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A modified carbon nitride photocatalyst demonstrates the feasibility of cellulose photobiocatalytic conversion with >75% cellulose conversion and >75% gluconic acid selectivity via a one-pot sequential cascade reaction.

As the world works to move away from traditional energy sources, effective efficient energy storage devices have become a key factor for success. The emergence of unconventional electrochemical energy storage devices, including hybrid batteries, hybrid redox flow cells and bacterial batteries, is part of the solution. These alternative electrochemical cell configurations provide materials and operating condition flexibility while offering high-energy conversion efficiency and modularity of design-to-design devices. The power of these diverse devices ranges from a few milliwatts to several megawatts. Manufacturing durable electronic and point-of-care devices is possible due to the development of all-solid-state batteries with efficient electrodes for long cycling and high energy density. New batteries made of earth-abundant metal ions are approaching the capacity of lithium-ion batteries. Costs are being reduced with the advent of flow batteries with engineered redox molecules for high energy density and membrane-free power generating electrochemical cells, which utilize liquid dynamics and interfaces (solid, liquid, and gaseous) for electrolyte separation. These batteries support electrode regeneration strategies for chemical and bio-batteries reducing battery energy costs. Other batteries have different benefits, e.g., carbon-neutral Li-CO2batteries consume CO2and generate power, offering dual-purpose energy storage and carbon sequestration. This work considers the recent technological advances of energy storage devices. Their transition from conventional to unconventional battery designs is examined to identify operational flexibilities, overall energy storage/conversion efficiency and application compatibility. Finally, a list of facilities for large-scale deployment of major electrochemical energy storage routes is provided.Graphical abstract

A range of Desulfovibrio spp. can reduce metal ions to form metallic nanoparticles that remain attached to their surfaces. The bioreduction of palladium (Pd) has been given considerable attention due to its extensive use in areas of catalysis and electronics and other technological domains. In this study we report, for the first time, evidence for Pd(II) reduction by the highly corrosive Desulfovibrio ferrophilus IS5 strain to form surface attached Pd nanoparticles, as well as rapid formation of Pd(0) coated microbial nanowires. These filaments reached up to 8 µm in length and led to the formation of a tightly bound group of interconnected cells with enhanced ability to attach to a low carbon steel surface. Moreover, when supplied with high concentrations of Pd (≥ 100 mmol Pd(II) g

Hydrogen evolution from biomass photoreforming has been widely recognized as a promising strategy for relieving the pressure from energy crisis and environmental pollution, as it could generate sustainable H2 and value-added bioproducts simultaneously. Combining p-type semiconductors with n-type semiconductors to form n-p heterojunction is an effective strategy to improve the photocatalytic quantum efficiency by enhancing the separation of photogenerated electrons and holes, which could greatly facilitate the realization of such biomass photorefinery concept. However, the incompact contact between the n-type and p-type semiconductors often induces the aggregation of photogenerated electrons and holes. In this work, we design and synthesize an ultrafine n-p heterojunction TiO2-NiO core-shell structure to overcome the incompact contact in the n-p interface. When the n-p heterojunction photocatalysts are evaluated for photocatalytic water splitting and biomass lignin photoreforming respectively, the as-fabricated TiO2-NiO nanocomposite with 3.25% NiO demonstrates the highest hydrogen generation of 23.5 mmol h−1 g−1 from water splitting and H2 (0.45 mmol h−1 g−1) and CH4 (0.03 mmol h−1 g−1) cogeneration with reasonable amount of fatty acids (palmitic acid and stearic acid) production from lignin photoreforming. The excellent photocatalytic activity is ascribed to the synergistic effects of high crystallinity of TiO2 ultrafine nanoparticles, core-shell structure and n-p heterojunction with NiO nanoclusters. This present work demonstrates a simple and efficient method to fabricate ultrafine n-p heterojunction core-shell structure for noble-metal free catalyst for both water splitting and biomass photoreforming.

Microbial reduction of sulfate to hydrogen sulfide is highly undesirable in several industrial settings. Some sulfate-reducing bacteria are also able to transform metal ions in their environment into metal phases that remain attached to their outer cell surface.

A wide range of bacteria can synthesize surface-associated nanoparticles (SANs) through exogenous metal ions reacting with sulfide produced via cysteine metabolism, resulting in the emergence of a biological-nanoparticle hybrid (bionanohybrid). The attached nanoparticles may couple to extracellular electron transfer, facilitating de novo photoelectrochemical processes. While SAN-cell coupling in hybrid organisms is opening a range of biotechnological possibilities, observation of bionanohybrids in nature is not commonly reported and their lab-based behavior remains difficult to control. We describe the critical role environmental synergy (microbial growth stage, cell densities, cysteine, and exogenous metal concentrations) plays in controlling the form and occurrence of Escherichia coli and Moorella thermoacetica bionanohybrids. SAN development depends on an appropriate cell density to metal ratio, with too few cells resulting in nanoparticle suppression through cytotoxicity or inhibition of cysteine conversion, and with too many cells diluting the number and size of particles produced. This cell number is governed by the concentration of cysteine present, which acts to protect the cells from metal ion toxicity. Exposing cells to metal and cysteine during the lag phase leads to SAN development, whereas cells in the exponential growth phase predominantly produce dispersed nanoparticles. Applying these principles more broadly, E. coli is shown to biosynthesize composite Bi/Cu sulfide SANs, and Clostridioides difficile can be coaxed into a bionanohybrid lifestyle by fine-tuning the cysteine dosage. Bionanohybrids maintain a remarkable ability for binary fission and sustained growth, opening doors to the production of SANs tailored to specific technological functions. IMPORTANCE Some bacteria can produce nanoscale-sized particles, which remain attached to the surface of the organism. The surface association of these nanoparticles creates a new mode of interaction between the microbe’s environment and its internal cellular function, giving rise to a new hybrid lifeform, a biological nanoparticle hybrid (bionanohybrid). These hybrid organisms gain new or enhanced biological functions, and thus their creation opens a wide range of biotechnological possibilities. Despite this potential, the fundamental controls on bionanohybrid formation and occurrence remain poorly constrained. In this study, Escherichia coli K-12, Moorella thermoacetica, and Clostridioides difficile were used to test the combined influences of the growth phase, cell density, cysteine dose, and metal concentration in determining single and composite metal sulfide surface-associated nanoparticle production. The significance of this study is that it defined the critical synergies controlling nanoparticle formation on bacterial cell surfaces, unlocking the potential for bionanohybrid applications in a range of organisms.

The research was supported by the project of the National First-class Disciplines (PNFD) and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions. This research is also undertaken thanks to funding from the Canada First Research Excellence Fund (CFREF).

The world’s energy system is still dominated by fossil fuels. While there is a rapid reduction in the cost of renewable energy and the environmental costs of continued carbon dioxide emissions from fossil fuel recovery and use are well understood, current economic, infrastructure and political constraints sustain the fossil fuel enterprise as a dominant component of the energy system. Though routes to decarbonizing fossil fuel use, such as carbon capture and storage, have been proposed and have been demonstrated at commercial scale, current CCS CO2 storage quantities are very small and no large-scale practical route to providing fossil fuel energy, without the CO2 emissions attendant with fuel production and use has been proposed. Here we look at some of the boundary conditions and possible routes to production of emissions free energy from fossil fuels, and specifically petroleum reservoirs. Focusing on the production of electrical power we look at possible applications of microbially mediated hydrocarbon oxidation, coupled to a range of energy harvesting strategies, to the provision of electrical power at surface at a range of scales suitable for grid power provision, powering upstream oilfield facilities or for powering in situ sensing and exploration systems. We also ask the question, even if practical, would direct production of electrical power from oil and gas fields be a politically and economically sensible strategy as part of the energy transition away from traditional fossil fuel use.

The invention provides a membrane-free redox cell utilizing auxiliary electrodes that facilitate fast charging and discharging of anolyte and catholyte for electrochemical energy storage. The anode and cathode chambers are ionically separated, and electrically connected through a conductor joining auxiliary electrodes comprised of a redox material. In use, charging/discharging of the galvanic cell takes place between primary electrodes, and the redox material is immersed in the electrolyte in both anode and cathode chambers.

Electrochemical oxidation of biomass to fuels and value-added chemicals represents an emerging strategy for storing renewable energy and achieving a higher grade of sustainability in chemical industries. While research is still in its infancy, it is important to analyse the economic feasibility of such a process. In this study, we present a detailed techno-economic analysis (TEA) of a potential photo-biorefinery approach for sunlight-driven electro-oxidation of glucose to produce valuable fuels and chemicals i.e., H2, gluconic acid (GNA) and glucaric acid (GRA). Under a base case scenario, the results are promising with a minimum selling price (MSP) of GRA at $6.94 per kg, which will be ∼70% lower than the current market price. The detailed breakdown and sensitivity analysis suggest that unlike conventional water electrolysis, the cost of raw materials and separation has a significant impact on the economics. Furthermore, we also establish performance targets for conversion (90%), selectivity (90%), feed concentration (0.5 M) and operating current density (0.4 A cm−2) such that if these targets are achieved, photo-electrochemical conversion of biomass to fuels and chemicals can become a very profitable option with a MSP of GRA as low as $1.42 per kg.

Glucose photoreforming provides a promising alternative strategy for biomass valorization. However, the use of harsh environment (high alkalinity or organic solvents) and low product selectivity due to non-selective free radical oxidative cleavage limit their application in large-scale settings. Here, we show photoreforming of glucose to arabinose with high selectivity in water using gold nanoparticles decorated three dimensionally ordered macroporous TiO2 (3DOM TiO2-Au). We demonstrate that the hierarchically porous 3DOM architecture and Au nanoparticles enhance glucose conversion and arabinose selectivity by improving glucose-photocatalysts interaction, electron generation, charge separation, and localized surface plasmon resonance (LSPR) induced light absorption. The 3DOM TiO2-Au produces arabinose via the direct C1-C2 α-scissions mechanism as evidenced by 13C labeled glucose at C1 position. Our experimental results demonstrate the presence of Au(I) is crucial for glucose to arabinose selective conversion. Aside from arabinose production, 3DOM TiO2-Au also generates considerable amount of gas fuels (H2, CH4 and CO) from transient dehydration and hydrogenation reaction of the by-product formic acid. The present work demonstrates a green and promising approach to convert biomass derived feedstocks into value-added chemicals along with gas fuel production.

The physical and chemical properties of oil residing in reservoir core samples are strongly susceptible to evaporative processes during storage. In a case study from the Peace River oil sands of Alberta, we performed dead oil viscosity measurements on oils recovered by mechanical extraction of fresh core, the equivalent cores stored for 7 months frozen plus 3 months at ambient conditions (time 1) and for 7 months frozen plus 8 months at ambient conditions (time 2). The dead oil viscosity of oil recovered from fresh core material (8100 cP at 20 °C) was more than an order of magnitude lower than that of the oil subsequently recovered from an equivalent core sample stored frozen for 7 months and then at ambient temperature for 8 months (313,500 cP at 20 °C). The evaporation of light hydrocarbons such as toluene and xylenes during storage is a continuous process responsible for progressive increase in dead oil viscosity. Meanwhile, when comparing the oils recovered from fresh core and aged core samples, the composition of the heavy (low volatility) hydrocarbons remains essentially the same. Because biodegradation is the primary control on oil viscosity and variation in hydrocarbon compositions for this oil sample suite, partial least squares models based on viscosity versus geochemical data may still be used to predict viscosity. Although the physical properties of the oil may be compromised during storage, the distributions of the high molecular weight components retain characteristics, similar to a bar code, that are inherited and representative of the original (fresh) core sample. Therefore, with the proviso that the distributions of high molecular weight components are comparable between fresh cores and aged cores, the viscosity of oil residing in stored core samples can be effectively restored by chemometric-based correlation methods.

Summary Photocatalytic transformation of biomass into value-added chemicals coupled with co-production of hydrogen provides an explicit route to trap sunlight into the chemical bonds. Here, we demonstrate a rational design of Zn1-xCdxS solid solution homojunction photocatalyst with a pseudo-periodic cubic zinc blende (ZB) and hexagonal wurtzite (WZ) structure for efficient glucose conversion to simultaneously produce hydrogen and lactic acid. The optimized Zn0.6Cd0.4S catalyst consists of a twinning superlattice, has a tuned bandgap, and displays excellent efficiency with respect to hydrogen generation (690 ± 27.6 μmol·h−1·gcat.−1), glucose conversion (~90%), and lactic acid selectivity (~87%) without any co-catalyst under visible light irradiation. The periodic WZ/ZB phase in twinning superlattice facilitates better charge separation, while superoxide radical (⋅O2-) and photogenerated holes drive the glucose transformation and water oxidation reactions, respectively. This work demonstrates that rational photocatalyst design could realize an efficient and concomitant production of hydrogen and value-added chemicals from glucose photocatalysis., Graphical Abstract, Highlights • Zn1-xCdxS ZB-WZ homojunction was designed to improve charge separation efficiency • Bandgap engineering improved the hydrogen production from glucose photoreforming • Optimized Zn0.6Cd0.4S ZB-WZ exhibited high lactic acid yield and selectivity • Rational photocatalyst design realizes biomass valorization and H2 coproduction, Chemistry; Catalysis; Engineering; Materials Science

Most of the oil in low temperature, non-uplifted reservoirs is biodegraded due to millions of years of microbial activity, including via methanogenesis from crude oil. To evaluate stimulating additional methanogenesis in already heavily biodegraded oil reservoirs, oil sands samples were amended with nutrients and electron acceptors, but oil sands bitumen was the only organic substrate. Methane production was monitored for over 3000 days. Methanogenesis was observed in duplicate microcosms that were unamended, amended with sulfate or that were initially oxic, however methanogenesis was not observed in nitrate-amended controls. The highest rate of methane production was 0.15 μmol CH4 g-1 oil d-1 , orders of magnitude lower than other reports of methanogenesis from lighter crude oils. Methanogenic Archaea and several potential syntrophic bacterial partners were detected following the incubations. GC-MS and FTICR-MS revealed no significant bitumen alteration for any specific compound or compound class, suggesting that the very slow methanogenesis observed was coupled to bitumen biodegradation in an unspecific manner. After 3000 days, methanogenic communities were amended with benzoate resulting in methanogenesis rates that were 110-fold greater. This suggests that oil-to-methane conversion is limited by the recalcitrant nature of oil sands bitumen, not the microbial communities resident in heavy oil reservoirs.

Photoreforming of lignocellulosic biomass is an emerging and sustainable strategy for coproduction of high-value chemicals and fuels. Challenges remain to selectively convert biomass macromolecular via sunlight-driven photocatalysis due to limited mass diffusion, insufficient charge separation and lack of mechanistic understanding. Herein, inspired by natural photosynthesis, we demonstrate a hierarchically threedimensionally ordered macroporous (3DOM) TiO2-Au-CdS Z-scheme heterojunction photocatalyst to improve mass diffusion, charge separation and light absorption efficiency. We show the photocatalytic cleavage pathway of cellulose β-1,4-glycosidic linkage (the most abundant linkage within biomass) over 3DOM TiO2-Au-CdS heterojunction by using cellobiose as a model component. Similar to the oxidative enzymes in nature, the all-solid-state Z-scheme photocatalyst demonstrates oxygen insertion at C1 position followed by the elimination reaction, which oxidatively cleaves the β-1,4-glycosidic bond and results in gluconic acid and glucose generation. In presence of oxygen, glucose is further oxidized into gluconic acid which is subsequently oxidized or decarboxylated into glucaric acid or arabinose. The present study may serve as a framework to rationally design photocatalyst to reveal mechanistic understanding of biomass photoreforming towards high-value fuels and chemical feedstocks.

The hydrocarbon composition of the Grosmont Formation bitumen was investigated in 51 core samples by gas chromatography–mass spectrometry (GC–MS). The bitumen composition is highly variable and is heavily to severely biodegraded. Molecular ratios based on biodegradation-resistant compounds are highly uniform laterally and vertically, even across shale barriers indicating the bitumens are genetically related. Biodegradation-resistant biomarker maturity parameters suggests the bitumen was likely sourced during the early oil window stage of petroleum generation. Biomarkers responding to biodegradation display strong lateral and vertical variations in composition with geochemical profiles based on concentration data, displaying dramatic offsets when shales are present indicating the reservoir units are compartmentalised. Considering the relationship between 25-norhopanes and hopanes, the hydrocarbon composition data indicate progressive hopane degradation, both with concomitant formation of 25-norhopanes and hopane degradation without the formation of 25-norhopanes. In wells 07-08-085-18W4 and 10-12-093-24W4, the degradation of hopanes occurs in Upper Grosmont unit 3 (UG3) without the formation of 25-norhopanes (unless 25-norhopanes have been synchronously consumed), whereas in unit UG2, hopane degradation occurs with the concomitant formation of the 25-norhopanes. Therefore, the shale compartmentalizes the reservoir creating two isolated environments whereby the biogeochemical setting contributing to 25-norhopane formation is found in the UG2 unit, whereas it is absent or inactive in unit UG3. The degradation of the 22R epimer prior to the 22S epimer in the C31–C33 17α-hopanes was recognized in well 16-05-088-19W4, which indicates that the consortia of microbes more readily biodegraded the epimer having the biological conformation.

Correction for ‘An auxiliary electrode mediated membrane-free redox electrochemical cell for energy storage’ by Senthil Velan Venkatesan et al., Sustainable Energy Fuels, 2020, 4, 2149–2152, DOI: 10.1039/c9se00734b.

The conventional shake flask technique for determining oil-water partition ratios of benzene, toluene, ethylbenzene and xylene (BTEX) cannot accurately assess the extremes of high pressure and low water temperatures found in submarine oil spill conditions. An oil-water partitioning device has been constructed to experimentally simulate the partition behavior of BTEX compounds under submarine oil spill conditions, using simulated live oil (methane-charged), with saline waters over a range of pressure (2–15 MPa) and temperature (4–20 °C). Within the investigated ranges, the partition ratios of BTEX compounds increase proportionally with an increase in methane charging pressure (oil saturation pressure) and the degree of BTEX alkylation, and decrease with increase in temperature. The variation of the partition ratio values due to changes in system pressure and increasing oil methane concentration, is much more significant than those seen due to change in the temperature over the range studied. This data may be used in near-field and far-field distribution modeling of the environmental fate of highly toxic BTEX compounds, derived from submarine oil spills and their impact on the ecosystem. The parameters will also aid in the prediction of oil migration and dispersion away from the spill thus helping to improve response strategies.

Geochemical studies can provide a record of environmental changes and biogeochemical processes in sedimentary systems. Analytical methods are in need of high-throughput procedures targeting recalcitrant and multiple chemical species for delineating ecological patterns and ecosystem health. The goal of this chapter is to summarize the analytical methods, recalcitrant molecules and transformed organic material used in previous studies as chemical indicators of the impact and fate of Deepwater Horizon (DWH) oil residues in sediments. Further monitoring of recalcitrant molecules and transformed material will help to elucidate the long-term fate of the DWH weathered oil in sedimentary environments of the Gulf of Mexico (GoM).

The oil spill from the Ixtoc 1 well in 1979 in the southern Gulf of Mexico (sGoM) was in many aspects very similar to the Deepwater Horizon (DWH) blowout offshore Louisiana 30 years later (2010), most importantly because of the subsurface nature of the oil release, the amount of oil released, and the extensive environmental distribution of the spilled oil, including coastal impacts. Because of that, the Ixtoc 1 spill can serve as an excellent analog to study and model the long-term oil weathering processes in coastal environments. In 2016, a research expedition sponsored by the Gulf of Mexico Research Initiative (GoMRI) visited many coastal sites in the sGoM, previously known to be impacted by the Ixtoc 1 spill, and collected oil residues. The residues were analyzed using targeted (GC-MS/MS) and non-targeted (FTICR-MS) approaches in order to assess their origin and the nature of weathering transformation products. The initial results suggest multi-decadal preservation potential of Ixtoc 1 spill residues in certain low-energy environments, such as coastal mangrove forests. These results provide valuable input for the modelling of long-term fate and impacts of the DWH spill.

During the past decade, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been established as a technique of choice for the comprehensive chemical assessment of some of the most complex organic mixtures, such as petroleum, or dissolved organic matter. In the aftermath of the Deepwater Horizon (DWH) blowout, FTICR-MS demonstrated its applicability for the characterization of oil spill residues produced by abiotic weathering, such as photooxidation, and/or microbial processes and interactions, for example, marine oil snow aggregation. Such residues are abundant in high molecular weight, polar, and heteroatom-bearing chemical species, which cannot be analyzed by the typical oil spill forensics tools such as gas chromatography. Therefore, the expansion of the analytical window afforded by FTICR-MS is crucial for the monitoring and understanding of long-term oil spill fate. Furthermore, capability of FTICR-MS to characterize non-hydrocarbon petroleum fractions will be very important in the case of potential future spills of heavy, unconventional oils, such as bitumen.

The 2010 Deepwater Horizon blowout in the northern Gulf of Mexico (GoM) was the first major oil spill to impact the deep sea. This lack of precedent creates challenges for predicting the long-term fate of spilled oil constituents in the deep GoM. Depletion of oil residues in oxygenated seafloor sediments is thought to be relatively rapid, but as impacted horizons are buried by sediments and oxygen is depleted, biodegradation rates are likely to decrease. The sedimentary record of the 1979 Ixtoc 1 oil spill (southern GoM), the second largest marine oil spill to date, affords a window for forecasting the fate of constituents of spilled oil in the northern GoM over multi-decadal time scales.

The Deepwater Horizon (DWH) discharge is unique in that it represents the first large spill that occurred in the deep sea, and unparalleled volumes of chemical dispersant were applied during emergency response efforts. Thus, the DWH incident raised new challenges with regard to predictions of petroleum hydrocarbon (PHC) biodegradation and the fate of discharged hydrocarbons in the deep sea, which is permanently cold (~4 °C) and exposed to high hydrostatic pressure (1 MPa per 100 m). Although extensive information is available on the rates and controls of PHC biodegradation in marine environments, relatively few studies have been conducted under conditions resembling the deep sea. In particular, hydrostatic pressure is a key environmental parameter that has been largely overlooked in biodegradation studies, due to methodological challenges and the difficulty to obtain samples. Considering the rapid expansion of oil and gas drilling into deeper waters, there is an urgent need to improve understanding of the influence of low temperature and high pressure on biodegradation in order to better constrain the fate of hydrocarbons in the deep sea. This chapter addresses the current understanding of deep sea PHC biodegradation, highlighting discoveries made during the scientific response to the DWH disaster.

Crude oil-amended microcosms were prepared with inocula from eleven anoxic environments (4 river sediments, 3 lake sediments, and 4 sludges from wastewater treatment reactors) to determine their ability to produce methane from the biodegradation of crude oil. Over incubation periods of up to 1150 days, oil-stimulated methanogenesis and concomitant loss of alkanes occurred in microcosms prepared with five of the inocula whereas six of the inocula did not show oil-stimulated methane production. Bacterial and archaeal communities from microcosms exhibiting high levels of oil-stimulated methanogenesis were distinct from communities where methanogenic crude oil degradation was not detected. Successional changes were consistent with the quantitative enrichment of syntrophic hydrocarbon degrading bacteria and methanogens over time. In conclusion, in oil-impacted environments methanogenic crude oil-degrading microbial consortia are present in relatively low abundance and exhibit slow growth, and while they may be ubiquitously distributed they may not be present at sufficiently high abundance to be detected.

Oil industries generate large amount of oil wastewater worldwide and it is challenging to develop a sustainable technique to treat them due to the potential risk of contamination and recalcitrance. In this study, we employed microbial fuel cell to investigate biodegradation of crude oil with concomitant power generation. MnO2 coated anode was used to facilitate anoxic oil degradation due to better biofilm attachment, and fuel cell performance was compared with the uncoated carbon anode. Our study revealed that MFC with coated anode produced comparatively higher power density (47 mW m−2) than uncoated carbon anode (38 mW m−2), suggesting better removal of hydrocarbon components, also confirmed by oil-biodegradation studies (36% compared to 25.5% removal of total alkanes). The performance of the two cells was additionally evaluated by electrochemical, morphological, elemental and microbial community analysis. The prevalence of communities associated with hydrocarbon degradation and electrogenesis signify crude oil degradation with power generation.

Renewable energy sources are forecasted to supply half of the global energy demand in the future. Development of improved and cost-effective energy storage methods are in high demand due to the intermittency and locally distributed nature of renewable energy sources [1]. Redox flow battery (RFB) is a candidate technology for large-scale energy storage that can be coupled with renewable energy to alleviate intermittency problem [2]. A major contributor to the cost (40%) of RFB is the polymer electrolyte membrane, which is supposed to separate the catholyte and the anolyte [3]. Here, we propose membrane-free design wherein the classical anolyte and catholyte compartment, each with a redox auxiliary electrode pair, are connected by a metal wire. This design relieves the restriction of finding a common electrolyte for the anode and cathode chamber and eliminates the cross-over of undesirable ions between the two chambers. Thus, the new design offers the flexibility of using a wide variety of redox electrolytes (alkaline/acidic or aqueous/non-aqueous) in anode and cathode chambers independently [4]. For example, two compartment redox cell with a pair of auxiliary electrode allows the use of aqueous (acidic/alkaline) or nonaqueous (acidic/alkaline) electrolytes in anode and cathode chambers independent of one another, with electron conducting material connecting the auxiliary electrodes in both chambers during charging and discharging reactions as shown in Figure 1. When oxidation occurs at the anode, corresponding auxiliary electrode udergoes reduction and hence an oxidized materials must be supplied here. Whereas, reduction occurs at the cathode and corresponding auxiliary electrode udergoes oxidation and hence a reduced materials must be supplied to enable a spontaenous charging and discharging of the redox electrolyte. The novel design helps couple spatially separated oxidation and reduction processes. Since, there is no membrane and mass transport across the chambers, the cost, performance, and degradation issues related to membrane are avoided. Alkaline and acidic electrolytes can be used indepenedent of the content in the other chamber. When the solubility of one type of redox electrolyte is limited or zero in aqueous solvent, that particular redox electrolyte alone can be dissolved in a different media/solvent and retain the counter electrolyte in aqueous based solvent [5]. Acknowledgements This research was undertaken thanks in part to funding from the University of Calgary and the Canada First Research Excellence Fund. References 1. Larcher, D. Tarascon, Jean-Marie. Nat. Chem. 7 (2015)19-29. 2. Grigorii Soloveichik, Nature. 505 (2014) 163-165. 3. Puiki Leung, T. Martin, Akeel A. Shah, Mohd Rusllim Mohamed, Marc A. Anderson, Jesus Palma, J. Power Sources. 341 (2017) 36-45. 4. Senthil Velan Venkatesan, Venkataraman Thangadurai, Steve Larter, Kunal Karan, Jagos Radovic, US provisional patent application 62/887,464 filed August 15, 2019. 5. Senthil Velan Venkatesan, Kunal Karan, Steve Larter, Venkataraman Thangadurai, Sustainable Energy & Fuels. (2019) doi:1039/C9SE00734B. Figure 1

Canada’s oil sands region (COSR) is located in its western province of Alberta which contains one of the largest oil reserves in the world, in the form of biodegraded heavy oils and bitumens, but also has conventional oil containing reservoirs. In this chapter, we analyzed historical cases of oil releases related to oil production and transport in COSR, in order to determine long-term trends and the main causes of spills. Furthermore, we assessed the potential postspill environmental behavior, fate, and effects of nonhydrocarbon-rich COSR oil resources, in the context of their unique physicochemical properties. The long-term spill record shows a decreasing trend through time of released volumes relative to total oil output from COSR. Some of the largest oil releases occurred due to pipeline ruptures or leaks, often caused by corrosion. High oil viscosity and density reduce spill spreading, but can cause sinking of oil when spilled into water. The high concentrations of heteroatom-containing species in many COSR oils is a poorly understood risk factor affecting water solubility and environmental behavior in these polar compound-rich oil fractions. Advanced analytical tools and methods are needed to better understand the environmental impacts of spills of heteroatom-rich heavy oils and bitumens, and to improve spill response, monitoring, and remediation strategies.

Many of the molecular proxies commonly used for paleoenvironmental reconstruction are focused on a limited set of glycerol ether lipids, mainly due to the lack of more comprehensive analytical methods and instrumentation able to deal with a more diverse range of species. In this study, we describe an FTICR-MS-based method for rapid, nontargeted screening of ether lipid biomarkers in recent marine sediments. This method involves simplified sample preparation and enables rapid identification of known and novel ether lipid species. Using this method, we were able to identify complete series of core glycerol dialkyl glycerol tetraethers (GDGTs with 0 to 8 alicyclic rings), including the complete resolution of GDGT-4 and the unexpected detection of GDGTs with more than 5 rings, in sediments from mesophilic marine environments (sea surface temperature, SST, of 24-25 °C). Additionally, mono- and dihydroxy-GDGT analogs (including novel species with2 rings), as well as glycerol dialkanol diethers, GDDs (including novel species with5 rings) were detected. Finally, we putatively identified other, previously unreported groups of glycerol ether lipid species. Adequacy of the APPI-P FTICR-MS data for the determination of commonly used GDGT-based proxy indices was demonstrated. The results of this study show great potential for the use of FTICR-MS as both a rapid method for determining existing proxy indices and, perhaps more importantly, as a tool for the early detection of possible new biomarkers and proxies that may establish novel geochemical relationships between archaeal ether lipids and key environmental-, energy-, and climate-related system variables.

The ability to mitigate toxicity of oil sands process-affected water (OSPW) for return into the environment is an important issue for effective tailings management in Alberta, Canada. OSPW toxicity has been linked to classical naphthenic acids (NAs), but the toxic contribution of other acid-extractable organics (AEOs) remains unknown. Here, we examine the potential for in situ bioremediation of OSPW AEOs by indigenous algae. Phosphate biostimulation was performed in OSPW to promote the growth of indigenous photosynthetic microorganisms and subsequent toxicity and chemical changes were determined. After 12 weeks, the AEO fraction of phosphate-biostimulated OSPW was significantly less toxic to the fission yeast Schizosaccharomyces pombe than unstimulated OSPW. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analysis of the AEO fraction in phosphate-biostimulated OSPW showed decreased levels of SO3 class compounds, including a subset that may represent linear arylsulfonates. A screen with S. pombe transcription factor mutant strains for growth sensitivity to the AEO fraction or sodium dodecylbenzenesulfonate revealed a mode of toxic action consistent with oxidative stress and detrimental effects on cellular membranes. These findings demonstrate a potential algal-based in situ bioremediation strategy for OSPW AEOs and uncover a link between toxicity and AEOs other than classical NAs.

We have examined, using a 12 Tesla FTICR-MS instrument, the impact of varying thermal maturity level on a suite of 9 related crude oils charged from source rocks covering most of the liquid petroleum generating portion of the oil window (0.68–1.11% vitrinite reflectance equivalent (%Re)). The sample suite was analyzed as whole oils under three different conditions, electrospray ionization (ESI) in positive and negative ion mode to analyze basic and acidic components, respectively, and atmospheric pressure photoionization (APPI) in positive ion mode, for sulfur and hydrocarbon species. Increasing oil maturity level had a strong influence on the composition of all compound classes in the oils with several major observations evident: The relative apparent abundances of all heteroatom containing compound classes detected in this study, using all ionization modes, decrease systematically with increasing oil maturation levels. Both aromatic hydrocarbons, detectable in APPI mode, and NSO compound classes (detectable in both ESI and APPI modes), as broad classes, are becoming more aromatic (shift to a greater predominance of higher DBE group members) and dealkylated (decreasing average molecular mass of individual compound groups), with increasing maturation level in the oil suite. Several putative oil maturity level dependent, molecular ratios were identified in the study. Of particular note, the relative abundance ratios of heteroatom compound classes tentatively identified as alkylated carbazoles, quinolines and benzothiophenes, compared to their benzannulated homologues are very sensitive to maturation level. Several groups of compounds show interesting and specific carbon number distributions, suggesting there may be hints of specific molecular markers in the FTICR-MS data. One observation of note is the strong increase in the relative abundance of protonated hydrocarbon components with DBE 5. We speculate this might reflect the presence of previously unreported higher molecular weight diamondoid (diamantane) species in oils with up to 40 carbon atoms or more, at advanced maturity levels. Such species may prove very valuable as molecular markers in highly mature fluids, such as those currently being produced from some shale reservoirs. Covariation of quantitative GC–MS data for alkylated hetero aromatic sulfur and nitrogen compounds in this oil suite, together with the corresponding FTICR-MS data from compounds believed to be, based on accurate mass, alkylated sulfur and alkylated nitrogen compounds, suggests that FTICR-MS already has some very rudimentary quantitation capabilities.

Oil sands are a mixture of “bitumen” (a very viscous, heavily biodegraded crude oil), unconsolidated sand, and water bound together by the bitumen and confining stresses. Economic incentives to produce reserves from the western Canada oil sands have driven geological and geochemical mapping to assess fluid quality controls and improve our understanding of the fundamental principles of the biodegradation of oils. While much of this activity has been for practical application, researchers have also had the opportunity to make fundamental advances in our understanding of subsurface biogeochemical processes and the boundaries of life in Earth's crust. Indeed, the huge size and shallow location of oil sands, coupled with the many thousands of wells drilled, mean that on a per cell basis, oil sands represent a most accessible portion of the deep biosphere. Perhaps the most exciting future for the oil sand resource is on the biological front rather than as an energy resource.

The presence of dissolved metal ions in waters associated with crude oils has many negative implications for the transport, processing, and refining of petroleum. In addition, mass spectrometric analysis of sodium containing crude oil samples suffers from ionization suppression, unwanted adduct formation, and an increase in the complexity of data analysis. Here, we describe a method for the reduction/elimination of these adverse effects by modification of the source region gas-inlet system of a 12 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Several acids were examined as part of this study, with the most suitable for on-line desalting found to have both high vapor pressure and low pK(a); 12.1 M HCl showed the strongest desalting effect for crude oil samples with a sodium removal index (SRI) of 88%-100% ± 7% for the NaOS compound class. In comparison, a SRI of only 38% ± 9% was observed for a H₂O/toluene solution-phase extraction of oil 1. These results clearly demonstrate the increased efficacy of pseudo-vapor phase desalting with the additional advantages that initial sample solution conditions are preserved and no sample preparation is required prior to analysis.

We describe a mechanical extraction method, referred to here as “the plunger”, for the recovery of heavy oil and bitumen samples, equivalent to produced oil samples, from clastic and carbonate reservoir cores. We demonstrate the efficacy of the plunger relative to the centrifugation method through comparing the physical properties and chemical compositions of the heavy oils and bitumens recovered from oil sands cores. Over the dead oil viscosity range from 21,000 cP to 1.4 × 106 cP at 20 °C and 9.6 × 106 cP at 25.5 °C, the plunger consistently yielded correspondingly lower viscosity oils compared to the oils recovered by centrifugation from the same sample material, as well as lower sediment fines and water content. For an example of extremely viscous oil, the plunger yielded 3.3 g of 9.6 × 106 cP oil (25.5 °C), while centrifugation produced only 50 mg of fluid, adequate for geochemical analysis but insufficient for viscosity and density determination. The plunger has many advantages that favor its use over centrifugation such as successful recovery of highly viscous oil from cores, lower oil sediment fines/water content and faster sample extraction (typically 30 min to 1 h versus 2 h). The plunger has also been operated at the rig site to generate oil viscosity logs immediately following core recovery (prior to or during petrophysical logging) affording real time data acquisition to support decisions for conducting production flow tests while drilling rigs are onsite. Incidentally, due to the improved preservation of physical properties controlling volatile liquid components, repeated plunging of larger volumes of sample core can be used to recover large enough volumes of heavy oil or bitumen for PVT or specialist assay analysis. Since the plunger is operated under a sealed system the device may be configured in such a way to interface with a PVT cell. Gas introduced into the plunger system ultimately can lead to the production and collection of “enlivened oils” for viscosity measurements.

In situ burning is often used as a response method for oil slicks in the marine environment. This process however forms viscous tar-like residues that either float on the surface or sink through the water column, introducing organic species into the water phase. The interaction of this burn residue with the water phase also introduces dissolved organics into the water column. In this study, we conducted laboratory-scale experiments to characterize and compare the organic species entering the water phase from the petrogenic (fresh oil) and pyrogenic (burnt oil) input during oil spills. The oil and water-soluble organics were characterized using ultra-high-resolution mass spectrometry (FTICR-MS). The results show that burning strongly increases concentrations of oil-related constituents entering the water phase, due to transformation reactions producing oxidized organic species with higher water solubility. The pyrogenic water-soluble organics also showed a higher percentage of unsaturated compounds relative to the petrogenic fraction. The effect of these highly unsaturated and oxygenated organic species on oil spill fate and their ecosystem impacts is currently unknown.

A combined geochemical, geological and microbiological analysis of an actively biodegrading 24.5 m thick oil column in a Canadian heavy oil reservoir has been carried out. The reservoir properties associated with the cored vertical well are characterised by a 15.75 m thick oil column and an 8.75 m zone of steadily decreasing oil saturation below the oil column, referred to as the oil–water transition zone (OWTZ), grading down into a thin water leg. The oil column exhibits systematic gradients in oil physical properties and hydrocarbon composition and shows variations in biodegradation level throughout the reservoir consistent with the notion that the biodegradation of oil is focussed in a bioreactor zone at the base of the oil column. Through the oil column, the dead oil viscosity measured at 20 °C ranged from 50,000 cP (0.05 McP) at the top of the oil column to 1.4 McP at the oil–OWTZ contact, and continued to increase to 10.5 McP within the OWTZ. The saturated and aromatic hydrocarbons are characterised by systematically decreasing bulk fraction and component concentrations down through the oil column. Different compound classes decreased to levels below their detection limit at different depths within the OWTZ, defining a likely bioreactor extent of over 5 m in depth with, for example, n-alkanes being reduced to their detection limit concentration at the bottom of the oil column/top of the OWTZ, while branched isoprenoid alkanes were not completely degraded until well into the OWTZ. Core samples from the oil column and the lower part of the OWTZ were estimated to contain ca. 104–105 bacterial cells/g, based on qPCR of bacterial 16S rRNA genes, while samples from a narrow interval in the OWTZ immediately below the oil column contained on the order of 106–107 cells/g of sediment. Interestingly, these latter numbers are typical of those observed in active deep subsurface biosphere systems with the notion that microbial activity and abundance in the deep subsurface is elevated at geochemical interfaces. The numbers of organisms are not constant throughout the OWTZ. The highest bacterial abundance and geochemical gradients of, for example, methylphenanthrene biodegradation define a zone near the oil–water contact as likely the most active in terms of biodegradation. The largest bacterial abundances in the upper part of the OWTZ are in line with the trend of bacterial abundance with depth that has emerged from extensive analysis of microbial cells in deep subsurface sediments, implying that in terms of deep biosphere cell abundance, oil reservoirs are similar to other deep subsurface microbial environments. This is puzzling, given the atypical abundance of organic carbon in petroleum reservoirs and may imply a common large scale control on microbial abundance and activity in the deep biosphere, including in oilfields.

The subsurface microbiology of an Athabasca oil sands reservoir in western Canada containing severely biodegraded oil was investigated by combining 16S rRNA gene- and polar lipid-based analyses of reservoir formation water with geochemical analyses of the crude oil and formation water. Biomass was filtered from formation water, DNA was extracted using two different methods, and 16S rRNA gene fragments were amplified with several different primer pairs prior to cloning and sequencing or community fingerprinting by denaturing gradient gel electrophoresis (DGGE). Similar results were obtained irrespective of the DNA extraction method or primers used. Archaeal libraries were dominated by Methanomicrobiales (410 of 414 total sequences formed a dominant phylotype affiliated with a Methanoregula sp.), consistent with the proposed dominant role of CO2-reducing methanogens in crude oil biodegradation. In two bacterial 16S rRNA clone libraries generated with different primer pairs, > 99% and 100% of the sequences were affiliated with Epsilonproteobacteria (n = 382 and 72 total clones respectively). This massive dominance of Epsilonproteobacteria sequences was again obtained in a third library (99% of sequences; n = 96 clones) using a third universal bacterial primer pair (inosine-341f and 1492r). Sequencing of bands from DGGE profiles and intact polar lipid analyses were in accordance with the bacterial clone library results. Epsilonproteobacterial OTUs were affiliated with Sulfuricurvum, Arcobacter and Sulfurospirillum spp. detected in other oil field habitats. The dominant organism revealed by the bacterial libraries (87% of all sequences) is a close relative of Sulfuricurvum kujiense – an organism capable of oxidizing reduced sulfur compounds in crude oil. Geochemical analysis of organic extracts from bitumen at different reservoir depths down to the oil water transition zone of these oil sands indicated active biodegradation of dibenzothiophenes, and stable sulfur isotope ratios for elemental sulfur and sulfate in formation waters were indicative of anaerobic oxidation of sulfur compounds. Microbial desulfurization of crude oil may be an important metabolism for Epsilonproteobacteria indigenous to oil reservoirs with elevated sulfur content and may explain their prevalence in formation waters from highly biodegraded petroleum systems.

In addition to the previously reported 25-norhopanes and 25-norhopanoic acids, for the first time we report the identification of 25-norbenzohopanes. The hydrocarbon composition of the bitumen from Palaeozoic carbonates in northern Alberta displays molecular evidence for severe levels of biodegradation characterised by the removal of C 30 –C 35 hopanes. Biodegradation is also indicated by the removal of C 32 and C 33 benzohopanes. The appearance of C 31 and C 32 25-norbenzohopanes corresponds to the decrease in C 32 and C 33 benzohopanes, suggesting that 25-norbenzohopanes originate by demethylation of benzohopane counterparts. Demethylation at C-10 in the hopanoids affects a broader class of compounds that so far includes the hopanes and hopanoic acids, as well as the benzylated hopanoid species.

Summary Methanogenic degradation of polycyclic aromatic hydrocarbons (PAHs) has long been considered impossible, but evidence in contaminated near surface environments and biodegrading petroleum reservoirs suggests that this is not necessarily the case. To evaluate the thermodynamic constraints on methanogenic PAH degradation we have estimated the Gibbs free energy values for naphthalene, phenanthrene, anthracene, pyrene and chrysene in the aqueous phase, and used these values to evaluate several possible routes whereby PAHs may be converted to methane. Under standard conditions (25°C, solutes at 1 M concentrations, and gases at 1 atm), methanogenic degradation of these PAHs yields between 209 and 331 kJ mol−1. Per mole of methane produced this is 27–35 kJ mol−1, indicating that PAH-based methanogenesis is exergonic. We evaluated the energetics of three potential PAH degradation routes: oxidation to H2/CO2, complete conversion to acetate, or incomplete oxidation to H2 plus acetate. Depending on the in situ conditions the energetically most favourable pathway for the PAH-degrading organisms is oxidation to H2/CO2 or conversion into acetate. These are not necessarily the pathways that prevail in the environment. This may be because the kinetic theory of optimal length of metabolic pathways suggests that PAH degraders may have evolved towards incomplete oxidation to acetate plus H2 as the optimal pathway.

Biodegradation schemes based on the sequential removal of hydrocarbons are commonly applied to indicate the level of degradation that a petroleum accumulation may have experienced, but inconsistent patterns of degradation are typically seen if large data sets are examined, and oil mixing greatly complicates any attempt at seeking a globally consistent biodegradation scheme. In the Athabasca oil sands province, degradation of steranes, diasteranes and hopanes can occur simultaneously along with the formation of 25-norhopanes, highlighting the difficulties towards assigning a degradation level to reflect the degree of compositional alteration experienced by a heavy oil or bitumen. In addition, the aromatic hydrocarbons, such as the methyl phenanthrene isomers, show differential susceptibility to degradation. Whilst the 9-methylphenanthrene (9-MP) may show selective resistance to degradation compared to 1-methylphenanthrene (1-MP), we have also seen that 9-MP may be removed prior to 1-MP. In some cases, both 9-MP and 1-MP may be strongly removed in comparison with the 3- and 2-methylphenanthrenes. The complex interplay of charge history, reservoir environment (e.g. presence/absence of water legs) and extent and mass transport mechanics of the basal biodegradation reaction zone are most likely to have led to the many and varied petroleum compositions that are a feature of the Athabasca tar sands and many other degraded oil provinces.

Biodegradation of crude oil in subsurface petroleum reservoirs has adversely affected the majority of the world's oil, making recovery and refining of that oil more costly. The prevalent occurrence of biodegradation in shallow subsurface petroleum reservoirs has been attributed to aerobic bacterial hydrocarbon degradation stimulated by surface recharge of oxygen-bearing meteoric waters. This hypothesis is empirically supported by the likelihood of encountering biodegraded oils at higher levels of degradation in reservoirs near the surface. More recent findings, however, suggest that anaerobic degradation processes dominate subsurface sedimentary environments, despite slow reaction kinetics and uncertainty as to the actual degradation pathways occurring in oil reservoirs. Here we use laboratory experiments in microcosms monitoring the hydrocarbon composition of degraded oils and generated gases, together with the carbon isotopic compositions of gas and oil samples taken at wellheads and a Rayleigh isotope fractionation box model, to elucidate the probable mechanisms of hydrocarbon degradation in reservoirs. We find that crude-oil hydrocarbon degradation under methanogenic conditions in the laboratory mimics the characteristic sequential removal of compound classes seen in reservoir-degraded petroleum. The initial preferential removal of n-alkanes generates close to stoichiometric amounts of methane, principally by hydrogenotrophic methanogenesis. Our data imply a common methanogenic biodegradation mechanism in subsurface degraded oil reservoirs, resulting in consistent patterns of hydrocarbon alteration, and the common association of dry gas with severely degraded oils observed worldwide. Energy recovery from oilfields in the form of methane, based on accelerating natural methanogenic biodegradation, may offer a route to economic production of difficult-to-recover energy from oilfields.

In addition to previously reported 25-norhopanoic acids with the 17α(H), 21β(H) and 17β(H), 21α(H) configurations, for the first time we report the identification of 25-norhopanoic acids bearing the 17β(H), 21β(H) configuration in a suite of heavily biodegraded oils from China. The 17β(H), 21β(H) stereochemistry is a thermally unstable biologically-derived structure, suggesting that the 17β(H), 21β(H) 25-norhopanoic acids may derive from petroleum-degrading microbes. Rather than representing a direct input, we propose that demethylation of 17β(H), 21β(H) hopanoic acids derived from bacteria in the reservoir may give rise to 17β(H), 21β(H) 25-norhopanoic acids, implying that microbial reworking of biomass is occurring alongside petroleum degradation.

The composition of crude oils and rock extracts has been investigated by Iatroscan and combined gas chromatography–mass spectrometry. The Iatroscan technique reveals that core extracts from petroleum reservoirs are enriched in bulk NSO composition compared to the producible mobile phases recovered during drill stem tests. The NSO component appears to interact with the reservoir phase and if understood may indicate the degree of fluid–rock interaction in the reservoir during production. A comparative study of the polar non-hydrocarbon composition of core extract petroleum from a tar sand reservoir over a period of 6 months reveals that alteration processes occurring during sample storage modifies the composition of petroleum in stored cores. We find that the concentrations of fluorenones often increase in stored samples, while carbazole concentrations decrease with time. In our view, geochemical samples require immediate analysis after recovery from the subsurface, otherwise the procedures of core sampling, storage and handling need to be revised. Storage of samples for geochemical analysis appears not to be so critical for hydrocarbon determinations. However, some aromatic hydrocarbons, such as fluorene, are very easily affected by oxidation processes.