Catalytic dry reforming of methane (DRM) is a promising way for renewable syngas production due to the utilization of both CO2 and CH4 greenhouse gases. Current approaches were made to improve the ...catalytic activity and coke resistance by introducing a second metal into the Ni‐based catalytic system. This bimetallic catalytic system showed a significant improvement in coke resistance due to the synergistic effect of both metals towards the reaction. This review summarizes recent developments in bimetallic catalysts in DRM which focused on the evaluation of catalysts, deactivation studies, and reaction mechanisms of developed bimetallic catalysts.
Recent developments in bimetallic catalysts in catalytic dry reforming of methane are reviewed focusing on the evaluation of catalysts, deactivation studies, and reaction mechanisms of developed bimetallic catalysts. The latest insights in catalyst characteristics are given together with strategies on coke management and mechanism of bimetallic catalysts on catalytic dry reforming of methane.
Gemini surfactant corrosion inhibitor (CI) is one type of CI mainly used in mitigating corrosion in the complex system of oil/gas production industries. Computer modeling methods such as density ...functional theory (DFT) calculation and molecular dynamic (MD) simulation are required to develop new CI molecules focusing on their application condition as a prediction or screening process before the physical empirical assessment. In this work, the adsorption inhibition efficiencies of two monomer surfactants (2B and H) and their respective Gemini structures with the addition of different spacers (alkyl, benzene, ester, ether, and ketone) are investigated using DFT calculation and MD simulation method in 3% sodium chloride (NaCl), and 1500 ppm acetic acid solutions. In DFT calculation, 2B-benzene molecules are assumed to have the most promising inhibition efficiency based on their high reactivity and electron-donating ability at their electron-rich benzene ring region based on the lowest bandgap energy (0.765 eV) and highest HOMO energy value (-2.879 eV), respectively. DFT calculation results correlate with the adsorption energy calculated from MD simulation, where 2B-benzene is also assumed to work better as a CI molecule with the most adsorption strength towards Fe (110) metal with the highest negative adsorption energy value (-1837.33 kJ/mol at temperature 323 K). Further, diffusion coefficient and molecular aggregation analysis in different CI concentrations through MD simulation reveals that only a small amount of Gemini surfactant CI is needed in the inhibition application compared to its respective monomer. Computer simulation methods successfully predict and screen the Gemini surfactant CI molecules that can work better as a corrosion inhibitor in acetic acid media. The amount of Gemini surfactant CI that needs to be used is also predicted. The future planning or way forward from this study will be the development of the most promising Gemini surfactant CI based on the results from DFT calculation and MD simulations.
A green approach for the biosynthesis of silver nanoparticles (AgNPs) was developed using
Diplazium esculentum
aqueous extract as green reductant. The bio-stabilized AgNPs were characterized by ...UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and high-resolution transmission electron microscopy (HRTEM). The formation of AgNPs was indicated by the colour change and the absorption peak at 449 nm in the UV–Vis spectrum. FTIR spectral analysis suggested the possible biomolecules associated with the reduction of silver ions. The crystalline and face-centered cubic (fcc) structure of AgNPs was obtained by the XRD study. HRTEM analysis showed that the biosynthesized AgNPs composed of quasi-spherical, hexagonal, and ellipsoidal shapes with an average particle size of 23.385 ± 8.349 nm. The biosynthesized AgNPs exhibited good catalytic activity up to 91% reduction of Methylene blue (MB), which followed a reductive pathway rather than a photocatalytic route. The catalytic reduction follows a pseudo-first-order reaction with a rate constant of 0.1051 min
-1
. The disc diffusion technique (DDT) and minimal inhibitory concentration (MIC) results showed significant antibacterial capability against Gram-positive (
Escherichia coli
ATCC 11,229) and Gram-negative (
Staphylococcus aureus
ATCC 6538) bacteria.
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The field of green technology is evolving rapidly to address new industrial challenges, and deep eutectic solvents (DESs) have emerged as a potential alternative to traditional ...organic compounds and ionic liquids. Among their main classes, magnetic DESs (MagDESs) have gained significant attention due to their unique magnetic properties resulting from the presence of magnetic ions in the solvent. The unique magnetic properties of MagDESs, combined with their stability and compatibility, make them suitable for various applications, including magnetic separation and purification. The ease of separation of MagDESs from their respective mixtures via the application of an external magnetic field distinguishes them as a desirable solution, enabling quick extraction and easy collection without centrifugation. Moreover, DESs can serve to endow magnetic materials with new functionalities for a wide range of applications. Utilizing DESs enables the functionalization of magnetic materials without the use of volatile organic solvents or extended processing periods. MagDESs are expected to be used in the extraction of various compounds, but there are some limitations that must be considered, such as compatibility issues, recovery difficulty, and also long-term stability and sustainability of MagDESs in different environments and applications. Further research and development are necessary to fully understand and optimize the benefits and limitations of MagDESs.
This study demonstrated the performance of the sugarcane bagasse ash (SCBA) impregnated with calcium oxide (CaO) as a novel heterogeneous basic catalyst in biodiesel production. The SCBA was prepared ...by calcination for 2 h at 500 to 800 °C and impregnated with CaO loadings (10 to 40 wt.%). The prepared SCBA/CaO catalyst was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature programmed desorption of carbon dioxide (TPD-CO
2
), thermal gravimetric analysis (TGA), X-ray fluorescence (XRF) and Brunauer-Emmett-Teller (BET) surface characteristics. A series of transesterification reactions were conducted to evaluate the performance of the catalysts. As a result, highest FAME yield of 93.8% was obtained by using SCBA
600°C
CaO
(40%)
catalyst at 20:1 methanol-to-oil molar ratio, reaction temperature of 65 °C, with 6 wt.% catalyst in 3 h. Besides, the catalyst can be reused up to 5 reaction cycles with biodiesel yield of 93.0% and 70.3% at first and fifth cycles, respectively. In this work, it was found that the natural SiO
2
in the SCBA has a significant role to enhance the catalytic performance and reduce the catalyst’s deactivation drawback by minimizing the leaching of active sites.
The purpose of this study is to assess water-polymer interaction in synthesized starch-derived superabsorbent polymer (S-SAP) for the treatment of solid waste sludge. While S-SAP for solid waste ...sludge treatment is still rare, it offers a lower cost for the safe disposal of sludge into the environment and recycling of treated solid as crop fertilizer. For that to be possible, the water-polymer interaction on S-SAP must first be fully comprehended. In this study, the S-SAP was prepared through graft polymerization of poly (methacrylic acid-co-sodium methacrylate) on the starch backbone. By analyzing the amylose unit, it was possible to avoid the complexity of polymer networks when considering S-SAP using molecular dynamics (MD) simulations and density functional theory (DFT). Through the simulations, formation of hydrogen bonding between starch and water on the H06 of amylose was assessed for its flexibility and less steric hindrance. Meanwhile, water penetration into S-SAP was recorded by the specific radial distribution function (RDF) of atom-molecule interaction in the amylose. The experimental evaluation of S-SAP correlated with high water capacity by measuring up to 500% of distilled water within 80 min and more than 195% of the water from solid waste sludge for 7 days. In addition, the S-SAP swelling showed a notable performance of a 77 g/g swelling ratio within 160 min, while a water retention test showed that S-SAP was capable of retaining more than 50% of the absorbed water within 5 h of heating at 60 °C. The water retention of S-SAP adheres to pseudo-second-order kinetics for chemisorption reactions. Therefore, the prepared S-SAP might have potential applications as a natural superabsorbent, especially for the development of sludge water removal technology.
The conventional synthesis route of nanostructured titania-silica (Ti-SiNS) based on sol-gel requires the use of a surfactant-type template that suffers from hazardous risks, environmental concerns, ...and a tedious stepwise process. Alternatively, biomaterials have been introduced as an indirect template, but still required for pre-suspended scaffold structures, which hinder their practical application. Herein, we report an easy and industrially viable direct-continuous strategy for the preparation of Ti-SiNS from nanostructured-silica (SiNS) using a hydrolyzed rice starch template. This strategy fits into the conventional industrial process flow, as it allows starch to be used directly in time-effective and less complicated steps, with the potential to upscale. The formation of Ti-SiNS is mainly attributed to Ti attachment in the SiNS frameworks after the polycondensation of the sol-gel composition under acidic-media. The SiNS had pseudo-spherical morphology (nanoparticles with the size of 13 to 22 nm), short order crystal structure (amorphous) and high surface area (538.74 m²·g
). The functionalized SiNS into Ti-SiNS delivered considerable catalytic activity for epoxidation of 1-naphtol into 1,4-naphthoquinone. The described direct-continuous preparation shows great promise for a cheap, green, and efficient synthesis of Ti-SiNS for advanced applications.
Nanostructured hematite materials for advanced applications are conventionally prepared with the presence of additives, tainting its purity with remnants of copolymer surfactants, active chelating ...molecules, stabilizing agents, or co-precipitating salts. Thus, preparing nanostructured hematite via additive-free and green synthesis methods remains a huge hurdle. This study presents an environmentally friendly and facile synthesis of spherical nanostructured hematite (Sp-HNP) using rice starch-assisted synthesis. The physicochemical properties of the Sp-HNP were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DR UV-Vis), and nitrogen adsorption⁻desorption analysis. The Sp-HNP showed a well-crystallized structure of pure rhombohedral phase, having a spherical-shaped morphology from 24 to 48 nm, and a surface area of 20.04 m²/g. Moreover, the Sp-HNP exhibited enhanced photocatalytic degradation of methylene blue dye, owing to the large surface-to-volume ratio. The current work has provided a sustainable synthesis route to produce spherical nanostructured hematite without the use of any hazardous agents or toxic additives, in agreement with the principles of green chemistry for the degradation of dye contaminant.
The scientific investigation based on the molecular design of aromatic compounds for high-performance chemosensor is challenging. This is because their multiplex interactions at the molecular level ...should be precisely determined before the desired compounds can be successfully used as sensing materials. Herein, we report on the molecular design of chemosensors based on aromatic structures of benzene as the organic motif of benzene-1,3,5-tricarboxamides (BTA), as well as the benzene pyrazole complexes (BPz) side chain, respectively. In the case of BTA, the aromatic benzene acts as the centre to allow the formation of π–π stacking for one-dimensional materials having rod-like arrangements that are stabilized by threefold hydrogen bonding. We found that when nitrate was applied, the rod-like BTA spontaneously formed into a random aggregate due to the deformation of its hydrogen bonding to form inactive nitroso groups for non-optical sensing capability. For the optical chemosensor, the aromatic benzene is decorated as a side-chain of BPz to ensure that cage-shaped molecules make maximum use of their centre providing metal-metal interactions for fluorescence-based sensing materials. In particular, when exposed to benzene, Cu-BPz displayed a blue-shift of its original emission band from 616 to 572 nm (Δ = 44 nm) and emitted bright orange to green emission colours. We also observe a different mode of fluorescence-based sensing materials for Au-BPz, which shows a particular quenching mechanism resulting in 81% loss of its original intensity on benzene exposure to give less red-orange emission (λ = 612 nm). The BTA and BPz synthesized are promising high-performance supramolecular chemosensors based on the non-optical and optical sensing capability of a particular interest analyte.
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