Molar Ratio Research Articles

Efficient hydrodeoxygenation of cresol by hierarchical porous FLRC-TiO2 nanoflower

The construction of highly efficient and selective hydrodeoxygenation (HDO) catalysts is of great significance for upgrading pyrolysis oil. In this work, nickel and iron-based NiFe(x)/FLRC-TiO2 catalysts with a flower-like radial channel structure were successfully fabricated with a facile strategy. The effects of Ni/Fe molar ratios and operation conditions on the structure, morphology and HDO performance were investigated using p-cresol as model compound. Impressively, the NiFe(x)/FLRC-TiO2 catalysts exhibit a well-defined radial channel structure with an average pore diameter of 27.4 nm and the NiFe(5)/FLRC-TiO2 with appropriate Ni/Fe ratio of 5 exhibits the best HDO performance. Under the conditions of T=275 °C, p=3 MPa, and t=2.5, the conversion rate of p-cresol and the selectivity to the target product MCH reaches 100 % and 97.8 %, respectively, which supresses most of the reported Ni based catalysts. Combining with the structure and morphology charateriazation results, this excellent HDO performance could be ascribed to: (a) the unique flower-like radial channel structure of the catalysts stemmed from FLRC-TiO2 provides more exposed active sites for HDO and fast mass transfer; (b) an appropriate Ni/Fe ratio contributes to the increase of specific surface area and pore volume of the catalyst, which boots the higher catalytic HDO activity; (c) the addition of Fe enhances acidity of catalyst and promotes the hydrodehydration of C–OH to target product MCH, together with the synergistic effect of FeNi metal sites, favoring the higher catalytic HDO activity. The proposed strategy for the preparation of radial channel structure FLRC-TiO2 support can be extended to various other reactions.

Single-domain structure of Fe3O4 nanoparticles encapsulation by magnetic surfactant M(AOT)2 (M=Co, Ni)

Investigating the magnetic nanoparticle size and the effective magnetic interactions that form the magnetic domain can lead us to nanoparticles with targeted applications, such as targeted drug delivery and higher resolution MRI imaging. In this study magnetic susceptibility and coercive field properties, and the structure size range of single-domain magnetic capsules with high magnetization were obtained by structural analysis of volumetric DLS properties. In this regard, the role of exchange, anisotropy, and magnetostatic interaction was investigated in the structure of a magnetic capsule containing Fe3O4 nanoparticles (MCap-NPs). The stable capsules were synthesized in an emulsion solution with magnetic surfactants M(AOT)2 (M = Co, Ni). Vibrating Sample Magnetometer (VSM) and capsule relative volume (CRV) of Dynamic Light Scattering (DLS) were used to determine the magnetic properties of the single-domain (SD) structure. The produced emulsion samples were found to have superparamagnetic properties property with saturation magnetization in the range of 2–6 × 10−3emu/g for NiCap-NPs, and 5-13 × 10−3emu/g for CoCap-NPs. The results show that nanoparticles have the most significant effect on magnetization. The coercive field, the anisotropy energy values, and the SD of M(AOT)2 were determined using magnetic susceptibility distribution. The outcome results show that the surface of the magnetic capsule plays an essential role in forming a single-domain structure. It was also found that the saturation magnetization of the samples in the emulsion solution is proportional to the nanoparticle density and not to the mass of nanoparticles. All produced samples have distinct peaks in CRV versus capsule size, and each peak follows a log-normal distribution. For both samples, except for the samples with molar ratios ω of 23 (Co3 and Ni4 samples), the positions of the second and third relative volume peaks were constant at 269 ± 3 nm and 424±6 nm, respectively. The behavior of the CRV function normalized to the peak size showed a proportionality between the coercive field and the CRV.

Determination of hydrate phase equilibrium (H-L-V) data for the binary CO2–CH4 gas mixture in the presence of 1,3 dioxolane

Present work details the determination of three phase hydrate equilibrium data (H-L-V) using temperature search method for the binary CO2/CH4 gas mixture (50:50 molar ratio) in presence of 1,3 dioxolane (DIOX). DIOX concentration used for phase equilibrium determination were 1,3 and 5.56 mol% respectively. In the presence of DIOX, it was observed that phase equilibrium curve was shifted right with respect to the curve using same gas mixture with no additive (pure water). This indicates that the presence of DIOX moderates the hydrate formation equilibrium conditions. Also, as DIOX concentration increases from 1 mol% to 5.56 mol%, a decrement in phase equilibrium pressure at same temperatures was observed, confirming the potential of DIOX as an effective thermodynamic promoter. Enthalpy of hydrate dissociation was calculated for CO2/CH4 gas mixture in presence of DIOX using Clausius- Clapeyron plot and it was found to be 90.81±6.55 KJ/mol which confirms the sII structure of CO2-CH4-DIOX mixed hydrate. Besides providing the phase equilibrium data of formed hydrates with CO2/CH4 gas mixture using different concentration of DIOX, the present study will aid in determining suitable experimental conditions for examining kinetics and performing separation studies of CO2/CH4 gas mixture through hydrate formation.

Sustainable Biodiesel Production from Waste Cooking Oil and Crude Palm Oil Using a Custom Mini Pilot Plant

The widespread practice of reusing Waste Cooking Oil (WCO) in hawker food stalls, often for multiple frying cycles, presents a significant public health concern due to the degradation of the oil, which can lead to the formation of toxic compounds. These practices not only pose health risks, such as increasing the potential for cardiovascular diseases and cancer, but also contribute to environmental pollution when the oil is improperly disposed of. This study seeks to address these issues by converting WCO, along with crude palm oil (CPO), into biodiesel using a custom-designed mini pilot plant. The biodiesel production process involved a two-step reaction. The first step, esterification, was conducted using a 55:100 alcohol-to-oil volume ratio with 1% by volume sulfuric acid (H₂SO₄) as the acid catalyst, at 60°C, with a reaction time of 30 minutes and a stirring speed of 800 rpm. The second step, transesterification, utilized a 6:1 alcohol-to-oil molar ratio, with 1 wt.% sodium hydroxide (NaOH) as the alkaline catalyst, carried out at 70°C over the course of one hour. These conditions were carefully selected to optimize the conversion efficiency and to minimize the free fatty acid content, which is crucial for achieving a high yield of biodiesel. The results demonstrated that the mini pilot plant is highly effective in producing biodiesel from both WCO and CPO. The study also led to the development of a standard operating procedure (SOP) for the biodiesel production process, ensuring reproducibility and efficiency.

Intense intrusion of low-oxygen waters into mid-Cambrian surface ocean carbonate factories

The Phanerozoic surface ocean is characterized by its high dissolved oxygen content owing to mixing with the atmosphere. However, atmospheric oxygen levels varied in the early Paleozoic and it remains unclear whether the surface ocean was susceptible to significant redox fluctuations in response to extreme environmental events. In this study, we probed the redox structures of shallow middle Cambrian marine depositional environments across the North China Platform, ranging from open tidal flats to relatively deep subtidal environments. We utilized a combination of least diagenetically altered carbonate materials (such as ooid cortices, calcimicrobes, and their fringing cements), as well as in situ element measurement and imaging techniques. By analyzing a set of redox-related elements (e.g., Ce anomaly, Zn/Fe molar ratio, Mn and Cr) and mineralogical proxies (hydrogenetic Fe oxides), we revealed a stratified redox structure in the Drumian surface oceans. Compared to earlier Drumian conditions, late Drumian surface oceans experienced significant intrusions of ferruginous waters, probably reaching into shallow subtidal environments with water depths less than 10 m. Furthermore, we identified shallow subtidal microbial O2-producing factories, characterized by dendritic Epiphyton thalli. These calcimicrobes exhibited more oxygenated signatures (negative Ce anomalies and enrichment of hydrogenetic Fe oxides) relative to contemporaneous less oxic shallower and deeper environments. This finding indicates that they produced oxygen oases or refuges during periods of both normal and poor dissolved O2 conditions. This study has the potential to broaden our understanding of redox conditions and microbial oxygen-producing mechanisms in the surface ocean, particularly during intervals characterized by low atmospheric oxygen levels or episodic anoxic events.

Enzymatic Transesterification Using Different Immobilized Lipases and its Biodiesel Effect on Gas Emission

Biodiesel, a third-generation bio-fuels, offering several advantages over regular diesel fuel. Waste cooking oil (WCO) emerges as an ideal feedstock due to its availability and easy accessibility. In this work, biodiesel is utilized from two different types of immobilized lipases: Rhizomucor miehei lipase (RMIM) and Candida antarctica lipase B (CALB). The impact of the molar ratio of oil to methyl acetate (1:3-1:12) was evaluated for both lipases, and the resultant biodiesel was tested in diesel engine. The enzymatic transesterification was carried out in ultrasonic assistance and the results showed that the greatest yield of 81.20% at 45℃, using CALB as a biocatalyst, 1.8% (w/v) lipase and oil to methyl acetate molar ratio of 1:12 within 3 hours. Triacetin, by-product was determined their concentration for each molar ratio and analyzed using FTIR range of 500cm-1 to 4000cm-1, revealing a significant absorption peak at 1238.90cm-1. Biodiesel was blended with commercial diesel fuel in varying quantities of 7, 10, and 20% by volume (B20). The results were compared to Industrial Diesel Fuel 7% (B7) and Commercial Diesel Fuel 10% (B10). NOx and CO2 emission drops as the percentage of diesel/biodiesel blends increases, supporting WCO as a cost-effective biodiesel feedstock with low petrol pollution.

Recovery of fluoride from wastewater in the form of cryolite granules by fluidized-bed homogeneous crystallization process

Aquatic ecosystems are harmed by high fluoride levels, which can disturb the equilibrium of water, plants, and animals and reduce biodiversity. Fluoride contamination in water sources can pose health risks and it is crucial to remove fluoride to prevent adverse effects on the environment and public health. Green technology is employed to recover fluoride from simulated fluoride-rich wastewater. The fluidized bed homogeneous crystallization (FBHC) process is an advanced methodology that removes contaminants from wastewater through supersaturation to recover nontoxic granules that can be used for other purposes. This study compared the fluoride recovery between batch crystallization and the FBHC process in terms of the molar ratio (MR) of [F−]:[Al3+] between [1] and [3] and the pH influence on the recovery and crystallization. The concentration of [Al3+] was varied at 37, 74, and 111 mM, along with the influent flow rates of 4, 8, and 12 mL·min−1. FBHC systems offer improved control of pH levels, creating a stable environment for crystallization. Unlike batch systems, these continuous operating systems are more resilient to pH fluctuations due to efficient mixing, maintaining a consistent pH throughout the process. Using Box-Behnken Design (BBD) for the FBHC, optimal conditions were 74 mM initial [Al] concentration, MR of [F−]:[Al3+] of [2]:[1], and 8 mL·min−1 influent flow rate resulted in 93 % fluoride removal (FR) and 91 % crystallization ratio (CR). XRD and SEM-EDS data showed similarities between the peaks and compositions of cryolite (Na3AlF6). FBHC was able to produce granules based on the reaction mechanism in the synthesis of cryolite.

Synthesis and Characterisation of Graphene Oxide Catalysts for Glycerol Acetylation

Glycerol in large quantities as a by-product of biodiesel production is a promising feedstock to be converted into more valuable products such as acetin. In this work, acetin converted from glycerol acetylation with acetic acid was performed over graphene oxide as a catalyst in a batch reactor. The study's objective was to evaluate the effect of sodium nitrate amount in the catalyst preparation on the catalyst's characteristics and catalytic performance. The graphene oxide (GO) catalysts were charac­terised by various tests, such as SEM-EDX for their morphology, the nitrogen adsorption capacity using Breneur-Emmet Teller (BET), structural analysis using XRD, functional group us­­ing FTIR, and catalytic activity on glycerol acetylation. The GO1, GO2, and GO3 catalysts were varied based on the NaNO3 amount in the modified Hummer method. The experiments found that the NaNO3 amount in catalyst preparation plays a vital role in GO structure formation. The GO2 catalyst has the highest performance, as indicated by the highest surface area, pore volume, and size. High glycerol conversion (94 %) and selectivity toward the interest products of triacetin (24 %) and diacetin + triacetin (83 %) were reached in 2 h of reaction using three wt.% catalysts, 110 °C reaction temperature, and 1:9 molar ratio of glycerol to acetic acid. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Structure and optical properties of ZnxCd1-xS and Cu:ZnxCd1-xS templated on DNA molecules

One-dimensional ZnxCd1−xS and Cu: Zn x Cd1−x S nanostructures were prepared using DNA as a template to promote growth along the molecular axis. The formation of homogeneously alloyed nanocrystals with cubic zinc blende-type structures was verified using x-ray diffraction and Raman spectroscopy. X-ray photoemission spectra revealed the presence of Cu(I) in the doped Cu: Zn x Cd1−x S nanocrystals. The effectiveness of the DNA template to direct the semiconductor growth in one dimension was demonstrated by AFM and TEM. The nanostructures displayed a granular morphology comprising nanoparticles with an average diameter of 14 nm composed of assemblies of smaller crystallites of 2.0 nm in size. Rope-like assemblies with an average diameter of 48 nm and extending in length to several hundred micrometres were obtained by evaporation-induced self-assembly. UV-Vis absorption and emission spectra indicated that the optical bandgaps (2.89–4.00eV) and photoluminescence peaks (608–819 nm) of the DNA-templated nanocrystals could be precisely controlled by modifying the molar ratios of their Zn/Cd precursors. Doping with Cu(I) gave an increase in photoluminescence intensity and a composition-independent red-shift of 0.23 eV. The preparation of DNA-templated Zn x Cd1−x S and Cu: Zn x Cd1−x S provides a simple, low-temperature route to aqueous dispersions of inorganic materials with controlled optical gap.

Investigation of biological activity of oxindole semicarbazones based copper (II) complexes: Synthesis, antimicrobial activities and molecular modelling

Copper (II) acetate reacted with 2-oxindole semicarbazone (2-Hoxsc, H1L), 3-methyl 2-oxindole semicarbazone (3-MeHoxsc, H2L) and 6-Chloro-2-oxindole semicarbazone (6-ClHoxsc, H3L) in 1:2 (M:L) molar ratio to form complexes of general formula, [Cu(L2)] (1L, 1; 2L 2; 3L 3. Stoichiometric ratio of complexes was established using UV–Vis spectroscopy. All the complexes were characterised by the CHN analysis, IR, ESR spectroscopy and Mass spectrometry. From the ESR spectrum, g values obtained (g‖ = 2.20; g⊥ = 2.05) for complex 2 confirms axial symmetry for this complex, whereas a broad isotropic signal in 1 and 3 (giso = 2.060, 1; 2.057, 3) indicates extensive exchange coupling. All the synthesized compounds (ligands and complexes) complexes were examined for their anti-tubercular activity against M. tuberculosis H37RV strain. Compounds were also tested for their anti-bacterial (B. subtilis, K. pneumonia) and antifungal (C. auris, C. albicans) activities. Biological investigations revealed that the antimicrobial activities (anti-TB, antibacterial and antifungal) of ligands get improved on complexation with Cu (II) due to formation of chelate ring, which can make the ligand a more powerful biological agent. Complex 3 has shown excellent anti-TB (MIC = 1.6 g/ml) and antibacterial (ZOI = 26 mm at 5 mg/mL) activities. Strong binding of complex 3 was observed (Kb = 24.22 × 105 M−1) with Human Serum Albumin (HSA) using fluorescence spectroscopy. Molecular modelling of complex 3 was also done with the active site of amino acid of M. tuberculosis enoyl reductase. The minimal binding energy of −10.1 kcal/mol indicated significant intermolecular interaction between M. tuberculosis enoyl reductase and complex 3 and is in well agreement with experimental data.

Investigation of the extraction efficiency and antioxidant capacity of deep eutectic solvent-enhanced Paeonia lactiflora

Study has demonstrated that Paeonia lactiflora contains a significant number of polyphenolic compounds; however, there is little research literature focus on phenolic acids in Paeonia lactiflora. In this study, an ultrasound-assisted extraction method based on ternary DESs was developed for the extraction of biologically active polyphenols in Paeonia lactiflora. The results indicated that the ternary solvent composed of choline chloride, DL-lactic acid, and 1,2-propanediol in a molar ratio of 1:4:2 achieved a superior extraction of polyphenols than that of conventional solvents and other ternary solvents. Subsequently, the response surface method was used to optimize the selected parameters of solid–liquid ratio, extraction time, and temperature for the extraction of phenolic by the DES, and the optimal extraction conditions were as follows: a solid–liquid ratio of 1:13.8 g/mL, an extraction time of 47.5 min, and an extraction temperature of 34.5 °C, with a total polyphenol yield of 79.77 mg/g, which is 1.09 times that of the traditional solvent. Furthermore, the extract of Paeonia lactiflora obtained through the DES method exhibited promising in vitro antioxidant activity and reducing ability. Studies have shown that DES is an efficient and environmentally friendly extraction solvent for extracting polyphenols from natural products, providing a new direction for the development and industrial production of Paeonia lactiflora.

Hydrogenation of CO2 to p-xylene over ZnZrOx/hollow tubular HZSM-5 tandem catalyst

The conversion of CO2 into specific aromatics by modulating the morphology of zeolites is a promising strategy. HZSM-5 zeolite with hollow tubular morphology is reported. The morphology of zeolite was precisely controlled, and the acid sites on its outer surface were passivated by steam-assisted crystallization method, so that the zeolite exhibits higher aromatic selectivity than sheet HZSM-5 zeolite and greater p-xylene selectivity than chain HZSM-5 zeolite. The tandem catalyst was formed by combining hollow tubular HZSM-5 zeolites with ZnZrOx metal oxides. The para-selectivity of p-xylene reached 76.2% at reaction temperature of 320 °C, pressure of 3.0 MPa, and a flow rate of 2400 mL g−1 h−1 with an H2/CO2 molar ratio of 3/1. Further research indicates that the high selectivity of p-xylene is due to the pore structure of hollow tubular HZSM-5 zeolite, which is conducive to the formation of p-xylene. Moreover, the passivation of the acid site located on the outer surface of zeolite effectively prevents the isomerization of p-xylene. The reaction mechanism of CO2 hydrogenation over the tandem catalyst was investigated using in-situ diffuse reflectance Fourier transform infrared spectroscopy and density functional theory. The results showed that the CO2 to p-xylene followed a methanol-mediated route over ZnZrOx/hollow tubular HZSM-5 tandem catalysts. In addition, the catalyst showed no significant deactivation in the 100 h stability test. This present study provides an effective strategy for the design of catalysts aimed at selectively preparing aromatics through CO2 hydrogenation.

Exceptional indoor carbon capture using epoxide-modified polyamine functionalized materials

In addressing concerns related to symptoms like dizziness, nausea, and reduced productivity stemming from elevated indoor CO2 levels, the primary objective of the current CO2 adsorption technology is to enhance the adsorption capacity. However, the stability and applicability of the adsorbent are of greater importance in indoor carbon capture than in other settings. This study examines the performance and stability of indoor CO2 capture using propylene oxide-modified tetraethylenepentamine supported on novel super carbon, gas-phase hydrophilic silica dioxide, and graphitic phase carbon nitride carriers. The corresponding painted films were developed to facilitate the application in indoor CO2 capture. Thermogravimetric analysis demonstrates that the propylene oxide-modified materials are more stable than the unmodified compositions. The findings indicate that an optimal adsorption capacity is achieved when water is used as the solvent and carboxymethyl cellulose sodium as a dispersant, while maintaining a carrier-to-tetraethylenepentamine mass ratio of 1:0.75. Furthermore, the painted films are stably formed by using isopropanol instead of water, and the tetraethylenepentamine-to-propylene oxide molar ratio of 1:2 for super carbon and graphitic phase carbon nitride as carriers, which exhibit notable enhancements in adsorption performance by 160.0 % and 41.8 %, respectively. The film using super carbon as supporter exhibited the highest adsorption capacity of 122.83 mg/g. This suggests that the compositions are more readily available for indoor CO2 capture by coating in everyday scenarios. Notably, even after undergoing five adsorption–desorption cycles, the desorption efficiency of the solid amine adsorbent remains consistently above 95 %.

Disposal of used oils as a prospective method of production of biodiesel

The article is devoted to the improvement of the production technology of diesel biofuel from waste oils, which are a significant source of environmental pollution. Environmental pollution is one of the biggest environmental problems of our time. Used oils that are not properly disposed of cause serious environmental problems, including water and soil pollution. The use of waste oils for the production of biofuel is a promising technology that allows reducing the amount of pollution and reducing dependence on fossil fuels. Biodiesel from waste oils has significant environmental, economic and sustainable advantages. The main goal of the article is a detailed analysis of modern technologies for the production of diesel biofuel from waste oils and an assessment of their improvements and impact on ecology, economy and society. The article discusses innovative approaches to the processing of used oils, their purification and preparation for further use. An analysis of the main methods of transesterification, hydrogenation, esterification and enzyme catalysis, as well as the latest technologies, such as ultrasonic and microwave intensification of biofuel production, was carried out. New technological solutions for the preliminary preparation of used oils with a high content of free fatty acids using a combination of acid catalysts are proposed, and a technological scheme of the full production cycle is developed. The rational parameters of the equipment for the preliminary preparation of used oils with a high content of free fatty acids have been determined. Recommended conditions include hydrogenation temperature not higher than 80°С, duration of the process not less than 40 minutes; separation of the water-protein part by centrifugation at a rotation frequency of the centrifuge rotor of 3000 rpm for 20 minutes; the esterification reaction temperature is no more than 60°C; molar ratio of alcohol to oil 9:1; acid catalyst concentration within 1-15%; the intensity of mixing in the reactor is 31.42 s-1; the duration of the process is not less than 120 minutes. It was established that it is advisable to use potassium hydroxide for the transesterification reaction. The use of potassium hydroxide is beneficial because the potassium salts formed during the technological process of diesel biofuel production can be used as mineral fertilizers. According to the results of the research, the optimal parameters for the transesterification reaction were chosen: the amount of methanol - 20% by mass. from the weight of the oil, the KOH 1 catalyst is 1.5%, the temperature of the process is 60°C and the duration is 60-70 minutes. Examples of successful implementation of these technologies in various countries of the world, in particular in Europe, the USA and Asia, are presented. Additionally, recommendations are provided for further research and technology development, including the need to improve waste oil purification methods, optimize transesterification processes, and integrate renewable energy sources. The prospects and challenges of the industry of biofuel production from waste oils are considered, in particular the issues of regulatory support, financial incentives and investment attraction.

Enzymatic synthesis of structured lipids rich in α‐linolenic acid: impacts of triacylglycerol profile on physicochemical characteristics

SummaryMedium‐ and long‐chain triacylglycerols rich in α‐linolenic acid (ALA‐MLCT) are a kind of functional structural lipids that provide ω‐3 fatty acid and faster energy supply to human body. To improve the functional and nutritional properties of vegetable oils, we proposed an effective strategy for the synthesis of ALA‐MLCT by enzymatic interesterification of coconut oil and flaxseed oil. Lipase UM1 exhibited the highest interesterification activity compared with commercial Lipozyme RM IM, Lipozyme TL IM and Novozym 435. MLCT (76.59%) and ALA‐MLCT (45.03%) were obtained under the optimum reaction conditions: substrate molar ratio (coconut oil/flaxseed oil) 1:1, temperature 40 °C, Lipase UM1 loading 25 U g‑1. Furthermore, we identified 14 characteristic triacylglycerols molecules between enzymatic interesterification and physical blend by orthogonal partial least squares‐discrimination analysis (OPLS‐DA) model. The content of triunsaturated type triacylglycerols in enzymatic interesterification product (11.29%) was lower than that of physical blend (36.25%). Enzymatic interesterification product had lower solid fat content and 2.44 times oxidative stability than physical blend. These findings provide an effective strategy for the synthesis of functional ALA‐MLCT and advance the understanding of the relationship between triacylglycerols composition and physicochemical characteristics.

Performance of mesoporous ceria supported Ru catalysts for oxidative degradation of aqueous solution of plastic monomer bisphenol A in a fixed bed flow reactor: Structure-activity insights, optimization of reaction conditions, kinetics, catalyst stability, and characterization

One of the important defects is the oxygen vacancy on metal oxide surfaces, and the defects function as the active sites in different catalytic reactions. Herein, Ru/CeO2-rod and Ru/CeO2-cube catalysts were prepared via the ESI method, and CeO2-rod and CeO2-cube supports were synthesized by hydrothermal processes. The activity of these catalysts was tested in a high-pressure fixed-bed reactor, and the oxidative degradation of industrial organic raffinate containing the plastic chemical bisphenol A (BPA) was compared with their oxygen vacancy concentration estimated after calcination. The Ru/CeO2-rod catalyst showed higher catalytic activity with 90 % BPA conversion at 453 K, 30 bar, 0.5 % Ru metal content, 15 O2 to BPA molar ratio, and 2 g−1.h−1 BPA feed weight hourly space velocity (WHSV). In contrast, 80 % BPA degradation was achieved using the Ru/CeO2-cube catalyst under similar reaction conditions. The higher oxygen vacancy concentration and the higher interfacial surface area between metal and the support of the CeO2-rod supported Ru catalyst triggered the higher BPA degradation at low oxidation conditions. Besides, the atomic ratio, Ce3+/Ce4+, is lower in the Ru/CeO2-rod catalyst than that of the Ru/CeO2-cube catalyst, indicating the higher Ce4+ available in the catalyst, leading to the higher degradation of BPA. Moreover, the Ru/CeO2-rod catalyst possesses {111} planes that boost the generation of energetic Ru to improve the pursuit of the catalyst. The Weisz-Prater modulus and Thiele modulus values indicated that the surface reaction is the rate limitation step and there is no diffusion limitation. TEM, HRTEM, XPS, Raman, H2-TPR, XRD, CO chemisorption and BET surface area analyzers were used to characterize the catalysts.

Zirconium titanium phosphonates for enhanced lanthanide recovery from acidic wastes

Metal phosphonates show promise for recovery of valuable lanthanide (Ln) elements from acidic waste streams due to their selectivity, high capacity, fast kinetics and chemical stability. To optimise these properties, a balance is needed between free phosphonate groups available to bind Ln and P-O-metal linkages to provide stability. This work demonstrates how astute choice of metal precursors can be used to control the phosphonate structure and maximise both sorption and stability. Relative to single metal zirconium phosphonate, mixed metal zirconium titanium phosphonate sorbents had more free phosphonate groups and greater porosity, increasing Ln capacity by 30 % and the kinetic rate constant by 90 %. Acid stability was also improved upon Ti inclusion. Use of metal propoxide and tert-butoxide precursors were also compared, revealing different reactivities with Zr versus Ti. Specifically, the tert-butoxide precursor increased P-O-Zr linkages and acid stability with Zr, but increased formation of leachable P-O-Na2 groups in the presence of Ti that decreased acid stability. The optimised zirconium titanium phosphonate sorbent used metal propoxide precursors and a Zr:Ti molar ratio of 1:1 to achieve (1) selectivity for Ln over Co, Sr and Cs, (2) sorption capacity of approximately 70 mg Eu/g, (3) fast kinetics with > 99 % sorption in 10 min and (4) retention of 60 % sorption capacity after contact with 5 M nitric acid. The enhanced chemical stability, capacity and kinetics achieved via incorporating Ti drastically improves the practicality of these sorbents for Ln recovery from acidic leachates of magnets, phosphors and other wastes.

Sulfidized nanoiron-loaded carbon for efficient removal of Cr(VI) from wastewater

With the advancement of industrial development, the threat of chromium (Cr) pollution in the aquatic environment has escalated significantly. So, it is essential to develop economically and environmentally friendly means to remove Cr(VI). In this experiment, a novel material, activated carbon loaded sulfidized nanoscale zero-valent iron (S-nZVI@AC) was prepared by sulfide modification and activated carbon (AC) loading modification. According to the data, the most effective material was found to have a S/Fe molar ratio of 0.07 and an S-nZVI@AC mass ratio of 3:1, with a removal rate (RR%) was as high as 99.9% at 60 min. The RR% of the dosage of 0.8 g/L was 99.9% and demonstrated good economic efficiency. The RR% of S-nZVI@AC for Cr(VI) was higher at pH = 3 or 7, reaching 99.8% and 99.6%, respectively. The presence of coexisting ions significantly impacted the RR%, with SO42−, K+, and high concentration of Na+ promoting removal, while PO43−, CO32− and Ca2+ had an inhibitory effect. Of these, PO43− could even reduce the RR% to about 10%, whereas a low concentration of Na+ had minimal impact. S-nZVI@AC also exhibited good resistance to aging, maintaining approximately 80% removal after being soaked in water for 10 days. Furthermore, using kinetic and thermodynamic studies, the pseudo-first-order kinetic model, Freundilch, and Elovich models were found to suit the experimental data better. Cr(VI) was eliminated by S-nZVI@AC via a combination of adsorption, reduction, co-precipitation. In summary, it is concluded that S-nZVI@AC was a new material that showed promise in the treatment of Cr(VI) effluent.

In-situ stabilized lipase in calcium carbonate microparticles for activation in solvent-free transesterification for biodiesel production

Biodiesel serves as a crucial biofuel alternative to petroleum-based diesel fuels, achieved through enzymatic transesterification of oil substrates. This study aims to investigate stabilized lipase (LP) within calcium carbonate (CaCO3) microparticles as a catalyst for solvent-free transesterification in biodiesel synthesis. The specific hydrolysis activity of the in-situ immobilized LP was 66% of that of free LP. However, the specific transesterification activity of immobilized LP in the solvent-free phase for biodiesel production was 2.29 times higher than that of free LP. These results suggest that the interfacial activation of LP molecules is facilitated by the inorganic CaCO3 environment. The immobilized LP demonstrated higher biodiesel production levels with superior stability compared to free LP, particularly regarding methanol molar ratio and temperature. To the best of our knowledge, there are no previous reports on the in-situ immobilization of LP in a CaCO3 carrier without any crosslinker as an interfacial-activated biocatalyst for biodiesel production.

SnO2-Co3O4 nanocomposite sensor: Achieving ultra-selective hydrogen detection in mixed gas environments

This paper addresses the long-standing challenge of poor selectivity in MOS sensors towards gases with similar properties, exemplified by the difficulty in distinguishing between H2 and CO in mixed environments. In this paper, n-SnO2/p-Co3O4 nanocomposites have been prepared as sensing materials by a straightforward pyrolytic bimetallic organic framework method. Optimal hydrogen detection is achieved with a Sn: Co molar ratio of 1:0.15, demonstrating a high response (S=Ra/Rg=22.75 for 300 ppm H2) and exceptional anti-interference capability against CO (SH2/SCO=11.67) at 325°C. Furthermore, the incorporation of Extreme Learning Machine (ELM) model for predicting hydrogen concentration significantly reduces the interference effect common in mixed gases, achieving a high prediction accuracy a remarkably low relative error of just 0.6 %. The mechanism behind the enhanced sensitivity and selectivity of the sensor is elucidated in the paper, offering both theoretical insight and practical solution to the issue of selectivity in MOS sensors.