Nitrogen Physisorption Research Articles

Novel Antitumor Agents Based on Fluorescent Benzofurazan Derivatives and Mesoporous Silica

Two novel fluorescent mesoporous silica-based hybrid materials were obtained through the covalent grafting of [4-hydrazinyl-7-nitrobenz-[2,1,3-d]-oxadiazole (NBDH) and N1-(7-nitrobenzo[c][1,2,5]-oxadiazol-4-yl) benzene-1,2-diamine (NBD-PD), respectively, inside the channels of mesoporous silica SBA-15. The presence of fluorescent organic compounds (nitrobenzofurazan derivatives) was confirmed by infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG), and fluorescence spectroscopy. The nitrogen physisorption analysis showed that the nitrobenzofurazan derivatives were distributed uniformly on the internal surface of SBA-15, the immobilization process having a negligible effect on the structure of the support. Their antioxidant activity was studied by measuring the ability to reduce free radicals DPPH (free radical scavenging activity), in order to formulate potential applications of the materials obtained. Cytotoxicity of the newly synthesized materials, SBA-NBDH and SBA-NBD-PD, was evaluated on human B16 melanoma cells. The morphology of these cells, internalization and localization of the investigated materials in melanoma and fibroblast cells were examined through fluorescence imaging. The viability of B16 (3D) spheroids after treatment with SBA-NBDH and SBA-NBD-PD was evaluated using MTS assay. The results showed that both materials induced a selective antiproliferative effect, reducing to various degrees the viability of melanoma cells. The observed effect was enhanced with increasing concentration. SBA-NBD-PD exhibited a higher antitumor effect compared to SBA-NBDH starting with a concentration of 125 µg/mL. In both cases, a significantly more pronounced antiproliferative effect on tumor cells compared to normal cells was observed. The viability of B16 spheroids dropped by 40% after treatment with SBA-NBDH and SBA-NBD-PD at 500 µg/mL concentration, indicating a clear cytotoxic effect of the tested compounds. These results suggest that both newly synthesized biomaterials could be promising antitumor agents for applications in cancer therapy.

Synthesis of Core–Shell Magnetic Nanoparticles Containing Ultrasmall Domains of Silicalite‐1

AbstractSynthesis of core–shell nanostructures with magnetic core and zeolitic shell is an ongoing challenge. Herein, a strategy is presented for preparation of γ‐Fe2O3@mesoporous silica (mSiO2) core–shell nanoparticles containing ultrasmall domains of silicalite‐1 in the shell (γ‐Fe2O3@mSiO2/silicalite‐1). The strategy consists in a solid‐state reorganization of the precursor amorphous mSiO2 shell into silicalite‐1 using a tetrapropylammonium hydroxide (TPAOH) as an organic structure‐directing agent (OSDA) under mild hydrothermal (HT) conditions. The formation of silicalite‐1 crystalline domains is investigated through the detailed characterization of products obtained at different times of HT treatment by X‐ray diffraction (XRD), Raman spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) with energy dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM), and nitrogen physisorption. By careful tuning the time of HT treatment, the γ‐Fe2O3@mSiO2/silicalite‐1 nanostructures are prepared. Benefitting from the unique mesopores/microporous structure formed, the γ‐Fe2O3@mSiO2/silicalite‐1 core–shell nanostructure shows superior adsorption capacity to remove aniline from aqueous solutions than the γ‐Fe2O3@mSiO2. Moreover, the γ‐Fe2O3@mSiO2/silicalite‐1 nanostructure is easily separated from aqueous solutions using magnetic separation technique within 1 min.

Post-synthetic modification of graphitic carbon nitride with PCl3 and POCl3 for enhanced photocatalytic degradation of organic compounds

Graphitic carbon nitride (g-C 3 N 4 ) was synthesised from melamine at 550 °C in the air for a period of 4 h. As such prepared g-C 3 N 4 was dispersed in PCl 3 and POCl 3 with and without pyridine at an ambient temperature for us to dope g-C 3 N 4 with phosphorus. The bulk structural properties of g-C 3 N 4 examined by X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were not changed. On the contrary, a surface modification in terms of pore size distribution studied using physisorption of nitrogen and electron microscopy was observed. Using PCl 3 (in the presence of pyridine), nitrogen vacancies were filled with phosphorus and phosphoramidate groups were formed (with and without pyridine). When POCl 3 was used nitrogen vacancies were removed and the surface structure was rearranged, but no phosphorus was doped in g-C 3 N 4 . The band gap energies varied from 2.69 to 2.73 eV and specific surface areas varied from 8 to 11 m 2 g −1 . The g-C 3 N 4 surface structure rearrangement was associated with altered electronic properties which led to higher photocatalytic activity observed by the degradation of Ofloxacin, Amoxicillin and Rhodamine B (RhB) under LED irradiation of 420 nm. A degradation efficiency decreased in the order: Ofloxacin > RhB > Amoxicillin. Superoxide radicals were found to be able to react with all the organic compounds, but holes could react only with Ofloxacin and RhB. All the modified materials were more active than the pristine g-C 3 N 4 and the best photocatalyst was prepared through the reaction with PCl 3 in the presence of pyridine. • g-C 3 N 4 was synthetized from melamine at 550 °C in the air for 4 h. • Then, g-C 3 N 4 was modified with PCl 3 and POCl 3 . • Using PCl 3 , the surface of g-C 3 N 4 was doped with phosphorus. • In the case of POCl 3 , g-C 3 N 4 was undoped but its surface structure was changed. • These modifications led to the enhanced photocatalytic activity of g-C 3 N 4 .

Efficient and Stable Rice Husk Bioderived Silica Supported Cu2S-FeS for One Pot Esterification and Transesterification of a Malaysian Palm Fatty Acid Distillate

A novel heterogeneous catalyst composite (CuS-FeS/SiO2) derived from rice husk silica was engineered following pyrolysis, chemical precipitation, and chemical redox technique. The resulting catalyst was applied to the conversion of palm fatty acid distillate to biodiesel. The presence of CuS and FeS on the catalyst was verified using X-ray diffraction and Fourier transform infrared spectroscopy, nitrogen physisorption, scanning electron microscopy (FESEM) with energy dispersive X-ray (EDS) spectroscopy, and temperature-programmed desorption of NH3 (TPD-NH3), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and TGA; a specific surface area of approximately 40 m2·g−1 was identified. The impact of independent variables, i.e., reaction temperature, reaction duration, methanol:oil ratio and catalyst concentration were evaluated with respect to the efficacy of the esterification reaction. The greatest efficiency of 98% with a high productivity rate of 2639.92 µmol·g−1·min−1 with k of 4.03 × 10−6 mole·S−1 was achieved with the following parameters: temperature, 70 °C; duration, 180 min; catalyst loading, 2 wt.%; and methanol to oil ratio, 15:1. The CuS-FeS/SiO2 catalyst showed relatively high stability indicated by its ability to be reused up to five times.

The Dilemma of Reproducibility of Gating Isotherms for Flexible MOFs.

Porous materials receive a high level of scientific and technological interest due to their applications in various fields such as adsorption, separation and storage, catalysis, ion exchange, nanotechnology, etc. Gas adsorption is a well-established tool for the characterization of the texture of porous solids. Physisorption isotherms are generally expected to be well reproducible for rigid adsorbents, but this is not always the case for nonrigid (flexible) materials. The presence of a metastability region and sensitivity of the activation barriers to the material's texture often influence the isotherms' run. Here, we address the complexity that arises in terms of reproducibility and sample handling for flexible metal-organic frameworks, with the example of DUT-8(Ni). It belongs to the group of "gate opening" metal-organic frameworks and is a typical representative of the pillared layer compounds. We propose characteristic parameters for the analysis and comparison of adsorption isotherms, showing the "gate opening" step, associated with the adsorption-induced solid-state phase transition. A set of 50 nitrogen physisorption isotherms measured at 77 K were analyzed and correlated with the synthetic and outgassing conditions. The study highlights the importance of accurate descriptions and record-keeping of experimental details and their role in the replication of scientific results.

Environmentally Friendly Fabrication of High-Efficient Fe-ZnO/Citric Acid-Modified Cellulose Composite and the Enhancement of Photocatalytic Activity in the Presence of H2O2

In the present study, a novel Fe-ZnO/citric acid-modified cellulose composite (x%Fe-ZnO-y%CAC) was synthesized using an environmentally friendly hydrothermal method. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), nitrogen physisorption, and electrochemical and photocurrent density analyses. The influence of the additives from the series of x%Fe-ZnO-y%CAC photocatalysts with Fe content from 0 to 5% and CAC content from 0 to 80% on photocatalytic degradation of ibuprofen (IBU) under simulated solar light was investigated. The photocatalyst 0.5%Fe-ZnO-40%CAC showed high photocatalytic activity of 0.0632 min−1 first-order kinetic rate constant and 46% TOC reduction of IBU under simulated solar light irradiation. Additionally, H2O2-assisted photocatalytic process was investigated for facilitating the IBU degradation in the presence of 0.5%Fe-ZnO-40%CAC; the first-order kinetic rate constant was 2.7 times higher compared to the process without addition of H2O2. Moreover, the effect of radical scavengers was examined to explain the degradation mechanism of IBU by synthesized photocatalysts supported with H2O2. The demonstrated system provides a low-cost and green approach to improve the photocatalytic activity of x%Fe-ZnO-y%CAC photocatalysts.

Enhancing high selectivity production of light aromatics from in-situ catalytic upgrading of cellulose pyrolysis vapors by regulating hierarchical core-shell ZSM-5@MCM-41

The catalytic upgrading of cellulose pyrolysis vapors is one of the effective methods to realize its high value utilization. Tuning the pore structure and acid sites of ZSM-5 (Z5) is a necessary strategy to develop effective catalysts for the production of light aromatics and the inhibition of carbon formation. In this study, a core-shell structure ZSM-5 @MCM-41 was developed and used for the first time in catalytic fast pyrolysis (CFP) of cellulose to prepare light aromatic hydrocarbons. The successful synthesis of the hierarchical core-shell ZSM-5 @MCM-41 was confirmed by nitrogen physisorption, X-ray diffraction (XRD), and transmission electron microscope (TEM) analysis. In aromatic hydrocarbon production, 1.0SH-Z5 @ M41 (1.0 mol/L, ZSM-5 @MCM-41) has the highest relative content of 98.76%. The relative content of BTEX (benzene, toluene, ethylbenzene, and xylene) is up to 89.83%, which is 2.39 times that of traditional microporous Z5. The quadratic polynomials were developed to correlate the Brønsted-to-Lewis acid site strength ratio (BLR) and mesopore-to-micropore volume ratio (MMR) with the relative content of BTEX. The mechanism of in-situ catalytic upgrading of cellulose pyrolysis vapor over ZSM-5 @MCM-41 was revealed. Due to high selectivities and low coke formation, ZSM-5 @MCM-41 offers an improved option for making monocyclic aromatics from cellulosic biomass.

Beneficial effects of nickel promoter on the efficiency of alumina-supported Co3O4 catalysts for lean methane oxidation

In this work bimetallic Ni catalysts supported over Co-Al2O3 and monometallic Co-Al2O3 and Ni-Al2O3 catalysts were examined for the complete oxidation of methane. With a 30 % total metallic loading, the samples were synthesized by a sequential precipitation route. All samples were characterized by nitrogen physisorption, X-ray fluorescence, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, scanning-transmission electron microscopy, X-Ray photoelectron spectroscopy, and temperature-programmed reduction with hydrogen and methane. Their catalytic performance was investigated in the temperature range of 200–600 °C with a space velocity of 60.000 h−1. The bimetallic catalysts showed a better behavior in the oxidation reaction than the monometallic counterparts, mainly due to the good dispersion of Ni on the surface of the Co-Al2O3 samples. This has enabled the insertion of Ni2+ ions into the cobalt spinel lattice, which in turn provoked an increase in the amount of Co3+ species, and a subsequent enhanced mobility of oxygen species in the spinel. In this sense, the 5Ni/25Co catalyst showed the best performance, thus reducing the value of the T50 by 25 °C with respect to the monometallic catalysts.

Washcoated open-cell foam cobalt spinel catalysts for N2O decomposition

The Co3O4 modified with 1 wt.% Cs was deposited on α-Al2O3 open-cell foam covered with different washcoats (MgO, MnO2, SiO2, TiO2), investigated by XRD, Raman microspectroscopy, nitrogen physisorption, XPS, SEM and TPR-H2 in order to elucidate interactions between Cs-Co3O4 and the washcoat and their effect on surface area, reducibility, dispersion, and low temperature decomposition of N2O. The samples with SiO2 and TiO2 washcoats had the largest surface areas. Only SiO2 did not interact with the active phase and did not change the reducibility of the catalyst. Although the same Cs concentration was adjusted during preparation of all catalysts, differences in the Cs/Co surface molar ratio were observed due to a different level of Co3O4 particles aggregation and cesium dispersion. Catalytic activity correlated with the surface Cs/Co molar ratio closely interconnected with the surface Co3+/Co2+ molar ratio while there were no direct relationships to the redox properties and surface area. The highest activity was achieved for the MgO washcoat prepared from carbonate with the highest Co3+/Co2+ molar ratio corresponding to the optimal Cs/Co surface molar ratio around 0.1.

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N 5 Site for Enhanced Electrocatalytic Reaction

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N ₅ Site for Enhanced Electrocatalytic Reaction

Highly Selective Gas-Phase Catalytic Hydrogenation of Acetone to Isopropyl Alcohol

Current industrial synthesis procedures of isopropyl alcohol (IPA), by the direct or indirect hydration of propylene in the gas or liquid phase, suffer from the low conversion of propylene, the requirement for high pressure, and the harmfulness to the environment. In this context, we report a single-step, gas-phase process for the green synthesis of IPA via acetone hydrogenation, in a fixed-bed reactor, under ambient pressure and within a temperature range of 100–350 °C. Composite catalysts with various ratios of ruthenium nanoparticles supported on activated charcoal and nano-zinc oxide (n-Ru/AC/n-ZnO) were used. Catalytic activity and selectivity were functions of n-Ru/AC/n-ZnO loading ratios, reaction temperature, and the hydrogen to acetone molar ratio. The composite catalysts were characterized by X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR) analysis, and nitrogen physisorption. High yields of IPA were obtained over 3n-Ru/AC/2n-ZnO) catalyst, which showed the highest selectivity of 98.7% toward isopropyl alcohol and acetone conversion of 96.0% under a hydrogen to acetone mole ratio of 1.5 at 100 °C. Reaction rates, calculated from the model equation, were in reasonable agreement with those measured experimentally. The apparent activation energy (Ea) value for acetone hydrogenation was found to be 17.2 kJ/mol. This study proved that immobilized Ru catalysts were potential superior catalysts for the selective hydrogenation of acetone to IPA in exceptionally mild green synthesis conditions.

RGO-WO3 Heterostructure: Synthesis, Characterization and Utilization as an Efficient Adsorbent for the Removal of Fluoroquinolone Antibiotic Levofloxacin in an Aqueous Phase.

Herein, the heterostructure rGO-WO3 was hydrothermally synthesized and characterized by HRTEM (high-resolution transmission electron microscopy), FESEM (field emission scanning electron microscopy), XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron microscopy), nitrogen physisorption isotherm, Raman, TGA (thermogravimetric analysis) and zeta potential techniques. The HRTEM and FESEM images of the synthesized nanostructure revealed the successful loading of WO3 nanorods on the surface of rGO nanosheets. The prepared heterostructure was utilized as an efficient adsorbent for the removal of a third-generation fluoroquinolone antibiotic, i.e., levofloxacin (LVX), from water. The adsorption equilibrium data were appropriately described by a Langmuir isotherm model. The prepared rGO-WO3 heterostructure exhibited a Langmuir adsorption capacity of 73.05 mg/g. The kinetics of LVX adsorption followed a pseudo-second-order kinetic model. The adsorption of LVX onto the rGO-WO3 heterostructure was spontaneous and exothermic in nature. Electrostatic interactions were found to have played a significant role in the adsorption of LVX onto the rGO-WO3 heterostructure. Thus, the prepared rGO-WO3 heterostructure is a highly promising material for the removal of emerging contaminants from aqueous solution.

Effects of Cu Species on Liquid-Phase Partial Oxidation of Methane with H2O2 over Cu-Fe/ZSM-5 Catalysts

In this study, a Cu-promoted Fe/ZSM-5 catalyst was examined to reveal the effects of Cu species in selective oxidation of methane into methane oxygenates using H2O2 in water. Cu/ZSM-5, Cu-Fe/ZSM-5, and Fe/ZSM-5 catalysts were prepared using wet impregnation, solid-state ion exchange, and ion-exchange methods. Various techniques, including nitrogen physisorption, temperature-programmed reduction with H2, UV-vis spectroscopy, and FT-IR spectroscopy after NO adsorption, were utilized to characterize the catalysts. The promotional effect of Cu on the Cu-Fe/ZSM-5 catalyst in terms of methanol selectivity was confirmed. The preparation method has a considerable influence on the catalyst performance, and the ion-exchange method is the most effective. However, leaching of the Cu species was observed during this reaction, which can affect the quantification of formic acid by 1H-NMR. The homogeneous Cu species increase hydrogen peroxide decomposition and CO2 selectivity, which is undesirable for this reaction.

Impact of Sulfate Adsorption on Particle Morphology during Precipitation of Ni-Rich Precursors for Li-Ion Cathode Active Materials

Current standard industrial manufacturing of lithium layered transition metal oxides (LiMO2) as cathode active material (CAM) can be divided into two major process steps: The first step involves coprecipitation of mixed transition metal hydroxide (M(OH)2) particles (M consisting mainly of Ni, Co, and Mn) by mixing a transition metal sulfate solution (MSO4(aq.)) and a sodium hydroxide solution (NaOH(aq.)) in a stirred tank reactor. The resulting hierarchally structured secondary particles are composed of many primary particles which are used as precursors for CAMs (referred to as pCAM). Subsequently, the obtained pCAM is mixed with a lithium source such as Li2CO3 or LiOH and calcined at elevated temperatures to yield LiMO2.1 Recently, reports in the literature have shown clear correlations of CAM morphology with their electrochemical performance in a battery cell.2 Furthermore, it has been demonstrated that the electrochemical performance of a CAM is affected by the morphology of the associated pCAM.3, 4 However, a detailed understanding of the impact of the process parameters on the course of precipitation reaction and on the physical properties of the pCAM precipitate is still lacking.In order to gain a mechanistic understanding of the M(OH)2 pCAM particle formation, ten distinctive Ni0.8Co0.1Mn0.1(OH)2 particle lots were prepared by the coprecipitation method in a stirred tank reactor. The precipitation pH-value was systematically varied between pH = 8.6-12.7, while all other process parameters were kept constant. The S-content of the resulting pCAM powders, representing the residual sulfate (SO4 2-) content, was investigated by S-combustion and is depicted as a function of precipitation pH-value in Figure 1a. In the pH-value range between 8.57 and 10.27 (red), a slight increase in residual SO4 2- from 10.29 mol% to 12.60 mol% is observed until it decreases again to 11.10 mol%. Between pH = 10.27 and pH = 10.74, a sharp transition takes place and residual SO4 2- is reduced by a factor of 4 from 11.10 mol% to 2.60 mol%, which even decreases further with increasing pH-value, namely from 2.60 mol% at pH = 10.74 to 0.35 mol% at pH = 12.69 (green). Interestingly, the turning point in S-content between pH = 10.27 and pH = 10.74 (dashed blue line in Figure 1a) coincides with the point-of-zero-charge (pzc) of Ni(OH)2, which is reported to be at pH = 10.50-10.60.5 This result is rationalized by a pH-dependent SO4 2- adsorption equilibrium that is governing the SO4 2- uptake during the precipitation reaction, as depicted schematically in Figure 1b. For a precipitation below the pzc, positive charged surface hydroxyl-groups of Ni0.8Co0.1Mn0.1(OH)2 attract SO4 2-, resulting in high SO4 2- uptake during M(OH)2 formation and vice versa.In light of these results, it is further demonstrated by x-ray diffraction analysis that SO4 2- adsorption not only governs the crystallinity of the Ni0.8Co0.1Mn0.1(OH)2 material, but also suppresses the vertical crystal growth in the 001-direction during particle formation. This in turn seems to affect the vertical primary particle size as well as the secondary particle porosity, both observable by SEM imaging. The morphological trend is quantitatively verified by extracting the primary particle size distribution from SEM images and by measurements of the secondary particle porosity via nitrogen physisorption. As proof-of-concept for the proposed adsorption mechanism, precipitation reactions at pH = 12.0 with different metal feed sources (MX(aq.), with X = SO4 2-, (NO3 -)2, (CH3COO-)2) were conducted. The resulting clearly distinct physical properties of the Ni0.8Co0.1Mn0.1(OH)2 particles obtained from the different anion systems with different anion adsorption affinities can be well understood based on the Fajans-Paneth-Hahn law for crystallization.6 Finally, desorption experiments indicate options to reduce the residual SO4 2- amount after the Ni0.8Co0.1Mn0.1(OH)2 particle formation has been completed.Based on the results of this study, guidelines for pCAM design are formulated and discussed with respect to composition and subsequent manufacturing steps in industrial CAM production.

Local Hydrophobicity of Atomically Dispersed Fe-N-C Catalysts and Its Impact on the Oxygen Reduction Reaction in Membrane Electrode Assembly

Non-precious metal electrocatalysts with atomically dispersed transition metal sites have shown promising performance for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. The Fe-N-C catalysts, with single iron atom coordinated by nitrogen atoms (FeNx) on carbonaceous supports, exhibits outstanding ORR activity as compared to its other metal counterparts (M-N-C). [1] The Fe-N-C catalysts synthesized via sacrificial support method (SSM) showed superior ORR performance and this family of Fe-N-C electrocatalysts is so far the only commercially available PGM-free catalysts for fuel cell application. [2] For membrane electrode assembly (MEA) performance, the pore structure [3] and surface hydrophobicity [4] of the carbon matrix are of particular significance, because the high current throughput requires good oxygen transport and well-controlled water management on cathodes. In this talk, we present the local hydrophobicity of SSM-based Fe-N-C electrocatalysts [1] and its impact on the ORR macrokinetics in MEA. Specifically, nitrogen physisorption and water vapor physisorption were used to study the pore morphology and the local surface hydrophobicity, respectively. As shown in Figure 1, the sacrificial templated Fe-N-C catalyst showed a large amount of mesoporosity while its surface was very hydrophobic, as indicated by the little water uptake through whole pressure range. Such porosity and local hydrophobicity features were further correlated to its macrokinetic performance in a study of water partial pressure dependence under MEA configuration. Reference [1] T. Asset and P. Atanassov, Joule, 2020, 4, 33.[2] https://pajaritopowder.com [3] Y. Huang, Y. Chen, M. Xu, T. Asset, P. Tieu, A. Gili, D. Kulkarni, V. de Andrade, F. de Carlo, H. S. Barnard, A. Doran, D. Y. Parkinson, X. Pan, P. Atanassov, and I. Zenyuk, Materials Today, 2021, 47, 53.[4] L. Liu, S. J. Tan, T. Horikawa, D. D. Do, D. Nicholson and J. Liu, Adv Colloid Interface Sci, 2017, 250, 64. Figure 1

Development of novel composite adsorbents based on biopolymers/vermiculite using the ionic imprinting technique for cerium biosorption

Cerium is a rare earth metal with high demand in diverse industrial applications, thus, its recovery from secondary sources is of fundamental importance, in a circular economy perspective. Biosorption is a recovery technique that stands out for its simplicity and efficiency. The combination of different materials is a strategy to produce biosorbents with improved properties. Biopolymers and clay minerals are considered promising because they are abundant and biodegradable. Functionalization techniques, such as ionic imprinting can improve the characteristics of biosorbents. The present work proposed the development of composite particles based on expanded vermiculite-biopolymers (chitosan, κ-carrageenan, or alginate) and to evaluate their performance in terms of Ce3+ removal and particles solubility. The alginate-based composite provided the best results and was used in the synthesis of novel Ce3+ imprinted biosorbents. The particles with the best performance, composed of vermiculite (3% w/v) and alginate (2% w/v), without and with Ce3+ imprinting, presented biosorption capacities of 0.446 and 0.579 mmol/g, respectively. The kinetic study showed that the biosorption of Ce3+ by VALG3-II followed the pseudo-first order model. The selectivity of VALG3-II followed the order of Ce3+ > Al3+ > Fe2+ > Zn2+ > Ni2+ > Ca2+> Mg2+ > Na+ > K+. Additionally, the characterization of the composite without and with Ce3+ imprinting was performed by thermal analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, mercury intrusion porosimetry, helium pycnometry, and nitrogen physisorption.

Targeted delivery and apoptosis induction activity of peptide-transferrin targeted mesoporous silica encapsulated resveratrol in MCF-7 cells.

Resveratrol (Res) was a naturally occurring polyphenol compound. It has various beneficial effects, including anti-inflammatory, anti-oxidant and anti-cancer effects. However, the anti-cancer activity was hindered by its low targeting and drug release performance. Thus, we synthesized transferrin-cathepsin B cleavable peptide modified mesoporous silica nanoparticle encapsulated Res (Tf-Res-MSN). Res was encapsulated in mesoporous silica nanoparticles (MSN), which was a kind of drug carrier complex. Tf was modified to recognize the cancer cells. Cathepsin B cleavable peptide (Pep) was used to combine Res-MSN complex and Tf to construct the final product. Pep was used as linker and trigger for Res release. The smart nanocarriers were increased the drug release performance of Res in human breast cancer (MCF-7) cells. The physicochemical properties of Tf-Res-MSN were assessed by zeta potential, UV-Prove, diffraction scanning calorimetry (DSC), nitrogen physisorption analysis and transmission electron microscope (TEM). MTT assay, AO and Annexin V-FITC/PI staining were performed to explore the anti-tumour activity of Tf-Res-MSN. The results showed that Tf-Res-MSN significantly decreased cell viability and increased cell apoptosis. The inhibition rate and apoptotic rate of Tf-Res-MSN in MCF-7 cells were 95.75% and 80.8%, respectively. Our study demonstrated that Tf-Res-MSN was a valuable technique with potential value in breast cancer applications.

Holmium promoted yttria-zirconia supported Ni catalyst for H2 production via dry reforming of methane

Herein, a series of 5NixHo/YZr (x = 1, 2, 3, 4, 5 wt%) materials, never reported before, were tested in DRM reaction and characterized using several techniques like Nitrogen physisorption, X-ray diffraction, UV–vis and RAMAN spectroscopies, High Resolution Transmission Electron Microscopy, H2-Temperature Programmed Reduction, CO2-Temperature Programmed De-adsorption and Thermogravimetry. The incorporation of Yttria in the structure modifies pore sizes and stabilizes cubic Zirconia phases, whereas the addition of Ho as a promotor brings stable cubic zirconia, stable cubic holmium zirconium oxide phase and a wide range of reducible NiO-interacted species. In particular, an optimum Ho loading of 4 wt%, characterized by a minimum bandgap, strong suppression of RWGS reaction and maximum amount of reducible NiO-interacted species allows to achieve 84.1% H2 yield and 84.1% CO yield constantly over 420-min time on stream. The least basic sites availability over 5Ni5Ho/YZr results into inferior catalyst performance.

Rice husk-derived activated carbon electrode in redox-active electrolyte – New approach for enhancing supercapacitor performance

Processing of renewable, abundant, and low-cost biomass into porous carbon materials for application in supercapacitor electrodes has been attracting interest in last years. In this study, activated carbons (ACs) were produced via carbonization of rice husk followed by the chemical activation with KOH. SEM, Raman spectroscopy, XPS, and low temperature nitrogen physisorption were used to characterize the morphology, defectiveness, surface composition and textural parameters of the synthesized ACs. Activation significantly increased the specific surface area of AC up to 2700 m2·g−1 forming a well-developed porous structure favorable for charge accumulation. The electrochemical performance of ACs was tested in the 1 M Na2SO4 and 1 M Na2SO4 + 0.03 M K3Fe[CN]6 electrolytes by cyclic voltammetry, galvanostatic charge – discharge measurements and impedance spectroscopy. The addition of redox-active K3Fe[CN]6 to the conventional 1 M Na2SO4 electrolyte noticeably (in 3.6 times) increased the specific capacitance of the AC-based electrode up to 400 F·g−1 at a current density of 0.5 A·g−1. The high capacitance retentions of 99.6 % in 1 M Na2SO4 and 97.7 % in 1 M Na2SO4 + 0.03 M K3Fe[CN]6 after 5000 charge–discharge cycles, developed microporosity and high electrochemical performance make the rice husk-derived AC a promising electrode material for energy storage applications. At a current density of 0.5 A·g−1 the symmetric AC2-based supercapacitor with the redox-active electrolyte delivered an energy density of 16.7 Wh·kg−1 at power density of 0.4 kW·kg−1.

Continuous Formation of Limonene Carbonates in Supercritical Carbon Dioxide.

We present a continuous flow method for the conversion of bioderived limonene oxide and limonene dioxide to limonene carbonates using carbon dioxide in its supercritical state as a reagent and sole solvent. Various ammonium- and imidazolium-based ionic liquids were initially investigated in batch mode. For applying the best-performing and selective catalyst tetrabutylammonium chloride in continuous flow, the ionic liquid was physisorbed on mesoporous silica. In addition to the analysis of surface area and pore size distribution of the best-performing supported ionic liquid phase (SILP) catalysts via nitrogen physisorption, SILPs were characterized by diffuse reflectance infrared Fourier transform spectroscopy and thermogravimetric analysis and served as heterogeneous catalysts in continuous flow. Initially, the continuous flow conversion was optimized in short-term experiments resulting in the desired constant product outputs. Under these conditions, the long-term behavior of the SILP system was studied for a period of 48 h; no leaching of catalyst from the supporting material was observed in the case of limonene oxide and resulted in a yield of 16%. For limonene dioxide, just traces of leached catalysts were detected after reducing the catalyst loading from 30 to 15 wt %, thus enabling a constant product output in 17% yield over time.