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Cremated bones are a commonly preserved material and often found in burial environments where unburned bone may not be preserved. As such direct radiocarbon dating of cremated bone could be essential in determining the chronology of an event. Pretreatment of cremated bone exploits the structural carbonate component of the bone which survives cremation. However, due to the low abundance (ca. 0.1%) of this component, the extraction of an amount of endogenous carbon sufficient for radiocarbon dating may represent a challenge. Here we investigate two modifications to the phosphoric acid digestion protocol used during the preparation of cremated bones at the Oxford Radiocarbon Accelerator Unit (ORAU). The first of these was to use ultrasonication to release evolved CO2 from the viscous phosphoric acid and cremated bone mixture that is formed during digestion. The second was to double the amount of time during which evolved CO2 was removed from the reaction vessel by transfer into a cryogenically cooled ampoule. Ultrasonication of the digestion mixture failed to produce a significantly higher carbon yield, while double-time collection resulted in an average 21.5±13.8% increase of C yield without affecting the measured age. Extending the collection time can better enable reliable dating of small (less than 1 g) samples. [ABSTRACT FROM AUTHOR]

The study involved single-stage carbonization and physical activation of Kevlar woven fabric to convert into activated carbon fabric. The carbonization process was optimised for high carbon yield and low electrical resistivity of activated carbon fabric using Box-Behnken experimental design and response surface methodology. The three process parameters namely charcoal amount, gas flow rate, and carbonization temperature were selected. The empirical equations obtained through response surface methodology for carbon yield and electrical resistivity were found in good agreement with the experimental values. An optimum amount of charcoal, optimum nitrogen flowrate, and low carbonization temperature was found suitable for higher carbon yield. On the other hand, high charcoal amount, high carbonization temperature, and optimum nitrogen flow rate resulted in low electrical resistivity of activated carbon fabric. Later, the activated carbon fabrics were prepared under the optimum carbonization conditions to get high carbon yield and low electrical resistivity. The optimized sample for electrical resistivity showed higher electromagnetic interference (EMI) shielding properties at lower as well as higher frequencies due to its highly porous morphology and electrical conductivity. [ABSTRACT FROM AUTHOR]

Electrochemical energy storage devices play key roles in collecting energy from new energy power sources, transferring energy in place and time difference, and supplying energy for those energy consumers. In this work, in order to further improve the high energy density of Li-ion battery, a hard carbon anode is suggested by chosen epoxy as carbon source, accompanied by the simultaneous introduction of three curing agents (dicyandiamide, phytic acid (PA), and ferric acetylacetone). Furthermore, dicyandiamide supplies N-dopant, while PA gives P-dopant and also increases the yield of hard carbon from 23.6 to 40.9%. Based on the synergistic effect of N and P atoms, as well as catalytic effect of Fe, the optimized hard carbon of CNFP-60–700, as Li-ion battery anode, exhibits a reversible capacity of 779.2 mAh g−1 and an initial Coulombic efficiency (ICE) of 58.8% at 0.1 A g−1 for the first cycle, and it still retains a capacity of 508.3 mAh g−1 after 160 cycles. [ABSTRACT FROM AUTHOR]

The present study compares the kinetics and thermodynamics of the pyrolysis process of coffee and tea waste with respect to their physicochemical properties to analyze their potential as an energy and carbon source. Coffee and tea waste exhibit a promising source as a biofuel that has gross calorific values of 22.7 MJ kg−1 and 20.2 MJ kg−1, with significant differences in the overall volatile conversion of 76 % and 65 %, and as final carbon with a yield of 22 % and 31 %, respectively. Kinetic analyses using isoconversional methods show a trend of activation energy and frequency factor with conversion for both samples, with a significant difference at a conversion beyond 0.6 due to the higher lignin content in coffee waste. The predicted master plots indicate complex pyrolysis kinetics for both samples. Furthermore, the reaction kinetics determined by the multivariate regression approach, assuming parallel independent reactions of the nth order applicable to all heating rates, provide the individual mass change and carbon yield of each reaction process that can be controlled using experimental conditions. Finally, the thermodynamic parameters indicate that the pyrolysis process of both coffee and tea waste is nonspontaneous and endothermic, and its reactivity increases with conversion.

This study focused on the development of an environmentally friendly binder system based on lignin and collagen for uniaxial pressed MgO–C refractories as an alternative to commonly used resin or pitch binders. Additionally, recycled MgO–C refractories from steel plants were partially utilized as raw material, investigating their influence on the resulting physical and mechanical properties. The binder system showed reliable binding properties, although the recyclate-containing MgO–C exhibited higher porosity, slightly lower density, and lower strength compared to the reference batches without recyclates. However, antioxidants significantly improved the properties of the recyclate-containing MgO–C samples. Scanning electron microscopy analysis with energy-dispersive X-ray spectroscopy revealed the formation of whiskers, as well as oxidation and nitridation of aluminum particles. This research highlights the potential of environmentally friendly binders and the utilization of recycled materials in MgO–C refractories to mitigate their environmental impact and enhances the environmental performance of carbon containing refractory materials.

Converting more CO2 absorbed by plant photosynthesis into biomass-activated carbon effectively reduces carbon emissions. In this study, we used a one-step preparation of biomass-activated carbon loaded with MgO nanoparticles to investigate the effect of Mg loading on the catalytic pyrolysis process. The influences of magnesium loading on biochar yield and fixed carbon production were assessed. The addition of 1% Mg weakened the carbonyl C=O, inhibited the dehydroxylation reaction, enhanced the C-H signal strength, and the formation of MgO inhibited the weaker- bound substituent breakage. Additionally, the addition of magnesium altered the morphological features and chemical composition of the biochar material. It also increased the activated carbon mesoporosity by 3.94%, biochar yield by 5.55%, and fixed carbon yield by 12.14%. The addition of 1% Mg increased the adsorption capacity of the activated carbon to potassium dichromate, acid magenta, methylene blue, and tetracycline effluents by 8.71 mg, 37.15 mg, 117.68 mg, and 3.53 mg, respectively. The results showed that MgCl2 played a significant role in promoting the thermal degradation of biomass and improving the solid yield and adsorption performance of activated carbon. [ABSTRACT FROM AUTHOR]

[Display omitted] • A redox balance strategy was developed to product butyl butyrate (BB) anaerobically. • Acetate and glucose were metabolized stoichiometrically by the engineered E. coli. • The engineered E. coli was able to maintain the intracellular redox homeostasis. • The highest titer and carbon yield of BB ever reported in E. coli were obtained. The carbon and energy efficiency of a biomanufacturing process is of crucial importance in determining its economic viability. Formate dehydrogenase has been demonstrated to be beneficial in regenerating NADH from formate produced during sugar metabolism, thereby creating energy-efficient systems. Nevertheless, introducing enzyme(s) for butyryl butyrate (BB) biosynthesis based on this system, only 1.64 g/L BB with 14.3 % carbon yield was obtained due to an imbalance in NADH-NAD+ turnover. To address the issue of NADH accumulation, a joint redox-balanced pathway for BB biosynthesis was developed in this study by coupling acetate and glucose metabolism. Following overexpression of acetyl-CoA synthetase in the BB-producing strain, acetate and glucose were co-utilized stoichiometrically and intracellular redox homeostasis was achieved. The engineered strain produced 29.02 g/L BB with carbon yield of 43.3 %, representing the highest yield ever reported for fermentative production of BB. It indicated the potential for developing a carbon- and energy-effective route for biomanufacturing. [ABSTRACT FROM AUTHOR]

Converting more CO2 absorbed by plant photosynthesis into biomass-activated carbon effectively reduces carbon emissions. In this study, we used a one-step preparation of biomass-activated carbon loaded with MgO nanoparticles to investigate the effect of Mg loading on the catalytic pyrolysis process. The influences of magnesium loading on biochar yield and fixed carbon production were assessed. The addition of 1% Mg weakened the carbonyl C=O, inhibited the dehydroxylation reaction, enhanced the C-H signal strength, and the formation of MgO inhibited the weaker- bound substituent breakage. Additionally, the addition of magnesium altered the morphological features and chemical composition of the biochar material. It also increased the activated carbon mesoporosity by 3.94%, biochar yield by 5.55%, and fixed carbon yield by 12.14%. The addition of 1% Mg increased the adsorption capacity of the activated carbon to potassium dichromate, acid magenta, methylene blue, and tetracycline effluents by 8.71 mg, 37.15 mg, 117.68 mg, and 3.53 mg, respectively. The results showed that MgCl2 played a significant role in promoting the thermal degradation of biomass and improving the solid yield and adsorption performance of activated carbon.

As the most commonly used method for industrial activated carbon preparation, physical activation is usually accompanied by significant loss of raw materials, especially when the pore structure of activated carbon is well developed. This not only reduces yields, but also increases costs. To enhance both yield and pore structure of activated carbon, we proposed a facile and scalable method called "fast pyrolysis-physical activation". After fast pyrolysis, although the initial pore volume of the semi-coke decreases, the rapid release of volatiles promotes the increase of mesopore and macropore volumes and the development of micron-scale cracks, which is beneficial for CO 2 mass transfer and reduces diffusion resistance. Therefore, compared to slow pyrolysis, the activated carbon produced through this method has a higher pore volume (increased by 25.9 %–30.0 %) and a larger S BET (increased by 26.7 %–38.3 %), while the yield remains almost unchanged. Consequently, due to the increase in pore volume and high yield of the activated carbon, the CO 2 adsorption capacity (25 °C, 1 bar) of ACB-K700 increases from 2.02 mmol/g to 2.37 mmol/g compared to ACB-M700, and the total CO 2 adsorption capacity of activated carbon prepared from the same mass of raw coal (1 g) increases from 1.07 mmol to 1.16 mmol. Due to the pre-formed pores inside the semi-coke, the gas activator molecules are able to penetrate deep into the particles, which not only reduces the ineffective etching that occurs on the surface, but also promotes the development of pore structure. In conclusion, this study provides a new pore development model for physical activation, and also provides a new method to produce activated carbon rapidly and massively, while the pore structure is well developed. • A new pore-forming mechanism is proposed based on fast pyrolysis-physical activation. • The S BET significantly increases by 26.7–38.3 % at similar yields (49.12–53.01 %). • The rapid escape of volatiles increases the pore volume for semi-coke. • Pre-formed pores in the semi-coke reduces ineffective etching of activator. • The CO 2 absorption capacity at 25 °C and 1 bar can be up to 2.37 mmol/g. [ABSTRACT FROM AUTHOR]

One of the most serious threats in the 21st century is carbon dioxide (CO 2) emissions. In the past ten years, a range of methodologies have been developed to convert CO 2 into cost-effective products, reducing atmospheric pollution simultaneously. The overall economic effect hinges on the application potential of the obtained products, hence controllable synthesis of functional carbon materials is significant. Herein, this review provided insights into the material preparation methods using CO 2 as feedstock on typical carbon materials, including graphene, porous carbon, onion-like carbon, carbon nanotubes and nanofibers, and others, while highlighting their chemical features under distinct reactions to understand the microstructural evolution and carbon conversion rate. We attempted to achieve controllable synthesis of specific CO 2 -derived carbon and yield optimization by discussing the influencing factors in different methods. Finally, we discussed the current application scenarios for the obtained materials, including batteries, gas catalysis, and water treatment in order to elucidate the potential capability to leverage CO 2 -based materials. Moreover, the main challenges and prospects of carbon materials prepared by CO 2 related to the environment and economy are summarized so as to highlight and serve as references for upcoming research on a large scale in the development of high-performance CO 2 -derived carbon materials. [Display omitted] • A review of synthesis methods for various carbon materials using CO 2. • A general mechanism analysis and yield evaluation of different methods have been made. • Discussion of the application scenarios of high-performance CO 2 -derived carbon materials. • The economic and environmental advantages of CO 2 -derived carbon materials are presented. [ABSTRACT FROM AUTHOR]

Due to concerns regarding fossil greenhouse gas emissions, biogenic material such as forest residues is viewed nowadays as a valuable source of carbon atoms to produce syngas that can be used to synthesise biofuels such as methanol. A great challenge in using gasified biomass for methanol production is the large excess of carbon in the syngas, as compared to the H2 content. The water–gas shift (WGS) reaction is often used to add H2 and balance the syngas. CO2 is also produced by this reaction. Some of the CO2 has to be removed from the gaseous mixture, thus decreasing the process carbon yield and maintaining CO2 emissions. The WGS reaction also decreases the overall process heat output. This paper demonstrates the usefulness of using an extra source of renewable H2 from steam electrolysis instead of relying on the WGS reaction, for a much higher performance of syngas production from gasification of wood in a simple system with a fixed-bed gasifier. A commercial process simulation software is employed to predict that this approach will be more efficient (overall energy efficiency of about 67%) and productive (carbon conversion yield of about 75%) than relying on the WGS reaction. The outlook for this process that includes the use of the solid oxide electrolyser technology appears to be very promising because the electrolyser has the dual function of providing all of the supplemental H2 required for syngas balancing and all the O2 required for the production of a suitable hot raw syngas. This process is conducive to biomethanol production in dispersed, small plants using local biomass for end-users from the same geographical area, thus contributing to regional sustainability. [ABSTRACT FROM AUTHOR]

• The highest conversion of CO 2 into carbon biomass was reached at pH 7. • The theoretical maximal biological conversion of CO 2 was estimated to be ca. 60 %. • Lower and higher pH favoured respectively the amoebae and copepod development. • pH can be a tool for favouring one microalgal species among a natural assemblage. Recently, CO 2 recycling for the production of valuable microalgae has acquired substantial interest. Most studies investigating CO 2 conversion efficiency in algal cultures were based on single species, although a stabilising effect of algal diversity on biomass production was recently highlighted. However, addition of CO 2 into polyalgal cultures requires a careful control of pH; performance of CO 2 conversion, growth and carbon biomass production are affected by pH differently, depending on the species of microalgae. This study investigates the efficiency of CO 2 conversion by natural marine algal assemblage cultivated in open, land-based raceways (4.5 m3, 10 m2), working as high rate algal ponds (HRAP). Ponds were enriched with nitrogen and phosphate, pure CO 2 was added and algal cultures were grown under three different fixed pH levels: pH 6, 7 and 8. The highest conversion of photosynthetically fixed CO 2 into carbon biomass (40 %) was reached at pH 7, an intermediate level, due to the partial CO 2 asphyxiation of algal predators (copepods, ciliates), while being under the suboptimal conditions for the development of marine amoebae. Under this pH, the theoretical maximal biological conversion of available CO 2 into carbon biomass was estimated to be 60 % in naturally inoculated open ponds. [ABSTRACT FROM AUTHOR]

Biological production of citramalate has garnered attention due to its wide application for food additives and pharmaceuticals, although improvement of yield is known to be challenging. When glucose is used as the sole carbon source, carbon loss through decarboxylation steps for providing acetyl-CoA from pyruvate is inevitable. To avoid this, we engineered a strain to co-utilize glucose and cost-effective acetate while preventing carbon loss for enhancing citramalate production. The production pathway diverged to independently supply the precursors required for the synthesis of citramalate from glucose and acetate, respectively. Moreover, the phosphotransferase system was inactivated and the acetate assimilation pathway and the substrate ratio were optimized to enable the simultaneous and efficient utilization of both carbon sources. This yielded results (5.0 g/L, 0.87 mol/mol) surpassing the yield and titer of the control strain utilizing glucose as the sole carbon source in flask cultures, demonstrating an economically efficient strain redesign strategy for synthesizing various products.

• Dissolved organic carbon (DOC) yields were calculated for river systems in Maine. • DOC yields (kg C/ha/season) were similar between tributaries and major river outlets. • DOC yields were similar moving downstream on the main stems of major rivers. • The evidence points towards conservative transport of DOC in Maine rivers. Transport and fate of dissolved organic carbon (DOC) in rivers are important aspects of the carbon cycle and the critical linkage between terrestrial, aquatic, and marine systems. Recent studies have quantified fluvial export to the marine environment in many systems, but in-stream losses of DOC are poorly constrained. This study compares DOC yields (kg C/ha) between the area-weighted averages of several tributaries within larger watersheds with the DOC yields of the larger watersheds to gain insight on in-stream losses in larger river systems. Four large watersheds, 22 tributaries to those watersheds, and 5 additional main stem locations in Maine were studied during 1 April to 15 November in 2011 through 2013. There were no significant differences in the area-weighted average DOC yield of the tributaries and the larger watersheds indicating little net in-stream loss in the main stems of the larger rivers. It is unlikely that inputs of DOC from un-gauged areas compensated for losses from gauged tributaries based on similarity in DOC yield longitudinally along the main stems of two of the rivers. In addition, wetland abundance, which is associated with higher DOC yield in this environment, did not consistently increase from tributaries to the larger watershed or longitudinally along the main stems. This geographic distribution of wetlands therefore also indicates that it is unlikely that inputs of DOC from un-gauged areas compensated for losses from gauged tributaries. These findings suggest that in-stream losses of DOC in these larger river systems are minimal and that the vast majority of DOC in major rivers in Maine is transported conservatively to the coastal ocean. [ABSTRACT FROM AUTHOR]

Abstract Owing to the low cost and abundant resource of sodium, sodium-ion batteries demonstrate bright application prospects for large-scale energy storage systems. Microstructure-controlled amorphous carbon with proper surface area and high electronic conductivity is considered to be one of the most promising anode material. Nevertheless, the cost of the reported carbon materials is still high because of the low carbon yield and expensive precursors. Besides, the low initial coulombic efficiency is also a big challenge. Herein, a high-yielding (70%) microstructure-controlled amorphous carbon is achieved via a pre-oxidation stabilization process and following carbonization of the mixed pitch and phenol formaldehyde resin precursor. The effects of pre-oxidation stabilization on adjusting the microstructure of amorphous carbon are systematically investigated, as well as the electrochemical performance. The optimal sample exhibits high initial coulombic efficiency (82%), high reversible capacity (268.3 mAh g−1 at 0.1 C) and good rate capability (106 mAh g−1 at 4 C) as an anode material of sodium-ion batteries. This high-performance amorphous carbon material is prepared via a controllable and low-cost strategy, presenting an appealing development of practical anode materials for sodium-ion batteries. Graphical abstract Image 1 Highlights • High yielding amorphous carbon is obtained via an oxidative stabilization strategy. • In-situ FTIR spectroscopy presents the interaction between the precursors. • The controlled disordered structures lead to a high initial coulombic efficiency. • The carbon shows good electrochemical properties in both half cells and full cells. [ABSTRACT FROM AUTHOR]

Due to concerns regarding fossil greenhouse gas emissions, biogenic material such as forest residues is viewed nowadays as a valuable source of carbon atoms to produce syngas that can be used to synthesise biofuels such as methanol. A great challenge in using gasified biomass for methanol production is the large excess of carbon in the syngas, as compared to the H2 content. The water–gas shift (WGS) reaction is often used to add H2 and balance the syngas. CO2 is also produced by this reaction. Some of the CO2 has to be removed from the gaseous mixture, thus decreasing the process carbon yield and maintaining CO2 emissions. The WGS reaction also decreases the overall process heat output. This paper demonstrates the usefulness of using an extra source of renewable H2 from steam electrolysis instead of relying on the WGS reaction, for a much higher performance of syngas production from gasification of wood in a simple system with a fixed-bed gasifier. A commercial process simulation software is employed to predict that this approach will be more efficient (overall energy efficiency of about 67%) and productive (carbon conversion yield of about 75%) than relying on the WGS reaction. The outlook for this process that includes the use of the solid oxide electrolyser technology appears to be very promising because the electrolyser has the dual function of providing all of the supplemental H2 required for syngas balancing and all the O2 required for the production of a suitable hot raw syngas. This process is conducive to biomethanol production in dispersed, small plants using local biomass for end-users from the same geographical area, thus contributing to regional sustainability.

Polyacrylonitrile (PAN) copolymers are important precursors for making high performance carbon fibers. In this study, a type of inert comonomer, methyl acrylate (MA), was copolymerized with AN, and the effects of AN sequence distribution on the cyclization, oxidation and carbon yield were systematically studied. The sequence distribution of P(AN-co-MA) could be adjusted by altering MA/AN feeding ratio during radical polymerization. The number-average sequence length of AN in the copolymers decreases quickly along with the increase of MA content in PAN. The stabilization and carbonization weight losses were determined by thermogravimetric analysis, and the corresponding chemical changes were detected by Fourier transform infrared spectrums and X-ray photoelectron spectroscopy. The thermal cyclization and oxidation reactions were separated by altering gas environment from nitrogen to air, and were monitored by differential scanning calorimetry. It is concluded that the sequence distribution of AN in P(AN-co-MA) strongly affects reaction activation energies, cyclized structures and carbon yield. [ABSTRACT FROM AUTHOR]

There is currently a strong interest to derive the biological precursor cis,cis-muconic acid from shikimate pathway-branches to develop a biological replacement for adipic acid. Pioneered by the Frost laboratory this concept has regained interest: Recent approaches (Boles, Alper, Yan) however suffer from low product titres. Here an in silico comparison of all strain construction strategies was conducted to highlight stoichiometric optimizations. Using elementary mode analysis new knock-out strategies were determined in Saccharomyces cerevisiae and Escherichia coli. The strain construction strategies are unique to each pathway-branch and organism, allowing significantly different maximum and minimum yields. The maximum theoretical product carbon yields on glucose ranged from 86% (dehydroshikimate-branch) to 69% (anthranilate-branch). In most cases a coupling of product formation to growth was possible. Especially in S. cerevisiae chorismate-routes a minimum yield constraint of 46.9% could be reached. The knock-out targets are non-obvious, and not-transferable, highlighting the importance of tailored strain construction strategies.

The aim of this work is to study the pyrolysis of polymer precursors to carbon at lower temperatures using a catalyst. We have added different weight ratios of nickel acetate tetrahydrate (NiAc) and multi-walled carbon nanotubes (MWCNTs) as catalysts into two different precursors, polyacrylonitrile (PAN) and resorcinol-formaldehyde (RF), separately. PAN composite was stabilized whereas RF composite was dried under sub-critical conditions followed by pyrolysis carried out at different temperatures. To examine the effect of pyrolysis temperature and catalyst concentration, PAN- and RF-derived carbons were characterized by elemental analysis, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, Fourier transform infrared spectrophotometer and small angle X-ray scattering, respectively. It was found that addition of NiAc facilitated similar carbon yield at much lower temperature than what was obtained without a catalyst. The addition of MWCNTs enhanced the crystallinity of carbon samples, which is otherwise possible only by higher heat treatment. This study clearly suggests adopting catalyst-assisted less energy intensive low temperature pyrolysis for polymer precursors to carbon with better yield as well as crystallinity. [ABSTRACT FROM AUTHOR]

A type of photoheterotrophic bacteria contain a transmembrane light-driven proton pump called proteorhodopsins (PRs). Due to the prevalence of these organisms in the upper water column of the World’s Ocean, and their potential for light driven ATP generation, they have been suggested to significantly influence energy and matter flows in the biosphere. To date, evidence for the significance of the light-driven metabolism of PR-containing prokaryotes has been obtained by comparing growth in batch culture, under light versus dark conditions, and it appears that responses to light are linked to unfavorable conditions, which so far have not been well parameterized. We studied light responses to carbon yields of the PR-containing Photobacterium angustum S14 using continuous culture conditions and light-dark cycles. We observed significant effects of light-dark cycles compared to dark controls, as well as significant differences between samples after 12 h illumination versus 12 h darkness. However these effects were only observed under higher cell counts and lower pH associated with higher substrate concentrations. Under these substrate levels Pirt’s maintenance coefficient was higher when compared to lower substrate dark controls, and decreased under light-dark cycles. It appears that light responses by Photobacterium angustum S14 are induced by the energetic status of the cells rather than by low substrate concentrations.

A crucial challenge associated with high-density, commercial-scale, outdoor microalgal cultivation is maintaining pH stability without excessive use of CO 2 buffering. This includes a media-dependent, intracellular metabolic proton imbalance leading to the alkalization or acidification of growth media that results when algae consume, respectively, nitrate or ammonium ions. Feeding these two nitrogen sources can theoretically achieve balanced proton metabolism as well as pH control that is economically more favorable as compared to CO 2 buffering or acid/base addition. To accomplish this, a fed-batch nutrient feeding strategy must be adopted as a component of a model-based pH control system, particularly in the case of ammonium preference. This work represents a preliminary study of the challenges of implementing a nitrogen metabolism based open-loop pH control strategy in the challenging environment of an outdoor photobioreactor at the DOE-ATP 3 testbed facility in Mesa, Arizona during the high solar insolation period of summer 2015. The approach was limited to twice daily fed-batch addition while accounting for ammonium-N preference in a background of nitrate-based algae growth media. Despite these limitations, growth achieved for a photobioreactor operated based on predicted metabolic nitrogen demand (PND) was comparable to ‘CO 2 -on-demand’ (CoD) for pH control. PND reduced CO 2 usage to < 10% of CoD control, where the reduced buffering resulted in much greater pH fluctuations due to daily variations in light availability, and a much lower and more consistent media alkalinity (5.73–5.79 mEq/L) as compared to the CoD control (6.51–8.49 mEq/L). While this effort illustrates the utility of feed-forward model-based control, it further illustrates the need for far more sophisticated ‘real time’ monitoring and modeling to accommodate the dynamic outdoor conditions. A need for improved analytics for accurate closure of nitrogen mass balance is also indicated. [ABSTRACT FROM AUTHOR]

CNTCOOH was prepared from oxidation of carbon nanotube. Subsequently, CNTSi was prepared by grafting (3-glycidyloxypropyl) trimethoxysilane (GPTES) to the surface of CNTCOOH by a ring opening reaction of epoxy groups. Then, CNTA was obtained by formation of silicon oxide network between CNTSi and tetraethyl orthosilicate (TEOS). Finally, CNTA was used as an additive in novolac resin matrix to yield RCNTA composites with high carbon yield values. Additionally, modification of novolac resin by GPTES gives MR with silicon ethoxide moieties on its structure. Then, MRCNTA composites were obtained by formation of silica/siloxane network from MR, CNTSi, and TEOS. RCNTA composites were thermally compared with MRCNTA composites. Results from Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis showed that CNT and novolac resin were successfully modified. Aerogel formation was proved by Raman, X-ray diffraction, and scanning and transmission electron microscopies. BET shows that incorporation of CNT into the aerogel network results in lower cumulative pore volume value. The pore size of SA and CNTA ranges from 2 to about 100 nm which shows that both of them can be included in the mesoporous materials category. Finally, MRCNTA composites reached to the maximum increase of char yields; 11.94% increase of char yield was achieved by MRCNTA4 composite. [ABSTRACT FROM AUTHOR]

The use of algae as a potential platform for fuels or biochemical production requires process design and control that can be implemented at agronomic scales. Toward achieving pH control in large unmixed systems, we present a rigorous set of direct measurements of non-buffered proton uptake and efflux during growth on ammonium and nitrate, observing nearly unit molar proton imbalance H/OH respectively for these nitrogen sources. This proton imbalance can be shown to be consistent with the initial assimilation steps of nitrogen from glutamate to peptide bonds which indicates that the remainder of metabolism is largely net proton balanced. These results are refined by demonstrating pH balance for growth with incrementally fed nitric acid and ammonium hydroxide. In contrast to the typical assumption of simple charge balance, each displays a slight proton uptake (around 10 % excess) that is considerably lower than urea, which displayed a molar H uptake per N assimilated of up to 33 %. This work illustrates details of proton imbalance that have been largely obscured in laboratory work due to use of elevated CO and its associated carbonate equilibrium. Combined with the recent demonstration of preferential, mutually exclusive assimilation of ammonium over nitrate in Chlorella and Chlamydomonas, these results provide the stoichiometry and dynamics of photosynthetic algae growth needed to implement large-scale pH control in the absence of buffering. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) modified with furfuryl alcohol and (3-aminopropyl) triethoxysilane (GOFASi) was used in two separate ways for preparation of novolac resin nanohybrids. In the first procedure, graphene-containing silica aerogel (GA) was obtained by incorporation of GOFASi into silica aerogel network using tetraethyl orthosilicate (TEOS). Then, GA was used as an additive in novolac resin matrix. In the second procedure, the synthesis of a hybrid novolac resin was accomplished by network formation via the reaction of GOFASi with (3-glycidyloxypropyl)trimethoxysilane-modified novolac resin and TEOS. The thermal stability and the carbon yield of the hybrid resins obtained by the two procedures were compared. Fourier transforms infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis showed that both GO and the novolac resin were successfully modified. Aerogel formation was proved by Raman, X-ray diffraction, N 2 adsorption and desorption isotherms, and by scanning and transmission electron microscopies. [ABSTRACT FROM AUTHOR]

The effect of operating variables (reaction temperature, space velocity, and partial pressure of the carbon source) on carbon yield was determined for synthesizing MWCNTs by catalytic chemical vapor deposition using ethylene as the carbon source in a batch type fluidized bed reactor. Stable fluidization was maintained using the MWCNT agglomerate as the initial bed material and MWCNTs with high selectivity were synthesized. The optimal reaction temperature for the maximum carbon yield was 983 K and the apparent activation energy was 102 kJ/mol. The maximum carbon yield occurred at the space velocity of 136 h −1 . The carbon yield increased with increasing partial pressure of ethylene. However, the synthesis reaction of MWCNTs did not proceed at partial pressures above 0.63. A correlation is proposed to predict the yield of MWCNTs. [ABSTRACT FROM AUTHOR]

A type of photoheterotrophic bacteria contain a transmembrane light-driven proton pump called proteorhodopsins (PRs). Due to the prevalence of these organisms in the upper water column of the World's Ocean, and their potential for light-driven ATP generation, they have been suggested to significantly influence energy and matter flows in the biosphere. To date, evidence for the significance of the light-driven metabolism of PR-containing prokaryotes has been obtained by comparing growth in batch culture, under light versus dark conditions, and it appears that responses to light are linked to unfavorable conditions, which so far have not been well parameterized. We studied light responses to carbon yields of the PR-containing Photobacterium angustum S14 using continuous culture conditions and light-dark cycles. We observed significant effects of light-dark cycles compared to dark controls, as well as significant differences between samples after 12 h illumination versus 12 h darkness. However, these effects were only observed under higher cell counts and lower pH associated with higher substrate concentrations. Under these substrate levels Pirt's maintenance coefficient was higher when compared to lower substrate dark controls, and decreased under light-dark cycles. It appears that light responses by P. angustum S14 are induced by the energetic status of the cells rather than by low substrate concentrations. [ABSTRACT FROM AUTHOR]

Methane is the most stable hydrocarbon and the highest component of natural gas. The occurrence of vast resources of natural gas promotes the catalytic decomposition of methane to produce hydrogen and valuable carbon. Hydrogen is an excellent energy carrier and can play a very significant role in energy systems. The present study explored the decomposition of methane by iron catalyst to produce hydrogen and carbon. The catalysts were calcined at 700 °C and reduced with pure H 2 at 650 °C. The reaction was carried out at 700 °C. The study involved the use of different iron loadings (15–100%) supported on alumina catalysts obtained by co-precipitation technique. The yield of hydrogen production was investigated. Spent and fresh catalysts were characterized by BET, XRD, H 2 -TPR, TGA, EDS and HRTEM. The catalyst characterization revealed the formation of multi-walled nanotubes from alumina supported iron catalysts. Alternatively, time on stream tests of the supported catalyst for about 4 h at 700 °C showed the relative profiles of hydrogen production and hydrogen yield increased as the % loading of Fe was increased. The maximum H 2 yield of 77.2% was obtained using 60% Fe/Al 2 O 3 catalyst. Higher Fe loadings decreased the surface area of the catalyst. [ABSTRACT FROM AUTHOR]

The rapid heating of biomass in an oxygen-free environment optimizes the yield of fast-pyrolysis liquids. This liquid comprises a mix of acids, (dehydrated) carbohydrates, aldehydes, ketones, lignin fragments, aromatics, and alcohols, limiting its use. Deoxygenation of these liquids to replace hydrocarbons represents significant challenges. Catalytic pyrolysis is seen as a promising route to yield liquids with a higher quality. In this paper, literature data on catalytic fast pyrolysis of biomass are reviewed and deoxygenation results correlated with the overall carbon yield. Evidence is given that in an initial stage of the catalytic process reactive components are converted to coke, gas, and water, and only to a limited extent to a liquid product. Catalysts are not yet good enough, and an appropriate combination of pyrolysis conditions, reactive products formed, and different reactions to take place to yield improved quality liquids may be practically impossible. [ABSTRACT FROM AUTHOR]

In this article, we studied the synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) over Co3O4, Fe2O3-Co3O4, and NiO-Co3O4catalyst nanoparticles supported by MgO powder at 600–900°C. The size of the catalyst nanoparticles was controlled by changing metal nitrates concentration in aqueous solution by impregnation method. The most important strategy (part) of this research is that synthesis of CNTs was started suddenly without any preheating of catalyst nanoparticles. The yield of CNTs is much higher than with conventional preheating processes of catalyst nanoparticles on growth of CNTs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Slow pyrolysis of rice straw was investigated for temperatures of 300–700°C. [•] Biochar had a mass yield of about 25% from the organic fraction above 500°C. [•] Biochar was the primary product containing 40% of energy and 45% of carbon. [•] Bio-oil and light gases had about 60% of energy yield in total. [•] Drying of raw material was crucial to efficiently utilize the gases for process heat. [ABSTRACT FROM AUTHOR]

Hyperbranched polyborate (HBPB) is a new hyperbranched polymer with excellent thermal resistance, which can be used to improve the thermal stability, especially carbon yield, of phenolic resin (PR). In the present paper, thermal properties and curing degrees of the blends of PR and HBPB (PR-HBPB blends) are investigated. It is found that the curing degrees of PR-HBPB blends would be decreased, and the decrease of curing degree can be attributed to the improper ratio of phenol groups of HBPB to hydroxymethyl groups of PR. Paraformaldehyde (PFM) is introduced to remedy the deficiency of hydroxymethyl groups in PR-HBPB blends. The curing degrees of PR-HBPB blends are improved and the carbon yields of the blends of PR, HBPB, and PFM (PR-HBPB-PFM blends) can be up to 75-80% at 800°C in nitrogen. PR-HBPB-PFM blends can be explored as novel precursors for carbon materials with excellent properties, ease of preparation and low cost. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The influence of different activation conditions, including activating agent/CNFs mass ratio, activation temperature, activation time and He flow rate, on the pore structure development of herringbone carbon nanofibers (CNFs) has been studied. Activation conditions with a KOH/CNFs mass ratio=5/1, activation temperature=850°C, activation time=3h and He flow rate=700mLmin−1 gave rise to a material with a very high micropore volume, a quite narrow micropore distribution and the highest surface area (increased by a factor of 4.5 in comparison to the raw CNFs). The conditions outlined above also led to the creation of some mesopores in the activation process due to the strong interaction between the CNFs and the activating agent. On the other hand, the use of other activation conditions led to activated CNFs with different structural properties. For example, activated CNFs with the lowest mesopore volume were obtained when the activation conditions were KOH/CNFs mass ratio=5/1, activation temperature=900°C, activation time=3h and He flow rate=500mLmin−1. Therefore, depending on the final application of the activated CNFs, it is possible to control their pore structure by selecting appropriate activation conditions. [Copyright &y& Elsevier]

This study reports the dual-functions of ferrous sulfate, i.e. as a carbon-yield-enhancer and as a pore-size-controller, in the preparation of porous carbons from rice straws. Through the impregnation of rice straws with 0.5 M aq. FeSO4, the carbon yield of the resultant porous carbons increased by ca. 10% and the size of the newly created pores was precisely controlled at the diameter of 0.53 nm during carbonization process. The observed results were discussed from the view points of the thermal degradation mechanism of cellulose and the pillar effects by the in-situ formed crystallites of Fe3O4. The inherent magnetic property due to the presence of magnetite, Fe3O4, was an additional merit of the obtained porous carbons. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanofibers (CNFs) were prepared by the catalytic decomposition of ethylene over Ni/Y-zeolite at 550°C, followed by catalyst removal with hydrofluoric acid. The demineralised CNFs were impregnated in an aqueous solution of Ni(II) nitrate. The CNF-supported Ni exhibited high catalytic activity in the CVD synthesis of CNFs, proving that the structured CNF support served to stabilize Ni activity. Results clearly indicated that careful control of temperature and H2 content was important to achieve the desired product. Changing the total flow rate did not seem to alter the type of carbon deposited but did change the deposition rate. [Copyright &y& Elsevier]

Abstract: Changes in the gas composition during the methane chemical vapor deposition growth of single- and double-walled carbon nanotubes over metal-supported MgO catalysts were investigated in an attempt to increase the nanotube yield. Monitoring the gas composition by gas chromatography as a function of the reaction time provides information on the activity and lifetime of the catalyst. The degree of methane decomposition, i.e., the C–H bond dissociation, was closely related to the nanotube yield, and the Fe–Mo binary catalyst exhibited a high activity. The effects of water vapor on the catalytic nanotube growth were also studied by introducing water vapor in the inlet gas. An appropriate amount of water prolonged the lifetime of the catalyst and increased the nanotube yield by 35%. [Copyright &y& Elsevier]

Abstract: Ordered mesoporous carbon materials were successfully synthesized by the carbonization of sulfuric-acid-treated silica/triblock copolymer/sucrose composites. In the current approach, triblock copolymer P123 and sucrose were employed as both structure-directing agents for self-assembly of tetraethyl orthosilicate and carbon precursors, and sulfuric acid was used to cross-link P123 and sucrose in the as-synthesized composites in order to improve the carbon yield. When the weight ratio of sucrose relative to P123 was 1:4, ordered mesoporous carbon (C-S) with hexagonally arranged pore centered at 3.0nm was synthesized. However, when the weight ratio was increased to 1:2, the obtained carbon material (C-S-1) exhibited low-ordered pore structure. In addition, thermogravimetric analysis revealed that C-S consisted of ca. 26wt.% sucrose carbon and ca. 74wt.% P123 carbon, and there was noticeable interaction between sucrose and P123, where P123 was a key substance for the formation of ordered mesostructure, and sucrose was responsible for the increased carbon yield. [Copyright &y& Elsevier]

Abstract: In this study, we prepared a type of arylacetylene, poly(p-phenylene butadiynylene), PPPB, and studied its pyrolysis behavior. A pellet of PPPB maintained its shape and provided a carbonization yield of 94% by heat-treatment at 1000°C, although it experienced exothermal reaction and partial fusion at approximately 200°C. It was also found that PPPB did not show graphitization even when it was heat-treated at 3000°C. X-ray diffraction (XRD) study revealed the breakdown of the initial crystal structure of PPPB at 200°C and a formation of the carbon structure at above 650°C. By combining the results of TG–MS, FT-IR, and 13C NMR, a mechanism for pyrolysis of PPPB including the cross-link formation was proposed, which included a Diels–Alder type reaction between the terminal acetylene and the diene structure comprising of diacetylene and phenyl groups, which is facilitated by increased mobility due to the partial fusion and the presence of the terminal acetylene groups. [Copyright &y& Elsevier]

Abstract: The methane conversion and carbon yield of the chemical vapor deposition (CVD) reaction suggests that the optimum reaction conditions of the formation of multi-wall carbon nanotubes (MWCNTs) can be obtained by using a 50mg of nano-MgNi alloy under pyrolysis of the pure CH4 gas with the flow rate about 100–120cm3/min at 650°C for 30min. Raman results indicate the CNTs are in multi-wall structure, since no single-wall characteristic features appearing in the 200–400cm−1 region. This is consistent with those of the XRD and TGA findings. Under selected condition, the carbon yield and the CNTs purity can reach up to 1231% and 92% in the presence of hydrogen. It is presumable that the presence of hydrogen in the pyrolysis of CH4 prevents the deactivation of catalysts and enhances the graphitization degree of CNTs. In addition, the presence of Mg metal in the alloy can prevent the aggregation of the Ni metal and forms the active Mg2Ni phase to enhance the CH4 pyrolysis to form CNTs. After the purification procedures with both air oxidation at 550°C and HCl treatments, the final purified yield and purity of CNT reach to 73.2% and (98.04±0.2)% respectively. [Copyright &y& Elsevier]

Abstract: Highly ordered MCM-41 mesoporous molecular sieves in which silicon was isomorphously substituted with 0.5–4wt.% cobalt were synthesized using an alkyl template with a 16 carbon atoms alkyl chain length. These materials were used as catalysts for the synthesis of uniform diameter single wall carbon nanotubes (SWNT) by CO disproportionation (Boudouard reaction). The SWNT synthesis conditions were identical for all Co-MCM-41 samples, and consisted of pre-reduction of the Co-MCM-41 catalyst in hydrogen at 500°C for 30min followed by reaction with pure CO at 800°C and 6atm for 1h (conditions previously optimized for 1wt.% Co-MCM-41). The SWNT grown in the Co-MCM-41 catalysts were characterized by TGA, multi-excitation energy Raman spectroscopy and TEM. The state of the catalyst and the size of the metallic cobalt clusters formed in Co-MCM-41 during the SWNT synthesis were characterized by X-ray absorption spectroscopy. The mechanism controlling the diameter distribution of the SWNT produced is related to the size uniformity of the cobalt clusters nucleated in the Co-MCM-41 catalytic template: the SWNT growth selectivity and size uniformity is influenced by the cobalt concentration in the framework. If the cobalt is not initially strongly stabilized in the MCM-41 framework during template synthesis, the catalyst produces SWNT with a wider diameter distribution. Co-MCM-41 catalysts with up to 3wt.% cobalt can be used to grow SWNT with a diameter distribution similar to that obtained with 1wt.% Co-MCM-41, but at yields greater by a factor of approximately 2.4. [Copyright &y& Elsevier]

Abstract: We report the successful optimization of single-wall carbon nanotube (SWCNT) synthesis by catalytic chemical vapor deposition (CCVD) on FeMo/MgO catalyst using acetylene as carbon source. Taking a starting parameter set from the literature we optimized seven (catalyst composition, catalyst amount, reaction temperature, reaction time, preheating time, C2H2 volumetric flow rate, inert gas volumetric flow rate) factors to our local experimental system by relying on statistical design of experiments (DoE). Performance was assessed using two quantitative descriptors: mass of carbonaceous material formed and SWCNT content as calculated from FT-Raman spectra. The parameter space was first screened for important factors using a fractional factorial design, then the response surface defined by the three most significant parameters was obtained from Box–Behnken design and the optimal parameter set was found. The superiority of the DoE method over the conventional COST (change one separate factor at a time) approach is shown by the fact that we were able to optimize seven individual factors with only 21+2 runs. The described method can readily be used to swiftly adapt a literature-based CCVD process to the local instrumentation of any laboratory. [Copyright &y& Elsevier]

Abstract: The synthesis of carbon nanotubes (CNTs) through the catalytic decomposition of acetylene was carried out over gold nanoparticles supported on SiO2–Al2O3. Monodispersed gold nanoparticles with 1.3–1.8nm in diameter were prepared by the liquid-phase reduction method with dodecanethiol as protective agent. The carbon products formed after acetylene decomposition consist of multi-walled carbon nanotubes with layered graphene sheets, carbon nanofilaments (CNFs), and carbon nanoparticles encapsulating gold particles. The observed CNTs have outer diameters of 13–25nm under 850°C. The influence of several reaction parameters, such as kind of carriers, reaction temperature, gas flow rate, was investigated to search for optimum reaction conditions. The CNTs were observed at a relatively low temperature (550°C). The silica–alumina carrier showed higher activity for the formation of CNTs than others used in the screening test. With increasing temperature, the CNTs showed cured structures having thick diameters and inside compartments. When Au content on the support was over 5wt.%, the gold nanoparticles coagulated to form large ones >20nm in diameter and became encapsulated with graphene layers after decomposition of acetylene. [Copyright &y& Elsevier]

Abstract: Gd@C82 and Gd2@C80 were selectively reduced and extracted from the raw soot in a high yield by using Al–Ni alloy in toluene/tetrahydrofuran (THF). By tuning the ratio of toluene and THF, Gd2@C80 with purity higher than 95% was isolated directly from the raw soot without high performance liquid chromatography (HPLC) purification. Furthermore, we found that the anions of Gd@C82 and Gd2@C80 could react with aqueous NaOH to form water-soluble Gd–metallofullerols, which are potential magnetic resonance imaging contrast agents. [Copyright &y& Elsevier]

Abstract: A system combining pulse chemical vapor deposition (CVD) reaction and cryogenic gas sorption (BET) measurement capabilities was designed to allow the sequential synthesis and online analysis of single-wall carbon nanotubes (SWNTs). Cooling treatment in liquid nitrogen (77K) during BET measurement was found to be efficient for restoring catalysts when deactivation occurs after carbon deposition. By this treatment, the methane conversion could be enhanced by up to seven times, such as from 5.8% to 42.6% mol. When the temperature changes from 850°C to 77K, the metal particles on the tip of nanotubes might contract and be separated from the graphite layer of the nanotubes, leading to more active sites on metal particles being exposed. The single point BET analysis of SWNT has been tested as an efficient method for the rapid online analysis of SWNTs produced by CVD. [Copyright &y& Elsevier]

High-loaded Ni–SiO2 and Fe–SiO2 catalysts (85–90 wt.% of metal) for methane decomposition were prepared by the heterophase sol–gel method and studied at various stages of their preparation and operation using XRD, IR, TPR, TEM techniques and the stoichiographic method of differentiating dissolution. Carbon yield was demonstrated to depend on the interaction between nickel and silica. The yield equal to 384 g C/g Ni was characteristic of the catalyst free of silicates, while the presence of silicates in amount of 1.5–2 wt.% caused a decrease in the carbon yield to 40 g C/g Ni. The effect of silicates comprised in iron catalysts is not so unambiguous as for nickel catalysts, they can both inhibit and promote the process of carbon formation. [Copyright &y& Elsevier]

The toluene insoluble portion of petroleum pitch A240 was oxidized using pure oxygen under high pressures in the range of 100–500 psi. The effects of oxidation temperature, pressure and time on the percentage of weight gain were investigated. Carbonization of the oxidized pitch samples indicated that the pitch samples were well stabilized after high pressure oxidation. Analyses of X-ray diffraction and Raman spectra showed that the pitch samples, after high pressure oxidation, changed from an easily graphitizable carbon material to non-graphitizable. Measurements of carbon yield showed a decrease with the increase of oxidation weight gain. [Copyright &y& Elsevier]

Microbial cell factories using a single carbon source (e.g., sugars) have been used to produce a wide variety of chemicals. However, this process is often accompanied by stoichiometric constraints on carbons and redox cofactors. Here, a synthetic pathway was designed and constructed in Escherichia coli to synergistically use glucose and formate as mixed carbon sources. By optimizing this synthetic pathway via enzyme mining, protein engineering, and bioprocess approaches, the yield of pyruvate from glucose was enhanced to 94% of the theoretical glycolysis yield, reaching 1.88 mol/mol. Finally, the optimized synthetic pathway was integrated with a phosphite reductase-based NADH regeneration system in malate-producing E. coli , resulting in the conversion of glucose into l-malate with a high yield of up to 1.65 mol/mol. This synergistic carbon metabolism strategy can be used to establish carbon- and energy-efficient productive processes.

• Synthesis of p-conjugated poly(phenylacetylene) derivatives for carbon precursors. • Poly(PA-A) shows 90% C-yield but poor solubility. • Poly(PA-PA) shows 80% C-yield, good solubility, and facile thermal transformation. • Smooth dark-red poly(PA-PA) fibers were prepared using electrospinning. • The resulting carbon fibers exhibit a desirable polymorphous morphology. This paper investigates a family of poly(phenylacetylene) derivatives with a p-electrons conjugated polymer backbone and side groups containing only sp2 and sp carbons. The objective is to identify the suitable carbon precursor that is processible and can be transformed to carbonaceous material with high carbon yield by a simple (one-step) thermal transformation process (without any external reagent). Poly(phenylacetylene) with para -substituted acetylene group poly(PA-A) shows an exceptionally high C-yield (~90%) in one-step heating from ambient temperature to 1000 °C under N 2 atmosphere. Unfortunately, this poly(PA-A) polymer is quite sensitive to heat and light with very limited solubility. On the other hand, poly(phenylacetylene) with para -substituted phenylacetylene group, i.e. poly(PA-PA), offers a relatively high C-yield (~80%) and also good solubility in common organic solvents, such as toluene and tetrahydrofuran (THF). Several uniform dark-red poly(PA-PA) fibers with smooth surface and fiber diameter in the range of 3–6 μm were prepared from 30 wt% poly(PA-PA)/THF solution using electrospinning technique. The resulting precursor fibers were converted to the corresponding carbon structure in a one-step thermal heating process under N 2 atmosphere. Both X-ray and Raman spectra show the polymorphous carbon morphology with the graphene crystalline domains. [ABSTRACT FROM AUTHOR]