolved oxidant from SR-HP forms removed from field demonstration……………………………………………………………………….……69 Table 3-7: Discharge measured during the small-scale field demonstration at BH00690 and upstream and downstream measurements…………………………………..……….69 10 LIST OF FIGURES Page Figure 1-1. Locations of the three Appalachian Basin coal regions (from USGS, 2002).14 Figure 1-2. Slow release diffusion modeled in cross sectional view. (Lee and Schwartz, 2007a)..………………… ……………………………………………………………….21 Figure 1-3. Location of study site BH00690 within the Monday Creek Watershed (adapted fromMonday Creek Reclamation Project)……………………………………..23 Figure 1-4. Location of study site BH00690 in relation to Jobs New Pittsburg Rd and Brush Fork,and other AMD sampling points stored on NPS website (http://watersheddata.com)……………………………………………………………….24 Figure 1-5. Solubility of major and minor metals at different pHs (modified from Wei et al., 2005)…………………………………………………………………………………25 Figure 2-1: Release kinetics of SR-HP forms at 8 mL min -1 column test (adapted from Tong, 2013) …………………………………………………………………….………..31 Figure 2-2. Standard curve for Hydrogen Peroxide concentration determination……….33 Figure 2-3. Standard curve for Ferrous Iron concentration determination………………34 Figure 3-1: Small-scale field demonstration site, BH006900, located within the Monday Creek watershed. Baseline chemical sampling on June 10th, 2014…………………….37 Figure 3-2a. H2O2 release profile from a 1.66 : 1 SR-1 form during a column leaching test using a 7 ml min-1 flow rate………………………………………………………...42 Figure 3-2b. H2O2 release profile from a 2.5 : 1 SR-2 form during a column leaching test using a 7 ml min-1 flow rate…………………………………………………………......43 Figure 3-2c. H2O2 release profile from a 3.33 : 1 SR-3 form during a column leaching test using a 7 ml min-1 flow rate. …………………………………………….…………43 Figure 3-3a. H2O2 release profile from a 5 : 1 SR-4 form during a column leaching test using a 7 ml min-1 flow rate. …………………………………………………..………..44 Figure 3-3b. H2O2 release profile from a 5 : 1 SR-5 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………………45 Figure 3-3c. H2O2 release profile from a 6 : 1 SR-6 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………………45 Figure 3-3d. H2O2 release profile from a 6 : 1 SR-7 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………………46 Figure 3-3e. H2O2 release profile from a 5 : 1 SR-8 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………………46 Figure 3-3f. H2O2 release profile from a 5 : 1 SR-9 form during a column leaching test using a 7 ml min-1 flow rate. ………………………………………………...………….47 Figure 3-3g. H2O2 release profile from a 5 : 1 SR-10 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………………47 Figure 3-4a. H2O2 release profile from a 4.2 : 1 SR-11 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………….50 11 Figure 3-4b. H2O2 release profile from a 3.8 : 1 SR-12 form during a column leaching test using a 7 ml min-1 flow rate. ………………………………….……………………51 Figure 3-4c. H2O2 release profile from a 3.5 : 1 SR-13 form during a column leaching test using a 7 ml min-1 flow rate. …………………………………….…………………51 Figure 3-4d. H2O2 release profile from a 3.7 : 1 SR-14 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………….52 Figure 3-4e. H2O2 release profile from a 3.5 : 1 SR-15 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………….………………52 Figure 3-4f. H2O2 release profile from a 3.5 : 1 SR-16 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………….53 Figure 3-4g. H2O2 release profile from a 3.75 : 1 SR-17 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………………………………….53 Figure 3-5a. H2O2 release profile from a 3.75 : 1 SR-18 form during a column leaching test using a 7 ml min-1 flow rate. ……………………………….………………………54 Figure 3-5b. H2O2 release profile from a 3.5 : 1 SR-19 form during a column leaching test using a 7 ml min-1 flow rate. ………………………………….……………………54 Figure 3-5c. H2O2 release profile from a 3.5 : 1 SR-20 form during a column leaching test using a 7 ml min-1 flow rate.