Co-condensation Method Research Articles

Mesoporous Silica Administration as a New Strategy in the Management of Warfarin Toxicity; In Vitro and In Vivo Study

Purpose: Warfarin is one of the most widely used anticoagulants that function by inhibiting vitamin K epoxide reductase. Warfarin overdose, whether intentional or unintentional, can cause life-threatening bleeding. Here, we present a novel warfarin adsorbent based on mesoporous silica that can act as an antidote to warfarin toxicity. Method: Amino-functionalized mesoporous silica (MS-NH2) was synthesized based on co-condensation method through a soft template technique followed by template removal. The prepared structure and functional group were studied by FT-IR, XRD. The morphology was checked by SEM and TEM. The capacity of MS-NH2 in the adsorption of warfarin was evaluated in vitro, at pH=7.4 and pH=1.2. In vivo evaluation was performed in control and warfarin-overdosed animal models. Overdosed animals were treated with MS-NH2 by oral gavage. Biomarkers of organ injury were assessed in animal serum. Results: The MS-NH2 were relatively uniform, spherical with defined diameters (400 nm) and homogeneous structure. synthesized particles had a large surface area (1015 m2 g-1) and mean pore diameter 2.4 nm which leaded considerable adsorption capacity for warfarin 1666 mg/g. In vivo studies revealed that oral administration of MS-NH2 in mice poisoned with warfarin caused a significant difference (p < 0.05) on International Normalized Ratio (INR) and prothrombin time (PT). Moreover, the warfarin with MS-NH2 group demonstrated a notable decrease in biomarkers associated with tissue damage, such as bilirubin, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Conclusion: The results confirm that MS-NH2 administration can be an effective treatment for warfarin toxicity and could potentially mitigate the adverse effects of warfarin poisoning.

Enhancing the uranium (VI) adsorption performance of phosphoric acid functionalized porous silica by controlled introduction of phosphoric acid group

The post-grafting of porous silica with organic group is a common method for the synthesis of organo-functionalized silica adsorbent. However, this method usually produces adsorbents with limited adsorption performances due to the pore blocking caused by the irregular introduction of organic group. In this work, we report the controllable synthesis of phosphoric acid functionalized porous silica adsorbent based on the co-condensation method for uranium (VI) adsorptive removal with enhanced adsorption performance. Characterizations of the obtained silica verify its porous structure and confirm the homogeneous distribution of phosphoric acid groups inside the silica. This silica is able to efficiently remove 98 % of uranium from a 100 mg/L uranium (VI) solution within 10 min at a dosage of 0.6 g/L and the maximum uranium (VI) adsorption amount reaches 509 mg/g. Both adsorption capacity and adsorption rate of this silica are superior than that of the silica synthesized based on conventional post-grafting method. Moreover, this silica can be reused for five times with uranium (VI) removal efficiency above 95 % and it is well applied in adsorption column for dynamically adsorptive removal of uranium (VI) from real nuclear wastewater. Mechanism-related investigations reveal that uranium (VI) adsorption on this silica proceeds by effective ion exchange of uranium (VI) ion with either phosphoric acid or silanol group and the formation of uranyl phosphonate or uranyl silicate complex. This work provides a feasible strategy to synthesize functionalized porous silica without significant pore blocking, and demonstrates the enhancement effect of regulating surface adsorption groups on the adsorption performances of porous silica. Besides, this work offers a promising adsorbent for efficient treatment of uranium-containing nuclear wastewater and reveals the mechanism of uranium adsorption on those silica adsorbent containing phosphoric acid, thiol or thioether group.

Synergistic catalytic effect of titanium and iron incorporated to spherical MCM-41 in selective catalytic oxidation of diphenyl sulphide with H2O2

Spherical mesoporous silicas of MCM-41 type modified with titanium, iron or both these metals were prepared by co-condensation method and tested in the role of catalysts for selective oxidation of diphenyl sulphide with H2O2 to diphenyl sulphoxide and diphenyl sulphone. The monometallic catalysts containing titanium or iron were found to be active catalysts of diphenyl sulphide mainly to diphenyl sulphoxide. A very significant increase in catalytic activity was observed for the bimetallic samples, containing both titanium and iron. Moreover, in the case of bimetallic catalysts with higher titanium loading, diphenyl sulphone is a dominating reaction product. The increased activity of the bimetallic catalysts has been related to the synergistic operation of titanium and iron in conversion of hydrogen peroxide into reactive species, which in the next step oxidise diphenyl sulphoxide.

Development of pH-responsive Eudragit S100-functionalized silk fibroin nanoparticles as a prospective drug delivery system.

Silk fibroin nanoparticles (FNP) have been increasingly investigated in biomedical fields due to their biocompatibility and biodegradability properties. To widen the FNP versatility and applications, and to control the drug release from the FNP, this study developed the Eudragit S100-functionalized FNP (ES100-FNP) as a pH-responsive drug delivery system, by two distinct methods of co-condensation and adsorption, employing the zwitterionic furosemide as a model drug. The particles were characterized by sizes and zeta potentials (DLS method), morphology (electron microscopy), drug entrapment efficiency and release profiles (UV-Vis spectroscopy), and chemical structures (FT-IR, XRD, and DSC). The ES100-FNP possessed nano-sizes of ∼200-350 nm, zeta potentials of ∼ -20 mV, silk-II structures, enhanced thermo-stability, non-cytotoxic to the erythrocytes, and drug entrapment efficiencies of 30%-60%, dependent on the formulation processes. Interestingly, the co-condensation method yielded the smooth spherical particles, whereas the adsorption method resulted in durian-shaped ones due to furosemide re-crystallization. The ES100-FNP adsorbed furosemide via physical adsorption, followed Langmuir model and pseudo-second-order kinetics. In the simulated oral condition, the particles could protect the drug in the stomach (pH 1.2), and gradually released the drug in the intestine (pH 6.8). Remarkably, in different pH conditions of 6.8, 9.5, and 12, the ES100-FNP could control the furosemide release rates depending on the formulation methods. The ES100-FNP made by the co-condensation method was mainly controlled by the swelling and corrosion process of ES100, and followed the Korsmeyer-Peppas non-Fickian transport mechanism. Whereas, the ES100-FNP made by the adsorption method showed constant release rates, followed the zero-order kinetics, due to the gradual furosemide dissolution in the media. Conclusively, the ES100-FNP demonstrated high versatility as a pH-responsive drug delivery system for biomedical applications.

Chiral HPLC-MS/MS determination of hyoscyamine enantiomers in baby herbal infusions after preconcentration with sulfonic HMS mesostructured silica synthesized by co-condensation

Tropane alkaloids are considered a major food safety issue in recent years, due to their worrying appearance in many foods, such as herbal infusions, usually due to cross-contamination with weeds during harvest. (−)-Hyoscyamine is synthesized by tropane alkaloids-producing plants and its ingestion can cause all types of disorders in humans. Its enantiomerization occurs easily over time, so the inactive (+)-hyoscyamine can be found in foods in variable proportions. Therefore, the goal of the current work was to develop a chiral high performance liquid chromatography tandem mass spectrometry method for the enantiomeric determination of (−)- and (+)-hyoscyamine. Chromatographic separation was optimized, and the best chiral resolution (Rs = 1.59) was achieved in 6.5 min with a Chiralpak® AY-3 polysaccharide-based stationary phase column using ethanol with 0.05 % diethylamine as mobile phase. For the preconcentration of the sample, two types of mesostructured silicas with sulfonic groups were synthesized, by grafting and co-condensation methods, and characterized. The materials were evaluated as sorbents for strong-cation exchange solid-phase extraction of hyoscyamine in baby herbal infusions. Based on the findings gathered, silica denoted as HMS-SO3−(co) was the best sorbent due to the high number of functional groups attached to silica (2.63 mmol/g) and its textural properties. Under optimal conditions, the preconcentration factor obtained was 167, using only 50 mg of the material, and a very low racemization of the (−)-hyoscyamine to the (+) enantiomer was found (<20 %). The method was validated with recoveries of 94–99 %, good linearity (R2 > 0.99), precision (RSD < 20 %), no matrix effect for both analytes and low method quantification limit (0.089 µg/L and 0.092 µg/L for (+)-hyoscyamine and (−)-hyoscyamine, respectively) to meet its applicability in monitoring real samples. Two types of herbal teas for babies (instant and teabags) were analyzed with the developed methodology. Two of the instantaneous infusions analysed were contaminated, one of them with 0.21 µg/L of (−)-hyoscyamine and 0.09 µg/L of (+)-hyoscyamine (ratio 70(−)/30(+)) and the other with 0.075 µg/L of (−)-hyoscyamine (the (+)- enantiomer was below the limit of quantification of the method). Taking these results into account, it is important to evaluate the content of hyoscyamine enantiomers in the infusions to avoid overestimation of (−)-hyoscyamine exposure.

Mesoporous organosilicas with highly-content tyrosine framework as extractive phases for non-steroidal anti-inflammatory drugs in aquatic media

BackgroundAttentions regarding ordered mesoporous silica materials (OMSs), with large specific surface areas and narrow pore size distribution, which are prepared via self-assembly techniques, have been raised in sorption, separation, and sample preparation. However, in order to extend and improve their applications, a functionalization step is required. Organic units can be anchored on the inner or outer surface as well as in the silica wall framework by co-condensation-, grafting-, and periodic mesoporous organosilica (PMO) preparation approaches. Apparently, by synthesizing PMO with extensive and flexible organic bridging groups within the mesoporous wall, an efficient extractive phase can be achieved. ResultsWe employed tyrosine amino acid to synthesize a PMO-based extractive phase. The FT-IR, 1H NMR, HR-ESI-MS, Low angle-XRD, TEM, FESEM, BET, and EDX-MAP analyses confirmed the successful synthesis of PMO within the salt-assisted templating method. A comprehensive study on sorption behavior of PMO was performed and its efficiency was evaluated against the grafting and co-condensation methods. Then, it was implemented to the pipette tip-micro solid phase extraction (PT-μ-SPE) of widely used non-steroidal anti-inflammatory drugs (NSAIDs) in water/wastewaters. Limits of detection and quantification were obtained in the range of 0.1–1.5 and 0.3–5 μg L−1, respectively. The calibration plots are linear in the 1–1000, 3–1000, 10–750, and 3–750 μg L−1, respectively. The intra-and inter-day precision at 50 and 200 μg L−1 levels are 2.9–7.1 % and 3.5–8%, while recoveries are between 84 and 111 %. SignificanceHigh-capacity tyrosine functionalized PMO with 2D hexagonal symmetry silica mesoporous structures found to be highly efficient extractive media. Despite the bulkiness and flexibility of the bridging group within the mesoporous wall, the synthesis condition was optimized in order to load more organic content in the PMO structure. The PMO performance was superior over organically modified ordered mesoporous silica materials prepared by the grafting and co-condensation methods.

Physicochemical and textural properties of amino-functionalised mesoporous silica nanomaterials from different silica sources

A series of MCM-41 nanomaterials that could serve various scientific applications was synthesised from two silica sources, tetraethyl ortho silicate and sodium silicate. Calcination and solvent extraction were employed as surfactant removal methods, while surface functionalisation was done via co-condensation and post-grafting methods. The synthesised nanomaterials were characterised, and their physicochemical properties were compared using X-ray powder diffraction (XRD), Brunauer Emmett Teller (BET) analysis, Fourier Transform Infra-red spectroscopy (FTIR), Thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that the surfactant removal and surface functionalisation methods affected the synthesised nanomaterials' 2θ values, d-spacing, and unit cell parameters. However, surfactant removal methods did not affect the morphology of amino-functionalised nanomaterials. Mesoporous silica nanomaterials of specific surface areas (884.0–17.1 m2/g), pore volumes (1.0–0.1 cm3/g), pore size diameters (7.2–1.5 nm), and less orderly mesoporous structures were produced with co-condensation and amino functionalisation using both silica sources. These methods can produce mesoporous silica nanostructures with different morphologies for wastewater remediation, catalysis, bio-catalysis, drug delivery, CO2 capture, indoor air cleaning, bioanalytical sample preparation, and pervaporation membrane improvement.

Pyrene monomer-excimer dynamics to reveal molecular organization in mesoporous hybrid silica films.

Self-assembly and characteristics of hybrid mesoporous silica film templates remain a subject of inquiry. The short time scale of the inorganic condensation and formation of micelles makes our understanding of this process insufficient. To provide an insight into the evaporation-induced self-assembly of such films, we synthesized an efficient molecular probe of the triethoxysilane precursor bearing a pyrene derivative. The probe was introduced into the porous film at the synthesis stage through the sol-gel co-condensation method. At different synthesis stages, the emission of pyrene moieties was measured by fluorescence spectroscopy, revealing the placement of probes within the film. We also report dynamic excimer formation upon template removal. Moreover, we evaluate the influence of several parameters on the pyrene excimer formation phenomenon. The pore geometry, probe concentration, and the presence of another organosilane precursor are investigated in this work.

ZIF-67 hybridization and boron doping to enhance the photo-electrocatalytic properties of g-C3N4

Photo-electrocatalysis is a growing field, and cobalt-based metal-organic frameworks (Co-MOFs) are attracting much interest because of their porous nature, high surface area, and malleable structure. This study investigated the photo-electrocatalytic properties of g-C3N4 and boron-doped-g-C3N4 when hybridized with cobalt-based MOF (ZIF-67). In this work, we describe the preparation of novel g-C3N4/ZIF-67 and B-g-C3N4/ZIF-67 composites by poly-condensation and co-condensation methods, respectively. ZIF-67 hybridization caused a decrease in the band gap energy of g-C3N4 due to changes in the crystalline structure and size. EIS results indicated that only B-g-C3N4/ZIF-67 showed a response to light irradiation. At the same time, both B-g-C3N4/ZIF-67 and g-C3N4/ZIF-67 demonstrated sufficient light response when the potential applied was increased to -1.2 V vs. NHE in LSV analyses. CO2 reduction to ethanol was performed for 3 hours at -1 V vs. NHE under continuous light irradiation and CO2 bubbling for each catalyst. Ethanol production rates were recorded as 10.024, 12.0168, 30.7230, and 32.1096 μmol/cm2.h for g-C3N4, B-g-C3N4, g-C3N4/ZIF-67, and B-g-C3N4/ZIF-67, respectively.

Sustainable Sulfonic Acid Functionalized Tubular Shape Mesoporous Silica as a Heterogeneous Catalyst for Selective Unsymmetrical Friedel-Crafts Alkylation in One Pot.

The development of general and more sustainable heterogeneous catalytic processes for Friedel-Crafts (FC) alkylation reactions is a key objective of interest for the synthesis of pharmaceuticals and commodity chemicals. Sustainable heterogeneous catalysis for the typical FC alkylation of an easily accessible carbonyl electrophile and arenes or with two different arene nucleophiles in one-pot is a prime challenge. Herein, we present a resolution to these issues through the design and utilization of a mesoporous silica catalyst that has been functionalized with sulfonic acid. For the synthesis of sulfonic acid-functionalized mesoporous silica (MSN-SO3H), thiol-functionalized mesoporous silica was first synthesized by the co-condensation method, followed by oxidation of the thiol functionality to the sulfonic acid group. Sulfonation of mesoporous silica was confirmed by 13C CP MAS NMR spectroscopy. Further, the devised heterogeneous catalysis using MSN-SO3H has been successfully employed in the construction of diverse polyalkanes including various bioactive molecules, viz arundine, tatarinoid-C, and late-stage functionalization of natural products like menthol and Eugenol. Further, we have utilized this sustainable technique to facilitate the formation of unsymmetrical C-S bonds in a one-pot fashion. In addition, the catalyst was successfully recovered and recycled for eight cycles, demonstrating the high sustainability and cost-effectiveness of this protocol for both academic and industrial applications.

Enantioselective Oral Absorption of Molecular Chiral Mesoporous Silica Nanoparticles.

Inspired by the unique pharmacological effects of chiral drugs in the asymmetrical body environments, it is assumed that the chirality of nanocarriers is also a key factor to determine their oral adsorption efficiency, apart from their size, shape, etc. Herein, l/d-tartaric acid modified mesoporous silica nanoparticles (l/d-CMSNs) are fabricated via a one-pot cocondensation method, and focused on whether the oral adsorption of nanocarriers will be benefited from their chirality. It is found that l-CMSN performed better in the sequential oral absorption processes, including mucus permeation, mucosa bio-adhesion, cellular uptake, intestinal transport and gastrointestinal tract (GIT) retention, than those of the d-chiral (d-CMSN), racemic (dl-CMSN), and achiral (MSN) counterparts. The multiple chiral recognition mechanisms are experimentally and theoretically demonstrated following simple differential adsorption on biointerfaces, wherein electrostatic interaction is the dominant energy. During the oral delivery task, l-CMSN, which is proven to be stable, nonirritative, biocompatible, and biodegradable, is efficiently absorbed into the blood (1.72-2.05-fold higher than other nanocarriers), and helps the loaded doxorubicin (DOX) to achieve better intestinal transport (2.32-27.03-times higher than other samples), satisfactory bioavailability (449.73%) and stronger antitumor effect (up to 95.43%). These findings validated the dominant role of chirality in determining the biological fate of nanocarriers.

Silica-titania mesoporous silicas of MCM-41 type as effective catalysts and photocatalysts for selective oxidation of diphenyl sulfide by H2O2

Abstract Spherical Ti-MCM-41, synthetized by co-condensation method, presented very promising activity in catalytic and photocatalytic oxidation of diphenyl sulfide with H2O2 to obtain diphenyl sulfoxide and diphenyl sulfone. Mesoporous silica materials with various titanium content were analyzed with respect to chemical composition (inductively coupled plasma optical emission spectrometry), structure properties (X-ray diffraction), textural properties (low-temperature N2 adsorption–desorption), morphology (scanning electron microscopy), forms and aggregation introduced titanium species (diffuse reflectance spectroscopy, Raman spectroscopy), and surface acidity (NH3-TPD). Titanium introduced in the samples was present mainly in the form of highly dispersed species, presenting catalytic and photocatalytic activities in diphenyl sulfide oxidation with H2O2. Efficiency of the reaction increased with an increase in titanium loading in the samples and was significantly intensified under UV irradiation. The role of various Ti species in diphenyl sulfide oxidation was presented and discussed.

Preparation of HKUST-1 functionalized porous silica crosslinked sodium alginate composite: Efficient reduction of 4-nitrophenol to 4-aminophenol

In this paper, sodium alginate crosslinked porous silica carrier (SA-SiO2) was introduced by one-pot co-condensation method, and Cu2+ was adsorbed on the carrier by –COOH to in-situ synthesized composite materials (HKUST-1@SA-SiO2). A series of characterizations were carried out by FT-IR, BET, XRD, XPS, SEM, and TEM. The results showed that the carrier SA-SiO2 was successfully cross-linked, HKUST-1 was successfully surface functionalized and the composites was spongy with pores. The catalytic activity and reusability of the compound HKUST-1@xSA-SiO2 were investigated for the reduction of 4-nitrophenol to 4-aminophenol. Among them, HKUST-1@0.15SA-SiO2 had the best catalytic performance and the conversion rate constant was 0.45 min−1, which was better than that of the post-synthesis method. Its catalytic activity did not decrease significantly after five cycles.

Studies of NO Reduction with Ammonia Over Copper Species Deposited on MCM‐41 Nanospheres ‐ Experimental Evidence of Reaction Mechanism

AbstractNanospheres of MCM‐41 were modified with copper by template ion‐exchange (TIE) and cocondensation methods. In the samples modified by TIE, dispersion of copper was significantly improved by their post‐treatment in ammonia solutions. Highly dispersed copper species were significantly more active in low‐temperature NH3‐SCR than CuO aggregates. Copper dispersed on silica MCM‐41 catalytically operated at lower temperatures than copper deposited on silica‐alumina MCM‐41. The studies of reaction mechanism showed that ammonia and NOx species compete for these same adsorption sites (copper cations) and NH3 can remove NOx from such sites. Dispersed copper species are more active in NO to NO2 oxidation than CuO aggregates. Accumulation of oxidised NOx species in the absence of ammonia was more privileged on CuO aggregates. It is postulated that the main reaction pathway in the low‐temperature range is reaction of ammonia bounded to copper with NOx from gas phase or loosely bounded to the catalyst surface.

Dual Defective K-Doping and Cyano Group Sites on Carbon Nitride Nanotubes for Improved Hydrogen Photo-Production

In this work, dual defective potassium (K) doping and cyano group sites have been introduced into carbon nitride (CN) with various morphologies by a co-condensation method for highly efficient photocatalytic hydrogen production. The photocatalysts with potassium doping and inserted cyano groups display higher photocatalytic activity of hydrogen evolution under visible light irradiation in contrast to undoped bulk CN, CN nanosheets, and CN nanotubes. Potassium-doped CN nanotubes present the greatest hydrogen generation yield of 2.11 mmol g–1 h–1 with an apparent quantum efficiency of 5.28% at 420 nm, which is about 2.0 and 40 times that of K-incorporated bulk CN and the bare CN nanotubes, respectively. Benefiting from uniformly distributed potassium ions, the introduction of cyano groups, and the one-dimensional tubular structure of CN nanotubes, the resultant K-doped CN nanotubes have new charge transfer paths between potassium ions and adjacent heptazine units, accelerating photogenerated carrier transfer and enhanced photoreduction ability, thereby improving the photocatalytic performance. This study presents a reliable method for element doping of CN with various morphologies to photocatalytic hydrogen evolution through water splitting.

Residue Levels and Dietary Intake Risk Assessments of 139 Pesticides in Agricultural Produce Using the m-PFC Method Based on SBA-15-C18 with GC-MS/MS.

A survey was designed to investigate the pesticide residues in agricultural produce and to estimate their potential intake risks to inhabitants. A total of 314 samples of nine types of fruits and vegetables were collected from the supermarkets and vegetable markets of Shandong Province (China) from October 2020 to February 2022. An accurate and reliable multi-residue method, based on GC-MS/MS detection, as well as the multiplug filtration cleanup method, based on SBA-15-C18, was prepared by a solution chemical reaction. Additionally, an in situ co-condensation method was established for the quantification of 139 pesticide residues. Residues that contained no pesticides were detected in 66.5% of the 314 samples. Moreover, of the samples, 30.6% were at or below the MRLs, and 2.9% were above the MRLs. Residues of procymidone were found to be the one that most often exceeded the MRLs (1.3% of the samples). Tebuconazole was found most frequently in 22.0% of the samples analyzed. Consumer exposure to the 139 pesticides did not exceed 100% ADI and ARfD. This led to a consideration that these pesticide residues in the nine commodities may not raise the health risk of the consumers in the long and short term. The highest value of chronic dietary intake was obtained from spirodiclofen, which resulted in a 24.1% of ADI. Furthermore, the highest exposure levels in the short term were obtained from the consumption of leeks with procymidone (58.3% ARfD).

Selective removal of copper (II) ions from aqueous solution using pyridyl-bridged mesoporous organosilica hybrid adsorbent

The incorporation of active functional groups into the mesoporous organosilica hybrid materials is efficient for various applications. A newly designed mesoporous organosilica adsorbent was prepared using diaminopyridyl groups bridged-(bis-trimethoxy)organosilane (DAPy) precursor by using Pluronic P123 as structure directing template via sol-gel co-condensation method. The hydrolysis reaction of DAPy precursor and tetraethyl orthosilacate (TEOS) with a DAPy content of about 20 mol% to TEOS were incorporated into the mesopore walls of the mesoporous organosilica hybrid nanoparticles (DAPy@MSA NPs). Low-angle XRD and FT-IR, N2 adsorption-desorption analysis, SEM, TEM, and TG analysis were used to characterize the synthesized DAPy@MSA NPs. The DAPy@MSA NPs exhibit an order mesoporous structure with a high surface area, mesopore size and pore volume of approximately ∼465 m2/g, 4.4 nm and 0.48 cm3/g, respectively. The pyridyl groups integrated DAPy@MSA NPs showed the selective adsorption of Cu2+ ions from the aqueous medium by metal-ligand complex coordination of Cu2+ ions with the integrated pyridyl groups and the pendant hydroxyl (-OH) functional groups present into the mesopore walls of the DAPy@MSA NPs. In the presence of other competitive metal ions (Cr2+, Cd2+, Ni2+, Zn2+, and Fe2+), the DAPy@MSA NPs showed relatively high adsorption of Cu2+ ions (276 mg/g) from aqueous solution as compared to the other competitive metal ions at the same concentration (100 mg/L) of initial metal ion solution.

KIT-5 Structural and Textural Changes in Response to Different Methods of Functionalization with Sulfonic Groups.

In this project, KIT-5 materials were effectively functionalized with sulfonic groups introduced by grafting or the co-condensation method and tested as heterogeneous solid acid catalyst. A co-condensation procedure leading to the stable, -SO3H functionalized KIT-5 materials was successfully established. Moreover, the influence of both synthesis methods on the structural and textural parameters, as well as surface chemistry, morphology, and catalytic activity of -SO3H/KIT-5 materials was thoroughly investigated. The syntheses with 3-mepkaptopropyltrimethoxysilane (MPTMS) acting as a modifying agent resulted in samples in which functional groups were introduced into the structure and/or onto the mesoporous silica surface. The oxidation stage of -SH to -SO3H groups was carried out under mild conditions, using a "green" oxidant (H2O2). The application of different functionalization techniques and the introduction of different amounts of modifying agent allowed for an evaluation of the influence of these parameters on the ordering of the mesoporous structure of KIT-5 materials. The applied methods of assessment of the physicochemical parameters (XRD, low-temperature N2 sorption, TEM) showed that, especially when the co-condensation method was applied, as the number of functional groups increased, the ordering of structure characteristic of KIT-5 decreased. On the other hand, the samples modified by grafting had a stable structure, regardless of the amount of introduced MPTMS. Test reactions carried out on the basis of Friedel-Crafts alkylation process showed that the synthesized materials can be considered promising acid catalysts in heterogeneous catalysis reactions.

Convenient sorption of uranium by Amidoxime-functionalized mesoporous silica with magnetic core from aqueous solution

The use of inexpensive and biocompatible sorbents for effective removal of uranium from water environment is still an open challenge for many researchers. Herein, the magnetic amidoxime-functionalized mesoporous silica (MMS-AO) has been prepared by a combination of soft template method and co-condensation method in weak alkali oil/water phase. A feature of MMS-AO is core–shell configuration with Fe3O4 service as core, which makes the material easy to be recovered by an external magnetic field after sorption. Various characterization techniques of SEM, TEM, N2 sorption–desorption, FT-IR, TGA, Zeta potential and VSM were applied to evaluate MMS-AO. Batch sorption experiments confirmed that there were some good behavior to U(VI) removal on MMS-AO from aqueous including sorption capacity, selectivity and reusability. The experimental data fitted well to Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum sorption amount at 298 K and pH 5.50 was 236.70 mg·g−1 and the dynamic equilibrium can be reached in 90 min. The sorption process is spontaneous and endothermic via thermodynamic study. The analysis of XPS provided three insights on mechanism based on the chelation of U(VI) with amidoxime groups.

Diamine Groups on the Surface of Silica Particles as Complex-Forming Linkers for Metal Cations

Novel spherically shaped organosilica materials with (propyl)ethylenediamine groups were obtained via a modified one-pot Stöber co-condensation method. The porosity of these materials was tuned with the controlled addition of three silica monomers acting as structuring agents (tetraethoxysilane and bridged silanes with ethylene and phenylene bridges). The morphologies and structures of the synthesized materials were studied by SEM, DRIFT spectroscopy, CHNS elemental analysis, low-temperature nitrogen adsorption-desorption, and electrokinetic potential measurements. Their sizes were in the range of 50 to 100 nm, depending on the amount of structuring silane used in the reaction. The degree of the particles' agglomeration determined the mesoporosity of the samples. The content of the (propyl)ethylenediamine groups was directly related with the amount of functional silane used in the reaction. The zeta potential measurements indicated the presence of silanol groups in bissilane-based samples, which added new active centers on the surface and reduced the activity of the amino groups. The static sorption capacities (SSCs) of the obtained samples towards Cu(II), Ni(II), and Eu(III) ions depended on the porosity of the samples and the spatial arrangement of the ethylenediamine groups; therefore, the SSC values were not always higher for the samples with the largest number of groups. The highest SSC values achieved were 1.8 mmolCu(II)/g (for ethylene-bridged samples), 0.83 mmolNi(II)/g (for phenylene-bridged samples), and 0.55 mmolEu(III)/g (for tetraethoxysilane-based samples).