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Tan Y, Sun S, Deng Z, Alvarez PJJ, Qu X. Intrinsic peroxidase-like activity of dissolved black carbon released from biochar. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 898:165347. [PMID: 37419343 DOI: 10.1016/j.scitotenv.2023.165347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/04/2023] [Accepted: 07/04/2023] [Indexed: 07/09/2023]
Abstract
Dissolved black carbon (DBC) is an important constituent of the natural organic carbon pool, influencing the global carbon cycling and the fate processes of many pollutants. In this work, we discovered that DBC released from biochar has intrinsic peroxidase-like activity. DBC samples were derived from four biomass stocks, including corn, peanut, rice, and sorghum straws. All DBC samples catalyze H2O2 decomposition into hydroxyl radicals, as determined by the electron paramagnetic resonance and the molecular probe. Similar to enzymes that exhibit saturation kinetics, the steady-state reaction rates follow the Michaelis-Menten equation. The peroxidase-like activity of DBC is controlled by the ping-pong mechanism, as suggested by parallel Lineweaver-Burk plots. Its activity increases with temperature from 10 to 80 °C and has an optimum at pH 5. The peroxidase-like activity of DBC is positively correlated with its aromaticity as aromatics can stabilize the reactive intermediates. The active sites in DBC also involve oxygen-containing groups, as inferred by increased activity after the chemical reduction of carbonyls. The peroxidase-like activity of DBC has significant implications for biogeochemical processing of carbon and potential health and ecological impacts of black carbon. It also highlights the need to advance the understanding of the occurrence and role of organic catalysts in natural systems.
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Affiliation(s)
- Yi Tan
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China
| | - Su Sun
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China
| | - Zehui Deng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China
| | - Pedro J J Alvarez
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, United States
| | - Xiaolei Qu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China.
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2
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Tao W, Zhang P, Li H, Yang Q, Oleszczuk P, Pan B. Generation Mechanism of Persistent Free Radicals in Lignocellulose-Derived Biochar: Roles of Reducible Carbonyls. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:10638-10645. [PMID: 35839311 DOI: 10.1021/acs.est.1c06997] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Persistent free radicals (PFRs) in biochar can influence biochar reactivity, promoting organic contaminant degradation or even causing certain toxic impacts. However, the PFR generation mechanism is not still well understood. An investigation of the relationship between PFR formation and the chemical structure of biochar is essential for understanding the PFR formation mechanism. Our in situ measurement results showed that PFR intensities increased from 0-509.5 to 146-5678 a.u. after being pyrolyzed at 300 °C for 60 min. The significant positive correlation between PFR intensities and the peak areas of C═O and aromatic C═C groups indicated that the generation of PFRs was highly dependent on the C═O and aromatic C═C structures. The reduction of biochars by KBH4 resulted in a 32.2 ± 2.49% decrease in the C═O content and a relative increase in the C-O content, while other physicochemical properties did not change. Thus, the observed 49.3% decrease in PFR signals after this reduction suggested that the reducible C═O groups, possibly in aldehydes, aromatic ketones, and quinones, were closely associated with PFRs in biochars. This study provides an in situ insight into the PFR generation mechanism and guides the corresponding biochar design and property manipulation.
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Affiliation(s)
- Wenmei Tao
- Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
- Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, Yunnan, China
| | - Peng Zhang
- Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Hao Li
- Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Qiliang Yang
- Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, Yunnan, China
| | - Patryk Oleszczuk
- Faculty of Chemistry, Department of Radiochemistry and Environmental Chemistry, Maria Curie-Sklodowska University, 3 M. Curie-Sklodowska Sq., 20-031 Lublin, Poland
| | - Bo Pan
- Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
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Lu Y, Hu Y, Tang L, Xie Q, Liu Q, Zhong L, Fu L, Fan C. Effects and mechanisms of modified biochars on microbial iron reduction of Geobacter sulfurreducens. CHEMOSPHERE 2021; 283:130983. [PMID: 34153910 DOI: 10.1016/j.chemosphere.2021.130983] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 04/30/2021] [Accepted: 05/22/2021] [Indexed: 06/13/2023]
Abstract
Biochar was proved as an electron shuttle to facilitate extracellular electron transfer (EET) of electrochemically active bacteria (EAB); however, its underlying mechanism was not fully understood. In this study, we aimed to further explore how the regulation of surface functional groups of biochar would affect the microbial iron reduction process of Geobacter sulfurreducens as a typical EAB. Two modified biochars were achieved after HNO3 (NBC) and NaBH4 (RBC) pretreatments, and a control biochar was produced after deionized water (WBC) washing. Results showed that WBC and RBC significantly accelerated microbial iron reduction of G. sulfurreducens PCA, while had no effect in the final Fe (II) minerals (e.g., vivianite and green rust (CO32-)). Besides, Brunauer-Emmett-Teller (BET) surface area, electron spin resonance (ESR) and electrochemical measurements showed that larger surface area, lower redox potential, and more redox-active groups (e.g., aromatic structures and quinone/hydroquinone moieties) in RBC explained its better electron transfer performance comparing to WBC. Interestingly, NBC completely suppressed the Fe (III) reduction process, mainly due to the production of reactive oxygen species which inhibited the growth of G. sulfurreducens PCA. Overall, this work paves a feasible way to regulate the surface functional groups for biochar, and comprehensively revealed its effect on EET process of microorganisms.
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Affiliation(s)
- Yue Lu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China.
| | - Yingju Hu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China
| | - Lin Tang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China.
| | - Qingqing Xie
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China
| | - Qian Liu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China
| | - Linrui Zhong
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China
| | - Leiling Fu
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China
| | - Changzheng Fan
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, Hunan, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, Hunan, China
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Li H, McKay G. Relationships between the Physicochemical Properties of Dissolved Organic Matter and Its Reaction with Sodium Borohydride. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10843-10851. [PMID: 34291922 DOI: 10.1021/acs.est.1c01973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The reaction of dissolved organic matter (DOM) with sodium borohydride has been used to understand the geographic origin of DOM and investigate the photophysical model underlying DOM's optical properties. However, the physicochemical properties of DOM (e.g., molecular size and charge) that influence the kinetics and ultimate reducibility of DOM by borohydride remain poorly characterized. Herein, we studied the kinetics of DOM-borohydride reactions by recording absorbance and fluorescence spectra at a high temporal frequency (every ∼10 min for 24 h) for a diverse set of DOM isolates of aquatic and soil origin. The reducibility of DOM by sodium borohydride (as judged by relative removal of initial absorbance) varied appreciably among the DOM samples studied, with soil humic substances being less reducible than aquatic humic substances and natural organic matter. While statistically significant correlations were found between the reducibility of DOM and descriptors of molecular size, these descriptors were not able to differentiate the reducibility of soil versus aquatic DOM isolates that had similar bulk properties. Thus, it appears that the extent of absorbance removal by borohydride is largely driven by the origin of the humic substance isolate (aquatic vs soil) instead of molecular size or charge. Borohydride reduction resulted in increased fluorescence emission across UV and visible excitation wavelengths. However, the enhanced emission at visible excitation decreased over a time period of hours to days, suggesting that reduction of an important subset of DOM chromophores is reversible. This reversibility in fluorescence emission is consistent with the small role of quinones in the absorbance of DOM but suggests a more important role for quinone-containing charge-transfer contacts in the fluorescence of DOM, particularly at visible excitation wavelengths.
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Affiliation(s)
- Hang Li
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
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Wu B, Arnold WA, Ma L. Photolysis of atrazine: Role of triplet dissolved organic matter and limitations of sensitizers and quenchers. WATER RESEARCH 2021; 190:116659. [PMID: 33279742 DOI: 10.1016/j.watres.2020.116659] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/13/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
Atrazine, a widely used herbicide, is susceptible to photolysis. The role of triplet excited states of chromophoric dissolved organic matter (3CDOM*) in the photolysis of atrazine, however, is not well understood. The direct photolysis of atrazine under irradiation sources (natural sunlight/environmentally relevant simulated solar light) and its indirect photochemical reactivity with model triplet photosensitizers (benzophenone, 2-acetonaphthone, 3'-methoxy-acetophenone, 4-carboxybenzophenone, rose bengal, methylene blue, and anthraquinone-2-sulphonate) was investigated. The reactivity of the model sensitizers and DOM (Suwannee River natural organic matter, river/lake water, and wastewater effluent), were compared. The direct photolysis quantum yield was determined as 0.0196 mol Einstein-1 in a solar simulator and 0.00437 mol Einstein-1 under natural sunlight. Considerable photosensitization was induced by triplet state (n-π*) model sensitizers, while insignificant effects on atrazine loss were discerned in natural organic matter even when oxygen, a triplet quencher, was removed. The triplet sensitizers benzophenone and 2-acetylnaphthone reacted with L-histidine and 2-propanol that were intended to quench/ scavenge 1O2 and hydroxyl radical •OH, respectively, and benzophenone reacted with NaN3 as a 1O2 scavenger and furfuryl alcohol as a 1O2 trapping agent, indicating quenchers may have unanticipated effects when using model sensitizers. Atrazine loss via reaction with 3DOM* will be relevant only in selected conditions, and this work provides a more comprehensive view on the use of model photosensitizers to mimic triplet 3DOM*.
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Affiliation(s)
- Bin Wu
- School of Environmental Science and Engineering, Tongji University, Shanghai, China; Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Technology, Tongji University, Shanghai, China; Department of Civil, Environmental, and Geo- Engineering, University of Minnesota - Twin Cities, 500 Pillsbury Drive SE, Minneapolis, MN 55455, United States
| | - William A Arnold
- Department of Civil, Environmental, and Geo- Engineering, University of Minnesota - Twin Cities, 500 Pillsbury Drive SE, Minneapolis, MN 55455, United States
| | - Limin Ma
- School of Environmental Science and Engineering, Tongji University, Shanghai, China.
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6
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Wang Y, Ma J. Quantitative determination of redox-active carbonyls of natural dissolved organic matter. WATER RESEARCH 2020; 185:116142. [PMID: 32823193 DOI: 10.1016/j.watres.2020.116142] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
Natural dissolved organic matter (DOM) is ubiquitous in environment and plays an important role in numerous environmental processes. Although the molecular basis of the reactivity of DOM remains poorly understood due to its extreme complexity, redox-active carbonyls (aromatic ketones/aldehydes and quinones) within DOM are believed vitally important. Except the rough determination of total carbonyls (including non-redox active -COOR) based on inflexible 13C chemical shift range by expensive and time-consuming solid-state nuclear magnetic resonance (NMR), there is no ready method to quantify redox-active carbonyls in DOM. Here we show that after treatment with sodium borohydride (NaBH4) by selectively eliminating redox-active carbonyls, quenched fluorescence of carbon quantum dots (CD) by DOM recovered dramatically, and displayed a good linear relationship between redox-active carbonyls detected and DOM concentration (R2 ≥ 0.977), thus allowing first quantitative determination of the redox-active carbonyls of DOM. Eight DOM isolates present 0.59%-0.90% redox-active carbonyls by the current method. And this method is robust from coexisting proteins and salts. This method could provide better or equal instructive results compared with solid-state NMR for total carbonyls or electrochemical method for electron-accepting capacities (EAC). Our results provide the underlying structural basis of many important geochemical processes that mediated by DOM. We posit that this method could apply to other complex molecular systems such as the atmospheric aerosols and extracellular polymeric substances (EPS), too.
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Affiliation(s)
- Ya Wang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiahai Ma
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
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McKay G. Emerging investigator series: critical review of photophysical models for the optical and photochemical properties of dissolved organic matter. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:1139-1165. [PMID: 32270849 DOI: 10.1039/d0em00056f] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Optical measurements (absorbance and fluorescence) are widely used to track dissolved organic matter (DOM) quantity and quality in natural and engineered systems. Despite many decades of research on the optical properties of DOM, there is a lack of understanding with regards to the underlying photophysical model that is the basis for these optical properties. This review both summarizes advances to date on the photophysical properties of DOM and seeks to critically evaluate the photophysical models for DOM optical properties. Recent studies have refined the quantitative understanding of DOM photophysical properties such as excited state lifetimes and energies, rates of different photophysical processes, and quantum yields. Considering fundamental models, more clarity is needed on whether DOM photophysical processes are due to a superposition of non-interacting components (superposition model), or whether a portion of optical signals can be ascribed to electronically interacting moieties, for example in the form of electron donor-acceptor complexes (charge transfer model). Multiple studies over more than two decades have provided evidence for the charge transfer model. Questions have been raised, however, about the broad applicability of the charge transfer model. The charge transfer and superposition model are critically reviewed in light of this current research. Recommendations are given for future studies to help clarify the accuracy of these competing photophysical models.
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Affiliation(s)
- Garrett McKay
- Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX 77843, USA.
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8
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Xie P, Ma J. Insights into aqueous reduction of Cr(VI) by Fe3O4@NOM MNPs under irradiation: The role of carbonyl structures. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.123593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Schendorf TM, Del Vecchio R, Bianca M, Blough NV. Combined Effects of pH and Borohydride Reduction on Optical Properties of Humic Substances (HS): A Comparison of Optical Models. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6310-6319. [PMID: 31063364 DOI: 10.1021/acs.est.9b01516] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The combined effects of pH and borohydride reduction on the optical properties of a series of humic substances and a lignin model were examined to probe the molecular moieties and interactions that give rise to the observed optical properties of these materials. Increasing the pH from 2 to 12 produced significantly enhanced absorption across the spectra of all samples, with distinct spectral responses observed over pH ranges attributable to the deprotonation of carboxylic acids and phenols. Borohydride reduction substantially attenuated the broadband absorption enhancements with pH, clearly indicating that the loss of absorption due to ketone/aldehyde reduction is coupled with the pH-dependent increase in absorption due to deprotonation of carboxylic acids and phenols. These results cannot be easily explained by a superposition of the spectra of independently absorbing chromophores (superposition model) but are readily interpretable within a charge transfer (CT) model. Changes of fluorescence emission with pH for both untreated and borohydride reduced samples suggest that a pH-dependent structural reorganization of the HS may also be influencing the fluorescence emission. Independent of optical model, these results demonstrate that chemical tests targeted to specific moieties can identify distinct structural differences among HS sources as well as provide insight into the molecular moieties and interactions that produce the observed optical and photochemical properties.
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Del Vecchio R, Schendorf TM, Blough NV. Contribution of Quinones and Ketones/Aldehydes to the Optical Properties of Humic Substances (HS) and Chromophoric Dissolved Organic Matter (CDOM). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13624-13632. [PMID: 29125750 DOI: 10.1021/acs.est.7b04172] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The molecular basis of the optical properties of chromophoric dissolved organic matter (CDOM) and humic substances (HS) remains poorly understood and yet to be investigated adequately. This study evaluates the relative contributions of two broad classes of carbonyl-containing compounds, ketones/aldehydes versus quinones, to the absorption and emission properties of a representative suite of HS as well as a lignin sample. Selective reduction of quinones to hydroquinones by addition of small molar excesses of dithionite to these samples under anoxic conditions produced small or negligible changes in their optical properties; however, when measurable, these changes were largely reversible upon exposure to air, consistent with the reoxidation of hydroquinones to quinones. With one exception, estimates of quinone content based on dithionite consumption by the HS under anoxic conditions were in good agreement with past electrochemical measurements. In contrast, reduction of ketones/aldehydes to alcohols employing excess sodium borohydride produced pronounced and largely, but not completely, irreversible changes in the optical properties. The results demonstrate that (aromatic) ketones/aldehydes, as opposed to quinones, play a far more prominent role in the optical absorption and emission properties of these HS, consistent with these moieties acting as the primary acceptors in charge-transfer transitions within these samples. As a method, anoxic dithionite titrations may further allow additional insight into the content and impact of quinones/hydroquinones on the optical properties of HS and CDOM.
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Affiliation(s)
- Rossana Del Vecchio
- Earth System Science Interdisciplinary Center, University of Maryland , College Park, Maryland 20742, United States
| | - Tara Marie Schendorf
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Neil V Blough
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
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Xie P, Zhou L, Zhang Z, Ma J. Contribution to the reduction-induced fluorescence enhancement of natural organic matter: Aromatic ketones outweigh quinones. LUMINESCENCE 2017. [PMID: 28635059 DOI: 10.1002/bio.3354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This work involves the comparison of the fluorescence excitation - emission matrices of different low-molecular-weight carbonyl compounds and natural organic matter (NOM). The aim is to determine if quinone or aromatic ketone groups are more responsible for the reduction-induced fluorescence enhancement of NOM. After reduction, the aromatic ketones showed a significantly greater fluorescence change than the quinones, proving that the former play a more important role. Further analysis of the fluorescence of the NOM samples after re-oxidization by oxygen with a Cu2+ catalyst, provided additional reliable evidence in support of the dominant role of aromatic ketones in the fluorescence change. This work demonstrates that aromatic ketone moieties should be given more attention when considering the physicochemical properties of NOM and related environmental processes.
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Affiliation(s)
- Pengfei Xie
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing, China.,Sino-Danish Center for Education and Research, Beijing, China
| | - Lei Zhou
- HORIBA Scientific China, Beijing, China
| | - Zhiguo Zhang
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Jiahai Ma
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing, China
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Conroy NA, Zavarin M, Kersting AB, Powell BA. Effect of Natural Organic Matter on Plutonium Sorption to Goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:699-708. [PMID: 27935282 DOI: 10.1021/acs.est.6b03587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mgC·L-1 and 50 mgC·L-1 natural organic matter (NOM), 10-9-10-10 M 238Pu, and 0.1 g·L-1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increased Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. The results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.
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Affiliation(s)
- Nathan A Conroy
- Department of Environmental Engineering and Earth Sciences, Clemson University , Clemson, South Carolina 29634, United States
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Brian A Powell
- Department of Environmental Engineering and Earth Sciences, Clemson University , Clemson, South Carolina 29634, United States
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Emerson HP, Hickok KA, Powell BA. Experimental evidence for ternary colloid-facilitated transport of Th(IV) with hematite (α-Fe 2O 3) colloids and Suwannee River fulvic acid. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 165:168-181. [PMID: 27723529 DOI: 10.1016/j.jenvrad.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 09/29/2016] [Accepted: 10/01/2016] [Indexed: 06/06/2023]
Abstract
Previous field experiments have suggested colloid-facilitated transport via inorganic and organic colloids as the primary mechanism of enhanced actinide transport in the subsurface at former nuclear weapons facilities. In this work, research was guided by the hypothesis that humic substances can enhance tetravalent actinide (An(IV)) migration by coating and mobilizing natural colloids in environmental systems and increasing An(IV) sorption to colloids. This mechanism is expected to occur under relatively acidic conditions where organic matter can sorb and coat colloid surfaces and facilitate formation of ternary colloid-ligand-actinide complexes. The objective of this work was to examine Th transport through packed columns in the presence of hematite colloids and/or Suwannee River fulvic acid (SRFA). In the presence of SRFA, with or without hematite colloids, significant transport (>60% recovery within the effluent) of thorium occurred through quartz columns. It is notable that the SRFA contributed to increased transport of both Th and hematite colloids, while insignificant transport occurred in the absence of fulvic acid. Further, in the presence of a natural sandy sediment (as opposed to pure quartz), transport is negligible in the presence of SRFA due to interactions with natural, clay-sized sediment coatings. Moreover, this data shows that the transport of Th through quartz columns is enhanced in ternary Th-colloid-SRFA and binary Th-SRFA systems as compared to a system containing only Th.
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Affiliation(s)
- Hilary P Emerson
- Clemson University, Department of Environmental Engineering and Earth Sciences, 342 Computer Court, Anderson, SC 29625, United States.
| | - Katherine A Hickok
- Clemson University, Department of Environmental Engineering and Earth Sciences, 342 Computer Court, Anderson, SC 29625, United States
| | - Brian A Powell
- Clemson University, Department of Environmental Engineering and Earth Sciences, 342 Computer Court, Anderson, SC 29625, United States.
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14
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Andrew AA, Del Vecchio R, Zhang Y, Subramaniam A, Blough NV. Are Extracted Materials Truly Representative of Original Samples? Impact of C18 Extraction on CDOM Optical and Chemical Properties. Front Chem 2016; 4:4. [PMID: 26904536 PMCID: PMC4742635 DOI: 10.3389/fchem.2016.00004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 01/18/2016] [Indexed: 11/16/2022] Open
Abstract
Some properties of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) can be easily measured directly on whole waters, while others require sample concentration and removal of natural salts. To increase CDOM content and eliminate salts, solid phase extraction (SPE) is often employed. Biases following extraction and elution are inevitable, thus raising the question of how truly representative the extracted material is of the original. In this context, we investigated the wavelength dependence of extraction efficiency for C18 cartridges with respect to CDOM optical properties using samples obtained from the Middle Atlantic Bight (MAB) and the Equatorial Atlantic Ocean (EAO). Further, we compared the optical changes of C18 extracts and the corresponding whole water following chemical reduction with sodium borohydride (NaBH4). C18 cartridges preferentially extracted long-wavelength absorbing/emitting material for samples impacted by riverine input. Extraction efficiency overall decreased with offshore distance away from riverine input. Spectral slopes of C18-OM samples were also almost always lower than those of their corresponding CDOM samples supporting the preferential extraction of higher molecular weight absorbing material. The wavelength dependence of the optical properties (absorption, fluorescence emission, and quantum yield) of the original water samples and their corresponding extracted material were very similar. C18 extracts and corresponding water samples further exhibited comparable optical changes following NaBH4 reduction, thus suggesting a similarity in nature (structure) of the optically active extracted material, independent of geographical locale. Altogether, these data suggested a strong similarity between C18 extracts and corresponding whole waters, thus indicating that extracts are representative of the CDOM content of original waters.
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Affiliation(s)
- Andrea A Andrew
- Department of Chemistry and Biochemistry, University of Maryland College Park, MD, USA
| | - Rossana Del Vecchio
- Earth System Science Interdisciplinary Center, University of Maryland College Park, MD, USA
| | - Yi Zhang
- Department of Chemistry and Biochemistry, University of Maryland College Park, MD, USA
| | - Ajit Subramaniam
- Lamont Doherty Earth Observatory at Columbia University Palisades, NY, USA
| | - Neil V Blough
- Department of Chemistry and Biochemistry, University of Maryland College Park, MD, USA
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Fu H, Liu H, Mao J, Chu W, Li Q, Alvarez PJJ, Qu X, Zhu D. Photochemistry of Dissolved Black Carbon Released from Biochar: Reactive Oxygen Species Generation and Phototransformation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:1218-26. [PMID: 26717492 DOI: 10.1021/acs.est.5b04314] [Citation(s) in RCA: 180] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Dissolved black carbon (BC) released from biochar can be one of the more photoactive components in the dissolved organic matter (DOM) pool. Dissolved BC was mainly composed of aliphatics and aromatics substituted by aromatic C-O and carboxyl/ester/quinone moieties as determined by solid-state nuclear magnetic resonance. It underwent 56% loss of absorbance at 254 nm, almost complete loss of fluorescence, and 30% mineralization during a 169 h simulated sunlight exposure. Photoreactions preferentially targeted aromatic and methyl moieties, generating CH2/CH/C and carboxyl/ester/quinone functional groups. During irradiation, dissolved BC generated reactive oxygen species (ROS) including singlet oxygen and superoxide. The apparent quantum yield of singlet oxygen was 4.07 ± 0.19%, 2-3 fold higher than many well-studied DOM. Carbonyl-containing structures other than aromatic ketones were involved in the singlet oxygen sensitization. The generation of superoxide apparently depended on electron transfer reactions mediated by silica minerals in dissolved BC, in which phenolic structures served as electron donors. Self-generated ROS played an important role in the phototransformation. Photobleaching of dissolved BC decreased its ability to further generate ROS due to lower light absorption. These findings have significant implications on the environmental fate of dissolved BC and that of priority pollutants.
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Affiliation(s)
- Heyun Fu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China
| | - Huiting Liu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China
| | - Jingdong Mao
- Department of Chemistry and Biochemistry, Old Dominion University , Norfolk Virginia 23529, United States
| | - Wenying Chu
- Department of Chemistry and Biochemistry, Old Dominion University , Norfolk Virginia 23529, United States
| | - Qilin Li
- Department of Civil and Environmental Engineering, Rice University , Houston Texas 77005, United States
| | - Pedro J J Alvarez
- Department of Civil and Environmental Engineering, Rice University , Houston Texas 77005, United States
| | - Xiaolei Qu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China
| | - Dongqiang Zhu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China
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Tinnacher RM, Begg JD, Mason H, Ranville J, Powell BA, Wong JC, Kersting AB, Zavarin M. Effect of fulvic acid surface coatings on plutonium sorption and desorption kinetics on goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:2776-2785. [PMID: 25607800 DOI: 10.1021/es505120s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The rates and extent of plutonium (Pu) sorption and desorption onto mineral surfaces are important parameters for predicting Pu mobility in subsurface environments. The presence of natural organic matter, such as fulvic acid (FA), may influence these parameters. We investigated the effects of FA on Pu(IV) sorption/desorption onto goethite in two scenarios: when FA was (1) initially present in solution or (2) found as organic coatings on the mineral surface. A low pH was used to maximize FA coatings on goethite. Experiments were combined with kinetic modeling and speciation calculations to interpret variations in Pu sorption rates in the presence of FA. Our results indicate that FA can change the rates and extent of Pu sorption onto goethite at pH 4. Differences in the kinetics of Pu sorption were observed as a function of the concentration and initial form of FA. The fraction of desorbed Pu decreased in the presence of FA, indicating that organic matter can stabilize sorbed Pu on goethite. These results suggest that ternary Pu-FA-mineral complexes could enhance colloid-facilitated Pu transport. However, more representative natural conditions need to be investigated to quantify the relevance of these findings.
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Affiliation(s)
- Ruth M Tinnacher
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , P.O. Box 808, Livermore, California 94550, United States
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17
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Phillips SM, Smith GD. Further Evidence for Charge Transfer Complexes in Brown Carbon Aerosols from Excitation–Emission Matrix Fluorescence Spectroscopy. J Phys Chem A 2014; 119:4545-51. [DOI: 10.1021/jp510709e] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Sabrina M. Phillips
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Geoffrey D. Smith
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
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Baluha DR, Blough NV, Del Vecchio R. Selective mass labeling for linking the optical properties of chromophoric dissolved organic matter to structure and composition via ultrahigh resolution electrospray ionization mass spectrometry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:9891-9897. [PMID: 23915388 DOI: 10.1021/es402400j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The mass spectra acquired by ESI FT-ICR MS of untreated, borohydride-reduced, and borodeuteride-reduced samples of Suwannee River fulvic acid (SRFA) and a C18 extract from the upper Delaware Bay were compared to one another. Treatment of these samples with sodium borodeuteride was shown to produce unique mass labels for species which contain one or two ketone/aldehyde moieties. Approximately 30% of all identified peaks in the two samples were shown to comprise ketone/aldehyde-containing species. The molecular formulas of the majority of these species had O/C and H/C molar ratios typically attributed to lignin-derived compounds and/or carboxylic rich alicyclic molecules (CRAM). However, the significant loss of UV-vis absorption following reduction supports a lignin-based origin for the optical (and photochemical) properties of these samples. The mass-labeling method described and tested herein shows great promise as a means to further characterize the structure and composition of complex natural samples, especially in terms of identifying specific subsets of chemical species that contribute significantly to the optical and photochemical properties of such samples.
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Affiliation(s)
- Daniel R Baluha
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
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Tinnacher RM, Nico PS, Davis JA, Honeyman BD. Effects of fulvic acid on uranium(VI) sorption kinetics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:6214-6222. [PMID: 23550952 DOI: 10.1021/es304677c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study focuses on the effects of fulvic acid (FA) on uranium(VI) sorption kinetics to a silica sand. Using a tritium-labeled FA in batch experiments made it possible to investigate sorption rates over a wide range of environmentally relevant FA concentrations (0.37-23 mg L(-1) TOC). Equilibrium speciation calculations were coupled with an evaluation of U(VI) and FA sorption rates based on characteristic times. This allowed us to suggest plausible sorption mechanisms as a function of solution conditions (e.g., pH, U(VI)/FA/surface site ratios). Our results indicate that U(VI) sorption onto silica sand can be either slower or faster in the presence of FA compared to a ligand-free system. This suggests a shift in the underlying mechanisms of FA effects on U(VI) sorption, from competitive sorption to influences of U(VI)-FA complexes, in the same system. Changes in metal sorption rates depend on the relative concentrations of metals, organic ligands, and mineral surface sites. Hence, these results elucidate the sometimes conflicting information in the literature about the influence of organic matter on metal sorption rates. Furthermore, they provide guidance for the selection of appropriate sorption equilibration times for experiments that are designed to determine metal distribution coefficients (Kd values) under equilibrium conditions.
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Affiliation(s)
- Ruth M Tinnacher
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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Sharpless CM. Lifetimes of triplet dissolved natural organic matter (DOM) and the effect of NaBH₄ reduction on singlet oxygen quantum yields: implications for DOM photophysics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:4466-73. [PMID: 22439917 DOI: 10.1021/es300217h] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The natural lifetimes of triplet dissolved organic matter ((3)DOM) were determined by an O(2) saturation kinetics study of singlet oxygen quantum yields (Φ(1O2)) in buffered D(2)O. At least two distinct (3)DOM pools are present, and the observed lifetime range (∼20 to 80 μs) leads to a dependence of Φ(1O2) on O(2) concentrations between 29 and 290 μM. Thus, steady-state (1)O(2) concentrations will depend on [O(2)] in natural waters. The lifetimes are essentially identical for DOM samples of different origins and do not vary with excitation wavelength. However, Φ(1O2) varies greatly between samples and decreases with excitation wavelength. These data strongly suggest that (3)DOM quantum yields decrease with excitation wavelength, which gives rise to the Φ(1O2) variation. Borohydride reduction of several samples in both D(2)O and H(2)O lowers the absorbance and (1)O(2) production rates, but it does not alter Φ(1O2). This is consistent with a model in which (1)O(2) sensitizing chromophores are borohydride reducible groups in DOM, such as aromatic ketones. Interpreted in the framework of a charge transfer (CT) model for DOM optical properties, the collective data suggest a model in which electron acceptor moieties are important (1)O(2) sensitizers and where CT interactions of these moieties disrupt their ability to produce (1)O(2).
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Affiliation(s)
- Charles M Sharpless
- Department of Chemistry, University of Mary Washington, Fredericksburg, Virginia 22401, United States.
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Golanoski KS, Fang S, Del Vecchio R, Blough NV. Investigating the mechanism of phenol photooxidation by humic substances. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:3912-20. [PMID: 22394372 DOI: 10.1021/es300142y] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
To probe the mechanism of the photosensitized loss of phenols by humic substances (HS), the dependence of the initial rate of 2,4,6-trimethylphenol (TMP) loss (R(TMP)) on dioxygen concentration was examined both for a variety of untreated as well as borohydride-reduced HS and C(18) extracts from the Delaware Bay and Mid-Atlantic Bight. R(TMP) was inversely proportional to dioxygen concentration at [O(2)] > 50 μM, a dependence consistent with reaction with triplet excited states, but not with (1)O(2) or RO(2). Modeling the dependence of R(TMP) on [O(2)] provided rate constants for TMP reaction, O(2) quenching, and lifetimes compatible with a triplet intermediate. Borohydride reduction significantly reduced TMP loss, supporting the role of aromatic ketone triplets in this process. However, for most samples, the incomplete loss of sensitization following borohydride reduction, as well as the inverse dependence of R(TMP) on [O(2)] for these samples, suggests that there remains another class of oxidizing triplet sensitizer, perhaps quinones.
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Affiliation(s)
- Kelli S Golanoski
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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Sachs S, Bernhard G. Influence of humic acids on the actinide migration in the environment: suitable humic acid model substances and their application in studies with uranium—a review. J Radioanal Nucl Chem 2011. [DOI: 10.1007/s10967-011-1084-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ma J, Del Vecchio R, Golanoski KS, Boyle ES, Blough NV. Optical properties of humic substances and CDOM: effects of borohydride reduction. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:5395-5402. [PMID: 20557095 DOI: 10.1021/es100880q] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Treatment of Suwanee River humic (SRHA) and fulvic (SRFA) acids, a commercial lignin (LAC), and a series of solid phase extracts (C18) from the Middle Atlantic Bight (MAB extracts) with sodium borohydride (NaBH(4)), a selective reductant of carbonyl-containing compounds including quinones and aromatic ketones, produces a preferential loss of visible absorption (> or = 50% for SRFA) and substantially enhanced, blue-shifted fluorescence emission (2- to 3-fold increase). Comparison of the results with those obtained from a series of model quinones and hydroquinones demonstrates that these spectral changes cannot be assigned directly to the absorption and emission of visible light by quinones/hydroquinones. Instead, these results are consistent with a charge transfer model in which the visible absorption is due primarily to charge transfer transitions arising among hydroxy- (methoxy-) aromatic donors and carbonyl-containing acceptors. Unlike most of the model hydroquinones, the changes in optical properties of the natural samples following NaBH(4) reduction were largely irreversible in the presence of air and following addition of a Cu(2+) catalyst, providing tentative evidence that aromatic ketones (or other similar carbonyl-containing structures) may play a more important role than quinones in the optical properties of these materials.
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Affiliation(s)
- Jiahai Ma
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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Abstract
AbstractThe known IODO-GEN™-method [1] was adapted for radiolabeling of humic and fulvic acids with131I. The water insoluble oxidizing agent 1,3,4,6tetrachloro-3α,6α-diphenylglycoluril (IODO-GEN™) forms an iodous ion species (I+), which undergoes an electrophilic I/H-substitution on aromatic moieties of the humic and fulvic acids. This method offers mild conditions with a lesser extent of oxidative alterations of the target molecule, accompanied by an easy handling due to the virtual water-insolubility of the oxidizing agent. The method was optimized and different techniques were tested for the purification of the radioiodinated humic material. The yield of the labeling procedure varies between 45 and 75% depending on the provenance of the humic material and the applied purification method. A specific activity up to 40 MBq/mg was achieved. Furthermore, the known inherent photo-susceptibility of the iodinated humic substance and the influence of reducing agents were verified. An additional release of131I up to 20% and up to 35%, respectively were observed.
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Affiliation(s)
| | - H. Kupsch
- Institute of Interdisciplinary Isotope Research, Leipzig, Deutschland
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Badun GA, Chernysheva MG, Tyasto ZA, Kulikova NA, Kudryavtsev AV, Perminova IV. A new technique for tritium labeling of humic substances. RADIOCHIM ACTA 2010. [DOI: 10.1524/ract.2010.1695] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Badun GA, Kulikova NA, Chernysheva MG, Tyasto ZA, Korobkov VI, Fedoseev VM, Tsvetkova EA, Konstantinov AI, Kudryavtsev AV, Perminova IV. Tritium labeling: A unique tool for studying the behavior of humic substances in living systems. ACTA ACUST UNITED AC 2009. [DOI: 10.3103/s0027131409050083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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An evaluation of tritium and fluorescence labelling combined with multi-detector SEC for the detection of carbonyl groups in polysaccharides. Carbohydr Polym 2009. [DOI: 10.1016/j.carbpol.2008.10.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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28
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Tinnacher RM, Honeyman BD. Modeling the Chemical Conversion of Organic Compounds in Sodium Borohydride Reduction Reactions. Org Process Res Dev 2008. [DOI: 10.1021/op700267q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ruth M. Tinnacher
- Environmental Science and Engineering Division, Colorado School of Mines, Golden, Colorado 80401 U.S.A
| | - Bruce D. Honeyman
- Environmental Science and Engineering Division, Colorado School of Mines, Golden, Colorado 80401 U.S.A
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