Nitrogen Adsorption Isotherms Research Articles

Fabrication of Three‐Dimensional Net‐Structured Polyvinyl Alcohol Nanofibers Using Spray‐Freeze‐Drying Technique

ABSTRACTPolyvinyl alcohol (PVA) nanofibers have potential importance in industrial applications. In this study, three‐dimensional (3D) net‐structured PVA nanofibers are successfully fabricated using the spray‐freeze‐drying (SFD) technique for the first time. At first, different concentrations of PVA solutions from 0.001 to 5 wt% are applied to prepare PVA nanofibers using liquid nitrogen at −196°C by the SFD method. These nanofibers are characterized by scanning electron microscopy for morphological analysis, photo ruler software for diameter measurement, thermogravimetric analysis and differential scanning calorimetry for thermal stability and crystallinity, as well as nitrogen adsorption isotherms and pore size distribution curves for specific surface area and porous surface quality. Prepared SFD nanofibers with finer nano diameters, fewer beads, more regular 3D net‐structures and without any massive blocks are obtained from 0.05 to 1 wt%. These are compared with the nanofibers prepared by the freeze‐drying (FD) technique. The SFD method shows better results than the FD method in respect to fiber morphology, finer nanoscale diameter, crystallinity, specific surface area, and surface porous property. The best results are obtained from the nanofibers fabricated by the SFD method at 0.1 wt% concentration. Finally, the findings of this work open the opportunities for potential industrial applications and further development of PVA nanofibers.

Extraction of heavy metal ions from aqueous solutions by frame sorbents based on benzene-1,3,5-tricarboxylate (MBTC) and benzene-1,4-dicarboxylates (MB DC) of various metals

Pollution of soils and water sources with heavy metals leads to negative consequences for the environment associated with disruption of ecosystem balance, harm to the health of living organisms and humans. To solve this problem, organometallic frame sorbents capable of efficiently extracting heavy metal ions from aqueous solutions have been synthesized. During the conducted research, the regularities of the adsorption of cadmium, lead, copper, cobalt and nickel ions were studied using synthesized frame sorbents based on benzene-1,3,5-tricarboxylates (MBTC) and benzene-1,4-dicarboxylates (MBDC). The identification analysis performed on diffractograms of CoBTC and NiBTC powders showed the presence of structures [Co3(BTC)2·12H2O] and [Ni3(BTC)2·12H2O]. Unlike NiBTC, NiBDC dicarboxylate crystallizes in triclinic syngony (spatial group P1¯, Z = 1) and corresponds to the crystal structure [Ni3(OH)2(BDC)2··4H2O], the sample of the CuBTC compound crystallizes in cubic symmetry with the space group Fm3¯m (Z = 16) and corresponds to the crystal structure [Cu3(BTC)2·3H2O], and the CuBDC compound has a structure belonging to the monoclinic symmetry. The results of the analysis of isotherms of low-temperature nitrogen adsorption using synthesized MOFs made it possible to determine important textural characteristics of sorbents. It was noted that a strong adsorbate-adsorbent interaction is realized for CoBTC in the micropore region. It is shown that the specific surface area of synthesized sorbents, calculated by the Brunnauer-Emmett-Teller (BET) method, varies widely. Thus, for CoBTC and NiBTC compounds, it was 276.0 and 9.0 m2/g, respectively. The noted differences are due to the presence of a large number of micropores in the sorbent CoBTC. In most cases, the kinetic patterns of the adsorption of heavy metal ions can be described by a pseudo-second-order equation. The only example of the process proceeding according to the kinetic equation of the pseudo-first order is the adsorption of copper ions on the NiBDC sorbent. It is noted that cobalt, nickel and copper ions are better absorbed by sorbents containing the corresponding ions of the same name according to the Paneta-Faience rule. The linear relationship found between the sorption capacity and the logarithm of the ratio of the radius of ions to their electronegativity implies that the mechanism of adsorption of metal ions on MOFs is determined by the physicochemical properties of the ions themselves. The developed organometallic frame compounds can be effectively used in technologies for purification of water resources from toxic heavy metal ions.

Preparation and Evaluation of Ni/NiAl2O4 Core/Shell Nanostructures in Non-ionic Surfactant-based Vesicle

Background: Non-ionic surfactant-based vesicles (niosomes) as coherent and selforganization capability structures form organized core/shell nanostructures. Objective: In this academic research, Ni/NiAl2O4 core/shell nanostructures were successfully synthesized with the ultrasound-assisted direct micelle (UADM) method and these structures were used as a delivery system for minoxidil drugs. Method: The synthesis conditions for producing Ni/NiAl2O4 core/shell structures were optimized using a design of experiments (DOE) approach. Process control was systematically examined through analysis of variance (ANOVA) and response surface methodology (RSM). The Ni/NiAl2O4, core/shell nanostructures, underwent characterization using various techniques such as SEM (scanning electron microscopy), TEM (transmission electron microscopy), AFM (atomic force microscopy), FT-IR (Fourier-transform infrared spectroscopy), TGA (thermogravimetric analysis), BET analysis, differential thermal analysis (DTA), and nitrogen adsorption isotherms. The in vitro release of minoxidil from the Ni/NiAl2O4 core/shell nanostructures was studied using UV-vis spectroscopy at a wavelength of 486 nm. Results: Results indicated an encapsulation efficiency (EE%) of around 74% after 150 minutes. Furthermore, the loading efficiency of minoxidil in niosomes modified with Ni/NiAl2O4 core/shell nanostructures was calculated to be approximately 99.83% at 486 nm. Conclusion: Overall, this research lays a foundational framework for developing innovative nanomaterials with tailored properties for advanced delivery systems and other novel applications.

Surface areas and adsorption energies of biochars estimated from nitrogen and water vapour adsorption isotherms

Nitrogen adsorption isotherms, along with the BET model for interpretation, are recommended for estimating biochar surface area. The frequently measured small surface areas of biochars contrast with their high sorption and cation exchange capacities. We hypothesised that water adsorption provides a better tool for estimating the surface area of biochars. Although adsorption energy also appears to be a valuable surface characteristic, there is a lack of studies on this subject. We studied the surface areas and adsorption energies of three waste deposits – peat, willow dust and biochar prepared from these materials at different temperatures – using nitrogen and water vapour adsorption isotherms. The BET model accurately described all water vapour adsorption isotherms but failed for some nitrogen isotherms. Alternative methods for estimating surface areas and adsorption energies were proposed in cases where the BET model did not apply. Nitrogen adsorption was typically much lower than water vapour adsorption, and the estimated surface areas reflected this. However, nitrogen adsorption energies were significantly higher. Nitrogen surface areas increased with pyrolysis temperature, while water vapour surface areas decreased. The surface area estimated from nitrogen adsorption was generally much lower than needed to accommodate the surface-charged groups responsible for the cation exchange capacity of biochars.

Synthesis of a Novel Magnetic Biochar from Lemon Peels via Impregnation-Pyrolysis for the Removal of Methyl Orange from Wastewater

This research examined the elimination of methyl orange (MO) utilizing a novel magnetic biochar adsorbent (MLPB) derived from lemon peels via an impregnation-pyrolysis method. Material characterization was conducted using SEM, XRD, TGA, FTIR, and nitrogen adsorption isotherms. SEM-EDX analysis indicates that MLPB is a homogeneous and porous composite comprising Fe, O, and C, with iron oxide uniformly dispersed throughout the material. Also, MLPB is porous with an average pore diameter of 4.65 nm and surface area value (111.45 m2/g). This study evaluated pH, MO concentration, and contact time to analyze the adsorption process, kinetics, and isothermal behavior. Under optimal conditions, MLPB was able to remove MO dye from aqueous solutions with an efficiency of 90.87%. Results showed optimal MO removal at pH 4, suggesting a favorable electrostatic interaction between the adsorbent and dye. To ascertain the adsorption kinetics, the experimental findings were compared using several adsorption models, first- and second-orders, and intra-particle diffusion. According to the findings, the pseudo-second-order model described the adsorption kinetic promoting the formation of the chemisorption phase well. Modeling of intra-particle diffusion revealed that intra-particle diffusion is not the only rate-limiting step. A study involving isothermal systems showed that Langmuir is a good representation of experimental results; the maximum adsorption capacity of MLPB was 17.21 mg/g. According to the results, after four cycles of regeneration, the produced magnetic material regained more than 88% of its adsorption ability.

Understanding Structure Differences of Iridium Oxides Depends on Loading in Proton Exchange Membrane Electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) have drawn attention among various hydrogen production technologies due to their zero-emission, high conversion efficiency, high hydrogen purity (>99.99%), and quick response under dynamic operation.1,2 With these auspicious characteristics in PEMWEs, they are believed to produce 40 % of green hydrogen by 2050 among all electrolyzer technologies. Nonetheless, many bottlenecks within PEMWEs still hinder their broader commercialization. Iridium oxide is the most widely used oxygen evolution reaction (OER) electrocatalyst at the anode. Moreover, this catalyst occupies the biggest portion (26–47%) of the overall cost of PEMWE systems, mostly due to the scarcity of iridium.3 Commercial iridium oxide catalysts are generally two types depending on the material structure: amorphous IrOx and crystalline IrO2. The trade-off relationship exists in catalytic activity vs. stability between amorphous and crystalline IrOx catalysts.4–6 To overcome these problems, fundamental studies of iridium oxide need to be conducted to reduce catalyst loading while maintaining high performance.Herein, we report the new iridium oxide catalysts (amorphous IrOx, crystalline IrO2, Ishifuku Metal) for the first time. These new iridium oxide catalysts are physically and electrochemically characterized. To be specific, we confirm the distinct characteristics of each catalyst using scanning electron microscopy (SEM), focused ion beam SEM (FIB-SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis with nitrogen adsorption isotherm, Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). As a result, the crystalline IrO2 has a unique morphology with grown needles onto catalyst particles thereby the BET specific surface area of crystalline IrO2 (~110 m2 g-1) is over two times higher than amorphous IrOx (~50 m2 g-1). Electrochemical performance is evaluated for varied catalyst loadings of membrane electrode assembly (MEA). The catalyst loadings (0.10, 0.26, 0.35, and 0.85 mgIrOx cm-2) for both anode catalysts were prepared. The CV results of amorphous IrOx exhibit unique redox peaks under specific voltage (~0.8 and ~1.2 V vs. RHE), which indicates the transition of oxidation state. These peaks develop with CV cycling and become fully developed after 100 cycles, indicating that the surface of the catalyst takes some time to activate. On the other hand, crystalline IrO2 shows no specific redox peaks but rather has a double-layer capacitance under lower voltage (<0.5 V vs. RHE). Figure 1 shows 1.92 V (amorphous) and 1.94 V (crystalline) at 5 A cm-2 for 0.85 mg cm-2 loading, respectively. Both catalysts showed relatively low Tafel slopes of 43.8 mV dec-1 (amorphous IrOx) and 53.7 mV dec-1 (crystalline IrO2). This presentation will correlate the electrochemical performance described here to the structural properties of these two types of IrOx catalysts. Figure 1. Polarization curve for prepared iridium oxide catalysts (amorphous IrOx and crystalline IrO2). Both cells have anode loadings of 0.85 mg cm-2, cell temperature at 60 °C, 10 sccm for H2O flow rate at the anode, and dry for the cathode.

Antitumoral action of carvedilol–a repositioning study of the drug incorporated into mesoporous silica MCM-41

We have studied repositioning of carvedilol (an antihypertensive drug) incorporated into MCM-41 mesoporous silica. The repositioning proposes a reduction in the slow pace of discovery of new drugs, as well as toxicological safety and a significant reduction in high research costs, making it an attractive strategy for researchers and large pharmaceutical companies. We obtained MCM-41 bytemplatesynthesis and functionalized it by post-synthesis grafting with aminopropyltriethoxysilane (APTES) only or with folic acid (FA), which gave MCM-41-APTES and MCM-41-APTES-FA, respectively. We characterized the materials by scanning and transmission electron microscopy, zeta potential (ZP) measurements, Fourier transform infrared absorption spectroscopy, x-ray diffractometry, nitrogen gas adsorption, and CHNS elemental analysis. We quantified the percentage of drug that was incorporated into the MCM-41 materials by thermogravimetric analysis and evaluated their cytotoxic activity in non-tumor human lung fibroblasts and the tumor human melanoma and human cervical adenocarcinoma cell lines by XTT salt reduction (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-arboxanilide). The x-ray diffractograms of the MCM-41 materials displayed low-angle peaks in the 2θrange between 2° and 3°, and the materials presented type IV nitrogen adsorption isotherms and H2 hysteresis typical of the MCM-41hexagonal network. The infrared spectra, the charge changes revealed by ZP measurements, and the CHN ratios obtained from elemental analysis showed that MCM-41 was amino-functionalized, and that carvedilol was incorporated into it. MCM-41-APTES incorporated 23.80% carvedilol, whereas MCM-41 and MCM-41-APTES-FA incorporated 18.69% and 12.71% carvedilol, respectively. Incorporated carvedilol was less cytotoxic to tumor and non-tumor cells than the pure drug. Carvedilol repositioning proved favorable and encourages further studies aimed at reducing its cytotoxicity to non-tumor cells. Such studies may allow for larger carvedilol incorporation into drug carriers or motivate the search for a new drug nanocarrier to optimize the carvedilol antitumoral activity.

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.

Preparation of CYCU‐3/MCM‐41 Composites and Adsorption Properties for n‐Hexane

AbstractAdsorption method is one of the effective technologies for treating VOCs. Compared with activated carbon, silicon‐based materials have well‐ordered pore structure, good thermal stability and non‐flammability. In this paper, CYCU‐3/MCM‐41 composites were prepared by hydrothermal method through mixing MCM‐41 powder in situ. The nitrogen adsorption isotherms, saturation adsorption and cyclic adsorption/desorption curves of n‐hexane on CYCU‐3/MCM‐41 composites were experimentally measured. The results displayed that the CYCU‐3/MCM‐41 (3) exhibited the largest BET specific surface area (1631 m2/g). And its n‐hexane adsorption capacity was 776 mg/g, which was 19.4 % higher than that of MCM‐41, 1.42 times that of activated carbon, and 2.64 times that of molecular sieve. The kinetic fitting results showed that the pseudo‐first order kinetic model can more precisely embody the n‐hexane adsorption process on CYCU‐3/MCM‐41 composites, and the W‐M intraparticle diffusion model confirmed that intraparticle diffusion was not the only control step for the adsorption rate of n‐hexane on CYCU‐3/MCM‐41 composites. In addition, the regenerative rate of CYCU‐3/MCM‐41 (3) was over 98.9 % after ten adsorption and desorption cycles of n‐hexane, showing good desorption performance and excellent structural stability, and proving its broad application prospect in the field of VOCs treatment.

Fabricating a Robust Ultramicroporous Metal-Organic Framework for Purifying Natural Gas and Coal Mine Methane.

Purifying methane (CH4) from natural gas and coal mine methane (CMM) is of great significance but challenging in the chemical industry. Herein, a robust ultramicroporous metal-organic framework (MOF) is reported, which can be synthesized on a gram scale by stirring under room temperature. Single-component adsorption isotherms of gases (CH4, ethane (C2H6), propane (C3H8), nitrogen (N2)) and breakthrough experiments indicate that the MOF can separate CH4 efficiently from CH4/C2H6/C3H8 ternary mixture, with super high purity-CH4 production of 154.7 cm3g-1. Additionally, the MOF shows higher CH4 capacity than N2, resulting in excellent separation performance for the CH4/N2 mixture. Notably, the binding sites of gases can be precisely determined by single-crystal X-ray data, further confirmed by molecular simulation. It is found that there are multiple hydrogen bonds and C─H···π interactions between the gases and the framework. This work offers an excellent candidate material for CH4 purification with both high capacity and separation efficiency.

Cost‐Effective Approach for Fabrication of High‐Quality Expanded Vermiculite for Alizarin Red S Removal From Aqueous Media

AbstractVermiculite is extensively utilized for several applications, including as a hydroponic substrate, for soil conditioning, oil cleansing, and addressing trace metal pollution. In this study, the expansion of natural vermiculite was easily achieved by utilizing hydrogen peroxide (H2O2) with the aid of microwave technology. The characterization of expanded vermiculite involved the use of X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), nitrogen adsorption isotherm (BET), and energy dissipation X‐rays (EDX). The vermiculite has been enlarged to have a structure resembling flakes, and its surface area measures 73.9 m2/g. The adsorption of Alizarin Red S onto expanded vermiculite was investigated under varying conditions, such as pH, starting concentration, adsorbent content, and duration of exposure. The enlarged vermiculite achieved a maximum adsorption capacity of 182.5 mg/g for Alizarin Red S. Out of the three adsorption isotherm models, both the Freundlich and Temkin models accurately describe the adsorption of Alizarin Red S onto expanded vermiculite. When studying adsorption kinetics, the second‐order adsorption kinetic model is more appropriate than the first‐order adsorption kinetic model, as indicated by an R2 value of 0.8964.

Chloride permeation resistance of sulphoaluminate cement-based composite characterized by both alternating current section and RCM methods

Sulphoaluminate cement (SAC) was widely used for rapid repair and strengthening of building structures due to its excellent quick hardening and high early strength behavior. This study developed a SAC-based engineering cement composites (ECC) with ultra-high molecular weight polyethylene (UHMWPE) and investigated its mechanical properties. Chloride ion permeability coefficient were evaluated by new alternating-current sectioning and rapid chloride migration (RCM). The mechanism of the SAC-ECC against chloride erosion were quantified using nitrogen isothermal adsorption. The results show that the fracture energy, tensile strength and strain of SAC-ECC samples are higher than that of normal ECC. The polyethylene (PE) fiber could significantly improve the flexural strength and toughness with PE fiber content of 0.75 % by volume. The hydration products generated could react with chloride ion to make it chemically stabilized, leading to reduce the chloride ion diffusion coefficient significantly. Based on microscopic analysis (SEM), the pore structure in SAC-ECC composite improved remarkedly while the volume of harmful pore decreased evidently as well. SAC-ECC developed in this paper could be poetically applied to strengthening and repair of marine concrete structures.

Transformation of Organic Cacao (Theobroma cacao) Husk into Commercial

Introduction: agroindustrial wastes can be transformed to mitigate the negative impacts associated with their disposal. In cocoa production, cocoa pod husk (CPH) constitutes between 67% and 76% of the total cocoa weight. This study focuses on the potential of CPH as a valuable resource for producing activated carbon, cellulose, and potassium hydroxide (KOH)..Objective: The objective of this research was to characterize and transform the CPH obtained from an organic crop in San Bernardo-Ibagué (Colombia) into activated carbon, cellulose, and KOH.Methods: activated carbon was produced through chemical activation using KOH, with a specific procedure for characterizing the obtained product through thermal analysis (TGA) and nitrogen adsorption and desorption isotherms. For cellulose extraction, an alkaline treatment with 2% w/w NaOH was followed by a bleaching process with 2.5% w/w sodium hypochlorite. KOH was obtained by first extracting potassium carbonate and then causticizing it.Results: activated carbon (AC) was produced with a yield of 25.6%, exhibiting a surface area of 468 m²/g, a mean pore diameter of 10.8 nm, and a total pore volume of 0.228 cm³/g, with 60% fixed carbon, 27% volatile material, 6% ash, and 6% moisture. Conclusions: the transformation of cocoa pod husk into activated carbon, cellulose, and KOH provides a sustainable approach to managing agroindustrial waste, generating valuable products with significant potential for various applications. The results obtained demonstrate the feasibility of utilizing CPH as a resource in agroindustrial processes.

Surface‐Modified Mesoporous V2‐xSb2xO5‐δ Ceramics for Improving the Electrostatic Chemisorption of Methylene Blue

AbstractHerein, mesoporous V2‐xSb2xO5‐δ (Sb−V−O) compounds, encompassing a compositional range of x varying between, 0.05≤x≤0.08, with orthorhombic Pmmn space group symmetry, are synthesized by high‐temperature solid‐state reaction method. Scanning electron microscopy indicated the formation of microscale rods and flakes and EDS spectra affirmed the stoichiometric precision of their composition adhering to the formulated chemical formula. Nitrogen adsorption isotherms exhibited the distinctive type IV pattern, accompanied by an H3 hysteresis loop, signifying the formation of mesoporous micro rods and flakes. Brunauer‐Emmett‐Teller measurements demonstrated an augmented surface area, ranging from 16.67–28.74 m2/g, mirroring the effect of the increase in the concentration of Sb cations. The study demonstrated complete Methylene Blue dye removal within a brief 90 minute period, highlighting its efficacy in water remediation. The adsorption kinetics was aptly described by the pseudo‐second‐order model which exhibited a high degree of fit (R2=0.99). Freundlich adsorption isotherm was used to describe the multilayer adsorption of MB dye on the Sb−V−O surface indicating an exponential increase in adsorption active sites. Enhanced cationic MB dye adsorption on negative Sb−V−O surface is attributed to the electrostatic chemisorption by the interaction of NMe2+ on the negative surface modified Sb−V−O compounds.

Characteristics of granulated activated carbon from a mixture of plant raw material waste

Relevance. The need to increase the use of renewable energy sources in the economy to reduce the harmful effects on the environment. Aim. To assess the possibility of obtaining by the thermochemical method high-quality carbon adsorbents from a granular mixture of various wastes of plant origin. Objects. Samples of illiquid lumpy birch wood, walnut shells, sunflower seed husks, flax fires, anthracite coal. Methods. Physical experiments: conductive pyrolysis, water-steam activation and differential thermal analysis. The ash content and moisture content of the samples were determined according to SS R 56881-2016 and SS 33503-2015. Nitrogen adsorption isotherms were measured using a NOVA-1200e analyzer. The equilibrium activity for toluene was determined according to SS 8703-74, the adsorption activity for iodine was determined according to SS 6217-74. The determination of the density of the granules was carried out according to SS 15139-69. Results. The authors have established rational parameters for obtaining carbon adsorbents from granules of vegetable raw materials. The specific yield of pyrolysis products of a mixture of vegetable raw materials with pyrolysis resin was determined. The specific yield of carbonization products of the granular compacted mass showed an increase of 25% in comparison with the non-compacted mixture of vegetable raw materials. Rational parameters for obtaining activated carbon with the highest adsorption capacity are granules with a density of 1200 kg/m3 with a degree of burnout of the carbonization product of 70%. It was established that the obtained samples of adsorbents from granules of plant raw materials have high adsorption characteristics comparable to activated carbons obtained from fossil raw materials.

Na-Kenyaite as Efficient Basic Blue-41 Dye Removal: Synthesis and Regeneration Studies

Na-kenyaite materials are available in nature and can easily be prepared in the laboratory. These materials exhibit interesting adsorption properties; therefore, they can be invested in the new wastewater treatment technologies. This study investigates the removal of basic blue-41 (BB-41) dye from artificially contaminated water using Na-kenyaite materials in batch mode. Firstly, Na-kenyaites were prepared by the hydrothermal process at a temperature of 150 to 170 °C for a period of 2 to 7 days using different silica sources and ratios of SiO2/NaOH/H2O. The prepared materials were characterized by different techniques such as XRD, FTIR, 29Si MAS NMR, TGA/DTA, SEM, and nitrogen adsorption isotherms. A pure Na-kenyaite phase was successfully obtained using a fumed silica source and 5SiO2/Na2O/122H2O ratio. The removal experiments of basic blue-41 estimated the effectiveness of Na-kenyaites in removing properties, investigating the influence of the solid dosage, initial basic blue-41 concentration, and solution pH or Na-kenyaite solid. Results showed optimal dye removal of around 99% at pH levels above 7. Furthermore, the estimated maximum removal capacity from the Langmuir isotherm was between 124 and 165 mg/g. The results demonstrated efficient removal by Na-kenyaites and its prominence for wastewater treatment. Finally, this study explored the regeneration and reuse of Na-kenyaites through seven cycles and reported a design of a batch adsorber system to reduce the initial concentration of 200 mg/L at different percentages.

Multifunctional CoCe/silica and CoMnCe/silica spinel ferrite nanocomposite: in vitro and in vivo evaluation for cancer therapy

Multifunctional magnetic spinel ferrite based on CoCe and CoMnCe/silica nanocomposites (NCs) were developed for targeted cancer therapeutics. The formation of spinel ferrite and co-existence of spinel ferrite/silica/chemo-drug, surface/pore size distribution, morphological features and magnetic properties were investigated using different characterization techniques. XRD pattern confirmed the pure phase of CoCe and CoMnCe spinel ferrite with estimated crystal size of 27.9 nm. After silica coating and pegylation, the crystal size of CoCe and CoMnCe increases to 36.3 nm and 76.2 nm. Nitrogen adsorption isotherm confirm an effective embedment of both spinel ferrites into silica with large surface area (653 m2/g and 718 m2/g) and uniform pore size distributions (6.1 nm and 6.9 nm). FT-IR spectra confirm the magnetic spinel ferrite/silica interactions (977, 1705 and 3410 cm−1), cisplatin functionalization (1645 cm−1) and PEG (1275–2900 cm−1). Coating SFNPswith Si and/or Cp and/or PEG, tunes the magnetic characteristics of the NCs system. For both CoCe and CoMnCe SFNPs, saturation magnetization (Ms) of 14.96 and 10.91 emu/g, residual magnetization (Mr) of 4.40 and 2.42 emu/g, Hc (coercivity) of 1072.1 and 719.3 Oe gradually diminish upon Si, respectively. The chemical state of CoMnCe SFNPs, CoCe SFNPs, their silica and active cisplatin NCs (Pt0 and Pt2+) were investigated using X-ray Photoelectron Spectroscopy (XPS). The anti-cancer efficacy of pegylated nanoformulations were tested in in vitro cells (HeLa, HCT-116 and HEK-293) and Hemolysis assay. The toxicity of different nanoformulations administered in different concentrations (20–2000 mg/kg) in in vivo was estimated based on LD50 value.

Development of a sustainability-oriented university laboratory: Insight into adsorption kinetics models for the removal of pollutants from aqueous solution

The aim of the present research is to show the development of a sustainability-oriented lab that teaches adsorption concepts in a virtual environment based on the premise “learning-through-play”. Kinetic results in the virtual environment are contrasted to those obtained experimentally when diverse adsorbents prepared from Agave Bagasse (Raw Fibers, Hydrothermal Fibers, and Activated Fibers) were synthesized. Comparison between virtual and real-life experiments involving removal of methylene blue in solution showed that a pseudo-first-order model could describe adsorption kinetics satisfactorily. The study is complemented with a characterization of the adsorbents through SEM, nitrogen adsorption isotherms, FTIR and Raman. In addition, the environmental impact of the synthesis of adsorbents was evaluated through well-known methodologies (GAPI, NEMI, and Eco-Scale), which agree that raw fibers are the most eco-friendly material. This research provides an exciting opportunity to advance our knowledge on developing new technologies for teaching in engineering and to compliment real-life practices that consider environmental impacts with virtual experiments.

Synthesis of silver‐doped TiO2 nanoparticles with highly efficient adsorption of Congo red

AbstractTiO2 nanoparticles (NPs) doped with Ag were produced through a solvothermal method, with varying amounts of silver doping ranging from 0.5% to 1.5%. The samples were analyzed for crystallite sizes, structure, and metallic bondings using XRD, SEM, EDXS, and FTIR techniques. The BET surface areas were determined through nitrogen adsorption isotherms. The efficiency of the silver‐doped TiO2 NPs for removing Congo red (CR) was tested through adsorption experiments. The results showed that the synthesized TiO2 NPs doped with Ag were uniformly spherical in shape, with tiny average sizes ranging from 7.97 to 12.74 nm and large BET surface areas (98.41–166.1 m2 g−1). The silver‐doped TiO2 samples with a 0.5% Ag doping amount exhibited the highest adsorption capacity in CR removal, with a maximum adsorption capacity of 454.55 mg of dye per gram of adsorbent and a lower contact time of 20 min than other metal oxide NPs. The CR adsorption onto 0.5% Ag‐TiO2 obeyed the Langmuir isotherm model (R2 = 0.989), and the adsorption followed a pseudo‐second‐order kinetic equation. The adsorbent could be efficiently reused for five consecutive cycles to remove CR.

Evaluation of methane adsorption isotherms at ambient temperature on carbon materials from NLDFT pore size analysis derived from standard N2 and CO2 adsorption isotherms

In this paper, we attempt to estimate CH4 adsorption on carbon materials based on the pore size distribution (PSD) characteristics evaluated from standard nitrogen and carbon dioxide adsorption isotherms using the nonlocal density functional theory (2D-NLDFT), or more precisely, its two-dimensional version (2D-NLDFT). The PSDs of the carbons were calculated by the simultaneous fit of the NLDFT models to the corresponding N2 and CO2 adsorption data. This method is referred to in the literature as the dual gas analysis method which is implemented in SAIEUS software. Essential features of carbon PSDs affecting the shapes of methane adsorption isotherms measured at ambient temperature were identified as related to micro and mesopores carbon structure. We discuss how different micro and mesopore size ranges contribute to methane adsorption isotherms in the low and higher-pressure ranges. The results of the present study may serve as guidance for selecting and designing suitable carbon materials for practical applications such as PSA recovery of CH4 from its mixtures or for methane storage.