Magnetic Mesoporous Silica Material Research Articles

Synthesis and characterization of surface-modified magnetic mesoporous silicate materials for phosphate adsorption.

The magnetic mesoporous silica material, Mag-MCM-41, was synthesized by coating magnetite (Fe3O4) nanoparticles with a mesoporous material called MCM-41. Mag-MCM-41 and modified nanomaterials Mag-MCM-41-NN and Mag-MCM-41-NN-Fe+3 which were modified with aminopropyl functional groups. In water and wastewater, phosphate anions are considered significant contaminants due to their detrimental impact on the environment. They promote the growth of algae, leading to eutrophication. The purpose of this study is to investigate the removal of phosphate anions from aqueous solutions using modified magnetic silica particles. The Mag-MCM-41 material exhibits hexagonal properties and belongs to the class of "mesoporous" materials. It has a surface area of 923 m2.g-1, which was determined through N2 adsorption-desorption isotherms, FTIR, TEM, BET, and SAXS analysis. Kinetic and adsorption isotherm studies were conducted using Mag-MCM-41, Mag-MCM-41-NN, and Mag-MCM-41-NN-Fe+3 adsorbents to examine the behavior of phosphate anions. The kinetic and adsorption isotherm studies of phosphate anions revealed that the adsorption process on Mag-MCM-41, Mag-MCM-41-NN, and Mag-MCM-41-NN-Fe+3 adsorbents followed the chemical adsorption mechanism. Phosphate adsorption on all adsorbents occurred in a monolayer, and the MCM-41-NN-Fe+3 adsorbent exhibited the highest maximum adsorption capacity (qm) value of 112.87 mg.g-1 compared to the other adsorbents.

Highly effective removal of lead and cadmium ions from wastewater by bifunctional magnetic mesoporous silica

A bifunctionalized magnetic mesoporous silica (NZVI-SH-HMS) material with thiol and nanometer zero-valent iron immobilized on the surface was synthesized at ambient temperature by gel-sol and wet impregnation methods, which was successfully used to remove lead and cadmium ions from aqueous solution. SEM, TEM images and FTIR spectra showed that thiol and NZVI were stable and evenly dispersed onto the surface of HMS. N2 adsorption–desorption isotherms indicated NZVI-SH-HMS owned good porous properties with a large specific surface area (312.84 m2/g) and proper pore size (2.56 nm). XRD and XPS results confirmed the material was superparamagnetic and the main process for removing heavy metals was the formation of Pb3(CO3)2(OH)2, PbS, CdxFe(1-x)(OH)2 and Cd(OH)2. The theoretical maximum adsorption capacity of NZVI-SH-HMS was 487.8 mg Pb(II)/g and 330.0 mg Cd(II)/g, respectively. Adsorption isotherm and kinetics data fitted perfectly to Langmuir isotherm model and followed the pseudo-second-order kinetics. Batch experiments indicated that the main adsorption mechanisms could be precipitation/co-precipitation and surface complexation between the heavy metal ions and the adsorbents. Additionally, NZVI-SH-HMS exhibited excellent adsorption capacities and sorption recyclability in various simulated wastewater (the surface water, tap water, sewage plant wastewater and domestic wastewater), which showed the promising capabilities for the removal of heavy metal ions in actual water environment. These results suggested that the synergistic effects of NZVI and thiol greatly improved the adsorption performance of the bifunctionalized magnetic mesoporous silica materials.

Highly efficient and fast removal of colored pollutants from single and binary systems, using magnetic mesoporous silica

Magnetic mesoporous silica material was tested as adsorbent for removal of two usual colored compounds present in industrial wastewater. The magnetic mesoporous silica was synthesized by modified sol-gel method and characterized from the morpho-textural, structural and magnetic point of view. The specific surface area and the total pore volume indicate a good adsorption capacity of the material, and the obtained saturation magnetization strength value denotes a good magnetic separation from solution. The adsorption capacity of magnetic mesoporous silica increases with the increase of the initial dye concentration, and the removal efficiency of the dyes was dependent on the pH of the solution and decreased with increasing temperature. The pseudo-second-order kinetic model described best the adsorption mechanism, and the maximum adsorption capacities were determined from the Sips isotherm model, being 88.29 mg/g for Congo Red and 208.31 mg/g for Methylene Blue. A complete thermodynamic evaluation was performed, by determining the free energy, enthalpy and entropy, and the result showed a spontaneous and exothermic adsorption process. The recovery and reutilization of the adsorbent were estimated in five cycles of adsorption-desorption, and the results indicated a good stability and reusability of magnetic mesoporous silica. The new magnetic mesoporous silica can be easily separated from solution, via an external magnetic field, and may be effectively applied as adsorbent for elimination of dyes from colored polluted waters.

Advances in the Interfacial Assembly of Mesoporous Silica on Magnetite Particles

AbstractInterfacing magnetic particles with ordered mesoporous materials is an effective direction for the development of functional porous composite materials with rationally designed core–shell structures. Owing to the combined properties of magnetic nanoparticles and mesoporous silica (high surface area, large pore volume, porosity, and biocompatibility), core–shell magnetic mesoporous silica materials have generated tremendous interest in various disciplines, including chemistry, materials, bioengineering, and biomedicine. Interfacial assembly strategies enable the rational construction of magnetic mesoporous silica materials with well‐defined core–shell structure, morphology, pore parameters, and surface wettability, which can decisively influence their physical and chemical properties and thus improve their application performance. This Minireview summarizes recent progress in the synthesis of core–shell magnetic mesoporous silica and the adjustment of key parameters, including pore size, morphology, and pore orientation.

Advances in the Interfacial Assembly of Mesoporous Silica on Magnetite Particles.

Interfacing magnetic particles with ordered mesoporous materials is an effective direction for the development of functional porous composite materials with rationally designed core-shell structures. Owing to the combined properties of magnetic nanoparticles and mesoporous silica (high surface area, large pore volume, porosity, and biocompatibility), core-shell magnetic mesoporous silica materials have generated tremendous interest in various disciplines, including chemistry, materials, bioengineering, and biomedicine. Interfacial assembly strategies enable the rational construction of magnetic mesoporous silica materials with well-defined core-shell structure, morphology, pore parameters, and surface wettability, which can decisively influence their physical and chemical properties and thus improve their application performance. This Minireview summarizes recent progress in the synthesis of core-shell magnetic mesoporous silica and the adjustment of key parameters, including pore size, morphology, and pore orientation.

Magnetic mesoporous silica material (Fe3O4@mSiO2) as adsorbent and delivery system for ciprofloxacin drug

Magnetic mesoporous materials covered with mesoporous silica shells (Fe3O4@mSiO2) are the most promising material, which is fulfilling many applications especially for adsorption and delivering drugs system. The present research involves the preparation of magnetic nanoparticles Fe3O4 and mesoporous silica mSiO2 as coreshell materials using sol–gel method in the presence of amid propyl betaine surfactant as template. The surface texture, morphology and particle and crystalline size of the prepared adsorbent were characterized using SEM, TEM, XRD, and nitrogen adsorption–desorption techniques. The results show that the prepared adsorbent has surface area equal to 1670 m2/g, mesopores in range 2-10 nm with a high degree of ordering of the porous structure and has a crystalline size equal to 30.16 nm. The adsorption behavior of Ciprofloxacin drug from aqueous systems onto the adsorbent has been studied using a batch experiments method. The equilibrium of the process at temperature 293K was achieved within 120 min and 0.06 g of adsorbent dose. Adsorption isotherms were fitted with the Langmuir, Freundlich, Temkin, and Dubinin –Radushkevich models and the results show the Langmuir and Temkin model was best fitted, and the adsorption process is physical adsorption type. The kinetic data were analyzed and found to match well with pseudo-second order kinetic model. Ciprofloxacin drug loading and capacity of release of the Fe3O4@mSiO2 carrier was also studied.

Magnetic mesoporous silica of loading copper metal ions for enrichment and LC-MS/MS analysis of salivary endogenous peptides

Peptidomics research is of great significance for discovering potential biomarkers and monitoring human diseases. As a kind of common clinical biofluid, saliva known for its noninvasive collection and easy accessibility has been widely used in peptidomics research. In this article, we combined immobilized metal ions affinity chromotography (IMAC) with mesoporous material and proposed the copper ion doped magnetic mesoporous silica material (denoted as Fe3O4@mSiO2-Cu2+) which had a large surface area of 221 m2 g−1 and pore volume of 0.20 cm3 g−1. By immobilizing copper ions onto the mesopore walls, the standard peptide Angiotensin II could be identified in an extremely low concentration of 0.1 fmol μl−1 and in a mass ratio of 1:500 (Angiotensin II:BSA, m/m), which indicated significant sensitivity and a great size-exclusive ability. In addition, the introduction of polydopamine (PDA) made Fe3O4@mSiO2-Cu2+ more hydrophilic and biocompatible which could improve the profiling of endogenous peptides in bio-sample. Finally, 131 endogenous peptides were identified in human saliva after enrichment with Fe3O4@mSiO2-Cu2+. Therefore, Fe3O4@mSiO2-Cu2+ nanoparticles provided a promising candidate protocol for biomarker discovery.

Preparation of magnetic mesoporous silica composite for the solid-phase microextraction of diazinon and malathion before their determination by high-performance liquid chromatography.

A novel magnetic mesoporous silica material was synthesized and used as the sorbent for the magnetic solid-phase microextraction of diazinon and malathion before their quantification by high-performance liquid chromatography with UV detection. The sorbent was synthesized by a surfactant-templated one-pot sol-gel procedure using SiO2 -coated Fe3 O4 as the magnetic support, cetyltrimethylammonium bromide as the template and tetraethyl orthosilicate as the silicon source. The characteristics of the prepared sorbent were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The sorbent exhibited a high maximum adsorption capacity of 19.2 and 9.4mg/g for diazinon and malathion, respectively. The parameters affecting the microextraction were optimized by the MultiSimplex method. Under the optimized conditions, the calibration graphs were linear in the concentration ranges of 0.3-50.0 and 0.5-50μg/L with the limits of detection of 0.09 and 0.14μg/L for diazinon and malathion, respectively. The relative standard deviations (n = 5) at a concentration level of 10.0μg/L of analytes were less than 2.5 and 4% for intra and interday, respectively. The developed method was successfully used for the determination of diazinon and malathion in apple, tomato, cucumber, tap water, and well water samples.

Hydrophilic Mesoporous Silica Materials for Highly Specific Enrichment of N-Linked Glycopeptide.

Hydrophilic interaction liquid chromatography (HILIC) is a significant enrichment strategy in glycoproteomics profiling. In this report, hydrophilic magnetic mesoporous silica materials (denoted as Fe3O4@mSiO2-IDA) were designed and synthesized as an outstanding enrichment platform for glycopeptide analysis. By taking advantage of their merits, such as large surface area, excellent hydrophilicity and unbiased affinity toward all types of glycopeptides, the Fe3O4@mSiO2-IDA nanomaterials were successfully applied to capture glycopeptides from complex samples. A total of 25 glycopeptides from horseradish peroxidase (HRP) digests and 33 glycopeptides from IgG were identified, respectively. Especially, as a result, 424 glycopeptides assigned to 140 glycoproteins were identified from only 2 μL human serum.

Synthesis and characterization of pyridine-functionalized magnetic mesoporous silica and its application for preconcentration and trace detection of lead and copper ions in fuel products

We present a study on the synthesis, characterization and application of a pyridine-functionalized magnetic mesoporous silica material (called Py-Fe3O4@MCM-41) as an adsorbent for the solid phase extraction of trace quantities of lead and copper ions. The modified Fe3O4@MCM-41 can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, amount of functionalized Fe3O4@MCM-41, extraction time, type and quantity of eluent, desorption time, and interfering ions on the extraction efficiency were evaluated and optimized. Lead and copper ions were then quantified using a flame atomic absorption spectrophotometer. Under the optimized conditions, the detection limit for lead and copper ions was 0.1 μg L−1 and 0.08 μg L−1, respectively and the maximum adsorption capacity of the synthesized sorbent for lead and copper ions was 287 mg g−1 and 194 mg g−1, respectively. The Py-Fe3O4@MCM-41 sorbent was characterized by thermogravimetric analysis, differential thermal analysis, transmission electron microscopy, Fourier transform infrared spectrometry and X-ray diffraction.

Facile synthesis of yolk–shell magnetic mesoporous carbon microspheres for efficient enrichment of low abundance peptides

Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m(2) g(-1)), a large pore volume (0.31 cm(3) g(-1)), and a strong magnetic response (a saturation magnetization value of 34.57 emu g(-1)). As a result of the void between the core and the outer shell and the π-π stacking effect, adsorption capacity reached 191.64 mg g(-1) by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis.

High throughput detection and selective enrichment of histidine-tagged enzymes with Ni-doped magnetic mesoporous silica.

This work reports a simple and facile method to prepare novel magnetic mesoporous silica (MMS) materials with high magnetic strength for the convenient and high throughput detection of histidine-tagged enzymes with Ni-doped surfaces. These materials are designed by the incorporation of high-abundance and homogeneously dispersed iron nanoparticles within the mesopores by thermal hydrogen reduction after the incorporation of ferrous ions and demonstrated the selective enrichment and high-throughput recognition of His-tagged enzymes with multi-point anchoring by selective conjugation between the His-tag and Ni ions. Selective His-tagged enzyme enrichment efficiency was compared with nickel-based MMS materials, such as Ni2+-MMS and Ni-MMS, and nickel ion doped silica-coated magnetic nanoparticles (Ni2+-MNPs). The efficiency was calculated to be 100 ± 1.93%, 70.94 ± 1.95%, and 37.03 ± 5.93% for Ni2+-MMS, Ni-MMS, and Ni2+-MNPs, respectively. This method enables a high-throughput and advanced systematic approach for the separation and immobilization of proteins which cover a broad spectrum of polyhistidine-tagged proteins.

Preparation and morphology control of magnetic mesoporous silica via metalorganic amphiphiles self-assembly

A facile method, which was based on the cationic surfactant self-assembly and oxidation, was designed to fabricate magnetic mesoporous silica (MMS). Three types of metalorganic amphiphiles with a terminal ferrocene moiety were synthesized and used as structure-directing agents and iron source to prepare magnetic mesoporous silica. Among all the surfactants, FcC11PyBr (11-[(ferrocenyl carbonyl)oxy]-undecyl pyridinium bromide) exhibited the best ability to produce mesopores with tetraethoxysilane at a suitable molar ratio. Using FcC11PyBr as the structure-directing agent, it was also easy to control the morphology of MMS, which was turned from irregular powder to smooth sphere. After the oxidation reaction at 573K, the MMS material showed an obvious magnetic property, with a large surface area and pore volume. The MMS was characterized by X-ray diffraction, N2 adsorption–desorption isotherms, SEM, TEM, SQUID magnetometry and X-ray photoelectron spectrometry. The MMS was found to have a good absorptivity and used as magnetic adsorbent to remove some dye pollutants in water.

Effective heavy metal removal from aqueous systems by thiol functionalized magnetic mesoporous silica

A thiol-functionalized magnetic mesoporous silica material (called SH-mSi@Fe 3O 4), synthesized by a modified Stöber method, has been investigated as a convenient and effective adsorbent for heavy metal ions. Structural characterization by powder X-ray diffraction, N 2 adsorption–desorption isotherm, Fourier transform infrared spectroscopy and elemental analyses confirms the mesoporous structure and the organic moiety content of this adsorbent. The high saturation magnetization (38.4 emu/g) make it easier and faster to be separated from water under a moderate magnetic field. Adsorption kinetics was elucidated by pseudo-second-order kinetic equation and exhibited 3-stage intraparticle diffusion mode. Adsorption isotherms of Hg and Pb fitted well with Langmuir model, exhibiting high adsorption capacity of 260 and 91.5 mg of metal/g of adsorbent, respectively. The distribution coefficients of the tested metal ions between SH-mSi@Fe 3O 4 and different natural water sources (groundwater, lake water, tap water and river water) were above the level of 10 5 mL/g. The material was very stable in different water matrices, even in strong acid and alkaline solutions. Metal-loaded SH-mSi@Fe 3O 4 was able to regenerate in acid solution under ultrasonication. This novel SH-mSi@Fe 3O 4 is suitable for repeated use in heavy metal removal from different water matrices.