Mesoporous Research Articles

Boosted Enzyme Activity via Encapsulation within Metal-Organic Frameworks with Pores Matching Enzyme Size and Shape.

A novel and versatile approach called "physical imprinting" is introduced to modulate enzyme conformation using mesoporous materials, addressing challenges in achieving improved enzyme activity and stability. Metal-organic frameworks with tailored mesopores, precisely matching enzyme size and shape, are synthesized. Remarkably, enzymes encapsulated within these customized mesopores exhibit over 1670% relative activity compared to free enzymes, maintaining outstanding efficiency even under harsh conditions such as heat, exposure to organic solvents, wide-ranging pH extremes from acidic to alkaline, and exposure to a digestion cocktail. After 18 consecutive cycles of use, the immobilized enzymes retain 80% of their initial activity. Additionally, the encapsulated enzymes exhibit a substantial increase in catalytic efficiency, with a 14.1-fold enhancement in kcat/KM compared to native enzymes. This enhancement is among the highest reported for immobilized enzymes. The improved enzyme activity and stability are corroborated by solid-state UV-vis, electron paramagnetic resonance, Fourier-transform infrared spectroscopy, and solid-state NMR spectroscopy. The findings not only offer valuable insights into the crucial role of size and shape complementarity within confined microenvironments but also establish a new pathway for developing solid carriers capable of enhancing enzyme activity and stability.

Silica extracts from fly ash modified via sol-gel methods and functionalized with CMPO for potential scavenging of rare earth elements La³⁺ and Ce³⁺

A mesoporous material was synthesized using silica extracts from fly ash and its properties were studied. Subsequently, it was functionalized with carbamoylmethylphosphine oxide (CMPO) to capture La3+ and Ce3+. The developed mesoporous material was obtained by the sol-gel method and was called Si-MMS (siliceous mesoporous materials), subsequently functionalized with APTMS (1-(2-aminoethyl)-3-aminopropyl trimethoxysilane) in a reflux system, which led to the synthesis of Si-MMS-APTMS. This derivative was modified with carbonyldiimidazole (CDI) and diethylphosphonoacetic acid, which finally resulted in the synthesis of Si-MMS-CMPO as the final product. The materials were characterized by DRIFT, XRD, SEM-EDS, TEM, XPS, elemental analysis and nitrogen isotherms at −196 °C, confirming that the synthesis and subsequent modification of the mesoporous structure was successful. Adsorption studies in batch systems indicated that the optimal pH for La3+ was 6, the Langmuir isotherm model and the non-linear Sips models were perfectly fitted and the best fitting kinetics is the Elovich model. For Ce3+ the optimal pH was 7.5, the non-linear Sips isotherm fit the best and the non-linear Pseudo-second order kinetics was the mechanism that best represents the adsorption. The maximum experimental adsorption capacity qe of La3+ was 17.00 mg g−1 and for Ce3+ was 30.09 mg g−1. In both cases, the rapid adsorption suggests an open porous matrix that facilitates the formation of chelates between the adsorbates and the phosphoryl group -PO32-.

Microwave pyrolysis of waste biomass and synthesis of micro-mesoporous activated carbons: The role of textural properties for CO2 and textile dye adsorption

Hierarchical porous activated carbons (ACs) were efficiently synthesized in less than 2 min using microwaves and phosphoric acid (H3PO4), exhibiting excellent potential as adsorbent for carbon dioxide (CO2) and Methylene Blue (MB). The method emphasizes the development of selective physicochemical and textural properties crucial for CO2 post-combustion capture and textile dye removal from water, using agricultural waste as carbon precursor to address the environmental and economic challenges associated with the preparation of ACs. Dielectric properties confirmed H3PO4 increased the microwave absorption properties of the biomass. Employing a single-step method, the resulting ACs exhibited large specific surface areas exceeding 1000 m2g−1, achieved in less than 2 min and relatively low energies (2.4 GJ ton-1). Sample 0.4H4 displayed a surface area of 1145 m2g−1 and a significant ultra-micropore (<0.7 nm) content, demonstrating a CO2 uptake of 4.1 and 2.8 mmolg−1 at 0 and 25 °C, with high CO2/N2 selectivity (>38). The sample exhibited rapid CO2 uptake in 5 min and efficient regeneration after 20 adsorption–desorption cycles. Sample 0.3H3 developed large mesoporosity and a high surface area of 1217 m2g−1 with less than 3 min of treatment. The maximum dye removal was 281 mgg−1 and adsorption mechanisms involved diffusion into the mesoporous matrix, electrostatic interactions, H-bonding between AC and MB acid groups, and π–π interactions. The experimental data best fitted the Freundlich model. The results confirmed that microwaves have the potential to convert waste to micro-mesoporous ACs that can be used for a wide range of applications with significant processing time reductions and superior product qualities compared to conventional technologies.

Box-Behnken design for the synthesis optimization of mesoporous sulfur-doped carbon-based materials from birch waste: Promising candidates for environmental and energy storage application

The development of biomass-based carbon materials has accelerated the research interest in environmental (e.g., adsorbents for wastewater decontamination) and energy applications (e.g., batteries). In this paper, we developed a series of carbon materials (CMs) using a sulfur doping strategy to improve the physicochemical, adsorptive and energy storage properties of the aforementioned CMs. CMs were prepared and optimized using an experimental design denoted as the Box-Behnken design approach with three independent factors (i.e., the temperature of pyrolysis, zinc chloride: biomass ratio and sulfur: biomass ratio), and the responses were evaluated, namely the Specific Surface Area (SBET), mesopore area (AMeso) and micropore area (AMicro) with the help of Nitrogen Physisorption. According to the statistical analysis, under the studied conditions, the responses were mainly influenced by the pyrolysis temperature and ZnCl2 ratio, while the sulfur content did not give rise to any remarkable differences in the selected responses. The physicochemical characterization of the CMs suggested that very high Specific Surface Areas ranging from 1069 to 1925 m2 g−1 were obtained. The sulfur doping resulted in up to 7.33 wt% of sulfur in the CM structure, which yielded CMs with more defects and hydrophilic surfaces. When tested as adsorbents, CMs exhibited a very high adsorption capacity (190 – 356 mg g−1), and as anodes, they demonstrated a competitive Lithium Ion Battery (LIB) storage capacity, at least during the first five cycles (306 mAhg−1 at 1 C for CM9). However, further studies on long-term cyclability are required to prove the CM materials suitability in LIBs. This work extends our understanding of how pyrolysis and sulfur doping of biomass feedstock affects carbon materials' usability, final characteristics and potential to use in wastewater decontamination by adsorption and as anodes in LIBs.

Micro and mesoporous materials based on zeolite Y for the florol synthesis via the prins cyclization of isoprenol

Several parents and Sn-modified microporous and mesoporous catalysts were investigated in Prins cyclization of isoprenol with isovaleraldehyde for the production of the desired cis isomer of pyranol, Florol ® using dimethylcarbonate as a solvent in the temperature range of 30–60 °C. The highest selectivity to pyranols, 70% was obtained over microporous Sn-Y-80 (number denotes SiO2/Al2O3 ratio) at 40 °C, while 64% selectivity to pyranols was obtained at 99% conversion over dealuminated H-Y-80 exhibiting mesoporosity and low Brønsted to Lewis acid ratio of 0.16. For microporous catalysts even higher BA/LA ratio and large amounts of Lewis acid sites were beneficial, as was the case for H-Y-30 modified with SnCl2, because the reaction occurred mainly on the outer surface of the catalyst.

A incorporation of metal into worm-like mesoporous silica materials for selective adsorption of MB in dyestuff

Worm-like mesoporous silica was synthesized using hydroxyethyl cellulose (HEC) as the template agent and sodium metasilicate as the silicon source (hereinafter referred to as HECMS). Different types of metal-doped adsorbents (namely Zr-HECMS-P, Fe-HECMS-P, and Al-HECMS-P) were prepared using the post-grafting method. The three adsorbents were used for the selective adsorption of methylene blue (MB) from an MB/methylene orange (MO) solution. Results showed that under acidic conditions, Fe-HECMS-P exhibited simultaneous adsorption of MB and MO, whereas Zr-HECMS-P and Al-HECMS-P preferably adsorbed MB. Zr-HECMS was determined to be the best adsorbent based on the evaluation results of the selective-adsorption effect of MB in different adsorption environments. Furthermore, different zirconium-silicon molar ratio samples were synthesized (The name is designated as Zr(0.01)-HECMS-P, Zr(0.02)-HECMS-P and Zr(0.04)-HECMS-P.). Results revealed that at pH = 3 and an initial MB concentration of 25 mg/L, Zr(0.01)-HECMS-P exhibited the best selective-adsorption performance for MB, reaching adsorption equilibrium in 2 h with a maximum removal rate of 97.8 %. The adsorption process followed a pseudo-second-order model, and the adsorption mechanism involved coordination and electrostatic action. In a simple binary system (MB + MO), the Zr(0.01)-HECMS-P adsorbent exhibited good selectivity for the MB dye. Finally, after five cycles of regeneration, the adsorption performance of Zr(0.01)-HECMS-P remains stable.

In English

Samples of MnOx-Na2WO4/SiO2 based on a mesoporous silica matrix were synthesized using manganese acetate, sodium tungstate, tetraethoxysilane (TEOS) as precursors and cetyltrimethylammonium bromide (CTAB), citric acid and triethanolamine as pore generating agent and characterized by scanning electron microscopy with energy dispersive elemental analysis (SEM/EDS), X-ray diffractometry (XRD), electron magnetic resonance (EMR), N2 adsorption-desorption measurements and tested as a catalyst for the reaction of oxidative condensation of methane (OCM). It is shown that the MnNaW/SiO2 catalyst consists of Mn2O3, MnO2, Na2WO4 and SiO2 phases. The EMR and SEM/EDS data indicate a noticeable effect of the reaction conditions on the surface structure and the distribution of catalytically active components in the catalyst structure. Significant changes in the values of the specific surface area and pore volume of the samples with increasing temperature and duration of the reaction were found (the values of the specific surface area and pore volume, respectively, 116.8 m2/g and 0.590 cm3/g - up to and 46.1 m2/g and 0.232 cm3/g after 15 hours of catalyst operation in the OCM reaction at 800 °C). It has been shown that under the conditions of the OCM reaction, the elemental composition of the surface of the MnOx-Na2WO4/SiO2 catalyst changes, and the degree of change depends on the duration of the OCM reaction. Under the influence of the reaction mixture CH4/O2, the content of Mn and W decreases in the first two hours, and the trend towards a decrease in their amount on the catalyst surface with an increase in the duration of the OCM reaction is generally preserved. A detailed X-ray phase analysis also indicates a change in the phase composition of this catalyst under the influence of the CH4/O2 reaction mixture. It is assumed that under the reaction conditions (700–800 °C) the MnOx-Na2WO4/SiO2 catalyst is silicon dioxide particles basely with the cristabolite structure, the surface of which is coated with molten sodium tungstate containing nanosized particles of MnOx structures activated by sodium ions and WOx.

Hydration and wetting mechanism of borosilicate – Polyvinyl alcohol (PVA) hybrid aerogels of potential bioactivity

Mesoporous borosilicate – polyvinyl alcohol (PVA) hybrid aerogels show positive bioactivity when interacting with dental pulp stem cells. The surface characteristics and the nanostructures of the hydrated aerogel particles are important in determining the biological response. This study reports the comparative structural characterization of pristine and stepwise hydrated hybrid aerogels, and proposes a qualitative mechanism for the wetting and pore-filling processes of these mesoporous materials. Nuclear magnetic resonance (NMR) relaxometry and cryoporometry revealed the extensive hydration of PVA macromolecules in the hybrid skeleton when contrasted to the wetting of pure silica aerogels. In spite of this extensive hydration, the open and permeable pore-structure of the hybrid borosilicate-PVA aerogels are preserved even when completely filled with liquid water. The conservation of the nanoscale architecture of the hybrid aerogels upon wetting was further confirmed by SANS. Finally, it was shown that the incorporation of microcrystalline hydroxyapatite into the hybrid skeleton does not alter the advantageous morphological features and wetting mechanism of the hybrid aerogels. The rough nanostructured skeleton is advantageous for cell binding and ensures facile mass transport through the particles in aqueous suspensions.

Construction of multi-porous Ni-based monolithic catalyst by combining wood carbon and SBA-15 for strengthening CO2 methanation

Monolithic catalysts meet the needs of practical application compared with powder catalysts. In this work, we constructed a Ni-based monolithic catalyst (Ni/SAB-15/WWC) by in situ growth of rod-like mesoporous SBA-15 in the microchannels of wood carbon. The small Ni-based nanoparticles (∼5.3 nm) were uniformly dispersed into the mesoporous channels via a post-loading method. The monolithic Ni/SAB-15/WWC catalyst with a multilevel porous structure could provide a laminar gas flow on the surface of Ni active sites, increasing the low-temperature activity and high-temperature durability of CO2 methanation. The Ni/SAB-15/WWC with low Ni loading (∼2%) displayed superior CO2 methanation catalytic performance in terms of low-temperature activity and CH4 selectivity compared with the powder Ni/SAB-15 with high Ni loading (∼15 %). The combination of wood carbon and mesoporous materials is an innovative strategy for the design monolithic catalysts with low metal loading and excellent catalytic performance.

Development of a simple paste for 3D printing of drug formulations containing a mesoporous material loaded with a poorly water-soluble drug

Poorly soluble drugs represent a substantial portion of emerging drug candidates, posing significant challenges for pharmaceutical formulators. One promising method to enhance the drug’s dissolution rate and, consequently, bioavailability involves transforming them into an amorphous state within mesoporous materials. These materials can then be seamlessly integrated into personalized drug formulations using Additive Manufacturing (AM) techniques, most commonly via Fused Deposition Modeling. Another innovative approach within the realm of AM for mesoporous material-based formulations is semi-solid extrusion (SSE). This study showcases the feasibility of a straightforward yet groundbreaking hybrid 3D printing system employing SSE to incorporate drug-loaded mesoporous magnesium carbonate (MMC) into two different drug formulations, each designed for distinct administration routes. MMC was loaded with the poorly water-soluble drug ibuprofen via a solvent evaporation method and mixed with PEG 400 as a binder and lubricant, facilitating subsequent SSE. The formulation is non-aqueous, unlike most pastes which are used for SSE, and thus is beneficial for the incorporation of poorly water-soluble drugs. The 3D printing process yielded tablets for oral administration and suppositories for rectal administration, which were then analyzed for their dissolution behavior in biorelevant media. These investigations revealed enhancements in the dissolution kinetics of the amorphous drug-loaded MMC formulations. Furthermore, an impressive drug loading of 15.3 % w/w of the total formulation was achieved, marking the highest reported loading for SSE formulations incorporating mesoporous materials to stabilize drugs in their amorphous state by a wide margin. This simple formulation containing PEG 400 also showed advantages over other aqueous formulations for SSE in that the formulations did not exhibit weight loss or changes in size or form during the curing process post-printing. These results underscore the substantial potential of this innovative hybrid 3D printing system for the development of drug dosage forms, particularly for improving the release profile of poorly water-soluble drugs.

Ethylenediamine-modified activated carbon photocatalyst with the highest TiO2 attachment/dispersion for improved photodegradation of sulfamethazine

Due to the high pollution caused by several molecules, it is necessary to develop efficient materials to degrade these contaminants. Activated carbons (ACs) are exceptional and versatile adsorbents, and titanium dioxide (TiO2) has remarkable photocatalytic properties. The combination of activated carbon (AC) and TiO2 provides a system capable of simultaneously adsorbing and degrading several emerging contaminants. This study presents a new absorbent/photocatalyst material by modifying the AC with ethylenediamine (ET) and impregnated with TiO2 (AC-ET/TiO2). AC modified with amine groups keeps the TiO2 nanoparticles more bound onto its surface. A study exploring the dispersion onto the surface of unmodified AC revealed that the material lacked stability, releasing TiO2 particles into the solution. The characterization by nitrogen adsorption/desorption isotherms showed a mesoporous material that can have a synergic effect between the adsorption and photocatalysis. The photocatalyst was analyzed by field emission gun scanning electron microscopy (FEG-SEM) and demonstrated the presence of TiO2 dispersed on the surface. The AC-ET/TiO2 exhibited an improved photodegradation of sulfamethazine (SMT), superior to the commercial TiO2 – P25, by removing more than 90% of the SMT in 2 h of UV light irradiation. The reuse of the AC-ET/90TiO2 showed that this material is active after three photoreactions. In conclusion, amino groups insertion into AC is essential for the stability of the TiO2 on the surface. Besides, this material has increased photocatalytic activity with speedy degradation of SMT.

Mesoporous materials functionalized with polyaniline for the removal of the phenol from the aqueous solution

The functionalization of mesoporous solids with polyaniline (PANI) is explored as an alternative for the adsorption of phenol. It investigates the impact of the nature of the surface (homogeneous SBA-15 vs. heterogeneous Bone Char, BC) on adsorption efficiency. The results highlight that incorporating PANI into mesoporous materials intensifies π-π interactions, thereby enhancing the adsorption of aromatic compounds like phenol for SBA-15:SBA-15/PANI in a ratio of 1:2.3, and for BC:BC/PANI in a ratio of 1:1.8. The PANI functionalization decrease the surface area of the SBA-15 and BC in 32.9% and 57% respectively, but interaction and chemical properties of the composites allow increase the phenol adsorption. The phenol adsorption on SBA-15, Char, SBA-15/PANI, and BC/PANI follows the pseudo second-order kinetic with R2 = 0.994 and intraparticle diffusion. The maximum adsorption capacity was estimated to be SBA-15 (121.8 mg g−1), SBA-15/PANI (283.8 mg g−1), BC (21.59 mg g−1), and BC/PANI 38.59 mg g−1), this means that PANI allows exceeding the adsorption capacities than the original adsorbents.

Integration of strong oxide-support interaction and mesoporous confinement to engineer efficient and durable Zr/Al2O3 for catalytic solvent regeneration in CO2 capture

Integration of mesoporous confinement effect and strong metal oxide-support interaction, durable and efficient Zr/Al2O3 catalysts were proposed to boost the carbamate regeneration dynamics. The catalytic performance of powder and pelletized Zr/Al2O3 catalysts was verified and comprehensively evaluated according to lab-scale and bench-scale setup, while the promotion mechanism was explored based on characterization analysis and theoretical calculation. The maximum rate of carbamate decomposition (or CO2 desorption) using powder Zr/Al2O3 increased by 178% compared to the catalyst-free case, resulting in approximately 27% lower relative heat duty. Bench-scale testing (11 hours) with continuous CO2 absorption and desorption demonstrated an optimal capture efficiency of 54.2% with pelletized Zr/Al2O3, increased by 12.5% higher than the blank case. A 4-weeks hydrothermal testing indicated that the catalysts had minimal impact on solvent degradation. This work demonstrates a feasible strategy of utilizing mesoporous soild acid material to realize the energy-efficient slovent regeneration during amined-based CO2 capture.

Sonocatalytic Activity of Porous Carbonaceous Materials for the Selective Oxidation of 4-Hydroxy-3,5-dimethoxybenzyl Alcohol.

Selective oxidation, which is crucial in diverse chemical industries, transforms harmful chemicals into valuable compounds. Heterogeneous sonocatalysis, an emerging sustainable approach, urges in-depth exploration. In this work, we investigated N-doped or non-doped carbonaceous materials as alternatives to scarce, economically sensitive metal-based catalysts. Having synthesized diverse carbons using a hard-template technique, we subjected them to sonication at frequencies of 22, 100, 500, and 800 kHz with a 50% amplitude. Sonochemical reaction catalytic tests considerably increased the catalytic activity of C-meso (non-doped mesoporous carbon material). The scavenger test showed a radical formation when this catalyst was used. N-doped carbons did not show adequate and consistent sonoactivity for the selective oxidation of 4-Hydroxy-3,5 dimethoxybenzyl alcohol in comparison with control conditions without sonication, which might be associated with an acid-base interaction between the catalysts and the substrate and sonoactivity prohibition by piridinic nitrogen in N-doped catalysts.

Defect engineering enables an advanced separator modification for high-performance lithium-sulfur batteries

High-energy–density lithium-sulfur batteries have been rated as a promising, yet challenging, next-generation battery technology. Typically, the serious shuttle of polysulfide intermediates and sluggish solid–solid reaction kinetics often result in irreversibly sulfur loss, low Coulombic efficiency, and limited lifespan. Herein, we propose a facile and efficient separator modification strategy using a rationally designed sulfiphilic and lithiophilic mediator, i.e. in-situ confinement growth of oxygen-deficient TiO2-x nanoparticles within nitrogen-doped mesoporous carbon matrix to modulate the sulfur electrochemistry. The nanoscale defective catalyst within open mesoporous host affords favorable adsorption of polysulfides and catalytic conversion ability. Moreover, the versatile composite improves the electrolyte wettability and Li+ transfer kinetics and alleviates self-discharge behavior. Resultantly, the Li-S batteries using modified separator achieves significantly improved cycling stability with a low capacity decay of only 0.067% per cycle after 500 cycles at 2C. The defect engineering together with separator modification strategies enable efficient and durable Li-S batteries.

Significance of fluid properties, pore structure, and surface chemistry in CMK series mesoporous carbon materials for N2/CH4/CO2 separation

We employed a combination of macroscopic approaches (Ideal Adsorption Solution Theory, IAST, and Two-Dimensional Equation of State, 2D-EOS) and microscopic molecular simulations to explore the adsorption and separation of N2, CH4, and CO2 in mesoporous materials CMK-1, CMK-3, and CMK-5. Our findings reveal that these behaviors are intricately linked to the material's structure, surface properties, and the adsorbed fluid type. For nonpolar N2/CH4 supercritical fluid, both macroscopic theories align remarkably well with molecular simulations. For gas mixtures with a supercritical gas (N2 or CH4) and a subcritical gas (CO2), the impact of material structure on adsorption and separation varies. While both adsorption theories perform well for CMK-3, with excellent agreement to simulations, only IAST accurately predicts CMK-1. This discrepancy indicates that 2D-EOS has a less satisfactory predictive accuracy for CMK-1 compared to CMK-3 due to structural differences. The hexagonal arrangement of nanorods in CMK-3 leads to a more uniform adsorption site, while CMK-1's diverse adsorption sites, including nanorod surfaces and inter-rod grooves, contribute to a more complex adsorption behavior. In CMK-5, a unique jump in the CO2 adsorption selectivity is observed, attributed to a phase transition within the pores. Interestingly, this transition-induced jump defies accurate prediction by common theoretical models, except for IAST, which correctly predicts trends in selectivity and adsorption amounts. This phenomenon is specific to CMK-5's dual-pore structure, where most CO2 adsorption occurs inside the pipes until saturation, followed by adsorption on the external surface. Examining the impact of –COOH and –OH functional groups on adsorption behavior, we find minimal influence on separation in nonpolar N2–CH4 fluid, independent of the material type. However, in CO2-containing systems, the –COOH functional group has a substantial impact, highlighting its significance in influencing adsorption behavior.

Kinetic investigation of the aldol condensation of n-butanal on mesoporous and macro-mesoporous heterogeneous catalysts

The kinetics of the aldol condensation of n-butanal on modified mesoporous and macro-mesoporous heterogeneous catalysts was studied in the liquid phase. Applying liquid phase 1H NMR the degree of modification was determined quantitatively, in order to calculate the turnover numbers of the n-butanal conversion. The analysis of the kinetic data has shown that the reaction on primary amines follows a 1st order model, whereas on secondary amines the 2nd model gives the best correlation. Tertiary and aromatic amines were not active. Based on the kinetic measurements reaction mechanisms are proposed. The difference in the activation energies suggests that the modification process on mesoporous materials proceeds preferentially on the external surface, while on meso-macroporous materials the modification proceeds in the mesopores.

Fe3O4@SiO2 Magnetic Nanoparticles Modified with Cysteine: a New Adsorbent for Environmentally Friendly Adsorption/Desorption of Pb(II) ions

In recent years, nanoparticles have become the focus of scientific research because of their wide potential application value. Iron oxides show incredible magnetic saturation, stability, and intuitive properties on the surface, making them ideal for a variety of uses. In this paper, nanometer iron oxide particles are synthesized by co-deposition method, and silica is further used to avoid agglomeration. Functional synthesis of cysteine nanoparticles (FNMs-Cys).The optimum synthesis conditions and adsorption conditions were determined by orthogonal experiments. In addition, the anti-interference and regeneration cycle performance of FNMs-Cys are discussed. The samples were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), N2 adsorption and desorption automatic specific surface and porosity analyzer (BET), thermogravimetric analysis (TG) and hysteresis loop test (VSM). The adsorption process of Pb2+ by FNMs-Cys accords with quasi-second-order kinetics and Langmuir isothermal adsorption model, which shows that the adsorption is mainly through chemical adsorption of monolayer, In the Langmuir model, the maximum single-layer adsorption capacity of FNMs-Cys for Pb2+ reached 174.85 mg/g. After five cycles of adsorption-desorption regeneration, FNMs-Cys still showed good stability and recyclability. At present, it is of forward-looking significance to study the removal effect of Pb2+ in water by using amino acid modified mesoporous magnetic silica materials in laboratory.

Synthesis of schiff base-functionalized ordered mesoporous silica for effective adsorption of Re(VII)

Rhenium is an important emerging metal material. The scarcity of reserves and the difficulty in separation and enrichment have always been important reasons restricting its industrial application. In this work, aminated SBA-15 is used as substrate for the crosslinking reaction to prepare a type of Schiff base-containing mesoporous dioxide silica material (GA-MMA-0.2 N-SS) for high selectively recovering Re(VII) in aqueous solution. The results show that the using amount of APTES is small in the modification process of the adsorbent material, and the modified adsorbent still maintains the orderly mesoporous structure. The adsorption capacity of GA-MMA-0.2 N-SS for Re(VII) up to 198.77 mg·g−1 under pH 1.5, and it can still reach more than 97% after 4 elution cycles. Adsorption mechanism study indicated that the complex reaction between N atoms and ReO4- is the main adsorption mechanism of Re(VII) on GA-MMA-0.2 N-SS. This study provided a new adsorbent based schiff base and ordered mesoporous silica for the separation of Re(VII) from mixed solution, which also provides new ideas for the design of adsorbents in the future.

Mesoporous silica-grafted deep eutectic solvent-based mixed matrix membranes for wastewater treatment: Synthesis and emerging pollutant removal performance

Abstract Nano-enhanced membrane technology and deep eutectic solvents (DESs) have demonstrated effectiveness in addressing emerging environmental pollutants. This research centers on purifying water by removing heavy metals employing membranes enhanced with mesoporous silica and DES. Various DESs, including hexanoic acid, octanoic acid, and decanoic acid, were synthesized using tetrabutylammonium bromide (TBABr) as a base. The study combined a polysulfone-based membrane with mesoporous silica, aiming for efficient indigenous crafting to remove heavy metals. Mesoporous silica was blended with the synthesized DES solution, creating diverse membranes for heavy metal separation. The study characterized these membranes using various techniques such as scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and contact angle measurements. Surface mapping confirmed the integration of silicon-based DES, reducing the membrane surface roughness from 4 to 1.4 nm. By adjusting the carboxylic acid chain length with TBABr and adding mesoporous silica, leaching ratios were reduced from 4.2 to 2.3%. Silica-grafted DES-based membranes exhibited a progressive increase in flux from 2.6 to 26.67 L/m2 h. The synthesized silicon-based membranes demonstrated outstanding performance, achieving rejection rates exceeding 80% for chromium and arsenic, maintaining an impressive 90% flux recovery ratio even at high flux rates. This study will envision the potential of nano-enhanced membrane technology utilizing DES for sustainable water purification and wastewater treatment applications to achieve the sustainable development goal (SDG) of clean water and sanitation (SDG-6).