Graduate student/RA, Washigton State University
Chromatographic techniques are widely used to detect oxygenated compounds in jet fuel.
Jet fuel is a complex mixture of hundreds of species including normal alkanes, cycloalkanes, branched alkanes and aromatics. Except these, other non- hydrocarbon compounds such as oxygen, sulfur, and nitrogen hetero-atomic species are also present in trace quantities. The important classes of these trace compounds include phenols, indoles, thiophenes, amines and others. The concentration of polar species in jet fuel such as phenols are detrimental to engines and the concentration of these oxygenated compounds are responsible for thermal instability of engine and potential hazards to aircraft. Therefore, detection of these trace amounts of oxygenated compounds are vital in fuel industry. So, development of new analytical technique (biosensor) to detect oxygenated molecules in jet-A will be beneficial in fuel-industry.
Abstract: In this research work, electrochemical biosensor was fabricated based on immobilization of tyrosinase onto graphene-decorated gold nanoparticle/chitosan (Gr-Au-Chit/Tyr) nanocomposite-modified screen-printed carbon electrode (SPCE) for the detection of phenolic compounds. The nanocomposite film was constructed via solution casting method. The electrocatalytic activity of the proposed biosensor for phenol detection was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Experimental parameters such as pH buffer, enzyme concentration, ratio of Gr-Au-Chit, accumulation time and potential were optimized. The biosensor shows linearity towards phenol in the concentration range from 0.05 to 15 μM with sensitivity of 0.624 μA/μM and the limit of detection (LOD) of 0.016 μM (S/N = 3). The proposed sensor also depicts good reproducibility, selectivity and stability for at least one month. The biosensor was compared with high-performance liquid chromatography (HPLC) method for the detection of phenol spiked in real water samples and the result is in good agreement and comparable.
Pub.: 17 May '17, Pinned: 20 Jun '17
Abstract: Nowadays, biosensor technologies which can detect various contaminants in water quickly and cost-effectively are in great demand. Herein, we report an integrated channel waveguide-based fluorescent immunosensor with the ability to detect a maximum of 32 contaminants rapidly and simultaneously. In particular, we use waveguide tapers to improve the efficiency of excitation and collection of fluorescent signals in the presence of fluorophore photobleaching in a solid surface bioassay. Under the optimized waveguide geometry, this is the first demonstration of using such a type of waveguide immunosensor for the detection of microcystin-LR (MC-LR) in lake water. The waveguide chip was activated by (3-Mercaptopropyl) trimethoxysilane/N-(4-maleimidobutyryloxy) succinimide (MTS/GMBS) for immobilization of BSA-MC-LR conjugate, which was confirmed to have uniform monolayer distribution by atomic force microscopy. All real lake samples, even those containing MC-LR in the sub-microgram per liter range (e.g. 0.5 μg/L), could be determined by the immunosensor with recovery rates between 84% and 108%, confirming its application potential in the measurement of MC-LR in real water samples.
Pub.: 18 Jun '17, Pinned: 20 Jun '17
Abstract: In recent years, the production of bio-aviation fuels has received increased attention because of its renewability and environmental benefits. Catalytic hydrocracking is a convenient way to produce bio-jet fuel from vegetable oil. Among the different types of catalysts, sulphided zeolites showed more catalytic activity for bio-fuel conversion. However, the uses of different sulphiding agents in this process causes the emission of H2S gas and exposes the environment to sulphur residues, which are responsible for pollution and the greenhouse effect. Conversely, various non-sulphide zeolite catalysts, such as noble metal supported on ZSM-5, HZSM-5, SAPO-11, beta- zeolite, SBA-15 and mesoporous-Y zeolite, also showed considerable activity for bio-fuel conversion. Therefore, it is time to improve the non-sulphide zeolite catalysts for the production of bio-jet fuel to combat fuel recession and mitigate environmental problems. Several good reviews are available on the catalytic conversion of bio-jet fuel. This review is distinct from the previous ones, as it combines most of the previous reviews, illustrates the different supported non-sulphide zeolite-type catalysts and their preparation methods, characteristics and performance in bio-jet fuel production.
Pub.: 20 Mar '17, Pinned: 19 Jun '17
Abstract: An overview is presented on the central role that zeolites and other nanoporous materials currently play in the Fluid Catalytic Cracking (FCC) process as well as how this role evolved over the course of the years since its inception. Today, utilization in FCC constitutes the vast majority of global zeolite catalyst consumption by volume. FCC is the main conversion process in a typical fuels refinery, and as the most critical ingredient of the catalyst, zeolites are responsible for producing majority of the gasoline used around the world as well as taking an important role in the production of other transportation fuels (e.g., diesel, jet fuel) and building blocks for the petrochemical industry (e.g., propylene, butylenes). Therefore, it can be stated that zeolite catalysts fuel our industrialized society and provide the building blocks for its advancement; consequently, zeolites have a direct impact on the future of the global economy and its sustainability. Strategies that involve zeolites and other nanoporous materials for improving performance of FCC operation and ensuring its environmental sustainability were reviewed. Zeolite modifications were examined with each leading to an improvement in zeolite stability under severe conditions in an FCC unit. The importance of diffusion pathways within an FCC catalyst particle, leading to higher accessibility of the active zeolite sites, were explored, and the importance of a well-designed catalyst architecture, allowing FCC feed, intermediates, and final products to diffuse freely in and out of the catalyst particle were discussed. The role of contaminant metals in FCC was investigated, and some mitigation strategies for the most common FCC contaminants, nickel and vanadium, were presented. The impact of contaminant iron was discussed alongside catalyst architecture, particularly surface porosity of the catalyst particle. Utilization of other nanoporous materials in FCC, especially as environmental additives, was summarized. Testing considerations were screened with an emphasis on matching laboratory deactivation to refinery FCC observations.
Pub.: 02 Apr '17, Pinned: 19 Jun '17
Abstract: Water footprint analysis, when combined with water-focused life cycle assessment, can be an effective systems analysis tool for biofuel sustainability.Rapeseed is considered to be a promising sources for hydroprocessed ester and fatty acid (HEFA) jet fuel production as a means to address energy security and climate change mitigation. However, concerns have been raised about its impact on water, as large-scale biofuel production may place pressure on fresh water supplies and water quality. Water footprint (WF) analysis, when combined with water-focused life cycle assessment (LCA), can be an effective system analysis tool for water sustainability. This study developed a life cycle water footprint analysis informed by inputs from multiple models for rapeseed HEFA jet fuel production in North Dakota and evaluated the environmental impacts on water utilization and water quality due to large scale HEFA jet production. The biogeochemical-based EPIC model was incorporated to simulate crop growth that influences the hydrological cycle. Systematic LCA models were built in SimaPro to conduct life cycle blue WF analysis. Results using energy allocation indicate that rapeseed derived HEFA jet fuel has a WF of 131–143 m3 per GJ fuel over a rapeseed price range of $470–600, including all green, blue, and gray WF components. Discussions also indicate the importance of incorporating allocation within a life cycle approach when conducting biofuel WF analysis.
Pub.: 06 Apr '17, Pinned: 19 Jun '17
Abstract: A series of potassium promoted Fe–Mn catalysts for light olefin synthesis from CO hydrogenation were prepared by the co-precipitation-calcination-impregnation method. The impact of potassium promoter on the textural properties, reduction behavior, adsorption of hydrogen, bulk phase composition and their correlation with Fischer–Tropsch synthesis (FTS) performances were emphatically studied. As revealed by N2 physisorption, the increasing of potassium had no distinct effect on the size of α-Fe2O3 and surface area. H2 temperature-programmed reduction/desorption showed that potassium inhibited the reduction and hydrogen adsorbability of catalysts. CO temperature-programmed desorption showed that potassium enhanced the CO adsorption of catalysts. X-ray photoelectron spectroscopy indicated the enrichment of promoter atoms on the surface of catalysts. The X-ray diffraction and Mössbauer effect spectroscopy results revealed that potassium made carburization easy. After reduction with syngas (H2/CO = 20) for 48 h, FTS test was performed with the syngas (H2/CO = 3.5) in the high temperature Fischer–Tropsch synthesis process. The maximum of CO conversion and selectivity to light olefins was noted on increasing K content (2.8 mol% K/Fe), followed by a significant decline at the excessive potassium level. At the point, the selectivity of light olefins and olefin/paraffin (C2–C4) was 27.75 mol% and 8.54. The results indicated that potassium promoter could inhibit the water gas shift reaction, suppress hydrogenation ability, which promoted the production of light olefins via suppressing the secondary hydrogenation reaction.
Pub.: 25 May '14, Pinned: 19 Jun '17
Abstract: Abstract: The thermodynamics of jet fuel range alkane synthesis from carbon dioxide and hydrogen has been investigated. The hydrocarbon synthesis process is divided into three elementary steps, including light olefins formation (C2-C6) from hydrogenation of CO2, α-olefins (C7-C16) synthesis from oligomerization of light olefins, and hydrogenation of α-olefins (C8-C16) to straight-chain paraffin (C8-C16). The enthalpy changes and Gibbs free energy changes of the relevant reactions were calculated, and the equilibrium products distribution was computed based on the Gibbs free energy minimization method. The calculation results show that lower temperature (below 673.15 K), higher pressure (3 MPa), higher molar ratio of H2 to CO2 (3:1-4:1), and introducing a small amount of N2 in the reactants are favorable for the hydrogenation of CO2; lower temperature (below 500 K), higher pressure (2-3 MPa), addition of N2 is favorable for the oligomerization of light olefins; and lower temperature (below 700 K), higher pressure (2-3 MPa), and addition of N2 is favorable for the hydrogenation of α-olefins. The overall positive effect of introducing N2 results from its heat dilution of the process. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.
Pub.: 14 Jun '17, Pinned: 19 Jun '17
Abstract: In this study, a tailor-made biocatalyst consisting of a co-immobilized lignolytic enzyme cascade on multi-functionalized magnetic silica microspheres (MSMS) was developed. Physical adsorption was the most promising strategy for the synthesis of individual immobilized laccase (IL), immobilized versatile peroxidase (IP), as well as co-immobilized laccase (Lac) and versatile peroxidase (VP) with an enzyme activity recovery of about 79, 93, 27, and 27.5%, respectively. Similarly, the biocatalytic load of 116, 183, 23.6, and 31 U/g was obtained for IL, IP, and co-immobilized Lac and VP, respectively. The co-immobilized enzyme system exhibited better pH stability than the free and individual immobilized system by retaining more than 100% residual activity at pH 7.0 after a 150-h incubation; whereas, the thermal stability and kinetics of the co-immobilized biocatalyst were not much improved. IL and IP could be recycled for 10 cycles after which they retained 31 and 44% of their initial activities. Co-immobilized Lac and VP were reused for ten consecutive cycles at the end of which Lac activity was depleted, and 37% of VP activity was left. Free enzymes, IL, IP, co-immobilized Lac, and VP were applied to biorefinery wastewater (BRW) in a batch study to investigate the transformation of phenolic contaminants over a period of 5 days. The major classes of phenolic constituents in terms of their order of removal in a Lac-VP system was phenol >2-chlorophenol > trichlorophenol > dichlorophenol > cresols > dimethylphenol >2 methyl- 4, 6-dinitrophenol > 4-nitrophenol > tetrachlorophenols > pentachlorophenol. The free enzymes and individually immobilized enzymes resulted in 80% dephenolization in 5 days. By contrast, the co-immobilized biocatalyst provided rapid dephenolization yielding the same 80% removal within 24 h and 96% removal of phenols in 60 h after which the system stabilized, which is the major advantage of the co-immobilized biocatalyst. ᅟ Graphical abstract.
Pub.: 19 Jun '17, Pinned: 19 Jun '17