Electrochemical hydrogenation and oxidation of furfural (model bio-oil compounds) is an efficient and environmentally friendly process, particularly with the use of renewable electricity and water-derived hydrogen. Novel nitrogen-doped manganese-cobalt on carbon nanoparticles catalyst (prepared with the hydrothermal process) has been used effectively as an electrocatalyst for furfural conversion to furfural alcohol and furonic acid with high conversion and selectivity. The process can be carried out at ambient conditions and acidic medium. The yield, selectivity, and faradic efficiency for furfural conversion in a single electrochemical cell were found to be highly dependent on catalyst loading, potential, reaction conditions (e.g. pH), and residence time. The optimized electrochemical furfural conversion can reach around 70 percent within three hours of operation.
Desert pristine sands were collected, sieved, characterized and tested for the separation of surfactant-stabilized oil in water (O/W) emulsions in a cross-flow sand bed filter unit under the simulated natural gravity (ΔP = 0.1 bar). The wettability and morphology of sands was characterized. It was revealed that natural sand is a promising material for this application with superhydrophilicity and underwater superoleophobicity. It achieved separation efficiency and flux comparable or higher than commercial microfiltration membranes under natural gravity conditions, while the separation efficiency and flux are relatively stable with respect to the operation parameters
The Graphene Oxide (GO)/ Metal Organic Frameworks (MOFs) hybrid material has attracted the attention of researchers because of the synergistic effect of the two in the CO2 capture process, which can significantly enhance the CO2 capture performance of the hybrid material with respect to the individual adsorption of each of them. However, it is difficult to directly explore the role played by each of them in the hybrid material through experiments, as there may be some competing effects. Therefore, this research adopts computational simulation method to explore this problem by constructing a simplified GO/MOF-5 hybrid material model and exploring its properties. GO can play an important role in the CO2 capture process by the hybrid materials, significantly improving the adsorption selectivity and adsorption capacity of MOFs. Under the condition of 313K and 0.15bar, the CO2 capture performance of 30wt%GO/MOF-5 is 4 times that of pure MOF-5.
This work belongs to a long-term project implementing molecular dynamics (MD) and quantum mechanics (QM) as economic and time-saving tools to design ad-hoc corrosion inhibitor molecules, reaching the most of their adsorptive capabilities for internal metal protection. Our recent publication provides molecular insights on the effect of the aqueous media on three CIs adsorption, abbreviated TEPA, iTEPA and HC-iTEPA on iron surface. The QM parameters in water solvation anticipated higher electron transfer ability of iTEPA in aqueous conditions compared to TEPA and iTEPA, thus, leading to stronger adsorption on iron surface, corroborated by the MD simulations. Molecular dynamic simulations showed that nearly 53%, 39%, 59% reduction in adsorption energies was detected for single inhibitor molecule of TEPA, iTEPA, and HC-iTEPA shifting from water to CO2-saline media, respectively. Nevertheless, the multi-inhibitors study revealed strong adsorption of TEPA and iTEPA on the iron.
Lithium air batteries have attracted high attention especially in sustainable development fields, since they are promising storage devices with high energy density of 1000 Wh kg-1. It has been under development to address serious problems such as finite oil resources, high fuel prices and to meet the demand of vehicles electrification. Lithium-air batteries structure plays an important role in providing pathways for discharge products, oxygen and lithium ions. However major problems such as clogging, cathode passivation and low stability need to be avoided. Thus, metal-organic frameworks are a class of outstanding candidates as cathodes for Lithium-air batteries since they have high surface areas, tailorable pore sizes and catalytic centers. To get rid of these predicaments MOF-derived carbons were fabricated and tested in LAB using aprotic electrolyte. Three different classes of MOFs were investigated ZIF-8, MOF-177 and Ni-MOF74.
Molecular self-assembly occurs in nature in various forms with a wide range of applications in biology, chemistry and material science. For example, DNA condensation, the physiologically significant phenomenon of DNA assembly in all life forms, has been heavily studied. Experiments report ion effect in DNA condensation, while the fundamental physical principles governing this unique assembly process are still not fully understood. To provide a fundamental understanding, we employ computer simulations to study the DNA condensation process. We examined the role of sequence in divalent ion conditions and analyzed the intermolecular forces. We observed a strong correlation between the counterion dynamics and DNA-DNA interactions. The attraction among DNA molecules is facilitated by ions that bridge between strands and the bridging ion structure highly correlate with DNA sequence. Based on our analysis, we design DNA sequences that assemble readily in the presence of divalent salt.
Microalgae are novel organisms that host a number of high-value products (HVPs). Finding an efficient extraction technique to recover selected HVP is of interest to many scientists and industries. In our study, the possible use of supercritical CO2 (scCO2) and ionic liquid (IL) were investigated as a potential greener solvent, compared to conventional solvent used, to determine the extraction capability for carotenoids, namely ?-carotene, from dried Dunaliella Salina biomass. Possibility of combining ethanol with IL or scCO2 with ethanol or ILs as cosolvents has also been examined and compared with individual solvent use. It was concluded that the combined use of ethanol with IL resulted in 6 folds yield increase in extract extraction when compared to the use of pure IL and the addition of a cosolvent in supercritical extraction increased the yield by 2 folds that of pure scCO2, with IL use being preferred due to insolubility in scCO2.
This paper investigated the regeneration of a deep eutectic solvent (DES), namely MethylTriphenylPhosphonium Bromide: Triethylene Glycol at a molar ratio of 1:4, (MTPB: TEG (1:4)). Single-stage LLE was conducted with an oil model containing 76wt% n-heptane (diesel representative), 20 wt% toluene (aromatics representative), 2wt% thiophene (S-containing-aromatics representative) and 2wt% quinoline (N-containing-aromatics representative). Then, the used DES was regenerated via two methods: back-extraction with n-heptane, and washing with anti-solvent (distilled water or diethylether). Diethylether was excluded as it reacted with the DES. n-heptane and water removed all of toluene and thiophene. However, water was substantially better at removing quinoline compared to n-heptane. This paper found that three water washes reduced the quinoline content in MTPB: TEG (1:4) from 20.68wt% to 0.88wt%. Nonetheless, three back-extraction cycles reduced the quinoline to 16.78wt%. The extraction efficiency of the DES regenerated by water was slightly lower than the extraction efficiency of its fresh counterpart.
In recent years, novel algorithms for gradient descent optimization have found success in deep machine learning applications. However, these algorithms can also be used for geophysical inversion. In this paper, we survey and compare between four first-order algorithms when applied to 2D anisotropic seismic tomography. These algorithms include Momentum, NAG, AdaGrad and AMSGrad. Our method keeps all input model parameters and hyperparameters constant and only tunes the learning rate. The results revealed that the algorithms NAG, Momentum and AdaGrad exhibit a stable convergency while AMSGrad is not stable. Moreover, each algorithm has a limited range of learning rates for which it performs best. Overall, NAG algorithm was found to be the most promising.
The Lower Cretaceous oceanic anoxic event (OAE1a) on the Arabian Peninsula has been extensively studied. The negative carbon isotope excursion hosted by the Hawar Member reflects the perturbation in the carbon cycle that lid to global environmental changes and is considered the cause of ocean acidification. The global environmental perturbation has generated different feedback among carbonate calcifiers, leading to turnover, extinctions, and demise of most platforms. The Arabian platform represents an exception, keeping growing during the OAE. The high-resolution chemostratigraphy study of Wadi Mu'aydin outcrop, using oxygen and carbon isotopes and multi-element X-ray fluorescence (XRF), has produced a dataset that helps in define the environmental change at the Barremian -Lower Aptian boundary in the shallow water domain in northern Oman.
