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Background: The transition from fossil-derived jet fuels to sustainable aviation fuels represents one of the most viable strategies to decarbonize air transport and mitigate CO2 emissions generated by fossil fuel combustion. In the present investigation, a catalytic hydroprocessing upgrading approach was used to transform Yellow Dodolla oil—one of the most prominent inedible Brassica carinata vegetable oils (indigenous to Ethiopia)—into bio-jet fuel. Methods: The feedstock was upgraded to jet fuel through catalytic hydroprocessing under elevated hydrogen pressure (21 bar), varying temperatures (300 and 500 °C), and employing supported carbon-coated mesoporous and crystalline nanocatalysts (β-Mo2C/AlPO4-18, Ni3C/AlPO4-18, and WC/AlPO4-18) in a laboratory-scale continuous three-phase fixed-bed reactor system. Other variables, such as the volumetric flow rate of oil feedstock, volumetric flow rate of hydrogen gas, hydrogen gas-to-oil ratio, catalyst-to-oil ratio, liquid hourly space velocity, weight hourly space velocity, and residence time, were maintained constant throughout the experimental procedure. Subsequent to an in-depth evaluation of catalytic performance parameters (conversion, selectivity, yield, and deoxygenation rate), a detailed characterization of the liquid phase products was undertaken to explore their most significant properties. Results: The analysis results demonstrated that the catalytic hydroconversion of the feedstock resulted in a conversion range of 71.57–79.76 wt.%, with the highest conversion of 79.76 wt.% achieved by Ni3C/AlPO4–18 at the maximum temperature. Moreover, the rate of deoxygenation varied from 8.08 to 11.67 wt.% at 300 °C, with nickel catalyst reaching the maximum rate, while it sharply rose to vary from 57.31 to 96.67 wt.% using molybdenum as the temperature increased to 500 °C. It was also discovered that in comparison to bio-gasoline (2.63–8.72 wt.%) and biodiesel (1.18–4.58 wt.%), bio-jet fuel (C8–C16) had noticeably higher yields (23.34–27.31 wt.%), selectivity (37–45 wt.%), and a superb hydrocarbon product distribution (C9–C16) at the maximum temperature, with WC/AlPO4-18 producing the highest yields and selectivity of jet fuel. The characterization results revealed that the hydrocracked liquid products possessed virtually identical physicochemical properties, chemical compositions, hydrogen-to-carbon atomic ratios (1.90–1.92), oxygen-to-carbon atomic ratios (0.002–0.030), and gravimetric energy densities (41.35–42.89 MJ kg−1) to those of conventional jet fuels. Conclusions: The conclusions of the study demonstrated that the non-food Yellow Dodolla oil was successfully hydrocracked into sustainable aviation fuel using AlPO4-18 supported metal carbide catalyst nanoparticles under the right reaction conditions and reactor system, potentially supporting the significant efforts of the aviation industry to lower its carbon footprint. [ABSTRACT FROM AUTHOR]

Developing high-efficiency, high-stability, and low-cost deoxygenation and hydrocracking catalysts could be considered one of the most significant breakthroughs in catalytic hydroprocessing. The present study utilized aluminophosphate (AlPO4-18), a zeolite-like molecular sieve, as catalyst support for producing carbon-coated β-Mo2C, Ni3C, and WC nanoparticles. The synthesis used an incipient wetness impregnation followed by a temperature-programmed reduction-carburization approach which involved cracking a hydrocarbon gas, propane, in a hydrogen environment. The synthesis parameters were a 1:7 propane/hydrogen reductive-carburizing gas stream, 15 wt.% metal loading, an 800 °C carburization temperature ramped-up at a heating rate of 10 °C min−1, a 2-h holding time, and a 1-h holding time in hydrogen. The synthesized catalysts were characterized using thermogravimetry mass spectroscopy/temperature-programmed oxidation (TPO TG-MS), nitrogen physisorption at 77 K, X-ray diffraction (XRD), and transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM EDS). TPO TG-MS, nitrogen physisorption, TEM, and XRD characterization results proved that atomic carbon was successfully incorporated into the lattice interstitials, resulting in thermally stable, well-dispersed, crystalline and mesoporous β-Mo2C/AlPO4-18, Ni3C/AlPO4-18, and WC/AlPO4-18 nanoparticles. XRD analysis showed structural evolution during reduction-carburization, with average crystallite sizes of metal-containing particles of 8.2–9.22, 6.64–8.50, and 6.03–7.56 nm for β-Mo2C/AlPO4-18, Ni3C/AlPO4-18, and WC/AlPO4-18, respectively. These values did not significantly deviate from high-resolution TEM analysis. The surface areas of the nanoparticles were categorized in decreasing order as WC/AlPO4-18 > Ni3C/AlPO4-18 > β-Mo2C/AlPO4-18, with values of 193.79, 169.05, and 66.57 m2 g−1, respectively. In conclusion, these carbon-coated metal carbide nanoparticles with excellent thermal, structural, microscopic, and textural properties can be viable alternatives to noble metal catalysts for producing bio-jet fuel using the hydroprocessing pathway. [ABSTRACT FROM AUTHOR]

In this research, the simulation of an existing 31.5 MW steam power plant, providing both electricity for the national grid and hot utility for the related sugar factory, was performed by means of ProSimPlus® v. 3.7.6. The purpose of this study is to analyze the steam turbine operating parameters by means of the exergy concept with a pinch-based technique in order to assess the overall energy performance and losses that occur in the power plant. The combined pinch and exergy analysis (CPEA) initially focuses on the depiction of the hot and cold composite curves (HCCCs) of the steam cycle to evaluate the energy and exergy requirements. Based on the minimal approach temperature difference (∆Tlm) required for effective heat transfer, the exergy loss that raises the heat demand (heat duty) for power generation can be quantitatively assessed. The exergy composite curves focus on the potential for fuel saving throughout the cycle with respect to three possible operating modes and evaluates opportunities for heat pumping in the process. Well-established tools, such as balanced exergy composite curves, are used to visualize exergy losses in each process unit and utility heat exchangers. The outcome of the combined exergy–pinch analysis reveals that energy savings of up to 83.44 MW may be realized by lowering exergy destruction in the cogeneration plant according to the operating scenario. [ABSTRACT FROM AUTHOR]

Global energy security relies on fossil-based resources that are affiliated with the source of global warming, apart from punches of political and economic instabilities. Biomass is a promising alternative carbonaceous feedstock used for the production of clean energy that could have the potential to substitute for fossil fuels. This study aims to present a conceptual design that considers the criteria to identify the upper theoretical limits of biomass conversion, thus providing the potential approach to the conversion of three biomass (by-products: dry molasses, dry bagasse, and dry filter cake) through gasification, in order to contribute the biomass carbon-capturing by the model assessment of stoichiometric mass conversion and energy efficiency indicators into simple thermodynamic energy vectors, such as alcohols, alkanes, and syngas (a mixture of carbon monoxide and hydrogen). Modeling plays up the importance of stoichiometric efficiency of biomass conversion with the supply of oxygen and hydrogen. This realizes that the multi-product diversification of feedstock into syngas, hydrocarbons, and alcohol through integrated process schemes could have the potential to fill the energy gap and help to manage environmental load. In regard to biomass conversion results, the mass conversion and energy conversion efficiencies of dry bagasse have better conversion potential than molasses and F. cake (% mass conversion = 129 in syngas, 54.4 in alkane, and 43.4 in alcohol; % energy conversion = 94.3 in syngas and 93.3 in alkane and alcohol). [ABSTRACT FROM AUTHOR]

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Purpose: The overall aim of this work is to evaluate bio-refinery potential of Enset fiber. The effect of non-catalyzed and alkali-catalyzed hydrothermal processes was investigated to fractionate Enset fiber bundle. Methods: The treatments were made at 130 °C, 150 °C, 180 °C, and 200 °C and the composition of the solids regarding lignin and monomeric sugar and of the liquid phase were evaluated. The treated solid was further delignified by using ethanol alkali pulping at 40% ethanol concentration, 15% alkali concentration, 140 °C, 60 min. Results: Temperature-dependent mass loss was observed in both non-catalyzed and catalyzed treatment. The liquor was rich in oligosaccharides with a maximum recovery achieved with the alkali-catalyzed hydrothermal treatment at 130 °C for GOS (12.4 g/100 g of original dry sample) and at 180 °C for XOS (3.4 g/100 g of original dry sample). The fibrous nature of the material was preserved after the treatment. The maximum pulp yield of treated Enset fiber was found to be 61.0% per original sample which is comparable to pulping of original sample 69.1%. Conclusion: Therefore, the hydrothermal treatments can be applied as a first fractionation step in the valorization of Enset fibers, allowing the subsequent use of the solid as a fiber source for pulping. [ABSTRACT FROM AUTHOR]

A novel, simple, fast, cheap and pollution free method for utilizing waste X-ray film for silver recovery using sodium hydroxide and sodium sulfide by the stripping and precipitation processes, respectively has been reported. The yield of silver by this process is 1.07% w/w at a stripping temperature of 70.88°C, 10.97 min and NaOH concentration of 1.5M. The composition of recovered silver has been determined by XRF and the results are compared with existing literature for the purity of silver. The study warrants the application of NaOH and Na2S to recover silver from used X-ray photographic film. [ABSTRACT FROM AUTHOR]

This study focused on the leaching of uranium and thorium from a high grade Ethiopian tantalite ore using sulfuric acid. The effects of variables such as acid concentration, temperature and leaching time were studied. In general, the leaching efficiency of uranium increases with increasing temperature from 100 to 300°C whereas the opposite trend was observed for thorium. The amount of uranium leached increased from 69.1% at contact time of 1 hr to 88.6% when the tantalite ore was leached for 3 hrs. On the other hand, for the experiments conditions considered in this study, the leaching behavior of uranium and thorium did not change significantly with varying sulphuric acid concentration from 70 to 90 wt%. Overall, the highest dissolution of uranium and thorium were achieved at 100°C, 70 wt% H2SO4 concentration and 1 hr contact time. [ABSTRACT FROM AUTHOR]

ABSTRACT: The emphasis of the present study is to investigate the potential of magnetic iron oxide nanoparticles synthesized using bagasse from sugarcane (M‐NIOB). M‐NIOB was infused onto the modified batch reactor (M‐BR) stirrers using mesh structures for the adsorption of Cr6+ contained in effluent from the leather industry. M‐NIOB exhibited supermagnetic properties under an external magnetic field with a saturation magnetization value of 9.192 emu/g at room temperature. M‐NIOB nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, vibrating sample magnetometer, and Brunauer–Emmett–Teller analysis. The size of the M‐NIOB particles ranged from 50 to 200 nm. The most favorable time, pH, and temperature for the application of M‐NIOB to Cr6+ removal from tannery effluent was found to be 180 min, 5, and 318 K, respectively. M‐NIOB adsorbent performed its best at an adsorbent dosage of 800 mg/150 mL with a particle size of 150 nm. Kinetic and thermodynamic studies have been conducted. The applicability of various adsorption models for the Cr6+ adsorption data was tested. Moreover, the desorption studies carried out at 60 °C proved the capability of M‐NIOB for regeneration and reuse. Hence, M‐NIOB could be potentially applied for the treatment of effluent that has Cr6+ as a major constituent. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46683. [ABSTRACT FROM AUTHOR]

False banana /Ensete ventricosum [Welw.] Cheesman/ is exploited as a food crop in Ethiopia where it represents an important staple food. The plant is harvested and large amounts of biomass residues are originated, mainly from the pseudo stem (i.e., fiber bundles obtained from the leaf sheaths after being scrapped to produce starchy food) and the inflorescence stalk. These materials were studied in relation to their summative chemical composition, composition of lignin, lipophilic and polar extracts. Moreover, their structural characteristics, in view of their valorization, were scrutinized. The analytical studies were performed with the aid of FTIR, GC/MS, Py-GC/MS and SEM. The fiber bundles are aggregates of mainly long and slender fibers with low ash, extractives and lignin contents (3.8%. 4.4% and 10.5% respectively) and high holocellulose and α-cellulose contents (87.5% and 59.6% respectively). The hemicelluloses in the fibers are mostly highly acetylated xylans and the lignin is of the H-type (H:G:S, 1:0.7:0.8). This lignin composition is in line with the FTIR peaks at 1670 cm-1 and 1250 cm-1.The inflorescence stalk has high ash content (12.3% in the main stalk and 24.6% in fines) with a major proportion of potassium, high extractives (25.9%), and low lignin and α-cellulose contents (5.8% and 17.9% respectively). The stalk includes numerous starch granules in the cellular structure with the predominant presence of parenchyma. The potential valorization routes for these materials are clearly different. The fiber bundles could be used as a fiber source for paper pulp production with the possibility of a prior hemicelluloses removal while the inflorescence stalk has nutritional value for food and fodder. Furthermore, it can also be used for sugar fermentation products. [ABSTRACT FROM AUTHOR]

In this study, the decomposition behavior of Ta and Nb from the mangano-tantalite ore was investigated using HF/H2SO4 mixture and KOH fusion. The effects of reaction time, decomposition temperature, acid and alkaline concentrations, and particle size on the dissolution process were examined. Higher decomposition rates were achieved at 6:2 mol/dm3 ratio of HF and H2SO4, and with the addition of 10 g KOH in the alkali fusion step. In addition, similar trends in decomposition rates between two agents (HF/H2SO4 and KOH) and comparable dissolution performances were observed. The increase in the decomposition temperature initially increased the decomposition rate of manganotantalite for the two systems considered in this study. However, no significant change in the leaching rate of Ta and Nb was observed beyond 50 °C for the HF/H2SO4 system and above 400 °C when using the KOH fusion process. The elemental and compositional analyses of the leached residues using XRF, XRD, and FT-IR spectroscopy indicated that the acid (mixture of HF and H2SO4) decomposition resulted in slightly better dissolution performance for Ta compared with the alkaline fusion method. Overall, the results indicated that KOH can be a suitable alternative decomposition agent to the volatile, corrosive and toxic HF in the hydrometallurgical processing of tantalite ores. [ABSTRACT FROM AUTHOR]

Several optimization models, which consider economic and environmental perspectives, have been developed recently to support the sustainable biomass-to-biofuel supply chain (BBSC) design. All of the economic-environmental optimization models rely on solving long-term planning problems with a conventional hierarchical approach, where tactical decisions are made based on the optimal strategic decisions from the strategic-level model, despite it arousing non-optimal solutions. Moreover, almost all of them have used non-monetary-based environmental indicators, which result in difficulties with clarity when comparing with economic objectives. Therefore, in this work, an effort is made to develop a more reliable planning strategy that offers optimal strategic and tactical decisions simultaneously and maximizes the economic and environmental benefits. Furthermore, the environmental performance of the BBSC has been assessed in terms of monetary value by adopting an ecocost approach after performing an LCA on the system. The integrated model is applied in the real biofuel sector of Ethiopia to optimize the country's bioethanol and biodiesel supply chain over a 20-year horizon. Despite the abrupt rise in the model size, with it being a real countrywide case with many variables and large quantities of data, an alternative semi-heuristic method that offers a feasible solution to the multi-objective problem is provided. [ABSTRACT FROM AUTHOR]