Synthesis Mixture Research Articles

Amino acid assisted-construction of 2D-hierarchical MFI zeolites for adsorption of rhodamine B

Hierarchical and two-dimensional (2D) zeolites have drawn much attention in catalysis and separation process due to their fast mass transfer. However, the facile manipulation in controllable mesopore volumes and morphologies for hierarchical nanozeolites is full of challenges. Herein, a facile strategy is presented for the synthesis of single-crystalline 2D hierarchical MFI zeolite nanosheets (HNSs) with tunable mesopore volumes through the amino acid-assisted crystallization of nucleated amorphous silicon precursors (NASPs). The tailored synthesis of HNSs with controllable aspect ratios ((Lc + La)/Lb), b-axis thicknesses (a few tens of nanometers) and mesopore volumes is achieved by adjusting the preparation of the NASPs and the amount of amino acid in the synthesis mixture. The HNSs exhibit large BET surface area (>400 m2 g-1), high micropore volume (0.16–0.18 cm3 g−1) as well as rich mesopore volume (>0.10 cm3 g−1), indicating the high crystallinity of the hierarchical zeolite nanosheets. Specially, the higher adsorption capability and faster adsorption rate for the dye (Rhodamine B) adsorption demonstrate the excellent performance of the hierarchical zeolite nanosheets, which exhibits the maximum adsorption capacity of 115.7 mg g−1. The controllable manipulation of mesoporous volumes and morphologies in MFI zeolites represents a significant contribution to the field of zeolite microstructure engineering.

Cerium-Organic Framework UiO-66(Ce) as a Support for Nanoparticulate Gold for Use in Oxidation Catalysis.

An optimised synthesis of the metal-organic framework (MOF) UiO-66(Ce) is reported using a modulator-free route, yielding ~5 g of material with high crystallinity and 22 % ligand defect. Two methods are developed for loading gold nanoparticles onto the MOF. The first uses a double-solvent method to introduce HAuCl4 onto UiO-66(Ce), followed by reduction under 5 % H2 in N2, while the second is a novel one-pot method where HAuCl4 is added to the synthesis mixture, forming Au nanoparticles within the pores of the UiO-66(Ce) during crystallisation. Analysis using powder X-ray diffraction (PXRD), nitrogen adsorption isotherms, transmission electron microscopy and small-angle X-ray scattering (SAXS) reveals that the two-step double-solvent method yields gold crystallites on the external surface of the MOF particles that are visible by PXRD. In contrast, the one-pot method forms smaller gold crystallites, with a distribution of sizes centred on ~4 nm diameter as seen by SAXS, with evidence from PXRD for the smallest particles being present within the MOF structure. The Au-loaded UiO-66(Ce) materials are evaluated for the catalytic oxidation of vanillyl alcohol to vanillin at 60 °C. Our findings indicate that incorporating Au nanoparticles via the one-pot synthesis method, enhances redox activity, achieving 43 % conversion and 90 % selectivity towards vanillin.

Influence of anions on the structural and catalytic properties of CTA-MCM-41

CTA-MCM-41 — Mobil Composition of Matter 41 with cetyltrimethylammonium cations (CTA+) — is a hybrid silica known for its high basic catalytic activity due to anionic silanolate sites (Si−O-) that are bound to CTA+. The synthesis of this material depends on the properties of CTA+ micelles in aqueous dispersion which, in turn, depend on the surrounding anions. Thus, this study investigated different types and amounts of anions in the synthesis of CTA-MCM-41. Chloride (Cl-), bromide (Br-), iodide (I-), nitrate (NO3-) and hydroxide (OH-) anions in sodium form were added to the synthesis mixture, and the obtained silicas were tested in the transesterification reaction. It is hereby presented a comprehensive study on how micelles-anion interfaces play a key role in the synthesis of this important hybrid silica catalyst, and it was possible to synthesize a more active basic catalyst than the conventional CTA-MCM-41, just by exploring such surface chemistry effects. Three significant features are highlighted: (1) improved catalytic activity of CTA-MCM-41 applied in transesterification; (2) Synthesis of CTA-MCM-41 with higher retention of cations per silica and higher amount of silanolate basic sites; (3) deepening knowledge of the synthesis mechanism of materials from the MCM-41 family. The effects are more pronounced in the order I- > NO3- > Cl-, in accordance with the Hofmeister ion series. Hydroxide anions, however, led to the greatest increase in the number of sites and basic catalytic activity (up to 52.4 %). These results reinforce the validity of the {S+, X-, I-} (S: surfactant; X: anion; I: silica) silica formation mechanism and reveal a synthesis with hydroxide anions that produces a catalyst more active than conventional CTA-MCM-41.

Machine learning approaches for simultaneous spectrophotometric determination of heavy metal ions in water samples

In this study, the simultaneous determination of Co, Cd, Ni, Cu, and Pb was carried out as a color complex with 4-(2-pyridylazo) resorcinol in an aqueous solution under the assesting of machine learning. A partial least-squares multivariate linear regression and artificial neuron network for the analysis of mixtures of metals were developed. MATLAB is a powerful software machine learning program that was used to support matrix calculations and displays. The benefit of MATLAB in the construction of the machine learning model allows the development of a rapid and highly effective analysis of multiple components in the mixtures without separation and enrichment. For individual determinations, the working ranges were discovered as the important information for choosing the initial concentration of each heavy metal in a mixture, r. The results of analysis of Ni2+, Pb2+, and Cd2+ by two methods Partial Least Squares - PLS and Artificial Neural Networks - ANN are sensitive and accurate for simultaneous determination of the concentration of these ions in the synthesis mixture with a high regression coefficient of 0.993, respectively, 0.997, 0.997 for Ni2+, Pb2+ and Cd2+. As for Cu2+ and Co2+, the accuracy is higher when using the ANN method.

Novel Organic-Inorganic Nanocomposite Hybrids Based on Bioactive Glass Nanoparticles and Their Enhanced Osteoinductive Properties.

Inorganic-organic hybrid biomaterials have been proposed for bone tissue repair, with improved mechanical flexibility compared with scaffolds fabricated from bioceramics. However, obtaining hybrids with osteoinductive properties equivalent to those of bioceramics is still a challenge. In this work, we present for the first time the synthesis of a class II hybrid modified with bioactive glass nanoparticles (nBGs) with osteoinductive properties. The nanocomposite hybrids were produced by incorporating nBGs in situ into a polytetrahydrofuran (PTHF) and silica (SiO2) hybrid synthesis mixture using a combined sol-gel and cationic polymerization method. nBGs ~80 nm in size were synthesized using the sol-gel technique. The structure, composition, morphology, and mechanical properties of the resulting materials were characterized using ATR-FTIR, 29Si MAS NMR, SEM-EDX, AFM, TGA, DSC, mechanical, and DMA testing. The in vitro bioactivity and degradability of the hybrids were assessed in simulated body fluid (SBF) and PBS, respectively. Cytocompatibility with mesenchymal stem cells was assessed using MTS and cell adhesion assays. Osteogenic differentiation was determined using the alkaline phosphatase activity (ALP), as well as the gene expression of Runx2 and Osterix markers. Hybrids loaded with 5, 10, and 15% of nBGs retained the mechanical flexibility of the PTHF-SiO2 matrix and improved its ability to promote the formation of bone-like apatite in SBF. The nBGs did not impair cell viability, increased the ALP activity, and upregulated the expression of Runx2 and Osterix. These results demonstrate that nBGs are an effective osteoinductive nanoadditive for the production of class II hybrid materials with enhanced properties for bone tissue regeneration.

Synthesis of secretory leukocyte protease inhibitor using cell-free protein synthesis system.

Secretory leukocyte protease inhibitor (SLPI) functions as a protease inhibitor that modulates excessive proteolysis in the body, exhibits broad-spectrum antimicrobial activity, regulates inflammatory responses, and plays an important role in the innate immunity. The purpose of the study was to artificially synthesize a SLPI, an antimicrobial peptide, and investigate its effect on antimicrobial activity against Porphyromonas gingivalis and interleukin-6 (IL-6) production. SLPI protein with a molecular weight of approximately 13kDa was artificially synthesized using a cell-free protein synthesis (CFPS) system and investigated by western blotting and enzyme-linked immunosorbent assay (ELISA). Disulfide bond isomerase in the protein synthesis mixture increased the amount of SLPI synthesized. The synthesized SLPI (sSLPI) protein was purified and its antimicrobial activity was investigated based on the growth of Porphyromonas gingivalis and bacterial adhesion to oral epithelial cells. The effect of sSLPI on IL-6 production in human periodontal ligament fibroblasts (HPLFs) was examined by ELISA. Our results showed that sSLPI significantly inhibited the growth of Porphyromonas gingivalis and bacterial adhesion to oral epithelial cells and further inhibited IL-6 production by HPLFs. These results suggested that SLPI artificially synthesized using the CFPS system may play a role in the prevention of periodontal diseases through its antimicrobial and anti-inflammatory effects.

Controlling Crystal Morphology of Anisotropic Zeolites with Elemental Composition.

The morphology of zeolite crystals strongly affects their textural, catalytic, and mechanical attributes. However, controlling zeolite crystal morphology without using modifiers or structure-directing agents remains a challenging task because of our limited understanding of the relationships between zeolite crystal shape, crystallization mechanism, and composition of the starting synthesis mixture. In this study, we aimed at developing a general method for controlling the morphology of zeolites by assessing the impact of the Si/T molar ratio of the synthesis gel on the growth rate of zeolite crystals in various crystallographic directions and on the final crystal morphology of the UTL germanosilicate with a 2D system of intersecting 14- and 12-ring pores. Our results showed that flat UTL crystals progressively thicken with the Si/Ge molar ratio, demonstrating that Ge concentration controls the relative rate of crystal growth in the perpendicular direction to the pore system. The morphology of other zeolites and zeotypes with an anisotropic structure, including AFI (12R), IFR (12R), MWW (10-10R), and IWW (12-10-8R), can also be predicted based on their Si/T ratio, suggesting a systematic pattern across zeolite structures and in a wide range of zeolite framework elements. Combined, these findings introduce a facile and cost-efficient method for directly controlling crystal morphology of zeolites with anisotropic structures with a high potential for scale-up while providing further insights into the role of elemental composition in zeolite crystal growth.

Using different ratios of glycine to citric acid as fuel mixture in microwave-assisted combustion synthesis of Eu-doped Y2O3–Gd2O3 nanophosphors

Using different ratios of glycine to citric acid as fuel mixture in microwave-assisted combustion synthesis of Eu-doped Y2O3–Gd2O3 nanophosphors

Unveiling the Structural Characteristics of Intergrowth Zeolites Synthesized in the Presence of Isopropylimidazolium-Based Cations and Fluoride Anions.

Here, we present the synthesis of RTH/ITE and MEL/MFI intergrowth zeolites using 2-isopropylimidazolium-based cations as organic structure-directing agents (OSDAs) in concentrated fluoride media and their local structural properties. Phase selectivity in the synthesis of zeolite intergrowths was found to differ according to the concentration of OSDA cations and fluoride anions in the synthesis mixture as well as to the type of OSDA employed. Molecular modeling results suggest that the crystallization of intergrowth zeolites in fluoride media may be kinetically rather than thermodynamically controlled, as in ordered zeolites. Cs-corrected STEM analysis of MEL/MFI crystals synthesized at HF/OSDA = 2.0 in the presence of 2-isopropyl-1,3-dipropylimidazolium ions as an OSDA indicates the existence of previously unobserved MEL-MFI intergrowth along the [100] direction, leading to a partial blockage of MEL 10-ring channels.

Valorization of Naturally Abundant Low-Value Peat into Highly Active Non-Platinum Group Metal Oxygen Reduction Catalysts

As society continues to adopt an increasingly eco-friendly stance, the efficient usage of natural resources needs to be maximised. For instance, energy obtained from biomass covers roughly a tenth of the global demand. This biomass can instead be used as a carbon source to produce value-added materials such as tnon-platinum group metal (NPGM) oxygen reduction catalysts, which are desperately sought after as global demand for fuel cells continues to rise [1,2]. For example, peat is an extremely abundant biomass material in Estonia covering roughly 20% of the country [3]. Herein, the viability of using peat-based catalysts as oxygen reduction catalysts in alkaline media was investigated.The peat sourced from a local peatland was processed and modified with inexpensive iron and nitrogen precursors through the common double-pyrolysis and acid washing synthesis procedure into peat-based NPGM catalysts. Additionally, zinc chloride was used as a pore forming agent. The influence of several principal synthesis parameters, e.g. precursor compound type and amount, on the physical and electrochemical properties of these materials was investigated using various characterization methods.The NPGM catalysts obtained from naturally abundant peat were highly microporous systems due to the inclusion of zinc chloride in the synthesis mixture. High onset (~0.93 V vs RHE) and half-wave potential (~0.83 V vs RHE) values were obtained for most of the materials in activity screening experiments conducted with a rotating disc electrode setup using 0.1 M KOH. However, using an excessive amount of the nitrogen precursor in the synthesis proved to be detrimental to the obtained activity. The high activity of the obtained peat-derived catalysts was further investigated in a rotating ring disc electrode setup where the influence of the studied synthesis parameters on the oxygen reduction reaction selectivity was more evident. Acknowledgments This work was supported by the EU through the European Regional Development Fund under projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR “Nanomaterials - research and applications” (3.2.0304.12-0397), NAMUR+ core facility funded by the Estonian Research Council (TT 13), PRG676 “Development of express analysis methods for micro-mesoporous materials for Estonian peat derived carbon supercapacitors” (01.01.2020–31.12.2024) and PUT1581 (1.01.2017–31.12.2020). References F. Jaouen, D. Jones, N. Coutard, V. Artero, P. Strasser, A. Kucernak, Johns. Matthey Technol Rev. 2018, 62, 231. E4tech, 2022, The Fuel Cell Industry Review 2021. M. Orru, H. Orru, Est. J. Earth Sci. 2008, 57, 87.

Green Zeolite Synthesis Assisted with Plants Extract

The study explores the hydrothermal synthesis of zeolite using kaolin clay from Perak in the presence of two different reduction mediums, namely turmeric extract and ginger extract, and a 2M NaOH solution, measuring their efficiency and potential for green synthesis. Before the zeolite synthesis and transformation, the kaolin clay was heated at a temperature of 650 oC for 4 hours in the furnace to produce the metakaolin phase. The synthesized zeolite involves the reaction of NaOH with potential reduction plant extracts to assist the transformation of zeolite. The characterization of the synthesized particles after being ground into a fine powder and subsequently undergoing testing and characterization via X-ray diffraction (XRD) revealed the existence of zeolite phases in both plants with slightly different zeolite compositions. Synthesis mixtures with turmeric plants show better composition of the zeolite phase as compared to ginger mixtures. Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX) also revealed that the synthesized product using turmeric plant extract was able to produce zeolite LTA with a good grade. The current experimental work shows the possibility of obtaining a well crystalline zeolite from Malaysian kaolin, assisted with plant extract reduction medium.

Extracellular biosynthesis of CuO-TiO2 nanocomposites using Alcaligenes aquatilis for the photodegradation of reactive and azo dyes under visible light irradiation.

In this study, CuO/TiO2 nanocomposites were biologically synthesized using cell-free supernatant (CFS) of Alcaligenes aquatilis growth culture by two-step synthesis method, one-pot method with sequential addition of precursors, and one-pot method with simultaneous addition of precursors. The one-pot method with simultaneous addition of precursors was found to be the best method for the synthesis in terms of degradation of reactive blue-220 (RB-220) and acid yellow-17 (AY-17) dyes under visible light irradiation. CuO/TiO2 nanocomposite was found to have the crystallite size of 14.7nm and the bandgap energy of 2.5 eV. The effect of synthesis parameters such as synthesis time, pH of CFS, and the ratio of Cu to Ti in the synthesis mixture on the photocatalytic degradation efficacy of these nanocomposite structures under visible light irradiation was studied. The optimum conditions for the synthesis of CuO/TiO2 nanocomposite particles by one-pot method with simultaneous addition of precursors were found to be pH 12 of CFS, synthesis duration of 24 h, and molar ratio of Cu to Ti in the synthesis mixture as 1:22 for RB-220 dye and 1:25 for AY-17 degradation. CuO/TiO2 nanocomposite particles synthesized under the optimum conditions and without any calcination could degrade RB-220 and AY-17 dyes completely in 120 min and 150 min, respectively. The kinetics of degradation of RB-220 and AY-17 by CuO@TiO2 nanocomposite particles followed first-order kinetic model with rate constant of 0.028 min-1 and 0.018 min-1, respectively.

Highly-selective hybrid ultrafiltration membranes with AlPO4-5 zeotype fillers: Effect of filler loading, morphology, and metal substitution on performance and fouling resistance

In recent years, membrane technologies have emerged as a promising solution for water treatment, particularly ultrafiltration. However, fouling remains a significant challenge in membrane applications, leading to a decline in membrane performance over time. To address this issue, the development of antifouling membranes has garnered considerable attention. By tuning their hydrophilicity, roughness, and surface charge, such membranes aim to mitigate fouling effects and extend their operational lifespan. In this work, aluminophosphate zeotype AlPO4-5 and cobalt-substituted AlPO4-5 (CoAPO-5) fillers were hydrothermally grown, their physicochemical, structural, and morphological characteristics were evaluated, and both types of fillers were incorporated into polyethersulfone (PES) membranes via phase inversion to fabricate antifouling hybrid ultrafiltration membranes. Fabrication of PES/xCoAPO-5 (y) hybrid membranes (x: Co/Al2O3 mole%, y: H2O/Al2O3 molar ratio in the synthesis mixture of the zeolite synthesis) was realized by varying the loading of the zeolite in the casting solution. Water permeance and bovine serum albumin (BSA) rejection of the developed hybrid membranes were significantly enhanced depending on the metal content, filler morphology, and loading within the membrane matrix. The maximum water permeance (688.8 L m−2 h−1 bar−1) was obtained for the membrane loaded with 6 wt% AlPO4-5 (400), which was 66 % higher than the pristine one, while a superior BSA rejection rate of 99.4 % was obtained from the membrane loaded with 6 wt% of 5CoAPO-5 (400).

Facile and controllable preparation of mesoporous silica nanoparticles with ultra-large mesopores enabled by an ammonium chloride–assisted hydrothermal process

This work reports the facile preparation of monodispersed ultra-large mesopore mesoporous silica nanoparticles (ULP-MSNs) with controllable mesopore sizes and particle sizes. The key design to such preparation lies in the application of ammonium chloride (NH4Cl) assisted-hydrothermal (AAH) process to as-prepared conventional MSNs, whose small mesopore sizes of about 2 nm can be effectively enlarged to over 16 nm. Based on the systematic study of the synthetic parameters, it was recognized that the initial ethanol added in the synthesis mixture (1st ethanol), NH4Cl, and the ethanol added in the mixture (2nd ethanol) during the hydrothermal (HT) process and HT conditions play synergistic roles in enlarging mesopores by AAH process. The mechanism of mesopore enlargement was also studied. By this method, ULP-MSNs with variable mesopore sizes in a range of 14 nm–26 nm, large synthesis domain, and controllable particle sizes ranging from 106 nm to 267 nm can be produced in a facile manner. This work, we believe, represents a new strategy for the preparation of ULP-MSNs and will promote their various applications.

Unveiling the Roles of Precursor Structure and Controlled Sintering on Ni-Phyllosilicate-Derived Catalysts for Low-Temperature Methane Decomposition

Catalytic methane decomposition (CMD) is a promising technology for large-scale production of COx-free H2 from natural gas that can also produce valuable carbon byproducts. Although equilibrium conversions and reaction rates of CMD generally increase with temperature, operation in a low-temperature regime with simultaneous H2 recovery could potentially lead to operating cost and energy savings. Here, we report that well-dispersed Ni–SiO2, derived from high-temperature reduction of nickel phyllosilicates, is active for CMD at temperatures below 500 °C, with initial H2 production rates of up to 5.3 mol H2/gcat·h at 25% CH4 conversion. This ability to achieve rates comparable to other well-established catalysts is contrary to expectations that small (<ca. 10 nm) Ni nanoparticles are inactive for CMD because of rapid deactivation and attributed here to an unusual mobility of nickel–silica interfaces in the presence of CH4 that leads to controlled sintering of the originally well-dispersed Ni nanoparticles. We further show that the ratio of 1:1 and 2:1 nickel phyllosilicates in the precursor, which governs catalyst reducibility and can be tuned by adding NH4F to the synthesis mixture, is a key descriptor of catalytic performance. Our findings provide valuable insight into catalyst and process design for low-temperature CMD.

Molecular Modification of Zeolites with Cold Atmospheric-Pressure Plasma Jet: A Green and Facile Strategy

Widespread applications of zeolites demand the optimization of crystal size and morphology. Crystal growth modifiers (CGMs) have been proved effective for zeolite rational design, but the additional chemicals raise environmental and safety concerns. Herein, the industry-ready technique of cold atmospheric-pressure plasma jet (CAPPJ) was employed to induce reactive plasma species as green and eco-friendly CGMs. The synthesis mixtures of three aluminosilicate zeolites with assorted Si/Al ratios (SAR), channel dimensionalities, and pore apertures (i.e., MFI, LTA, and LTL framework types) were first subjected to Ar-CAPPJ treatment for up to 30 min during the aging period. Apparent size and shape modifications were successfully achieved for the resulting crystals with the emergence of rounded surfaces implying surface roughening at the molecular level. For the silicoaluminophosphate SAPO-34 (CHA type), the introduction of plasma CGMs was found to propel a phase transformation, promoting the crystallization of SAPO-18 (AEI type) impurity with reduced framework density. Experimental observations seem to suggest that the classical model of CGMs attaching to selected crystal surfaces is less likely to happen. Whereas, the investigation of zeolite L dispersions revealed enhanced concentrations and altered physicochemical properties of soluble species and amorphous precursors, alluding to the potential functional mechanism (s) of plasma CGMs. As a plausible technique to generate green and versatile CGMs, the impacts of CAPPJ on zeolite crystallization are systematically investigated for the first time, promoting the understanding of classical and nonclassical crystallization phenomena during zeolite synthesis.

Sub-micron sized hierarchical porous ZSM-5 particles with controllable mesoporous structures by changing the alkalinity in the synthesis using NaOH

This work reports that sub-micron sized hierarchical porous ZSM-5 particles with controllable mesoporous structures can be facilely synthesized in a seed-assisted system without using any secondary templates or organic additives. The results showed that typical samples so-obtained display relative uniform ellipsoidal sub-micron sized particles consisting of loosely packed primary nanocrystals. The mesoporous structures of ZSM-5 zeolite particles can be effectively introduced and adjusted by solely changing the quantity of NaOH in the initial synthesis mixture. The NaOH dosages significantly affect not only hierarchical mesoporosity but also the ratio of Si/Al and thus acidity of the final ZSM-5 product. Moreover, the effect of synthesis hydrothermal procedure was also investigated. The typical sample Z5-0.12 possesses high crystallinity, BET surface area, well-developed mesoporosity and improved catalytic performance in LDPE cracking. This approach constitutes a facile and cost-effective pathway to prepare sub-micron sized hierarchical porous ZSM-5 particles and might promote their application in industry.

Improving the Photocatalytic Performance of Porous Ceria under Visible Light Illumination via Mn Incorporation

Porous cerium oxide (ceria) nanoparticles were prepared with and without manganese (Mn) by using the flash combustion technique. Samples with different loadings (Ce/Mn ratio ranged from 100 to 10) were prepared by using a one-step process and water only as a solvent. Moreover, citric acid was utilized as a fuel in an aqueous medium, and the overall synthesis mixture was dried at 100 °C overnight and then calcinated at 550 °C for 3 h. The obtained final solid product was characterized by inductively coupled plasma (ICP), X-ray powder diffraction (XRD), diffuse reflectance ultraviolet-visible spectroscopy (DR-UV-Vis), and scanning electron microscopy (SEM), which was coupled with Energy Dispersive X-Ray Analysis (EDX), high resolution transmission electron microscopy (HR-TEM), and photoluminescence (PL) analysis. The characterization data showed that Mn ions were totally incorporated into the framework of ceria up to the applied loading. Under visible light illumination, the photocatalytic activity of the prepared samples was tested in the decolorization reaction of methyl green (MG) dye (wavelength greater than 425 nm). The results showed that increasing Mn content improved the photocatalytic activity of ceria. The sample with a Ce/Mn ratio of 10 performed 1.8 times better than bare porous ceria. Finally, the reusability of the best-performing sample was investigated in four consecutive runs without treatment, and slight deactivation was monitored after the fourth run.

Catalytic Reduction of p-Nitrophenol on MnO2/Zeolite -13X Prepared with Lawsonia inermis Extract as a Stabilizing and Capping Agent

p-nitrophenol (pNP) is a highly toxic organic compound and is considered carcinogenic and mutagenic. It is a very stable compound with high resistance to chemical or biological degradation. As a result, the elimination of this pollutant has been very challenging for many researchers. Catalytic reduction is one of the most promising techniques, if a suitable catalyst is developed. Thus, this work aims to prepare an eco-friendly catalyst via a simple and low-cost route and apply it for the conversion of the toxic p-nitrophenol (pNP) into a non-toxic p-aminophenol (pAP) that is widely used in industry. Manganese oxide was prepared in an environmentally friendly manner with the aid of Lawsonia inermis (henna) extract as a stabilizing and capping agent and loaded on the surface of 13X molecular sieve zeolite. The UV-Vis spectrum, EDS, and XRD patterns confirmed the formation of the pure MnO2 loaded on the zeolite crystalline network. The TGA analysis showed that the samples prepared by loading MnO2 on zeolite (Mn2Z, Mn3Z, and Mn4Z) lost more mass than pure MnO2 (Mn) or zeolite (Z), which is mainly moisture adsorbed on the surface. This indicates a better dispersion of MnO2 on the surface of zeolite compared to pure MnO2, and thus a higher number of active adsorption sites. SEM images and EDS confirmed the dispersion of the MnO2 on the surface of the zeolite. Results showed a very fast reduction rate, following the order Mn2Z > Mn3Z > Mn4Z > Mn > Z. With sample Mn2Z, 96% reduction of pNP was achieved in 9 min and 100% in 30 min. For Mn3Z, Mn4Z, and Mn, 98% reduction was achieved in 20 min and 100% in 30 min. Zeolite was the slowest, with only a 40% reduction in 30 min. Increasing the amount of zeolite in the synthesis mixture resulted in lower reduction efficiency. The kinetic study indicated that the reduction of p-nitrophenol on the surface of the prepared nanocomposite follows the pseudo-first-order model. The results show that the proposed nanocomposite is very effective and very promising to be commercially applied in water treatment, due to its low cost, simple synthesis procedure, and reusability.

BCN nanostructures conjugated nanoporous carbon with oxygenated surface and high specific surface area for enhanced CO2 capture and supercapacitance

Porous carbons, owing to their fascinating properties, are materials of high interest in several fields including gas capture and energy storage. The conjugation of nanostructures such as BCN and surface functionalization is a creative approach to enhance their application potential. However, maintaining high porosity along with the creation of such features is rather complicated. Herein, we report on BCN conjugated nanoporous carbons with the high specific surface area through a unique approach of integrating the synthesis method of BCN and nanoporous carbon with chemical activation. In this approach, the high nitrogen containing precursor, aminoguanidine was mixed with boric acid, casein, and potassium acetate at 900 °C. The characterization data revealed the existence of BCN nanostructures in nanoporous carbon with a high specific surface area (2991 m2 g−1) and oxygen functional groups. The BCN content and the physicochemical properties of the hybrids can be easily tuned by varying the amount of AG in the synthesis mixture. The optimized sample exhibited a high CO2 adsorption capacity of 23.25 mmol g−1 at 0 °C and 30 bar and a high specific capacitance of 182.5 F g−1 at 1 A g−1 with exceptional stability and low resistance in a three-electrode supercapacitor system. The superior performance of synthesized materials for intended applications can be attributed to the synergetic effect of unique porous characteristics, BCN conjugation, and oxygen functionalization in nanoporous carbon. These exceptional results make this facile method of BCN conjugation of porous carbon a highly useful pathway to synthesize a variety of hybrid nanoporous carbon nanostructures for adsorption using such materials, the use of which can further be extended to more applications.