Catalytic Activity of Pt Loaded Zeolites for Hydroisomerization of n-Hexane Using Supercritical CO2

Valorization and Repurposing of Citrus limetta Fruit Waste for Fabrication of Multifunctional AgNPs and Their Diverse Nanomedicinal Applications

Herein we propose an ecofriendly process for the biofabrication of AgNPs by applying fruit waste of Citrus limetta. The aqueous extracts from the peels of the fruit were used as green chelating and stabilizing agents. Structural, optical, vibrational, morphological, and magnetic properties were established using UV-Vis (ultraviolet visible spectroscopy), XRD (X-rays diffraction), FTIR (Fourier transformed infrared spectroscopy), EDS (energy dispersive spectroscopy), SEM (scanning electron microscopy), ESR (electron spin resonance), and PPMS (physical property management system), while the thermal properties were established using TGA/DTG (thermal gravimetric analysis/derivative thermogravimetry). XRD pattern revealed intense peaks with single-phase purity, while the Debye-Scherrer approximation revealed an average crystallite size of 33.18 nm. The W-H plot revealed the size of 55.2 nm and strain 2.68 × 10-4. FTIR spectra revealed the involvement of different functional groups and major IR vibrations were observed at 2329 cm-1, 2092 cm-1, 1794 cm-1, 1268 cm-1, and 754 cm-1. TGA/DTG revealed major weight loss events at 240 °C and 360 °C. SEM revealed spherical or quasi-spherical morphology, while EDS confirmed the presence of elemental silver. The M-H behavior for all measurement temperature shows diamagnetic behavior. Electron spin resonance (ESR) revealed a high proportion of free electrons. Furthermore, the pharmacognostic and nanomedicinal potential CL-AgNPs was established using multiple in vitro and in vivo bioassays. The in vivo wound healing assays in mice revealed excellent healing potential which were similar to positive control. The percent wound healing is reported to be 93% on the 14th day of incision after application of CL-AgNPs. Bioassays were performed to assess enzyme inhibition potential of the CL-AgNPs for Alzheimer disease and antidiabetic applications. The AChE and BChE potential of the CL-AgNPs was highest at 1000 µg mL-1, i.e., 92% and 56%, respectively. The α-glucosidase inhibition potential for the CL-AgNPs was higher as compared to the α-glucosidase, while the DPPH free radical scavenging was reported to be 70% to 11% at varying concentrations between 1000 and 62.5 µg mL-1. Overall, our results indicate that the waste fruit peels can be a sustainable and eco-friendly resource of synthesis of the multifunctional nanoparticles.

The influence of nano filter elements on pressure drop and pollutant elimination efficiency in town border stations

Natural gas stands as the most ecologically sustainable fossil fuel, constituting nearly 25% of worldwide primary energy utilization and experiencing rapid expansion. This article offers an extensive comparative analysis of nano filter elements, focusing on pressure drop and pollutant removal efficiency. The primary goal was to assess the superior performance of nano filter elements and their suitability as an alternative for Town Border Station (TBS). The research encompassed a six-month examination period, involving routine pressure assessments, structural examinations, and particle characterization of the filter elements. The results revealed that nano filters showed better performance in adsorbing aluminum than conventional filters, possibly due to their cartridge composition. Nano filters contained phosphorus, sulfur, and copper, while conventional filters lacked these elements. The disparity can be attributed to the finer mesh of the nano filter, capturing smaller pollutants. Although the nano filter had minimal silicon, the conventional filter showed some, posing concerns. Despite having 19 extra pleats, the nano filter maintained gas flow pressure while capturing more particles than the conventional filter.

Energy-efficient extraction of linear alkanes from various isomers using structured metal-organic framework membrane

Extraction of low concentration linear alkanes (C5-C7) from various isomers is critical for the petrochemical industry. At present, the separation of alkane isomers is mainly accomplished by distillation, which results in substantial energy expenditure. Metal-organic frameworks (MOFs) with well-tailored nanopores have been demonstrated to be capable of realizing molecule-level separation. In this study, oriented HKUST-1 membranes are formulated according to the morphology-biased principle and finally realized with a low dose synthesis method for terminating undesired crystal nucleation and growth. The fully exposed triangular sieving pore array of the membrane induces configuration entropic diffusion to split linear alkanes from mono-branched and di-branched isomers as well as their cyclical counterparts. Typically, the current separation technique consumes 91% less energy than vacuum distillation. Furthermore, our membranes can realize one-step extraction of normal-pentane, normal-hexane and normal-heptane from a ten-component alkane isomer solution that mimics light naphtha.

Hydrochar synthesis from waste corncob using subcritical water and microwave-assisted carbonization methods and ammonium enrichment of synthesized hydrochars

Corncob (CC) is an industrial biological waste that is generated in significant quantities, and converting such biological wastes into value-added hydrochars through a viable process such as hydrothermal carbonization can provide significant benefits. It is of great importance to ensure eco-friendly and appropriate methods that are suitable for the area where the hydrochar will be used. This study aimed to synthesize hydrochars from a solid food waste, CC, using two different hydrothermal carbonization methods based on microwave-assisted (MHC) and subcritical water (SHC) using them as a biosorbent for NH₄⁺ adsorption from water and characterizing their specific features. Hydrochars were synthesized in 1 h at 180 °C and 240 °C by MHC and SHC methods, respectively. Hydrochars synthesized by MHC and SHC methods were characterized by SEM-EDX, N₂ adsorption-desorption isotherms, and FT-IR analyses. According to the EDX results, the C/O ratio (atomic %) in MHC and SHC was determined to be 0.55 and 0.35, respectively. Nitrogen adsorption-desorption isotherms revealed that hydrochars obtained by both methods have three distinct pore types, namely, micro, meso, and macro. In the energy consumption per unit adsorbent, a lower value was obtained for MHC than SHC. NH₄⁺ adsorption using MHC and SHC was found to be compatible with the Langmuir isotherm model and the NH₄⁺ adsorption capacities were 13.09 and 10.54 mg/g, respectively. pH was the most effective variable on hydrochars in the NH₄⁺ adsorption based on the response surface method (RSM), and the highest adsorption occurred at pH 6.5 and 40 mg/L of initial NH₄⁺ concentration, using 1.5 g/L of adsorbent at 35 °C. The results revealed that MHC is a unique method that can be used for hydrochars derived from CC in NH₄⁺ adsorption, and MHC is more cost-effective than SHC in hydrochar production.

Bifunctional electrode of bismuth tungsten for electrochemical sensing applications

A co-precipitation technique has been used to prepare Bismuth tungstate nanoparticles (Bi₂WO₆) for electrochemical capacitors and electrochemical sensing of Ascorbic acid (AA). Using a scanning rate of 10 mV s ^-1, the electrode was performed as the pseudocapacitance behavior and the specific capacitance to be up to 677 Fg ^-1 at 1 A/g. Bi₂WO₆ versus Glassy carbon electrode (GCE) was also used to study the behavior of the Bi₂WO₆ modified electrodes in detecting ascorbic acid. This electrochemical sensor shows excellent electrocatalytic performance when ascorbic acid is present, as determined by differential pulse voltammetry. In solution, ascorbic acid diffuses to an electrode surface and controls its surface properties. Based on the results from the investigation, the sensor showed a detection sensitivity of 0.26 mM/mA, and a limit of detection (LOD) of 77.85 mM. It is clear from these results that Bi₂WO₆ may find application as an electrode material for supercapacitors and glucose sensors.

Ab initio calculations of CO2 adsorption on β-C2S(100) and M3-C3S(001) surfaces: An exploration of early CO2 sequestration pathways

Investigating CO₂ sequestration in cement-based materials is significant for achieving carbon neutrality in the cement and concrete industries. The early CO₂ sequestration pathways on cement-based materials are fundamental for CO₂ sequestration, which is not clear. Towards this, the adsorption behavior of CO₂ on β-C₂S(100) and M3-C₃S(001) was investigated at the atomic level using density functional theory calculations, which were then compared with water adsorption results. The molecular adsorption configurations of CO₂ on both β-C₂S(100) and M3-C₃S(001) were tilted from their initial configurations due to the influence of surface Ca and O atoms. The CO₂ adsorption energy on M3-C₃S(001) and β-C₂S(100) were -0.458 eV and -0.426 eV, respectively, indicating adsorption on M3-C₃S(001) was more energetically favorable. After CO₂ adsorption, electrons were transferred from the surface to the CO₂ molecule. Furthermore, the Ca-O bond orders of β-C₂S(100) and M3-C₃S(001) after CO₂ adsorption were maximally decreased by 2.79% and 6.99%, respectively. A more significant adsorption influence on surfaces was found for H₂O, with more negative adsorption energy, more evident electron transfer, and a greater decrease in bond order. The CO₂ adsorption on β-C₂S(100) and M3-C₃S(001) were still spontaneous at 298 K and 1 atm. This study provides important theoretical insights into early CO₂ sequestration at the atomic level, which has practical implications for the design of efficient CO₂ sequestration technologies.

Analytical and regulatory considerations to mitigate highly hazardous toxins from environmental matrices

The ubiquitous occurrence, toxicological influence, and bioaccumulation of toxic entities, e.g., pesticides and toxic elements in the environment, biota, and humans, directly or indirectly, are posing severe social, ecological, and human health concerns. Much attention has been given to the rising bioaccumulation of toxins and their adverse impact on various environmental matrices. For example, the inappropriate and exacerbated use of xenobiotics and related hazardous substances have caused the deterioration of the agricultural environment, e.g., fertile soils where plants are grown. Moreover, the harmful toxins have negatively impacted human health through the trophic chains. However, the analytical and regulatory considerations to effectively monitor and mitigate any or many pesticides and toxic elements from environmental matrices are still lacking in the existing literature. For decades, the scientific community has overseen the consequences caused by pollutants, however, the improvement of analytical detection methods and regulatory considerations are not yet fully covered. This review covers the notable literature gap by stressing the development and deployment of robust analytical and regulatory considerations for an efficient abatement of hazardous substances. Following detailed information on occurrence, toxicological influence, and bioaccumulation of pesticides and toxic elements, the most relevant analytical detection tools and regulatory measures are given herein, with suitable examples, to mitigate or reduce the damage caused by these pollutants.

Curauá-derived carbon dots: Fluorescent probes for effective Fe(III) ion detection, cellular labeling and bioimaging

This study reports the generation of curauá-derived carbon dots (C-dots) and their suitability for Fe(III) detection, bioimaging and FACS analysis. C-dots were generated from curauá (Ananas erectifolius) fibers by a facile one-step hydrothermal approach. They exhibited graphite-like structure with a mean diameter of 2.4 nm, high water solubility, high levels of carboxyl and hydroxyl functional groups, excitation-dependent multicolor fluorescence emission (in the range 450 nm - 560 nm) and superior photostability. C-dots were highly selective and effective for the detection of ferric Fe(III) ion in an aqueous medium with a detection limit of 0.77 μM in the linear range of 0-30 μM, a value much lower than the guideline limits proposed by the World Health Organization (WHO). In biological cell systems, C-dots were very well tolerated by B16F1 mouse melanoma and J774.A1 mouse macrophages cell lines, both of which effectively internalized C-dots in their cytoplasmic compartment. Finally, C-dots were effective probes for long-term live cell imaging experiments and multi-channel flow cytometry analysis. Collectively, our findings demonstrate that curauá-derived C-dots serve as versatile and effective natural products for Fe(III) ion sensing, labeling and bioimaging of various cell types. This study adds novel C-dots to the library of carbon-based probes and paves the way towards a sustainable conversion of a most abundant biomass waste into value-added products.

Covalent Organic Frameworks for Simultaneous CO2 Capture and Selective Catalytic Transformation

Combination of capture and simultaneous conversion of CO2 into valuable chemicals is a fascinating strategy for reducing CO2 emissions. Therefore, searching for heterogeneous catalysts for efficient catalytic conversion of CO2 is of great importance for carbon capture and utilization. Herein, we report a metalloporphyrin-based covalent organic framework (Co(II)@TA-TF COF) that can capture CO2 and simultaneously convert it into cyclic carbonates under mild conditions. The COF was designed to possess micropores for the adsorption of CO2 and integrated with cobalt(II) porphyrin (Co(II)@TAPP) units as catalytic sites into the vertices of the layered tetragonal networks. The structure of the Co(II)@TA-TF COF is unique where Co(II)@TAPP units are alternately stacked along the z direction with a slipped distance of 1.7 Å, which gives an accessible space to accommodate small molecules, making it possible to expose catalytic sites to substrates within the adjacent stacked layers. As a result, this COF is found to be highly effective for the addition of CO2 and epoxides. Importantly, the Co(II)@TA-TF COF exhibited a dramatic size selectivity for substrates. In conjunction with its reusability, our results highlight the development of a new function of COFs for targeting simultaneous CO2 absorption and utilization upon complementary exploration of the structural features of skeletons and pores. Such promising catalytic performance of the COF makes it possible for its potential practical application.

Effective remediation of petrochemical originated pollutants using engineered materials with multifunctional entities

The highly robust, effective, and sustainable remediation of hydrocarbon-contaminated wastewater matrices, which is mainly generated from petroleum and related petrochemical industries, is of supreme interest. Owing to the notable presence of suspended solids, oil, and grease, organic matter, highly toxic elements, high salts, and recalcitrant chemicals, crude oil emulsions, and hydrocarbon-contaminated wastewater are considered a potential threat to the environments, animals, plants, and humans. To effectively tackle this challenging issue, magnetic hybrid materials assembled at nano- and micro-scale with unique structural, chemical, and functional entities are considered robust candidates for demulsification purposes. The current research era on magnetic materials has superwettability, leading to an effective system of superwettability, which is vibrant and promising. The wettability of magnetic and magnetic hybrid materials explaining the theme of superhydrophobicity and superhydrophilicity under the liquid. Herein, we reviewed the applications of magnetic nanoparticles (MNPs) as effective demulsifiers. The demulsifier wettability, dose, pH, salinity, and surface morphology of compelling, magnetic nanoparticles are the main hidden factors in effective demulsifiers. There is a comprehensive discussion on the reuse and recyclability of MNPs after oil, water separation. Furthermore, the main challenges, coupled with the magnetic nanoparticles in the effective separation of emulsions, are intensified in detail. This review will compare the current literature and the utilization of MNPs for the demulsification of oil and water emulsions. This is envisioned that the MNPs would be critical in the petroleum and petrochemical industry to effectively eliminate water from a crude oil emulsion.

Engineered tyrosinases with broadened bio-catalysis scope: immobilization using nanocarriers and applications

Enzyme immobilization is a widely used technology for creating more stable, active, and reusable biocatalysts. The immobilization process also improves the enzyme's operating efficiency in industrial applications. Various support matrices have been designed and developed to enhance the biocatalytic efficiency of immobilized enzymes. Given their unique physicochemical attributes, including substantial surface area, rigidity, semi-conductivity, high enzyme loading, hyper catalytic activity, and size-assisted optical properties, nanomaterials have emerged as fascinating matrices for enzyme immobilization. Tyrosinase is a copper-containing monooxygenase that catalyzes the o-hydroxylation of monophenols to catechols and o-quinones. This enzyme possesses a wide range of uses in the medical, biotechnological, and food sectors. This article summarizes an array of nanostructured materials as carrier matrices for tyrosinase immobilization. Following a detailed background overview, various nanomaterials, as immobilization support matrices, including carbon nanotubes (CNTs), carbon dots (CDs), carbon black (CB), nanofibers, Graphene nanocomposite, platinum nanoparticles, nano-sized magnetic particles, lignin nanoparticles, layered double hydroxide (LDH) nanomaterials, gold nanoparticles (AuNPs), and zinc oxide nanoparticles have been discussed. Next, applied perspectives have been spotlights with particular reference to environmental pollutant sensing, phenolic compounds detection, pharmaceutical, and food industry (e.g., cereal processing, dairy processing, and meat processing), along with other miscellaneous applications.

Anchoring Water Soluble Phosphotungstic Acid by Hybrid Fillers to Construct Three-Dimensional Proton Transport Networks

Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm-1 for the composite membrane, which is quite stable during the water immersion test.

Preparation and Characterization of Mg-Al-B Alloy (Mg0.5Al0.5B2) Via High-Temperature Sintering

Boron and its alloys have long been explored as potential fuel and increasingly replace pure aluminum powder in high-energy formulations. The ignition and burning properties of boron can be improved by making boron alloys. In this study, an Mg–Al–B alloy was synthesized from magnesium, aluminum and boron powders in a 1:1:4 molar ratio by preheating to 600 °C for 30 min, followed by high-temperature sintering in a tube furnace. The effects of sintering temperature (700–1000 °C) and holding time (0.5–10 h) on the phase composition of mixed powders were studied. After the samples were cooled to room temperature, they were ground into powder. The phase composition, micromorphology and the bonding forms of elements of the synthesized samples were studied using XRD, SEM and XPS. The results show that each element exists in the form of simple substance in the alloy. The influence of the sintering temperature on the synthesis reaction of Mg_0.5Al_0.5B₂ is very important, but holding time has little effect on it. With the increase of sintering temperature, the content of the Mg_0.5Al_0.5B₂ phase gradually increases, and the phase content of residual metal gradually decreases. The phase and morphology analyses show that the optimum sintering temperature is 1000 °C with a minimum holding time of 0.5 h. It is expected to be used in gunpowder, propellant, explosives and pyrotechnics with improved characteristics.

Preparation of ROS active and photothermal responsive hydroxyapatite nanoplatforms for anticancer therapy

Photothermal responsive nanoplatforms are attracting for photothermal therapy (PTT) of cancer. Herein, we propose a strategy to prepare IR-780 modified hydroxyapatite (HAP) nanorods as photothermic agents (HAP@IR-780). The results demonstrated that the obtained HAP@IR-780 was photothermal responsive under near-infrared laser irradiation the photothermal conversion efficiency was 69.3%, and it remained photostability after 4 cycles of irradiation. This advantage overcomes the optical instability of IR780. MTT and cellular uptake research proved that HAP@IR-780 was biocompatible in appropriate concentration range (0-20 μg/mL) without laser irradiation. Concentration-dependent internalization and reactive oxygen species (ROS) related apoptosis of HAP@IR-780 for MCF-7 cells were observed. Animal experiments showed that the gathered HAP@IR-780 at the tumor site reached a photothermal responsive temperature up to 57.9 °C, which could almost ablate the tumor with volumes as large as 1500 mm³. In general, our photothermal material has good photothermal conversion characteristics, and may have the least safety problems while showing excellent therapeutic effects. Therefore, HAP@IR-780 has a brilliant prospect in the field of tumor photothermal therapy.