Rapid sonochemical synthesis of MCM-41 type benzene-bridged periodic mesoporous organosilicas

Ultrasound-assisted synthesis of MSNs/PS nanocomposite membranes for effective removal of Cd2+ and Pb2+ ions from aqueous solutions

Contamination of heavy metal (Cd²⁺ & Pb²⁺) ions in drinking water is producing major impacts on the environment and public health and is considered one of the greatest dangers to humanity. Membrane technology has been chosen over other processing methods due to its simplicity and high capacity for more effective removal of hazardous heavy metals. In the current study, amine, thiol, and bi-thiol functional groups were used to functionalize mesoporous silica nanoparticles (MSNs) to improve the efficiency of the silica nanoparticle. The morphology of the MSNs as well as the existence of amine and thiol on the surface of MSNs was demonstrated by a variety of characterization techniques, including FTIR, TEM, and SEM examination. The impact of surface-modified MSNs on the morphology, properties, and performance of polysulfone (PS) nanofiltration (NF) membranes was also evaluated. The membrane that incorporated amine with thiol-based MSNs (DiMP-MSNs/PS-NF membrane) had the highest pure water permeability (6.7 LMH bar^-1). As a result of the functional groups, the surface-modified MSNs/PS nanofiltration are extremely effective at removing heavy metal ions from aqueous solutions. The surface-modified MSNs/PS nano-filtration membranes exhibit unprecedented Cd²⁺ and Pb²⁺ removal rates of approximately 82% and 99%, respectively. This research indicates the possible application of the surface-modified MSNs/PS nanofiltration membrane as a promising platform to remove heavy metal ions from polluted water.

Selective adsorption of anionic and cationic dyes on mesoporous UiO-66 synthesized using a template-free sonochemistry method: kinetic, isotherm and thermodynamic studies

In this study, template-free mesoporous UiO-66(U) has been successfully synthesized in shortened time by sonochemical methods and provided energy savings. The synthesized mesoporous UiO-66(U) demonstrated irregular morphology particle around 43.5 nm according to the SEM image. The N₂ adsorption-desorption isotherm indicated an irregular, 8.88 nm pore width mesoporous structure. Ultrasonic irradiation waves greatly altered mesoporous materials. A mechanism for mesoporous UiO-66(U) formation has been proposed based on the present findings. Sonochemical-solvent heat saves 97% more energy than solvothermal. Mesoporous UiO-66(U) outperformed solvothermal-synthesized UiO-66(S) in adsorption. These studies exhibited that mesopores in UiO-66 promote dye molecule mass transfer (MO, CR, and MB). According to kinetics and adsorption isotherms, the pseudo-second-order kinetic and Langmuir isotherm models matched experimental results. Thermodynamic studies demonstrated that dye adsorption is spontaneous and exothermically governed by entropy, not enthalpy. Mesoporous UiO-66(U) also showed good anionic dye selectivity in mixed dye adsorption. Mesoporous UiO-66(U) may be regenerated four times while maintaining strong adsorption capability.

Recent Developments in Sonochemical Synthesis of Nanoporous Materials

Ultrasounds are commonly used in medical imaging, solution homogenization, navigation, and ranging, but they are also a great energy source for chemical reactions. Sonochemistry uses ultrasounds and thus realizes one of the basic concepts of green chemistry, i.e., energy savings. Moreover, reduced reaction time, mostly using water as a solvent, and better product yields are among the many factors that make ultrasound-induced reactions greener than those performed under conventional conditions. Sonochemistry has been successfully implemented for the preparation of various materials; this review covers sonochemically synthesized nanoporous materials. For instance, sonochemical-assisted methods afforded ordered mesoporous silicas, spherical mesoporous silicas, periodic mesoporous organosilicas, various metal oxides, biomass-derived activated carbons, carbon nanotubes, diverse metal-organic frameworks, and covalent organic frameworks. Among these materials, highly porous samples have also been prepared, such as garlic peel-derived activated carbon with an apparent specific surface area of 3887 m2/g and MOF-177 with an SSA of 4898 m2/g. Additionally, many of them have been examined for practical usage in gas adsorption, water treatment, catalysis, and energy storage-related applications, yielding satisfactory results.

Effect of washing conditions on adsorptive properties of mesoporous silica carbon composites by in-situ carbothermal treatment

Mesoporous silicon carbon (MSC) composites were prepared by in-situ carbothermal treatment of cetyl trimethyl ammonium bromide derived from mesoporous silica. MSC composites were used as adsorbent for methylene blue (MB) removal. Research was focused on investigating effect of washing conditions (deionized water or alkali) on surface properties and adsorption capacity of MSC composites. Results showed that best adsorption performance was given by the MSC composite washed by alkali at optimum pH 13.0. Adsorption mechanism for MB removal was systematically investigated by X-ray photoelectron spectrometer analysis, adsorption isotherms, adsorption kinetics and adsorption thermodynamics. MB adsorption by the MSC composites was found to be driven by three possible schemes: physical exothermic reaction, hydrogen bonds and π-interaction. The maximum adsorption capacity was 156.56 mg/g for MSC_a13. The negative values of ΔG⁰, ΔH⁰ and ΔS⁰ indicated that the adsorption process was a spontaneous exothermic reaction. The adsorbent can be regenerated for reuse.

Syntheses and applications of periodic mesoporous organosilica nanoparticles

Periodic Mesoporous Organosilica (PMO) nanomaterials are envisioned to be one of the most prolific subjects of research in the next decade. Similar to mesoporous silica nanoparticles (MSN), PMO nanoparticles (NPs) prepared from organo-bridged alkoxysilanes have tunable mesopores that could be utilized for many applications such as gas and molecule adsorption, catalysis, drug and gene delivery, electronics, and sensing; but unlike MSN, the diversity in chemical nature of the pore walls of such nanomaterials is theoretically unlimited. Thus, we expect that PMO NPs will attract considerable interest over the next decade. In this review, we will present a comprehensive overview of the synthetic strategies for the preparation of nanoscaled PMO materials, and then describe their applications in catalysis and nanomedicine. The remarkable assets of the PMO structure are also detailed, and insights are provided for the preparation of more complex PMO nanoplatforms.

Ultrasound assisted morphological control of mesoporous silica with improved lysozyme adsorption

The morphological control of mesoporous silica without any additives has attracted much attention. Discrete rod-like and string-of-beads like mesoporous SBA-15 can be achieved under ultrasound irradiation without changing the composition of synthesis system. The smaller particles of SBA-15 showed improved lysozyme immobilization capacity and higher adsorption rate over conventional rope-like SBA-15.

A Facile Synthesis of Ion Imprinted Mesoporous Silica Adsorbents by a Co-Condensation Pathway and Application in a Fixed-Bed Column Study for Lead Removal

Highly selective lead ion imprinted mesoporous silica adsorbents (PbII-IMS) were prepared through a co-condensation pathway with 3-(γ-aminoethylamino)propyltrimethoxysilane (AAPTS) (PbII-IMS-NN) and 3-aminepropyltriethoxysilyl (APTES) (PbII-IMS-N) as monomers. The prepared adsorbents were characterised by FT-IR spectroscopy, X-ray photoelectron spectroscopy, power X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and nitrogen adsorption–desorption techniques. The results showed that the synthesised adsorbents presented a highly ordered mesoporous structure. In comparison with PbII-IMS-N, PbII-IMS-NN demonstrated a higher adsorption capacity in a series of static and dynamic adsorption experiments, and was further applied to a continuous fixed-bed column study under different conditions. It was found that the breakthrough time of the fixed-bed increased with an increase in bed depth, but decreased with increased flow rate and initial PbII concentration, and the dynamic adsorption data was more consistent with the Thomas model than the Adams–Bohart model. Furthermore, the PbII-IMS-NN showed a greater recognition and binding affinity towards the target lead ions than PbII-IMS-N.

Sonochemical synthesis of cyclophosphazene bridged mesoporous organosilicas and their application in methyl orange, congo red and Cr(vi) removal

Cyclophosphazene-bridged mesoporous organosilicas have been synthesized by a fast sonochemical method which efficiently removed organic dyes and Cr(vi) ions.