Oxygen-bearing Functional Groups Research Articles

Rational design of natural leather-based water evaporator for electricity generation and functional applications

In recent years, water evaporation-induced electricity has attracted a great deal of attention as an emerging green and renewable energy harvesting technology. Although abundant materials have been developed to fabricate hydrovoltaic devices, the limitations of high costs, inconvenient storage and transport, low environmental benefits, and unadaptable shape have restricted their wide applications. Here, an electricity generator driven by water evaporation has been engineered based on natural biomass leather with inherent properties of good moisture permeability, excellent wettability, physicochemical stability, flexibility, and biocompatibility. Including numerous nano/microchannels together with rich oxygen-bearing functional groups, the natural leather-based water evaporator, LeatherEmblic-NPs-SA/CB, could continuously produce electricity even staying outside, achieving a maximum output voltage of ∼3 V with six-series connection. Furthermore, the leather-based water evaporator has enormous potential for use as a flexible self-powered electronic floor and seawater demineralizer due to its sensitive pressure sensing ability as well as its excellent photothermal conversion efficiency (96.3%) and thus fast water evaporation rate (2.65 kg m−2 h−1). This work offers a new and functional material for the construction of hydrovoltaic devices to harvest the sustained green energy from water evaporation in arbitrary ambient environments, which shows great promise in their widespread applications.

Localized Electron Density Regulation Effect for Promoting Solid-Liquid Ion Adsorption to Enhance Areal Capacitance of Micro-Supercapacitors.

The development of flexible microelectronic systems requires the construction of high-energy-output planar micro-supercapacitors (MSCs). Herein, the localized electron density, by introducing graphene quantum dots (GQDs) on the surface of electrodes, is regulated. The enhanced local field intensity promotes ion electrostatic adsorption at the solid-liquid interface, which significantly improves the energy density of MSCs in the confined space. Local electronic structure has been investigated from the perspective of the topological analysis of the electron localization function (ELF) and the electron density. Impressively, the edges of the simulated structure exhibit a higher electron density distribution than the CC skeleton. This finding indicates that the introduced GQDs reinforce the intrinsic electrical double-layer capacitance (EDLC) and the oxygen-bearing functional groups at the edge, further increasing the pseudocapacitance performance. Moreover, the edge electron aggregation effect enables the all-carbon-based symmetric MSCs to exhibit ultra-high areal capacitance (21.78mFcm-2 ) and excellent cycle stability (86.74% retention after 25000 cycles). This novel surface local charge regulation strategy is also applied for intensifying ion electrostatic adsorption on Zn-ion hybrid MSCs (polyvalent metal ions) and ion-gel electrolyte MSCs (non-metallic ions). With excellent planar integration, this device demonstrates excellent flexibility and has potential applications in timing and environmental monitoring.

Iron/manganese binary metal oxide-biochar nano-composites with high adsorption capacities of Cd2+: Preparation and adsorption mechanisms

Biochar has been widely used as an adsorbent to remove cadmium (Cd) from polluted waters because of its high specific surface area and rich functional groups. Efforts have been made to modify biochar to further improve its metal adsorption capacity. In this work, biochars prepared using cotton straw, corn straw, and rice husk, were first modified with ball-milling and iron/manganese (Fe/Mn) oxides to prepare Fe/Mn binary metal oxide-ball milled biochar (Fe/Mn-BMBCs). Compared with pristine biochars, Fe/Mn-BMBCs had rough surface with deposits of Fe/Mn oxide nanoparticles, larger specific surface areas (226.50–331.50 m2 g−1), and more oxygen-containing functional groups. The adsorption kinetics and isotherm of Cd2+ on both the pristine biochars and Fe/Mn-BMBCs were best described by the pseudo-second-order model and the Langmuir model, respectively, indicating that the adsorption of Cd2+ was primarily monolayer chemisorption. The adsorption capacities of Fe/Mn-BMBCs were 4.8–6.1 times higher than those of pristine biochars, respectively. When the solution ionic strength and valence of coexisting cation increased, the adsorption capacities of Fe/Mn-BMBCs decreased because of cation competition. In contrast, the adsorption capacities of Fe/Mn-BMBCs increased with the increasing solution pH value. Complexation with oxygen-bearing functional groups, ion exchange, Cd2+-π interaction and chemical precipitation were the main mechanisms of Cd2+ adsorption on Fe/Mn-BMBCs. Therefore, Fe/Mn-BMBCs prepared with different agricultural wastes have different Cd2+ adsorption capacities and can be used as environmentally friendly and effective adsorbents for Cd2+ removal from aqueous media.

The Spontaneous Combustion Potency of Lignite Coal Based on FTIR

To understand the role of functional groups in the spontaneous combustion of lignite coal, the distribution of functional groups in the lignite coal of the Sajau Formation in the Berau Basin, Indonesia, was studied. The functional group characterization was carried out using the Fourier Transform Infra Red (FTIR) method. The results revealed the presence of four functional groups, namely hydroxyl structures, aliphatic structures, oxygen-containing structures, and aromatic structures. The lignite contained more hydroxyl and oxygen-bearing functional groups, from which aliphatic and aromatic; therefore, spontaneous combustion becomes easy in lignite coal.

Spectroscopic investigation of Cr(VI) sorption on nZVI/biochar composites

Nanoscale zero-valent iron/biochar (nZVI/biochar) has been widely utilized in environmental remediation due to its excellent removal efficiency, easy synthesis, low-cost and environmental friendliness. Herein, the removal and interaction mechanism of Cr(VI) removal on nZVI/biochar was investigated by macroscopic and microscopic techniques. Compared to nZVI (25.84 mg/g), the high removal capacity (63.29 mg/g at pH 4.5), excellent reusability and chemical stability of nZVI/biochar were due to various oxygen-bearing functional groups and synergetic interaction. According to analysis of X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge fine (XANES) and extended X-ray absorption fine structure (EXAFS) spectra, the interaction mechanism of Cr(VI) on nZVI/biochar followed adsorption (complexation, electrostatic interaction), reduction and co-precipitation process with increasing reaction time. These findings are crucial for the application of nZVI/biochar for removal of heavy metals in actual environmental cleanup.

Functional carbon dots from a mild oxidation of coal liquefaction residue

Effective utilization of the solid-waste coal liquefaction residue (CLR) is important for the development of direct coal liquefaction technology, but remains big challenge due to the high ash of about 30 wt% in CLR. Herein, we propose a mild oxidation method to prepare functional carbon dots (CDs) using CLR as the carbon precursor and piranha solution (H2O2/H2SO4) as the oxidant. Through catalytic hydrogenation, the highly conjugated structure of coal converts to weakly linked structure by aliphatic chains in CLR, leading to an improved oxidation reactivity. The highly reactive aliphatic chains are oxidized and cut during oxidation, leading to the formation of CDs with enriched oxygen-bearing functional groups at the edge sites and simultaneous removal of ash. To present the special properties of CDs, we prepare a microporous carbon with high-surface area and compaction density (1345 m2 g−1 and 0.86 g cm−3) through homogeneous activation of CDs, performing both high gravimetric and volumetric capacitance for supercapacitors. CDs are also used as the functional reinforcing phase for activated carbon nanofibers, enabling high surface area, improved mechanical property, good conductivity, and extremely high rate performance for supercapacitors. Our work provides a new avenue for high efficient and high value-added utilization of CLR.

Graphene quantum dot inlaid carbon nanofibers: Revealing the edge activity for ultrahigh rate pseudocapacitive energy storage

The edge sites of carbon show high electrochemical activity because of the unique electronic structure and functionalization. But revealing their energy storage ability and the underlying mechanism are still challenging. Herein, we prepare a novel edge-enriched carbon nanofiber fabric by exposing the embedded graphene quantum dots (GQDs) through partial hydrolysis of the electrospun GQDs/polyacrylonitrile fabric. The edges of inlaid GQDs are mainly terminated by various oxygen-bearing functional groups even after high temperature treatment, simultaneously contributing to abundant surface redox active sites and good electrolyte wettability. Further facilitated by the entire conductive networks, the edge sites are proved to show an ultrafast pseudocapacitive performance (200 F g−1 at 1 A g−1, 130 F g−1 at 100 A g−1) because of the robust electrochemical kinetics. Moreover, at an ultra-high mass loading of 25.5 mg cm−2 (thickness: 1.4 mm), the multilayer-folded fabric performs a remarkable areal capacitance (3.95 F cm−2 at 25.5 mA cm−2), outstanding rate performance (2.04 F cm−2 at 510 mA cm−2), and good cycle stability (98% capacitance retention after 10,000 times), demonstrating the great potential of edge structure design for high power devices.

THE FTIR INVESTIGATION TO CHARACTERIZE OF FUNCTIONAL GROUPS IN BITUMINOUS COAL

The study of chemical functional groups in coal using the methods of an FTIR investigation has been carried out on five samples of bituminous coal from Bintuni Basin in West Papua, Indonesia. The FTIR spectra fitting results reveal that the aromatic chains of Steenkool Coals (SC) were dominated compared to aliphatic and oxygen-bearing. The aromatic SC’s molecular structures are mainly C=C and C-H followed by -CH. The oxygen-bearing SCs are mainly - C-O-C; and contain a small amount of C=O. The -CH2- is mainly in aliphatic SC. The apparent aromaticity (fa), Hal/Ha, (R/Cu), and other semi-quantitative parameters from the compared FTIR data indicated that the aromatic is increased with a decrease in aliphatic and oxygen-containing groups. The potential for spontaneous combustion resulting from the bituminous coal of the SC is relatively small, as more aromatic and aliphatic functional groups are detected than the oxygen-bearing functional groups.

Quantification of photooxidative defects in weathered microplastics using 13C multiCP NMR spectroscopy.

Weathering of microplastics made of commodity plastics like polystyrene, polypropylene and polyethylene introduces polar polymer defects as a result of photooxidation and mechanical stress. Thus, hydrophobic microplastic particles gradually become hydrophilic, consisting of polar oligomers with a significant amount of oxygen-bearing functional groups. This turnover continuously changes interactions between microplastics and natural colloidal matter. To be able to develop a better understanding of this complex weathering process, quantification of the corresponding defect proportions is a first and essential step. Using polystyrene, 13C enriched at the α position to 23%, we demonstrate that 13C cross polarisation (CP) NMR spectroscopy allows for probing the typical alcohol, peroxo, keto and carboxyl defects. Even the discrimination between in- and end-chain ketones, carboxylic acids and esters as well as ketal functions was possible. Combined with multiCP excitation, defect proportions could be determined with excellent accuracy down to 0.1%. For materials with 13C in natural abundance, this accounts for a detection limit of roughly 1%. The best trade-off between measurement time and accuracy for the quantification of the defect intensities for multiCP excitation was obtained for CP block lengths shorter than 250 μs and total build-up times longer than 2 ms. Further measurement time reduction is possible by using multiCP excitation to calibrate intensities obtained from series of 13C CP MAS NMR spectra. As photooxidation is an important degradation mechanism for microplastics in the environment, we expect these parameters to be transferable for probing defect proportions of weathered microplastics in general.

Leaching and Reactivity at the Sodium Aluminosilicate Glass–Water Interface: Insights from a ReaxFF Molecular Dynamics Study

In this study, we used ReaxFF reactive force field molecular dynamics (MD) simulations to investigate the dynamics associated with reactivity at the sodium aluminosilicate (NAS) glass–water interface. By combining van Hove correlation functions and visual analysis of individual trajectories, we found that when a Na+ ion leaves its initial position at the glass surface under the effect of water, it can be replaced either by a H+ ion or by another diffused Na+, resulting in a (Na+ ⇌ H+) ion exchange or (Na+ ⇌ Na+) ion exchange, respectively. These rearrangements at the NAS glass–water interface take place through many events such as the formation of oxygen-bearing functional groups (silanol Si(OH), germinal silanol Si(OH)2, and Al(OH)) and the agglomeration of Na+ ions on the glass surface. The high affinity between water and Na+ ions leads to two events, namely, the penetration of the water molecule into the first glass layer and the release of Na+ ions into the bulk water. The release of sodium ions into bulk water takes place via several successive steps: (1) leaving their original position to an area more exposed to bulk water, (2) diffusion to the surface of the glass, (3) leaving the surface toward the solution, and (4) coming back to the glass surface. Statistical analysis shows that oxygen-bearing functional group formation occurs both by protonation of the nonbridging oxygen (NBO) site and by filling defects such as SiIII, AlIII, and AlIV by OH– resulting from the dissociation of water molecules, while in the bulk, they could be produced by the proton jumps between two adjacent NBO sites and dissociation of the water diffused in deep layers of glass. Germinal silanol groups (Si(OH)2) are present in small amounts in the first layer of the glass after the protonation of two NBOs from a single SiIV. This process is accompanied by the conversion of AlIII and AlIV units into AlV units and SiIII units into SiIV units. By comparing the networks of Si and Al, we found that Al is more impacted by the occurrence of water molecules than Si, which is explained by an increase in the diffusion coefficient of Al compared with Si when these units become protonated (Si(OH) and Al(OH)).

Increased structural defects of graphene oxide compromised reductive capacity of ZVI towards hexavalent chromium

Graphene oxide (GO) was treated with irradiation beams to understand the defective degree of carbon structure of GO in relation to electron transfer property of impregnated zerovalent iron (ZVI). The GO-supported ZVI (ZVI/GO) was synthesized and then characterized by an X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The results showed that the oxygen-bearing functional groups, oxygen content and structural disorder were increased as a function of irradiation beam intensity. ZVI was dominant in the composites, but proportion of iron oxide increased with greater oxygen content. Batch sorption revealed that Cr(VI) removal decreased from 20.11 g kg−1 to 2.30 g kg−1 as solution pH rose from 3 to 9. Cr(VI) removal capacity was 26.39 g kg−1, 23.12 g kg−1 and 12.35 g kg−1 for ZVI/GO0, ZVI/GO12.3 and ZVI/GO36.9, respectively. The reduction capacity of sorbents followed similar trends as Cr(VI) sorption as per desorption experiment, which accounted for a major Cr(VI) detoxification mechanism by ZVI/GO composites. The electrochemical tests demonstrated that unfavorable electron transfer rate of ZVI/GO composites was aggravated by greater structural disorder of GO. Thus, higher dose of irradiations could create more disorder in graphitic carbon and promote oxidation of ZVI, which hindered Cr(VI) reduction.

Synthesis of graphene oxide from graphite by ball milling

The graphene oxides (GO) were prepared by a ball milling process with potassium perchlorate as oxidizing agent and deionized water as milling medium. GO samples were synthesized at different processing times and compared with a sample prepared by the Hummer's method. The prepared graphene oxides have been studied by Fourier transform infrared (FTIR), Raman spectroscopies, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). FTIR spectroscopy indicates presence of oxygen-bearing functional groups on the surface, Raman spectroscopy, XRD, SEM and TEM analysis confirm GO formation in ball milling. The sample processed for 12 h (GO 12 h) showed the highest yield of the product, presenting a suitable particle size (40 nm) for biomedical applications, especially in drug delivery systems. Ball milling can be considered as suitable method to obtain GO due to time processing, good quality of product and chemical components used.

A novel coal tar-based collector for effective flotation cleaning of low rank coal

Clean utilization of low-rank coal is an important problem in coal production and sustainable development. Flotation of low-rank coal is a major challenge for clean utilization of coal resources and environmental protection in the world. Common oily collectors were not effective for low-rank coal flotation, this paper proposed a novel collector named CTB collector, which is a mixture of diesel and extracted light components from coal tar using diesel as extractant. The Gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy analyses revealed that the CTB collector contained more aromatic compounds and oxygen-bearing functional groups than the diesel. The non-polar sites on coal surface can bind with the aromatic compounds through Van der Waals force and π-π stacking interaction. The polar sites can interact with the oxygen-bearing functional groups through hydrogen bond. The adsorption of macromolecular aromatic compounds on non-polar sites can also cover the polar sites adjacently. The hydrophobicity and floatability of low-rank coal were improved through above adsorption. The flotation results showed that the combustible matter recovery of CTB collector was 21%∼34% higher than that of diesel and the CTB collector can save 1500 g/t dosage than diesel while the flotation performance was still better. The coal flotation efficiency index of the CTB collector was 130–240 higher than that of the diesel. The particle carried index was designed to evaluate the carrying ability of a single bubble to coal particles. The flocs were significantly formed during flotation using the CTB collector. These flocs enhanced the recovery of low-rank coal. The particle carried index of the CTB collector-treated coal particles and bubble was higher than that of diesel-treated coal particles and bubble. The induction time results showed that the CTB collector accelerated the adhesion between coal particles and bubble while slowing down the adhesion between gangue particles and bubble. This study can not only provide new strategies for the design of coal flotation reagents and the evaluation of the adhesion efficiency between particles and bubbles, but also be beneficial to the clean utilization of coal energy and environmental protection.

Multistage Self-Assembly Strategy: Designed Synthesis of N-doped Mesoporous Carbon with High and Controllable Pyridine N Content for Ultrahigh Surface-Area-Normalized Capacitance

Nitrogen doping could improve the performance of carbon materials in electrocatalysis, CO2 adsorption, and energy storage. [1]However, the control of the doping type and the amount of nitrogen (N)-...

Removal and recovery of silver nanoparticles by hierarchical mesoporous calcite: Performance, mechanism, and sustainable application

The widespread use of silver nanoparticles (AgNPs) inevitably leads to the environmental release of AgNPs. The released AgNPs can pose ecological risks because of their specific toxicity. However, they can also be used as secondary sources of silver metal. Herein, hierarchical mesoporous calcite (HMC) was prepared and used to remove and recover AgNPs from an aqueous solution. The batch experiments show that the HMC has high removal percentages for polyvinylpyrrolidone- and poly (vinyl alcohol)-coated AgNPs (PVP- and PVA-AgNPs) over a wide pH range of 6–10. The adsorption isotherms indicate that the maximum removal capacities are 55 and 19 mg g−1 for PVP-AgNPs and PVA-AgNPs, respectively, corresponding to partition coefficients (PCs) of 0.55 and 0.77 mg g−1 μM−1. Furthermore, the removal performance is also not impaired by coexisting anions, such as Cl−, NO3−, SO42−, and CO32−. Their removal mechanisms can be ascribed to the electrostatic attraction and chemical adsorption between the HMC and polymer-coated AgNPs. Calcium ions on the HMC surface serve as active sites for coordination with the oxygen-bearing functional groups of AgNP coatings. Moreover, the AgNPs adsorbed onto HMC show high catalytic activity and good reusability for the reduction of the organic pollutant 4-nitrophenol. This work may pave the way not only to remove metal nanopollutants from waters but also to convert them into functional materials.

Nanoparticles incorporated graphene-based durable cotton fabrics

Graphene coated fabrics with incorporated nanoparticles can be smart textiles for multiple applications. The presence of an ample amount of oxygen-bearing functional groups on the surface can make the cotton fabric more suitable for modifications and functionalization. Here, we report the synthesis of reduced graphene oxide (RGO) coated-copper (Cu)/silver (Ag) nanoparticle incorporated cotton fabrics with excellent washing durability by ensuring strong bonding among graphene surface-cotton and nanoparticles. In our procedure, graphene oxide (GO) coating on the cotton fabric was followed by the incorporation of Cu/Ag nanoparticles via dip-coating approach using 3-glycidyloxypropyl trimethoxy silane as a coupling agent. Furthermore, the GO was reduced in the presence of sodium dithionite followed by heating at 180 °C under vacuum. The RGO coated and Cu/Ag incorporated cotton fabric samples exhibited improved hydrophobicity than pure cotton. Cotton-RGO-Cu showed remarkably lower surface resistance (6.42 KΩ/sq), better UV protection factor (46.45), and Joule heating capability as compared to Cotton-RGO-Ag and only Cotton-RGO. Moreover, the Cotton-RGO-Cu retained its resistance of 16.70 KΩ/sq after 20 wash cycles. Overall, the synergetic impact of enhanced hydrophobicity, high UV protectivity, low surface resistance, and thermal stability, have made the Cotton-RGO-Cu fabric suitable for smart textile and protective clothing.

Molecular evolution during hydrothermal reactions from formaldehyde and ammonia simulating aqueous alteration in meteorite parent bodies

Simple molecules such as formaldehyde and ammonia were expected to be incorporated into small bodies with water ice in the early accretion history. These molecules would have reacted to produce various organic compounds during aqueous alteration which most of the primitive carbonaceous chondrite parent bodies have experienced. Our previous hydrothermal experiments involving formaldehyde and ammonia have already shown formations of amino acids and organic solids that resemble to macromolecular organic matter in primitive meteorites. Here we focus on the characterization in liquid phases with various analytical methods including high-resolution mass spectrometry (HRMS), X-ray absorption near edge structure (XANES), and Fourier-transform infrared spectroscopy (FTIR), in addition to kinetic analyses of the reactions using in-situ FTIR spectroscopy with a heatable liquid cell.The HRMS results showed that soluble fractions contain various carbohydrates (CHO molecules) and these with nitrogen (CHON molecules). The mass defect plots of the reaction products suggested the reactions involving CH2O addition, CH2 addition, dehydration and decarboxylation. CC and CN bonds increased with temperature by condensation reactions. Behaviors of oxygen-bearing functional groups showed high complexity. In general, carboxyl/ester/aldehyde compounds formed at the early stage of the reactions, then some of these decomposed by decarboxylation. N-XANES indicated the presence of amide-bearing compounds that could be precursors of amino acids.The in-situ FTIR spectra showed that formaldehyde and ammonia reacted and formed hexamethylenetetramine (HMT) before starting the heating experiments at room temperature. Kinetic analyses showed that the apparent activation energy of decreases in HMT is ~130–140 kJ mol−1. The decrease in HMT is faster than the other reactions, indicating that the reactions involving HMT occurred at the early stage of the aqueous alteration. The kinetics of the ammonia–aldehyde system suggested that the reactions involving formaldehyde, ammonia and HMT are efficient for aqueous alteration in parent bodies of CI, CM, and CR chondrites.

Structure and chemistry of graphene oxide in liquid water from first principles

Graphene oxide is a rising star among 2D materials, yet its interaction with liquid water remains a fundamentally open question: experimental characterization at the atomic scale is difficult, and modeling by classical approaches cannot properly describe chemical reactivity. Here, we bridge the gap between simple computational models and complex experimental systems, by realistic first-principles molecular simulations of graphene oxide (GO) in liquid water. We construct chemically accurate GO models and study their behavior in water, showing that oxygen-bearing functional groups (hydroxyl and epoxides) are preferentially clustered on the graphene oxide layer. We demonstrated the specific properties of GO in water, an unusual combination of both hydrophilicity and fast water dynamics. Finally, we evidence that GO is chemically active in water, acquiring an average negative charge of the order of 10 mC m−2. The ab initio modeling highlights the uniqueness of GO structures for applications as innovative membranes for desalination and water purification.

Spontaneous Combustion in Relation to Drying of Low Rank Coal

ABSTRACT The water molecules associated with coal play a significant role in spontaneous ignition and combustion of coal. This paper deals with studies to evaluate the impact of moisture content on crossing point temperature (CPT) and ignition point temperature (IPT) of some low-rank coal and lignite after various stages of drying. Experimental data suggest (i) existence of critical moisture content value determining the propensity of a particular coal toward self-heating and (ii) content of moisture and nature of oxygen-bearing functional groups to be the most influencing factors in self-heating. The auto-oxidation cum self-heating characteristics of coal become more conducive with increase in the ratio of quantity of hydroxyl to carboxyl functional groups. The FTIR studies further corroborate that the initial stages of auto-oxidation cum self-heating occur presumably at the surface of the coal.

Impacts of redox conditions on dissolved organic matter (DOM) quality in marine sediments off the River Rhône, Western Mediterranean Sea

Sedimentary dissolved organic matter (DOM) is an important pool of intermediates produced and consumed during early diagenesis of organic matter in the anoxic subseafloor. Rapid degradation of organic matter in the coastal sediment results in stratification of redox zones. However, to date little is known about the selectivity with respect to organic matter of the initial microbially mediated anaerobic degradation processes under contrasting redox conditions and how these affect the composition of DOM. In order to study the effect of sulfate reducing vs. methanogenic conditions on DOM quality and degradation, sediments (0–18 cm) from the Rhône River Delta were incubated, with redox conditions being controlled by sulfate amendment. The progress of incubation was monitored by H2, CH4, sulfate, DIC, DOC and acetate production. DOM composition was determined by 3D Fluorescence Spectroscopy, i.e., Excitation Emission Matrix Spectroscopy (EEMs), and ultra-high-resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). Parallel factor analysis (PARAFAC) of EEMs was used to distinguish different groups of DOM (humic-like and protein-like compounds) to evaluate composition, conjugation and size of DOM. Prior to incubation, humic-like sedimentary DOM predominated; nearly half of the molecular formulae (>5000) identified by FT-ICR-MS were CHO and one third were CHNO compounds. During incubation, protein-like DOM and CHNO formulae with 3 and 4 N atoms formulae were rare under both sulfate reducing and methanogenic conditions. Incubation under sulfate reducing conditions resulted in rapid release and net accumulation of dissolved organic carbon (DOC). Protein-like DOM was rapidly cycled and humic-like DOM accumulated. Consistently, CHNO formulae with 3 and 4 N atoms decreased faster, whereas formulae with one N and oxygen-rich unsaturated compounds became more concentrated. In contrast, during incubation under methanogenic conditions, there was no net accumulation of DOC; blue-shift of humic-like peaks suggest the transformation possibly associated with loss of oxygen-bearing functional groups in conjugated structures of humic substances. This interpretation is consistent with the relative decrease of oxygenation and carbon number in the pool of aromatic and highly unsaturated compounds observed by FT-ICR-MS analysis. Approximately 90% of molecular formulae that were lost under methanogenic conditions were accumulated under sulfate reducing conditions. Our results suggest that under sulfate reducing conditions degradation of organic matter results in the accumulation of highly oxidized DOM, while protein-like compounds are selectively consumed. When the redox regime changes to methanogenic conditions, microbes apparently utilize the humic-like and oxygen-rich compounds of the oxidized DOM pool that accumulated under sulfate reducing conditions. Consequently, redox regimes and the associated biogeochemical processes influence rate and fractions of DOM released by and consumed in the deep biosphere, which could ultimately shape the composition of the preserved sedimentary organic matter and the DOM released to the ocean.