Aqueous dye adsorption on ordered mesoporous carbons

Ordered mesoporous carbons (OMCs) with varying pore size, and microporous carbon, CFY, were synthesized using ordered mesoporous silica SBA-15 and NaY zeolite as hard templates, respectively. N(2) adsorption tests show that the synthesized OMCs possess abundant mesopores and centralized mesopore distribution. Methylene blue (MB) and neutral red (NR) were used as probe molecules to investigate their adsorption behaviors on OMCs and CFY. As evidenced by adsorption tests, the volume of mesopores of which the pore size is larger than 3.5 nm is a crucial factor for the adsorption capacity and adsorption rate of MB on OMCs. However, the most probable pore diameter of OMCs was found to be vital to the adsorption capacity and adsorption rate of NR. Theoretical studies show that the adsorption kinetics of MB and NR on OMCs can be well depicted by using pseudo-second-order kinetic model.     

Multifunctional magnetic mesoporous silica nanocomposites with improved sensing performance and effective removal ability toward Hg(II)

In the present work, a multifunctional inorganic-organic hybrid nanomaterial (MMS-Py) was prepared by the immobilization of a pyrene-based receptor (Py) within the channels of magnetic mesoporous silica nanocomposites (MMS), and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, N(2) adsorption/desorption, superconducting quantum interference device, and photoluminescence spectra. This multifunctional nanomaterial exhibits superparamagnetic behavior, ordered mesoporous characteristics, and significantly improved fluorescence sensing properties that allow for highly sensitive and reproducible Hg(2+) detection. The fluorogenical responses of MMS-Py are stable over a broad pH range. A detection limit of 1.72 ppb is obtained, which is 2 orders of magnitude lower than that based on bulk mesoporous materials. Additionally, this nanomaterial shows high performance in convenient magnetic separability and efficient removal of Hg(2+). These results indicate that these multifunctional nanocomposites may find potential applications for simple detection and easy removal of Hg(2+) in biological, toxicological, and environmental areas.     

Synthesis and applications of mesoporous nanocomposites containing metal nanoparticles

Metal nanoparticles (NP) and mesoporous (MP) oxides are complementary materials, since the size scale of pores in MP oxides matches that of NP and both systems have potential applications in similar fields. Besides, nanocomposites obtained through their combination possess not only the intrinsic properties of each component, but also new features derived from the synergy between them, mainly due to the high interfacial area between the metal and the oxide. Thus, new optical, catalytic and sensing properties can be achieved that are not easily available from the individual components. In this review, we focus our attention on such NP@MP composites, not only from the point of view of the most common synthesis pathways but also briefly describing their applications in fields as diverse as (photo)catalysis, sensing, photochromism and other optical properties, as well as patterning.     

Preparation of novel magnetic hollow mesoporous silica microspheres and their efficient adsorption

Ordered mesoporous aluminas with high surface areas (up to 783 m²/g), large pore volumes (up to 0.82 cm³/g) and the presence of complementary micropores (up to 0.17 cm³/g) are synthesized with Pluronic® F127 or P123 triblock copolymers in a one-pot synthesis of metal alkoxide, template and cosolvent molecules such as 1,3,5-trimethylbenzene or 1,3,5-triisopropylbenzene in an acidic ethanol solution at 15 °C. Materials are characterized by nitrogen adsorption analysis, small-angle X-ray diffraction and transmission electron microscopy.     

NiO nanoparticle doped-PVA-MF polymer nanocomposites: Preparation,Congo red dye adsorption and antibacterial activity

The standard of living has been improved by industrial “revolution” and the demand of new production increases due to population explosion. In the race of industrialization humans are busy discharging harmful gases in atmosphere, dumping unhealthy wastes in soil and discharging of toxic sewage in natural water resources. The present work reports the synthesis of polymer nanocomposite of blend encapsulated with NiO nanoparticles (K1-K5). The polymer nanocomposite films (K1-K5) were characterized by FTIR, XRD, TGA and SEM. The electrostatic interaction between the polymer matrix and encapsulated NiO nanoparticles increases the chemical stability in this order water > NaOH > HCl solution confirmed by contact angle (55° to 99°). The Congo red (CR) dye adsorption values increases in polymer nanocomposite films (K1-K5) were analyzed by an effect by an effect of contact time 45% to 68%, by an effect of CR dye concentration 48% to 70%. But the CR dye adsorption by S3 composite and nanocomposite films (K1-K5) are inversely proportional to the pH scale 4–10. Among four different bacterial strains Bacillus subtilis 25 mm and Staphylococcus aureus 25 mm has shown best antibacterial activity. The result confirms enhancement of antibacterial activity of S3 blend after the doping of NiO nanoparticles. The present results may be a roadmap to develop some transparent and flexible polymer nanocomposite films for water treatment in textile industries and efficient antibacterial activity.     

Iron-based nanomaterials used as magnetic mesoporous nanocomposites to catalyze the preparation of N-sulfonylimines

A new magnetic nanocatalyzed synthetic method for the synthesis of aldimines was evidenced. The reaction was carried out in a Schlenk tube under reflux conditions using various solvents and different nanomaterials as catalysts. In these reactions, an excellent yield of aromatic aldimines was obtained in the presence of silica-coated magnetic nanomaterials. The prepared catalyst was also characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, nitrogen adsorption and desorption studies, energy dispersive X-ray spectroscopy, and small-angle X-ray scattering spectroscopy. It was shown that the magnetic nanocatalysts can be easily separated from the reaction mixture using an external magnet and reused.     

Comparison of dye adsorption by mesoporous hybrid gels: understanding the interactions between dyes and gel surfaces

Without using any templating agents, mesoporous hybrid gels were prepared using mixtures of tetraethoxysilane (TEOS) with n-propyltriethoxysilane (PTES), bis(trimethoxysilyl)hexane (TSH), or bis(trimethoxysilylpropyl)amine (TSPA) as precursors. Fourier transform infrared (FTIR), N2 adsorption/desorption, thermogravimetry (TG), point of zero charge (PZC), and water vapor adsorption measurements were used to characterize the gels. The adsorption of methyl orange (MO), methyl red (MR), bromocresol purple (BP), phenol red (PR), neutral red (NR), and brilliant blue FCF (BBF) by the gels in both 0.01 M HCl and 0.01 M NaOH solutions was compared comprehensively. The gel derived from TEOS/TSH (with -(CH2)6- groups, Gel 2) has the largest specific surface area (695 m2 g(-1)), the smallest pore volume (0.564 cm3 g(-1)), and the smallest average pore size (3.7 nm). The gels derived form TEOS/PTES (with -(CH2)2CH3 groups, Gel 1), and TEOS/TSPA (with -(CH2)3NH(CH2)3- groups, Gel 3) have similar textual properties. The PZC of Gels 1, 2, and 3 was estimated to be 6.28, 6.20, and 6.88, respectively. Gel 3 has the highest PZC due to the presence of -NH- groups. In general, Gel 2 shows the highest dye adsorption among all the gels in both acidic and basic solutions. All the dyes except NR have much lower adsorption in basic solutions than in acidic solutions. In acidic solutions Gels 1 and 2 have similar adsorption trends for the dyes, except for BP, with NR having the highest adsorption, and PR the lowest adsorption. Gel 3 presents a different trend from Gels 1 and 2, with BBF having the highest adsorption, and MR the lowest adsorption. In basic solutions the order of dye adsorption by all the gels is shown to follow the sequence NR>MR approximately BBF>MO>BP approximately PR. The adsorption results can be explained by considering the textural properties of the gels and the interactions between the gel surfaces and the dyes, which include hydrogen bonding, electrostatic, and hydrophobic interactions.     

Selective adsorption of 2,4-dinitrophenol on molecularly imprinted nanocomposites of mesoporous silica SBA-15/polyaniline

Surface imprinting and adoption of a nano-sized physical form are two effective approaches to overcome the template transfer difficulty within molecularly imprinted polymers (MIPs). This work is an attempt to conquer the problem of template transfer difficulty within MIPs by using a nano-reactor as a substrate for the reaction between the monomer and the template. Negatively charged hexagonal nano-channels of SBA-15 can act as a support for attachment of positively charged aniline monomers and the 2,4-dinitrophenol (2,4-DNP) template. The imprinted and non-imprinted SBA-15/polyaniline nanocomposites were characterized by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption isotherms. The results showed that the synthesized polymer possessed a highly ordered mesoporous structure. The distribution coefficient values of 2,4-DNP, K(d (2,4-DNP)), were estimated as 301.4 ± 2.3 and 101.2 ± 1.0 mL g(-1) for imprinted and non-imprinted polymers (NIP), respectively. The MIP-solid-phase extraction (SPE) process was optimized by evaluating the type of washing solvent and the composition and volume of the eluting solvent. The prepared MIP was used as a selective sorbent for SPE of 2,4-DNP in the presence of phenolic compounds in tap and sea water. The experimental results indicated that the MIP-SPE and NIP-SPE column yielded recoveries higher than 96% and 38%, respectively. The R.S.D. values were also lower than 3.2% and 4.6% for MIP-SPE and NIP-SPE, respectively.     

杂原子介孔Co-MCM-41分子筛的制备及其柴油深度吸附脱碱氮性能

以硝酸钴为钴源,采用水热法合成了MCM-41和不同Co含量的Co-MCM-41分子筛,并利用XRD、FT-IR和低温N2吸附-脱附等方法对合成的分子筛进行表征。当加入的Co/Si物质的量比达到0.1时,依然能够成功合成具有规整有序的介孔结构的Co-MCM-41。MCM-41和Co-MCM-41静态吸附脱除0#柴油中碱氮的实验结果表明,Co/Si物质的量比为0.06的Co-MCM-41(2)分子筛的吸附容量最大,达到5.324 mg(N)/g分子筛,明显高于MCM-41分子筛的吸附容量2.532 mg(N)/g,说明Co进入MCM-41分子筛骨架后显著提高了分子筛的吸附脱除碱氮能力。当加入的Co/Si物质的量比大于0.06时,分子筛吸附脱除柴油中碱氮的能力反而下降,这是由于加入过多Co会使其以Co3O4形式高度分散在分子筛孔道中,堵塞了吸附活性位,使其无法与碱性氮化物接触造成吸附脱氮能力下降。动态吸附脱除0#柴油中碱性氮化物的结果表明,每克CoM CM-41(2)分子筛可将35 m L柴油的碱氮从147.54μg/g吸附脱除到10μg/g以下,吸附容量为4.2 mg(N)/g(吸附剂),由于动态吸附的接触时间较短使MCM-41失去了吸附脱氮能力,说明Co-MCM-41(2)对柴油中的碱氮具有较好的选择性。     

High-temperature hydrothermal synthesis of magnetically active, ordered mesoporous resin and carbon monoliths with reusable adsorption for organic dye

Magnetically active, thermally stable, and ordered mesoporous resin (MOMR-200) and carbon (MOMC-200) monoliths were prepared by one-pot hydrothermal synthesis from resol, copolymer surfactant, and iron cations at high-temperature (200 ^°C), followed by calcination at 360 ^°C and carbonization at 600 ^°C. X-ray diffraction results show that both MOMR-200 and MOMC-200 have ordered hexagonal mesoporous symmetry, and N₂ isotherms indicate that these samples have uniform mesopores (3.71, 3.45 nm), high surface area (328, 621 m²/g) and large pore volume (0.31, 0.43 cm³/g). Transmission electron microscopy shows that iron nanoparticles, which are superparamagnetic in nature, are dispersed in the network. More importantly, the high temperature (200 ^°C) products exhibit much better stability than the samples synthesized at low temperature (100 ^°C). Interestingly, MOMC-200 has higher adsorption capacity for organic dyes when compared with commercial adsorbents (activated carbon and macroporous resin: XAD-4). Combining the advantages such as magnetically active, thermally stable networks, ordered and open mesopores, high surface area, large pore volume, adsorption of pollutants in water and desorption in ethanol solvent, MOMC-200 is potentially important for water treatments.     

Textural and adsorption properties of mesoporous silicophosphate

Low-temperature nitrogen adsorption-desorption and electron microscopy are employed to investigate the textural and adsorption properties of a silicophosphate material produced by the sol-gel method under the influence of two factors, pH of the sol-gel transition and the presence of a template, which predetermine the physical characteristics of the material. It is shown that the mesoporous structure of silicophosphate is composed of rather uniform bottle-shaped mesopores with necks the average diameter of which can be regulated in a targeted fashion in a narrow range of 3–5 nm. Templation with cetylpyridinium chloride leads to flattening the amorphous walls of the pores in silicophosphate and the formation of mesopores with large average diameters. The features of the supramolecular structure, which are revealed at different scale levels by electron microscopy and the analysis of the external and internal surface areas of silicophosphate, are not reflected in the pore-size distribution curves calculated from sorption isotherms, because they are governed by the interconnection of the mesopores rather than their individual shapes.     

Synthesis and characterization of monodisperse, mesoporous, and magnetic sub-micron particles doped with a near-infrared fluorescent dye

Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N₂ adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978 m²/g) with 3.40 nm pore diameter and a high fluorescence in the near infrared region at λ=700 nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulated by successfully trapping a hydrophobic ruthenium dye complex inside the particle with an estimated concentration of 3 wt%. Fluorescence imaging confirmed the presence of both NIR dye and the post-grafted ruthenium dye complex inside the particles. These particles moved at approximately 150 μm/s under the influence of a magnetic field, hence demonstrating the multifunctionality and potential for biomedical applications in targeting and imaging.     

Vesicle adsorption on mesoporous silica and titania

Lipid bilayer formation via vesicle fusion on mesoporous silica and mesoporous titania was investigated using quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescent recovery after photobleaching (FRAP). Results showed that lipid bilayers were formed on mesoporous silica and that intact vesicle adsorption was obtained on mesoporous titania. From the FRAP results, it could be concluded that the lipid bilayer was fluid; however, it had a smaller diffusivity constant compared to bilayers supported on a nonporous silica.     

A versatile hydrogel platform for oil/water separation,dye adsorption,and wastewater purification

The development of a versatile platform that can separate oil/water mixture, remove dye from water, and purify wastewater is extremely desirable, yet still hard to realize. Herein, to address this challenge, a composite hydrogel was produced by freezing–thawing treatment using chitosan, polyvinyl alcohol, and carbon black as the raw materials. The obtained hydrogel displayed both slippery oil-repellency and water-affinity in air, underwater, when submerged in oil, and exploiting this special wettability, the hydrogel coated mesh can be used to separate oil/water mixtures efficiently. After 25 oil–water separation cycles, the hydrogel-coated filter still had a separation efficiency of over 98%. With its superhydrophilicity and active functional groups, the resulting hydrogel was able to absorb dye molecules dissolved in water effectively. Due to the photothermal effect of carbon black, the local temperature of the hydrogel was increasing quickly under sunlight illustration, which allowed it to be an advanced platform for daily wastewater purification through solar distillation.

Graphical abstract

A versatile hydrogel platform for oil–water separation, dye adsorption, and domestic wastewater purification was developed.

     

Efficient synthesis of magnetic nanoparticle-Musa acuminata peel composite for the adsorption of anionic dye

The impregnation of magnetite (Mt) nanoparticle (NPs) onto Musa acuminata peel (MApe), to form a novel magnetic combo (MApe-Mt) for the adsorption of anionic bromophenol blue (BPB) was studied. The SEM, EDX, BET, XRD, FTIR and TGA were used to characterize the adsorbents. The FTIR showed that the OH and CO groups were the major sites for BPB uptake onto the adsorbent materials. The average Mt crystalline size on MApe-Mt was 21.13 nm. SEM analysis revealed that Mt NPs were agglomerated on the surface of the MApe biosorbent, with an average Mt diameter of 25.97 nm. After Mt impregnation, a decrease in BET surface area (14.89 to 3.80 m²/g) and an increase in pore diameter (2.25–3.11 nm), pore volume (0.0052–0.01418 cm³/g) and pH point of zero charge (6.4–7.2) was obtained. The presence of Pb(II) ions in solution significantly decreased the uptake of BPB onto both MApe (66.1–43.8%) and MApe-Mt (80.3–59.1%), compared to other competing ions (Zn(II), Cd(II), Ni(II)) in the solution. Isotherm modeling showed that the Freundlich model best fitted the adsorption data (R² > 0.994 and SSE < 0.0013). In addition, maximum monolayer uptake was enhanced from 6.04 to 8.12 mg/g after Mt impregnation. Kinetics were well described by the pseudo-first order and liquid film diffusion models. Thermodynamics revealed a physical, endothermic adsorption of BPB onto the adsorbents, with ΔH^o values of 15.87–16.49 kJ/mol, corroborated by high desorption (over 90%) of BPB from the loaded materials. The viability of the prepared adsorbents was also revealed in its reusability for BPB uptake.     

环氧功能化双功能磁性分子印迹聚合物的合成及其在多糖吸附中的应用

以淀粉为模板，以3-氨基苯硼酸（APBA）和2-丙烯酰胺-2-甲基丙磺酸（AMPS）为功能单体，以过硫酸铵（APS）为引发剂，在水溶液中成功合成了一种识别多糖的双功能分子印迹聚合物（Bi-MMIPs）。采用透射电镜、扫描电镜、傅里叶变换红外光谱等考察了Bi-MMIPs的合成效果。通过吸附试验深入研究了Bi-MMIPs对淀粉的吸附和识别特性。结果表明：Bi-MMIPs成功负载了两种功能单体，且对多糖（淀粉）具有很强的吸附亲和力和特异性识别能力，饱和吸附量达到13.88 mg/g；对于葡聚糖（M_r 5000 Da和70000 Da）的选择性系数分别为2.67和3.77；此外，Bi-MMIPs的印迹因子（α）达到了3.04，且易于再生。在机理上，APBA和AMPS分别提供可逆共价键和氢键，在合成双功能单体中表现出协同效应，可以有效改善模板分子结合位点的空间排列。     

Facile synthesis of ordered magnetic mesoporous gamma-Fe2O3/SiO2 nanocomposites with diverse mesostructures

On the basis of a sol–gel process, a facile, low cost, and one-step approach for preparing ordered magnetic mesoporous γ-Fe₂O₃/SiO₂ nanocomposites by an evaporation-induced self-assembly (EISA) approach is presented. Various mesostructured silica materials (P6mm or Im3m) incorporated with different amounts of iron oxide (n_Si/n_Fe=9/1, 8/2, 7/3, respectively) were synthesized and characterized by XRD, TEM, N₂-sorption analyses, and superconducting quantum interference device (SQUID) magnetometer. The HCl-leaching experiments together with TEM micrographs and nitrogen sorption analysis suggested that most of the γ-Fe₂O₃ domains of several nanometers were embedded in the silica walls, rather than dispersed in the mesopores, which could cause the significant pore clogging reported in some studies. The release behaviors of lysozyme from these magnetic porous nanocomposites were investigated for the possible application of drug targeting and control release. The influence of iron precursors was also studied and a possible mechanism was proposed. The hydrolysis of Fe³⁺ ions under weakly acidic conditions and the induced formation of SiOFe bonds may account for the synthesis of this kind of nanocomposite. These multifunctional nanostructured materials would have a wide range of applications in toxin removal, catalysis, waste remediation, and biological separation as well as novel drug-carrier technologies.     

Fabrication and characterization of mesoporous Co3O4 core/mesoporous silica shell nanocomposites

A mesoporous Co(3)O(4) core/mesoporous silica shell composite with a variable shell thickness of 10-35 nm was fabricated by depositing silica on Co(3)O(4) superlatticed particles. The Brunauer-Emmett-Teller (BET) surface area of the composite with a shell thickness of ca. 2.0 nm was 238.6 m(2)/g, which varied with the shell thickness, and the most frequent pore size of the shell was ca. 2.0 nm. After the shell was eroded with hydrofluoric acid, mesoporous Co(3)O(4) particles with a pore size of ca. 8.7 nm could be obtained, whose BET surface area was 86.4 m(2)/g. It is proposed that in the formation of the composite the electropositive cetyltrimethylammonium bromide (CTAB) micelles were first adsorbed on the electronegative Co(3)O(4) particle surface, which directed the formation of the mesoporous silica on the Co(3)O(4) particle surface. Electrochemical measurements showed that the core/shell composites exhibited a higher discharge capacity compared with that of the bare Co(3)O(4) particles.     

Multifunctional hybrids by combining ordered mesoporous materials and macromolecular building blocks

This critical review presents and discusses the recent advances in complex hybrid materials that result from the combination of polymers and mesoporous matrices. Ordered mesoporous materials derived from supramolecular templating present high surface area and tailored pore sizes; pore surfaces can be further modified by organic, organometallic or even biologically active functional groups. This permits the creation of hybrid systems with distinct physical properties or chemical functions located in the framework walls, the pore surface, and the pore interior. Bringing polymeric building blocks into the game opens a new dimension: the possibility to create phase separated regions (functional domains) within the pores that can behave as "reactive pockets" of nanoscale size, with highly controlled chemistry and interactions within restricted volumes. The possibilities of combining "hard" and "soft" building blocks to yield these novel nanocomposite materials with tuneable functional domains ordered in space are potentially infinite. New properties are bound to arise from the synergy of both kinds of components, and their spatial location. The main object of this review is to report on new approaches towards functional polymer-inorganic mesostructured hybrids, as well as to discuss the present challenges in this flourishing research field. Indeed, the powerful concepts resulting from the synergy of sol-gel processing, supramolecular templating and polymer chemistry open new opportunities in the design of advanced functional materials: the tailored production of complex matter displaying spatially-addressed chemistry based on the control of chemical topology. Breakthrough applications are expected in the fields of sustainable energy, environment sensing and remediation, biomaterials, pharmaceutical industry and catalysis, among others (221 references).     

Mechanistic aspects of magnetic MgAlNi barium-ferrite nanocomposites enhanced adsorptive removal of an anionic dye from aqueous phase

The mechanistic aspects of improved aqueous removal of methyl orange (MO) dyes using high performance novel magnetic MgAlNi barium-ferrite (MgAlNi-BaFe) ternary double layer hydroxide (LDH) nanocomposites is reported in this study. Detailed surface characterization coupled with kinetic, equilibrium, thermodynamics and regeneration studies were undertaken under different operational conditions of temperature (298–318 K), initial concentration (20–100 mg/L), pH (2–6). The kinetic results show that MO sorption was mainly, associated with pseudo-second order and intra-particular diffusion process. The MO adsorption onto the MgAlNi-BaFe nanocomposites suggests a multi-layered sorption process that is endothermic and spontaneous in nature. The MO adsorption mechanism insight taken in cognizance of FTIR, XRD, pKa, zeta potential, the adsorbates surface functional groups and the adsorbate-adsorbent surface charges interactions suggest involvement of hydrogen bonding and n-π interactions, predominantly via physisorption process (ΔG° = −7.406 to −5.69 kJ/mol). The excellent adsorptive performance of the MgAlNi-BaFe adsorbents for removal of MO from water compared with other magnetic LDH nanocomposites was further elucidated via the MgAlNi-BaFe nanomaterials high rates of regeneration and superior performances for three successive desorption-adsorption cycles. This study demonstrates the high potentials of employing MgAlNi-BaFe nanomaterials for removal of dyes from water and wastewater.