Brunauer Emmett Teller Measurements Research Articles

Experimental study on the effects of 1-butyl-3-methylimidazole ferric tetrachloride on shale properties and gas desorption

The exploration of shale gas has increasingly emerged in recent years. In this work, the ionic liquid (IL) of 1-butyl-3-methylimidazole ferric tetrachloride was firstly used as a chemical additive to improve the dissolution of shale and enhance shale gas desorption. The analyses of total organic carbon (TOC), Fourier transform infrared spectroscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller measurement were performed. The results revealed that the TOC content was reduced by 66.2% using a concentration of 0.1 mol/L 1-butyl-3-methylimidazole ferric tetrachloride with a solid-liquid ratio of 1:20 at 60 °C and a duration of 48 hr and the dissolution rate of shale was 18.95 wt%. Inorganic minerals within shale were dissolved, and irregular pores were observed, which improve the permeability of shale and the flow of shale gas. Meanwhile, the characterization of residues in the solution presented that the structures of long carbon chain, carbon-sulfur and amines, amides, or heterocyclic within kerogen may be disrupted, which is beneficial for the shale gas desorption. The isothermal adsorption results proved that the adsorption capacity of methane on the kerogen treated was decreased by 53.16%, which inferred that the desorption ability of shale gas can be improved.

Stability Assessment in Aqueous and Organic Solvents of Metal-Organic Framework PCN 333 Nanoparticles through a Combination of Physicochemical Characterization and Computational Simulations.

Mesoporous metal-organic frameworks (MOFs) have been recognized as powerful platforms for drug delivery, especially for biomolecules. Unfortunately, the application of MOFs is restricted due to their relatively poor stability in aqueous media, which is crucial for drug delivery applications. An exception is the porous coordination network (PCN)-series (e.g., PCN-333 and PCN-332), a series of MOFs with outstanding stability in aqueous media at the pH range from 3 to 9. In this study, we fabricate PCN-333 nanoparticles (nPCN) and investigate their stability in different solvents, including water, ethanol, and methanol. Surprisingly, the experimental characterizations in terms of X-ray diffraction, Brunauer-Emmett-Teller (BET), and scanning electron microscopy demonstrated that nPCN is not as stable in water as previously reported. Specifically, the crystalline structure of nPCN lost its typical octahedral shape and even decomposed into an irregular amorphous form when exposed to water for only 2 h, but not when ethanol and methanol were used. Meanwhile, the porosity of nPCN substantially diminished while being exposed to water, as demonstrated by the BET measurement. With the assistance of computational simulations, the mechanism behind the collapse of PCN-333 is illuminated. By molecular dynamics simulation and umbrella sampling, we elucidate that the degradation of PCN-333 occurs by hydrolysis, wherein polar solvent molecules initiate the attack and subsequent breakage of the metal-ligand reversible coordination bonds.

Influence of iron doping in mesoporous ceria on the physicochemical properties and catalytic activity in styrene oxidation

A series of nanosized Fe-Ce binary oxides (2, 5, 10, 20, and 30 wt% Fe) and pure oxides of Fe and Ce were prepared by the template-assisted coprecipitation method and evaluated for styrene oxidation. The synthesised binary oxides were investigated by Powder X-ray diffraction(PXRD), N2-physisorption, X-ray fluorescence (XRF), Field emission scanning electron microscopy (FE-SEM), Highresolutiontransmission electron microscopy (HR-TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Ultraviolet–Visiblediffuse reflectance spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopies (XPS), and Hydrogen-temperature programmed reduction (H2-TPR). In particular, the influence of quantity of doped iron on the structure, phase composition, surface morphology, reducibility, and the catalytic performance of ceria is deeply investigated. All the synthesized Fe-doped ceria catalysts exhibited the formation of solid solutions, but a little α-Fe2O3 segregated on the surface of ceria at 20 and 30 wt% Fe doped ceria. Among all Fe-Ce binary oxides, the 10 wt% Fe-doped ceria catalyst demonstrated superior efficiency due to its optimal Fe content which achieved the high surface area, lattice oxygens, reducibility, and low crystallinity, as confirmed by BET (Brunauer-Emmett-Teller) measurements, XPS, H2-TPR and powder XRD analysis, respectively. To optimize the reaction conditions, effect of several experimental variables, such as reaction temperature, duration, catalyst quantity, styrene/tert-Butyl hydroperoxide (TBHP) mole ratio, and solvent polarity were investigated. Furthermore, the catalyst stability and consistent activity were confirmed by testing six reusability cycles.

Optimizing 2-Nitrophenol and Chromium Adsorption from Water with Aluminium Oxide via Response Surface Methodology

Optimizing 2-Nitrophenol and Chromium Adsorption from Water with Aluminium Oxide via Response Surface Methodology

Magnetic chitosan-functionalized waste carton biochar composites for efficient adsorption of anionic and cationic dyes

In this study, BC-CoFe2O4-CS magnetic composite was successfully prepared from waste cardboard and investigated as an efficient adsorbent for the removal of amaranth and methyl orange in aqueous solution. First, the fibers obtained from the cardboard waste were carbonized by a hydrothermal process to produce biochar. Subsequently, the final magnetic composites were synthesized by in situ growth and Schiff base crosslinking reactions. The composites were characterized by zeta potential, Brunauer–Emmett–Teller measurements, Fourier transform Infrared spectroscopy, Scanning electron microscopy, Energy dispersive spectrometer,X-ray Diffraction, Thermogravimetry analysis and Vibrating sample magnetometer. The effects of adsorbent dosage and initial solution pH on dye removal efficiency were studied. The results showed that the maximum adsorption capacity of amaranth could reach 500.6 mg·g−1 at pH = 2, the adsorbent dosage of 0.5 mg·ml−1, and methyl orange could reach 644.0 mg·g−1 at pH = 4, the adsorbent dosage of 0.5 mg·ml−1. The adsorption process followed the pseudo-second order kinetic models and Langmuir isotherm. BC-CoFe2O4-CS was easily separated from the aqueous solution due to the loading of CoFe2O4 magnetic nanoparticles. Besides, the BC-CoFe2O4-CS could be further used after the adsorption experiments with or without desorption and still showed good adsorption performance in the actual water samples. Therefore, it is expected that the composite material prepared from waste cartons can be used for the treatment of dye-containing wastewater due to its low cost, high efficiency, and simple application.

Process optimisation and kinetic study for esterification of levulinic acid and n‐butanol using sulfonated titania–zirconia heterogeneous catalyst

AbstractBackgroundButyl levulinate (BL) was produced by the esterification of levulinic acid (LA) and n‐butanol (BOH) using a sulfonated nanocomposite of titania–zirconia as catalyst. A full factorial design was employed for studying the effects of reaction time, mole ratio and catalyst loading on LA conversion.ResultsThe synthesised catalyst was subjected to various characterisation techniques such as X‐ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller measurements, thermogravimetric analysis, temperature‐programmed desorption and scanning electron microscopy–energy dispersive X‐ray analysis indicating the presence of a nanocrystalline structure with good surface area and good stability at the operating temperature. The experimental data were analysed using the response surface method, and a complete quadratic regression model was built. The LA conversion was 85.37% for the optimised reaction conditions of 1:7 mole ratio, a catalyst loading of 1 wt% and a reaction time of 5 h at 110 °C. Based on the Langmuir–Hinshelwood–Hougen–Watson model, a kinetic model was developed. The activation energy was found to be 20.4 ± 0.8 kJ mol−1 from an Arrhenius plot. Reusability and leaching results are also reported.ConclusionThe catalyst exhibited good reusability and stability. Sulfonated TiO2–ZrO2 used to catalyse the reaction between LA and BOH to produce BL has proved to be a good candidate as a green catalyst. The results presented play an important part in directing subsequent research and commercialisation activities aimed at valorising LA to fuel additive. © 2023 Society of Chemical Industry (SCI).

Highly Efficient Cauliflower-like Palladium-Loaded Porous MOF as a Robust Material for the Degradation of Organic Dyes.

A series of porous MOF materials, viz., Pdx@IRMOF-9 (x = 2, 5, and 10%) were synthesized by loading varying concentrations of Pd(II) on IRMOF-9. The synthesized MOF materials were characterized by ltravioletisible (UV-Vis) spectroscopy, Fourier transform Infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET), and scanning electron microscopy (SEM) analyses. UV, FT-IR, and PXRD data of Pd(II)@IRMOF-9 were found to be in line with those of IRMOF-9, which suggests that the structure of the IRMOF-9 remained intact upon Pd(II) loading. Surface morphology of IRMOF-9 showed sheet-like structures, and upon incorporation of Pd(II) to IRMOF-9, porous cauliflower-shaped MOFs were obtained. The SEM area mapping of Pd10%@IRMOF-9 confirmed the homogeneous dispersion of Pd(II) on IRMOF-9. BET measurements suggested an increase in the surface area as well as pore size upon incorporation of Pd(II) on IRMOF-9. Due to high porosity and high petal density, Pd10%@IRMOF-9 demonstrated degradation of seven organic dyes, namely, orange G, methylene blue, methyl orange, congo red , methyl red, rhodamine 6G, and neutral red. It showed excellent results with >90% dye degradation efficiency in case of cationic, anionic as well as neutral dyes. Degradation of organic dyes followed the pseudo-first-order kinetics. Kinetic parameters, KM and Vmax, were calculated using the double reciprocal Lineweaver-Burk plot and were found to be 13.2 μM and 26.68 × 10-8 M min-1, respectively. Recyclability studies of heterogeneous Pd10%@IRMOF-9 demonstrated the degradation of CR dye for five consecutive cycles without significant loss of its catalytic activity. Herein, a robust and efficient material for the degradation of organic dyes has been developed and demonstrated.

Effective Removal of Acetaldehyde Using Piperazine/Nitric Acid Co-Impregnated Bead-Type Activated Carbon

Acetaldehyde (CH3CHO) in the atmosphere is associated with adverse health effects. Among the various options for use in removing CH3CHO, adsorption is often employed because of its convenient application and economical processes, particularly when using activated carbon. In previous studies, the surface of activated carbon has been modified with amines to remove CH3CHO from the atmosphere via adsorption. However, these materials are toxic and can have harmful effects on humans when the modified activated carbon is used in air-purifier filters. Therefore, in this study, a customized bead-type activated carbon (BAC) with surface modification options via amination was evaluated for removing CH3CHO. Various amounts of non-toxic piperazine or piperazine/nitric acid were used in amination. Chemical and physical analyses of the surface-modified BAC samples were performed using Brunauer–Emmett–Teller measurements, elemental analyses, and Fourier transform infrared and X-ray photoelectron spectroscopy. The chemical structures on the surfaces of the modified BACs were analyzed in detail using X-ray absorption spectroscopy. The amine and carboxylic acid groups on the surfaces of the modified BACs are critical in CH3CHO adsorption. Notably, piperazine amination decreased the pore size and volume of the modified BAC, but piperazine/nitric acid impregnation maintained the pore size and volume of the modified BAC. In terms of CH3CHO adsorption, piperazine/nitric acid impregnation resulted in a superior performance, with greater chemical adsorption. The linkages between the amine and carboxylic acid groups may function differently in piperazine amination and piperazine/nitric acid treatment.

Adsorption of Pyrethroids in Water by Calcined Shell Powder: Preparation, Characterization, and Mechanistic Analysis

Pyrethroids are common contaminants in water bodies. In this study, an efficient mussel shell-based adsorbent was prepared, the effects of factors (calcination temperature, calcination time, and sieved particle size) on the pyrethroid adsorption capacity from calcined shell powder were investigated via Box-Behnken design, and the prediction results of the model were verified. By characterizing (scanning electron microscopy, X-ray diffraction, Fourier infrared spectroscopy, and Brunauer-Emmett-Teller measurements) the adsorbent before and after the optimized preparation process, the results showed that calcined shell powder had a loose and porous structure, and the main component of the shell powder under optimized condition was calcium oxide. The adsorption mechanism was also investigated, and the analysis of adsorption data showed that the Langmuir, pseudo second-order, and intra-particle diffusion models were more suitable for describing the adsorption process. The adsorbent had good adsorption potential for pyrethroids, the adsorption capacity of the two pesticides was 1.05 and 1.79 mg/g, and the removal efficiency was over 40 and 70% at the maximum initial concentration, respectively.

Kaempferol molecularly imprinted polymers: preparation, characterization and application to the separation of kaempferol from ginkgo leaves

AbstractIn this work, kaempferol molecularly imprinted polymers (MIPs) were screened in detail and were applied to the separation of kaempferol from real complex systems. Kaempferol‐MIPs with high affinity and selectivity for kaempferol could be prepared successfully by using kaempferol as the template molecule, 4‐vinylpyridine as the functional monomer, ethylene glycol dimethacrylate or divinylbenzene as the crosslinker, acetone or acetonitrile as the solvent. Scanning electron microscopy observation and Brunauer–Emmett–Teller measurement showed that the prepared MIPs had a heterogeneous pore structure and large specific surface area. Static and dynamic adsorption experiments and solid‐phase extraction application were performed to evaluate the performance of the prepared MIPs. Only the MIPs with both higher distribution coefficient and higher imprinting factor in the dynamic experiments had better ability to retain kaempferol. Using the screened MIPs as solid‐phase extraction sorbents, kaempferol and quercetin were extracted directly from the crude ginkgo leaves hydrolysate with high recovery and purity. Control experiments also showed that the screened MIPs were superior to commercially available adsorbents in terms of the separation of kaempferol from crude extracts. © 2023 Society of Industrial Chemistry.

Magnetic/Zeolitic Imidazolate Framework-67 Nanocomposite for Magnetic Solid-Phase Extraction of Five Flavonoid Components from Chinese Herb Dicranopteris pedata.

A magnetically functionalized Fe3O4@ZIF-67 metal-organic framework (MOF) was prepared by electrostatic self-assembly using magnetic Fe3O4 nanoparticles as the core and ZIF-67 as the shell. The composite was characterized by electron microscopy, X-ray diffraction, Fourier- transform infrared spectroscopy, and Brunauer-Emmett-Teller measurements. Magnetic solid-phase extraction (MSPE) was performed on five flavonoids from Dicranopteris pedata using Fe3O4@ZIF-67 as an adsorbent. The developed MSPE method was combined with high-performance liquid chromatography-ultraviolet detection to preconcentrate and separate five flavonoids (rutin, quercitrin, kaempferol-3-O-α-L-rhamnoside, quercetin, and kaempferol) from Dicranopteris pedata. The factors affecting the extraction, such as the amount of Fe3O4@ZIF-67 adsorbent, salt ion concentration in the sample solution, vortex time, type and amount of desorbing solvent, concentration of formic acid to acidify the desorbing solvent, and acetonitrile ratio, were optimized. The developed method showed good linearity over the concentration range of 1.09-70.0 μg∙mL-1 for the five flavonoids, with R2 values between 0.9901 and 0.9945. The limits of detection and average recoveries for the five flavonoids were in the ranges of 39.5-56.2 ng∙mL-1 and 92.2-100.7%, respectively. The method presented herein is simple, efficient, and sensitive; it can be used for enrichment analysis of the five flavonoids in Dicranopteris pedata.

Layer‐by‐layer preparation of electromagnetic NH2‐SiO2/polypyrrole/Ni nanocomposites, characterization and their electrochemical properties

AbstractCombinations of organic conducting polymers and inorganic electromagnetic materials have drawn much attention in various fields like energy storage materials, biosensors, biomedical applications, catalysis and removal of heavy metals from water. In this investigation an attempt is made to decorate polypyrrole (PPy), a semiconducting electroactive polymer, with Ni nanoparticles on a functional silica (SiO2) support. First, amine‐functionalized mesoporous NH2‐SiO2 seed particles are prepared by the sol–gel method using hexamethylenediamine as a surface‐functionalizing agent and cetyltrimethylammonium bromide as a template. Second, NH2‐SiO2/PPy composite particles are prepared via in situ seeded chemical oxidative polymerization of pyrrole. The surface of the NH2‐SiO2/PPy composite particles is finally immobilized/doped with Ni nanoparticles via in situ chemical reduction of Ni(II) salt. The surface morphology, structure modification, size distribution and magnetic properties of the prepared NH2‐SiO2/PPy/Ni nanocomposite particles are confirmed using various spectroscopic techniques, electron microscopy, Brunauer–Emmett–Teller measurements, X‐ray diffraction and vibrating sample magnetometry. The NH2‐SiO2/PPy/Ni nanocomposite particles possess good paramagnetic properties. A comparative study of electrochemical properties revealed improvement in specific capacitance of NH2‐SiO2/PPy composite compared to PPy but further decoration with Ni nanoparticles under alkaline condition reduces the capacitance value. © 2022 Society of Industrial Chemistry.

PH dependent enhanced synchronous photocatalytic removal of cationic and anionic dyes by CoFe2O4 magnetic nanoparticles

This work reports the application of non-functionalized cobalt ferrite (CF) magnetic nanoparticles (MNPs) as a fast dye removing agent. Herein, we have synthesized the CF MNPs by chemical co-precipitation method. The photocatalytic activity is demonstrated with examples of cationic and anionic dyes depending on different pH. The synthesized CF MNPs were characterized by X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDAX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), selected area electron diffraction (SAED), vibrating sample magnetometer (VSM) and Brunauer-Emmett-Teller measurement (BET) to confirm the structural, morphological, magnetic property and surface area. We have shown its high efficiency in removal of both types of ionic dyes with moderate first order reaction rate under different pH. Because of its magnetic property it is easy to separate from the reaction mixture by magnetic separation method after its use, which is an added advantage in case of recycling. From the application point of view, these MNPs may be useful in promising industrial usage purpose because of its high stability, fast dye removal efficiency and low-cost.

Sintesis Nanopartikel Titanium Dioksida (TiO2) dengan Menggunakan Ekstrak Kulit Jeruk Gunung Omeh dan Karakteristiknya

In this study, TiO2 nanoparticles were synthesized without adding extract (0% v/v) (control) and with the addition of Gunung Omeh orange peel extract with various concentration, namely 4% v/v, 10% v/v, and 20% v /v. This study aims to study the use of Gunung Omeh orange peel extract on the formation of TiO2 nanoparticles and determine its characteristics. The characteristics of the resulting nanoparticles were characterized using X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy, Ultraviolet-Visible (DRS UV-Vis), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), Brunauer-Emmett-Teller (BET), Fourier Transform Infrared (FTIR), and Thermo Gravimetric and Differential Thermal Analyzer (TG-DTA). XRD results showed that the TiO2 phase formed was anatase. The optical property of TiO2 nanoparticles showed that the obtained TiO2 nanoparticles absorb in the UV region (200-400 nm). The results of SEM-EDX show that the resulting TiO2 nanoparticles are spherical. Meanwhile, the TOKJ20 sample has increased agglomeration so that the particle shape is rod-like. The EDX spectrum showes the presence of Ti and O peaks indicated the formation of TiO2. The results of BET measurement showed that the control TiO2 had a larger surface area of 66.11 m2/g compared to TiO2 using the addition of other orange peel extracts. From the results obtained, it was concluded that, in general, the addition of orange peel extract did not significantly affect the formation of TiO2 nanoparticles.

Role of a novel cationic gemini surfactant (CGS) on a one-step sol-gel process and photocatalytic properties of TiO2 powders.

TiO2 nanoparticles were prepared using a sol-gel process in combination with a novel cationic gemini surfactant (CGS) with amide functional groups at low temperatures. Titanium (IV) isopropoxide (TIP) and CGS were used as the starting materials and as effective agents, respectively, to orient the nanoparticles during the sol-gel synthesis. To reveal both the structural and morphological properties of the nanopowders prepared in this work, they were characterized using X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area apparatus. The pore volume and pore size were calculated using the Barrett-Joyner-Halenda (BJH) model on the desorption branch. The experimental results show that the surface area and average crystallite size of the obtained TiO2 nanopowders vary between 160-203 m2/g and 27-49 nm, respectively. It was observed that the N2 adsorption-desorption isotherms for almost all samples of TiO2-X% CGS (X: mass of CGS) show the typical Type I with a hysteresis loop of H4. The photocatalytic activities of the CGS-modified nanocomposites are evaluated not only by the photocatalytic degradation of methyl orange (MO) but also by the reduction of Cr(VI) as model pollutants in the presence of visible light.

Direct Hydrogen Production from Extra-Heavy Crude Oil under Supercritical Water Conditions Using a Catalytic (Ni-Co/Al2O3) Upgrading Process

The generation of hydrogen from unconventional oil is expected to increase significantly during the next decade. It is commonly known that hydrogen is an environmentally friendly alternative fuel, and its production would partially cover the gap in energy market requirements. However, developing new cheap catalysts for its production from crude oil is still a challenging area in the field of petroleum and the petrochemical industry. This study presents a new approach to synthesizing and applying promising catalysts based on Ni, Co, and Ni-Co alloys that are supported by aluminum oxide Al2O3 in the production of hydrogen from extra-heavy crude oil in the Tahe Oil Field (China), in the presence of supercritical water (SCW). The obtained catalysts were characterized via scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, transmission electron microscopy (TEM), and, X-ray diffraction analysis (XRD). The obtained XRD data showed 3.22% of Co2+ in the Co/Al2O4 catalyst, 10.89% of Ni2+ in the Ni/Al2O4 catalyst, and 1.51% of Co2+ and 2.42% of Ni2+ in the Ni-CoAl2O3 bimetallic catalyst. The BET measurements of the obtained catalysts showed a surface area ranging from 3.04 to 162 m2/g, an average particle size ranging from 0.037 to 0.944 µm, and micropore volumes ranging from 0.000377 to 0.004882 cm3/g. The thermal, SCW, and catalytic upgrading processes of the studied samples were conducted in a discontinuous autoclave reactor for 2 h at a temperature of 420 °C. The obtained results revealed that thermal upgrading yielded 1.059 mol.% of H2, and SCW led to 6.132 mol.% of H2; meanwhile, the presence of Ni-CoAl2O3 provided the maximal rate of hydrogen generation with 11.783 mol.%. Moreover, Ni-CoAl2O3 and NiAl2O3 catalysts have been found to possess good affinity and selectivity toward H2 (11.783 mol.%) and methane CH4 (40.541 mol.%). According to our results, the presence of SCW increases the yield of upgraded oil (from 34.68 wt.% to 58.83 wt.%) while decreasing the amount of coke (from 51.02 wt.% to 33.64 wt.%) due to the significant amount of hydrogen generation in the reaction zone, which reduces free-radical recombination, and thus, improves oil recovery. Moreover, the combination of SCW and the synthetized catalysts resulted in a significant decrease in asphaltene content in the upgraded oil, from 28% to 2%, as a result of the good redistribution of hydrogen over carbons (H/C) during the upgrading processes, where it increased from 1.39 to 1.41 in the presence of SCW and reached 1.63 in the presence of the Ni-CoAl2O3 catalyst. According to the XRD results of the transformed form of catalysts (CoNi3S4), after thermal processing, heteroatom removal from extra-heavy crude oil via oxidative and adsorptive desulfurization processes is promoted. These findings contribute to the expanding body of knowledge on hydrogen production from in situ unconventional oil upgrading.

Reversible Multi‐Electron Reaction Mechanism of Sodium Vanadium/Manganese Phosphate Cathode for Enhanced Na‐Storage Capability

AbstractSodium‐ion batteries are widely regarded as an important candidate for low cost large‐scale storage of intermittent energies. NASICON‐type vanadium‐based phosphate with formula of Na3V2(PO4)3 exhibits promising application as cathode material for sodium‐ion batteries due to robust structural framework and high electrochemical activity. However, it is intrinsically limited by low theoretical specific capacity (117 mAh g−1) owing to only two‐electron reaction mechanism below 4.0 V. Accordingly, exploring novel vanadium‐based phosphates cathode with multi‐electron reaction mechanism is essential. Herein, carbon‐coated sodium vanadium/manganese phosphate (Na3.25V1.75Mn0.25(PO4)3/C) was reported as enhanced cathode for sodium‐ion batteries. Its structural properties, charge/discharge performance and electrochemical redox mechanism were investigated by coupling X‐ray diffraction, Brunauer–Emmett–Teller measurement, X‐ray photoelectron spectroscopy, cyclic voltammetry, and galvanostatic technique. It was unexpectedly found that the material not only achieved a high practical capacity (126.1 mAh g−1) of larger than the theoretical value of traditional Na3V2(PO4)3 compound, but also exhibited good cycling stability with 96 % capacity retention after 40 cycles. Experimental evidences revealed that the material underwent a reversible multi‐electron reaction mechanism involving V4+/V3+, Mn3+/Mn2+ and V5+/V4+ redox couples during Na extraction/insertion process, and the improved capacity was attributed to additional contribution of manganese substitution‐activated V5+/V4+ redox reaction at the high potential of ∼3.8 V (vs Na+/Na).

Functionalized SnO2 nanoparticles with gallic acid via green chemical approach for enhanced photocatalytic degradation of citalopram: synthesis, characterization and application to pharmaceutical wastewater treatment

Eco-friendly stannic oxide nanoparticles functionalized with gallic acid (SnO2/GA NP) were synthesized and employed as a novel photocatalyst for the degradation of citalopram, a commonly prescribed antidepressant drug. SnO2/GA NP were characterized using high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller measurements and X-ray diffraction. A validated RP-HPLC assay was developed to monitor citalopram concentration in the presence of its degradation products. Full factorial design (24) was conducted to investigate the effect of irradiation time, pH, SnO2/GA NP loading and initial citalopram concentration on the efficiency of the photodegradation process. Citalopram initial concentration was found to be the most significant parameter followed by irradiation time and pH, respectively. At optimum conditions, 88.43 ± 0.7% degradation of citalopram (25.00 µg/mL) was obtained in 1 h using UV light (1.01 mW/cm2). Citalopram kinetics of degradation followed pseudo-first order rate with Kobs and t0.5 of − 0.037 min−1 and 18.73 min, respectively. The optimized protocol was successfully applied for treatment of water samples collected during different cleaning validation cycles of citalopram production lines. The reusability of SnO2/GA NP was studied for 3 cycles without significant loss in activity. This approach would provide a green and economic alternative for pharmaceutical wastewater treatment of organic pollutants.Graphical abstract

NOx Photooxidation over Different Noble Metals Modified TiO2

We compared the activity enhancement effect of noble metal deposited on TiO2 in photocatalytic nitrogen oxides oxidation. Titanium dioxide was decorated with Ag, Au, Pt or Pd in the sol-gel process. Synthesized catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller measurement (BET), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). All catalysts together with pure TiO2 obtained by sol-gel (SG) technique were tested for their photocatalytic activity towards nitrogen oxide oxidation (high concentrations of 50, 150 and 250 ppm). FTIR spectrometry was used to determine the gas phase composition and identify TiO2 surface species. The Ag0.1 sample turned out to be deactivated within 60 min of UV/Vis irradiation. Photocatalytic oxidation rate towards NO2 turned to be the highest over SG (photocatalyst without metal deposition). NO2 formation was also observed for Au0.1, Au0.5, Pt0.1, Pt0.5 and Pd0.1. The best NOx removal, i.e., conversion to final product HNO3 was obtained with the Au0.5 photocatalyst.

Reproducibility of methods required to identify and characterize nanoforms of substances

Nanoforms (NFs) of a substance may be distinguished from one another through differences in their physicochemical properties. When registering nanoforms of a substance for assessment under the EU REACH framework, five basic descriptors are required for their identification: composition, surface chemistry, size, specific surface area and shape. To make the risk assessment of similar NFs efficient, a number of grouping frameworks have been proposed, which often require assessment of similarity on individual physicochemical properties as part of the group justification. Similarity assessment requires an understanding of the achievable accuracy of the available methods. It must be demonstrated that measured differences between NFs are greater than the achievable accuracy of the method, to have confidence that the measured differences are indeed real. To estimate the achievable accuracy of a method, we assess the reproducibility of six analytical techniques routinely used to measure these five basic descriptors of nanoforms: inductively coupled plasma mass spectrometry (ICP-MS), Thermogravimetric analysis (TGA), Electrophoretic light scattering (ELS), Brunauer–Emmett–Teller (BET) specific surface area and transmission and scanning electron microscopy (TEM and SEM). Assessment was performed on representative test materials to evaluate the reproducibility of methods on single NFs of substances. The achievable accuracy was defined as the relative standard deviation of reproducibility (RSDR) for each method.Well established methods such as ICP-MS quantification of metal impurities, BET measurements of specific surface area, TEM and SEM for size and shape and ELS for surface potential and isoelectric point, all performed well, with low RSDR, generally between 5 and 20%, with maximal fold differences usually <1.5 fold between laboratories. Applications of technologies such as TGA for measuring water content and putative organic impurities, additives or surface treatments (through loss on ignition), which have a lower technology readiness level, demonstrated poorer reproducibility, but still within 5-fold differences. The expected achievable accuracy of ICP-MS may be estimated for untested analytes using established relationships between concentration and reproducibility, but this is not yet the case for TGA measurements of loss on ignition or water content. The results here demonstrate an approach to estimate the achievable accuracy of a method that should be employed when interpreting differences between NFs on individual physicochemical properties.