Synthesis Of Silica Research Articles

Non-hydrolytic sol-gel synthesis of amine-functionalized silica: Template- and catalyst-free preparation of mesoporous catalysts for CO2 valorization

Carbon dioxide utilization presents an important and topical research topic. However, the performance of catalysts needed for CO2 transformations does not achieve the necessary levels for their widespread application. To this end, we decided to study non-aqueous condensations providing amine-functionalized silica catalysts, possibly active in CO2-epoxide cycloaddition reaction. While non-hydrolytic sol-gel method is well-known for its efficiency in providing highly porous Lewis and Brønsted acid metallosilicates, here we show for the first time its application for the preparation of silica-based catalysts containing basic groups. First, the reaction conditions were screened to reproducibly obtain porous materials with preserved amine moieties. These were identified as follows: silicon tetraacetate and bridging tertiary amine silanes as precursors, toluene as a solvent, and temperature between 160 and 180 °C. In such a way, materials with up to 776 m2 g−1 and 1.58 cm3 g−1 were obtained in one-step process, without any template, after conventional drying step. Next, the amine-functionalized materials were tested in CO2-epoxide coupling providing cyclic organic carbonates with high selectivity (>99 %) and moderate activity (up to 86 % epichlorohydrin conversion after 1 h at 120 °C and 10 bar CO2). The characterization of spent catalysts revealed a presence of cyclic organic carbonates at the catalyst surface as well as conversion of tertiary amine groups to quaternary ammonium moieties.

High-efficiency synthesis of colloidal silica via suppression of foam layer

As an important fundamental material, colloidal silica is widely used in many fields. Hydrolysis of elemental silicon is an important method for the preparation of colloidal silica. This method has been widely studied because of its simple process, low cost, easy control of colloidal particle size and good stability. However, this method has the problem of low reaction conversion rate (RCR). This paper proposed an efficient method to increase RCR of colloidal silica by inhibiting the formation of a foam layer. After the size of the silicon powder particle, reaction time, and the defoamer types were optimized, the defoamer of hydrophobic fumed silica could effectively inhibit the increase of foam layer and improve the yield of colloidal silica, the RCR was significantly increased from 54.8 % to 85 % within 4 h. This research provides an innovative strategy for the efficient chemical synthesis of colloidal silica.

Thermodynamic manipulation of the particle size in the synthesis of spherical silica from a new aspect of interface wettability

In the stöber synthesis of spherical silica, the alcohol/water ratio is normally regarded as the major factor that determines the final particle size of the products, but a solid relationship between the alcohol/water ratio and the particle size is hard to be deduced, and the thermodynamic mechanism behind this phenomenon has not been fully discussed yet. In this paper, the methanol/ethanol/isopropanol-H2O solvents with different alcohol/water ratio are used to prepare spherical silica particles via a classic stöber synthesis. It is found that not only the surface tension of the reaction system, but also the interface contact angle can effectively influence the final particle size of the silica products, and an interfacial wetting effect could be deduced for the thermodynamic analysis of this phenomenon. In this interfacial wetting mode for the particle size manipulation, the particle size is proportional to the surface tension of the reaction system when the interface contact angle is below 90⁰, but an inverse proportional relationship will be applicable when the interface contact angle is above 90⁰. Assisted with this new mechanism, the iso-particle size contour curves based on pairs of surface tension and the interface contact angle could be deduced, and the controllable stöber synthesis of spherical silica particles could be reached in a more facile and accurate way.

Synergistic effect of graphene oxide and silica nanocomposites towards multifunctional biomedical applications

The development of advanced nanomaterials (NMs) has recently gained significant attention because of their potential in addressing various biomedical and healthcare challenges. This study focuses on the synthesis of silica (SiO2) nanoparticles (NPs) and their nanocomposite with graphene oxide (GO-SiO2), using a multifunctional approach to enhance antibacterial, antibiofilm, antioxidant, and antidiabetic properties. The synthesis of the GO-SiO2 involves the controlled growth of SiO2 NPs on the surface of the graphene oxide (GO) sheets. The synthesized NPs were characterized by UV–Visible spectroscopy, Fourier-Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) Spectroscopy. The crystallite sizes of SiO2 and GO-SiO2 were found to be 23.07 nm and 32.07 nm, respectively, by XRD analysis and 27.03 nm and 43.11 nm, respectively, by SEM. The Band gap of SiO2 was decreased from 3.76eV to 3.45eV in GO-SiO2. Disc diffusion method was used to perform antibacterial activity whereas ampicillin and moxifloxacin were taken as reference drugs. Biofilm inhibitions and minimum inhibitory concentrations were measured by microtiter plate method. The composite has shown higher antimicrobial activities against S. aureus, S. aureus MDR, K. pneumoniae, P. aeruginosa, P. aeruginosa MDR, E. coli, and P. vulgaris as compared to SiO2 NPs and GO. When IC50 values were compared with those of control (acarbose), GO-SiO2 and SiO2 demonstrated the highest and lowest antidiabetic activities, respectively. A 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging process was used to evaluate the antioxidant potential of NMs using ascorbic acid as a reference. GO-SiO2 displayed the negligible IC50 value compared to both SiO2 and GO. The nanocomposite (GO-SiO2) has shown higher antibacterial, antibiofilm, antioxidant, and antidiabetic potential as compared to those of GO and SiO2NPs.

Mixed bio-based surfactant-templated mesoporous silica for supporting palladium catalyst

The study aimed on the synthesis of bio-based surfactant-templated mesoporous silica for supporting palladium catalyst using mixed bio-based templating agents namely cashew nut shell liquid (CNSL) and castor oil for pore direction purposes. The materials prepared through co-condensation of 3-aminopropyltriethoxysilane (APTS) and tetraethyl orthosilicate (TEOS) in a 1:4 M ratio using 1:1, 4:1 and 9:1 ratio of CNSL and castor oil. The resulting porous materials were utilized to support the palladium(II) chloride catalyst, resulting in a heterogeneous catalyst-a better and more environmentally friendly catalyst than a homogeneous one. Different instruments were used to characterize the prepared materials such as nitrogen porosimeter, Powder X-ray Diffraction, Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Inductively coupled plasma optical emission spectroscopy. Physisorption studies of the prepared materials indicated that the largest pore diameter of 43.84 nm could be obtained by using a 1:1 M ratio of CNSL and castor oil. On the other hand, the largest surface area of 209 m2/g was obtained from a 9:1 whereas the largest pore volume was 1.55 cm3/g from a 4:1. Diffuse Reflectance Infrared Fourier Transform Spectroscopy analysis confirmed the presence of N-H group, the bending vibration bands at around 1640 and 1543 cm−1 indicating that the reaction of organoaminesilanes and tetraethyl orthosilicate had occurred. The palladium content of the supported catalyst was determined by ICP-OES which confirmed the attachment of palladium to the synthesized materials. The highest palladium loading was obtained from the adsorbent prepared by using 1:1 ratio of surfactants mixture which gave the adsorption value of 2.16 mmol/g. Powder X-ray Diffraction indicated that the synthesized organosilica materials are amorphous with improved crystallinity upon attachment of palladium catalyst. The incorporation of palladium in the synthesized materials using the mixed bio-based surfactant was successful.

Sintesis dan Karakterisasi Zeolit X dari Fly Ash Batu Bara Menggunakan Metode Sintesis pada Suhu Rendah

Many industries in Indonesia have switched to using coal fuel. The use of coal at PT PLTU Paiton has reached 250 tons per hour and produces 4% of waste by-products of combustion contained from bottom ash by 25% and fly ash by 75%. Fly ash waste will harm the environment and health. Fly ash contains many components, including SiO2 52%, Al2O3 31.86%, Fe2O2 4.89%, CaO 2.68%, and MgO 4.66%. This research aims to synthesize and characterize zeolite X from PT Paiton fly ash using a low-temperature synthesis method. Zeolite X synthesis in this study has 3 steps: The pretreatment process, silica synthesis process, and zeolite synthesis process. The results of silica synthesis obtained SiO2 55.54%. The resulting zeolite product has a typical peak at 2ϴ 28.72. Zeolite x has a wavelength of 430, 570, 695,7, and 965,7, which respectively indicates Si-O-Si and Si-O-Al bonds, double ring bonds, T-O ring symmetric strain (internal), and asymmetric (internal). The results of zeolite X crystal synthesis in this study could not be formed in the variable of adding time of 3-5 hours with a variation of moles of Al2O3 0,5-1,5 moles.

Enhancing lithium-storage properties through amino functionalization in two-dimensional lamellar carbon-supported mesoporous SiO2 nanospheres

Currently, common two-dimensional (2D) carbon materials composited with Si-based materials as anode for lithium-ion batteries exhibit excellent electrochemical properties. In this study, we describe the one-step synthesis of amino-functionalized mesoporous silica (SiO2) nanospheres through self-assembly. Morphology modulation and amino group grafting were performed simultaneously without secondary modification. Using tartaric acid and melamine as dual carbon sources, the 2D lamellar structure was constructed using the dehydration condensation reaction, with the mesoporous SiO2 nanospheres uniformly intercalated within the carbon sheets. The composites were securely bonded by chemical bonding, effectively addressing the issue of structural collapse often encountered in silica–carbon composites. Ultimately, the lamellar SiO2@NC composite exhibited stable capacity of 539.5 mAh g−1 after 500 cycles at 1 A g−1. This strategy is simple and effective, compared to the complex processes typically associated with 2D carbon materials synthesis, and can be potentially extended to applications in catalysis, adsorption, and separation within diverse fields.

Synthesis of hydrophobic silica without traditional aging process to construct the anti-reflective film with ultralow refractive index for improving power conversion efficiency

The fabrication of anti-reflective films to optimize sunlight utilization encounters various challenges. Herein, we have synthesized modified silica with hydrophobic properties, eliminating the conventional aging process to create an anti-reflective film with an ultralow refractive index of 1.05, marking the lowest value reported to date. This innovative methodology reduces tasks that typically require days or weeks to just a few hours, thereby significantly accelerating production. The power conversion efficiency of the photovoltaic device can increase by 6.2 % when coated with this film. This research not only advances the synthesis of silica but also develops anti-reflective films with record-low refractive indices. This breakthrough represents a substantial contribution, highlighting its significant impact on the photovoltaic field.

Synthesis and characterization of porous silica and composite films for enhanced CO₂ adsorption: A circular economy approach

This study explores the synthesis and application of carbon-negative technology that leverage circular economy and environmentally friendly methodologies. Porous silica using plant-derived silica sources and self-assembled lignin templates were prepared, achieving an impresive surface area of up to 104.76 m2/g. Additionally, we prepared porous composite films via a freeze-drying process incorporating polyvinyl alcohol (PVA). These films demonstrated enhanced tensile properties, with a tensile strength reaching 285.72 kPa. Notably, the film surfaces engaged in a third-body tribology mechanism, which endowed them with excellent abrasion resistance and a low friction coefficient. The specific surface area of the films was measured at 20.15 m2/g, making them ideal substrates for CO₂ adsorption functionalization. The functionalized films showcased outstanding CO₂ adsorption capabilities, with a maximum uptake of 29.38 mg/g. Furthermore, they retained over 90% of their adsorption capacity after five adsorption/desorption cycles. Under high CO₂ conditions, these composite films combine the desirable attributes of both solid and liquid adsorbents—high surface area, low volatility, and adsorption stability—contributing significantly to greenhouse gas mitigation and the pursuit of carbon neutrality.

Utilization of coal gasification fine slag-derived mesoporous silica supports for enhanced dry reforming of methane catalysts

Utilizing industrial waste coal gasification fine slag (CGFS) for the preparation of dry reforming of methane (DRM) catalyst supports presents an innovative approach to waste utilization. This strategy not only addresses solid waste pollution but also reduces the production costs associated with DRM catalysts. Currently, the industrialization of the DRM reaction remains elusive. Therefore, selecting an appropriate catalyst preparation method is imperative for potential industrial applications. This study centers on the synthesis of mesoporous silica (MS) supports using coal gasification fine slag. The impact of support structure, catalyst preparation method, and active metal loading on the resistance to sintering and carbon deposition of the catalysts is explored through diverse characterization techniques. The MS support derived from coal gasification fine slag showcases a unique disordered mesoporous architecture that enhances the dispersion of the metal across the support surface. In addition, we report a MS catalyst prepared by a co-precipitation method (MS–CP), which exhibits excellent catalytic activity and stability due to its strong metal-support interaction. Results suggest that during synthesis, the MS–CP catalyst activates the inert MS support by strongly interacting with Ni metal, resulting in the formation of Ni3Si2O5(OH)4 species. The Ni–O–Si bond can activate CO2, thereby promoting the availability of interfacial oxygen during the reaction. This process accelerates the gasification of surface Cn generated by CH4 decomposition. Notably, the loading analysis indicates that MS–CP loaded with 10 wt% Ni demonstrates the highest resistance to carbon deposition and sintering. Thus, the unique strong metal-supported interactions provide a new avenue for the development of nickel-based DRM catalysts.

Synthesis of hexagonal mesoporous silica from coal fly ash and their evaluation as adsorbent for gallium recovery

Adsorption of gallium (Ga) utilizing solid waste synthetic materials can achieve both high-value solid waste use and solve the supply–demand paradox of Ga. To efficiently recover Ga in solution, this article describes a hydrothermal synthesis technique of mesoporous materials from the acid leaching residue of coal fly ash (CFA). According to the findings, the mesoporous silica synthesized by hydrothermal reaction with CTAB: nSiO32-=1:0.085 around 120℃ during 24 h exhibits a maximum specific surface area (771.25 m2/g) along with hexagonal mesoporous structure. Pseudo-second-order kinetic model that has an excellent correlation coefficient (R2 > 0.99) can explain this adsorption system. Since Freundlich model fits this adsorption action better, the process is multi-molecular layer adsorption. The thermodynamic fitting results show that the adsorption of Ga by mesoporous silica is an endothermic and spontaneous chaotic reaction. The adsorption mechanism could be depicted using ion exchange and coupling. The adsorption efficiency of Ga is still higher than 80 % after the material has been regenerated by multiple resolution. In conclusion, mesoporous silica prepared by CFA acid leaching residue has the potential to adsorb Ga.

Microalgae-derived peptide with dual-functionalities of silica deposition and antimicrobial activity for biosilica-based biomaterial design

Peptides are relatively small macromolecules, and their functionalities are usefully combined with organic or inorganic materials to design highly-efficient biomedical devices. Marine organisms are potential resources to identify a novel peptide with such functionalities, which can be employed to improve both of the inorganic and organic properties, essential for biomaterial design. This study reported and characterized a newly-found peptide, TO, derived from marine diatom, Thalassiosira oceanica. The peptide exhibited extraordinary dual functions: silica deposition and antimicrobial activity. It has not yet been reported that a peptide had both silica synthesis ability and antibacterial activity. When the peptide was incorporated into polyurethane (PU) foam, this dual-functionality was employed, and each function varied by peptide and silica precursor concentrations. In particular, the PU form (PU@mTO@SiO2) with silica deposited by modified TO (mTO) showed increased water capacity by 200 %. Antimicrobial activities of PU@mTO@SiO2 and control PU@SiO2 (made w/o peptide) were evaluated against E. coli, P. aeruginosa, S. aureus, and B. subtilis. PU@mTO@SiO2 exhibited significant antibacterial activity toward the tested bacteria. The TO or mTO peptide will facilitate the designing of novel biosilica-embedded materials or systems with antimicrobial activity required in the biomedical field.

Irinotecan-loaded magnetite-silica core-shell systems for colorectal cancer treatment

Colorectal cancer represents a worldwide spread type of cancer and it is regarded as one of the leading death causes, along with lung, breast, and prostate cancers. Since conventional surgical resection and chemotherapy proved limited efficiency, the use of alternative drug delivery systems that ensure the controlled release of cytostatic agents possess immense potential for treatment. In this regard, the present study aimed to develop and evaluate the efficiency of a series of irinotecan-loaded magnetite-silica core–shell systems. The magnetite particles were obtained through a solvothermal treatment, while the silica shell was obtained through the Stöber method directly onto the surface of magnetite particles. Subsequently, the core–shell systems were physico-chemically and morpho-structurally evaluated trough X-ray diffraction (XRD) and (high-resolution) transmission electron microscopy ((HR-)TEM) equipped with a High Annular Angular Dark Field Detector (HAADF) for elemental mapping. After the irinotecan loading, the drug delivery systems were evaluated through Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry and differential scanning calorimetry (TG-DSC), and UV–Vis spectrophotometry. Additionally, the Brunauer–Emmett-Teller (BET) method was employed for determining the surface area and pore volume of the systems. The biological functionality of the core-shells was investigated through the MTT assay performed on both normal and cancer cells. The results of the study confirmed the formation of highly crystalline magnetite particles comprising the core and mesoporous silica layers of sizes varying between 2 and 7 nm as the shell. Additionally, the drug loading and release was dependent on the type of the silica synthesis procedure, since the lack of hexadecyltrimethylammonium bromide (CTAB) resulted in higher drug loading but lower cumulative release. Moreover, the nanostructured systems demonstrated a targeted efficiency towards HT-29 colorectal adenocarcinoma cells, as in the case of normal L929 fibroblast cells, the cell viability was higher than for the pristine drug. In this manner, this study provides the means and procedures for developing drug delivery systems with applicability in the treatment of cancer.

Synthesis and characterization of SBA-15 silica containing cyclam inside pores for capturing iron chloride: Analysis of interactions between ferrous chloride and cyclam in a system with strongly dispersed functional groups on the SiO2 surface

The use of the spatial structure of mesoporous silica combined with organic molecules opens up a wide range of possibilities in the field of separation of single atoms and the precise creation of their environment. Materials obtained in this way can find applications as single-atom catalysts (SAC) and in environmental applications in ion and molecule trapping processes. An example of such a material is silica of the SBA-15 type functionalized with cyclam (1,4,8,11-tetraazacyclotetradecane) anchored inside the pores with propyl chains. In this work, we present such a material containing 5% functional groups, additionally activated with iron(II) chloride, which was chelated by cyclam anchored inside the pores of silica. The presented nanocomposite has been thoroughly tested for its assumed molecular structure and stability. We compared it to a material containing only cyclam. The obtained results showed the high efficiency of the silica matrix with cyclam in the separation of single FeCl2 molecules and the correct molecular structure of the obtained material. The nanocomposite containing chelated molecules with iron showed good stability, while the structure of the material with cyclam alone collapsed with time.

Synthesis and characterization of mesoporous caged silica for efficient adsorption of methylene blue from aqueous solution

Addressing the challenge of removing dyes from textile industry wastewater is crucial for wastewater treatment. Adsorption, utilizing suitable materials, emerges as a promising solution. This work introduces caged silica as an effective adsorption material for wastewater treatment in the textile industry. The proposed caged silica was synthesized via the hard template synthesis method, commonly used in various applications such as catalysts and wastewater treatment. Caged silica exhibited an amorphous structure with notable BET surface area (448m2/g), pore volume (0.325cm3/g), and average pore size (2.4nm), confirmed through detailed characterization. Evaluation of its adsorption capacity for methylene blue (MB) revealed an impressive removal efficiency of approximately 95% within the initial 20 min. The adsorption process followed the pseudo-second-order model and adhered more closely to the Freundlich isotherm model than the Langmuir model. Additionally, the study investigates the effects of pH, percent removal efficiency, cyclic stability, and initial MB concentration on the adsorption procedure. Consequently, the synthesized caged silica stands out as a promising mesoporous material for efficiently removing MB from aqueous solutions, offering practical application potential in wastewater treatment.

Effect of Nitric Acid on the Synthesis and Biological Activity of Silica–Quercetin Hybrid Materials via the Sol-Gel Route

The sol-gel technique stands out as a valuable method for synthesizing biomaterials and encapsulating bioactive molecules, offering potential for controlled drug release and tissue regeneration in biomedical contexts. This study focused on synthesizing silica (Si)-based hybrid biomaterials containing 5% quercetin (Q5) using two different approaches: one involving nitric acid as a catalyst (SiQ5-HNO3) and the other being acid-free (SiQ5). Structural characterization using Fourier transform infrared (FTIR) and UV-vis spectroscopy revealed oxidation processes compromising the structural integrity of quercetin in both systems. However, it was observed that these oxidation processes led to the formation of oxidized derivatives of quercetin with distinct structures. Additionally, the bioactivity and release kinetics of quercetin from the silica matrices were evaluated, showing that both systems were capable of forming hydroxyapatite, indicating excellent bioactivity. Furthermore, SiQ5 exhibited a higher percentage release of the encapsulated drug at pH 7.4, representing the physiological environment, compared to SiQ5-HNO3, with a drastic reduction in drug release observed at pH 5.0 (cancer environment). Antibacterial efficacy assessment using the Kirby–Bauer test highlighted the greater antibacterial activity of the SiQ5-HNO3 system against all tested strains. Overall, this research aims to advance the development of more effective biomaterials for various biomedical applications, particularly in tissue engineering and infection control.

Optimization of the process synthesis of silica nanoparticles functionalized with silane agents destined for superhydrophobic coating

The aim of this study is to define the optimum process synthesis of silica (SiO2) nanoparticles functionalized with silane agents destined for superhydrophobic coating thus to determine the minimum required silane agent needed to obtain proper superhydrophobic properties. Spherical SiO2 nanoparticles were synthesized by using sol-gel method and functionalized to gain hydrophobic properties with two different silane agents: 1,1,1,3,3,3-hexamethyldisilazane (HMDS) and 1H,1H,2H,2H – perfluoroctyltrichlorosilane (PFOTS). The hydrophobic properties were evaluated by measuring the water drop contact angle and the inclination flowing angle. Results show that, through manufacturing process optimization, the quantity of HMDS could be reduced by 142%, while the quantity of PFOTS could be reduced by 20% compared to the lab scale synthesis method developed by ICPE-CA, without having a negative effect on the hydrophobic properties of the functionalized SiO2 nanoparticles.

Understanding the relationship between pore size, surface charge density, and Cu2+ adsorption in mesoporous silica

This research delved into the influence of mesoporous silica’s surface charge density on the adsorption of Cu2+. The synthesis of mesoporous silica employed the hydrothermal method, with pore size controlled by varying the length of trimethylammonium bromide (CnTAB, n = 12, 14, 16) chains. Gas adsorption techniques and transmission electron microscopy characterized the mesoporous silica structure. Surface charge densities of the mesoporous silica were determined through potentiometric titration, while surface hydroxyl densities were assessed using the thermogravimetric method. Subsequently, batch adsorption experiments were conducted to study the adsorption of Cu2+ in mesoporous silica, and the process was comprehensively analyzed using Atomic absorption spectrometry (AAS), Fourier transform infrared (FTIR), and L3 edge X-ray absorption near edge structure (XANES). The research findings suggest a positive correlation between the pore size of mesoporous silica, its surface charge density, and the adsorption capacity for Cu2+. More specifically, as the pore size increases within the 3–4.1 nm range, the surface charge density and the adsorption capacity for Cu2+ also increase. Our findings provide valuable insights into the relationship between the physicochemical properties of mesoporous silica and the adsorption behavior of Cu2+, offering potential applications in areas such as environmental remediation and catalysis.

Synthesis of large mesoporous silica for efficient CO2 adsorption using coal gasification fine slag

Coal gasification fine slag (CGFS), a byproduct of the coal gasification process, is currently being recognized as a resource with significant potential for value addition and sustainable applications, especially in synthesizing CO2 adsorbents. The overarching challenges in this domain include the attainment of high-efficiency, environmentally benign transformation of CGFS into useful products, and the development of cost-effective adsorbent materials featuring precisely engineered pore structures. In this study, a hierarchical porous nanostructured silica material is synthesized rapidly, efficiently, and cost-effectively through acid leaching and alkaline dissolution-assisted hydrothermal treatment, employing CGFS as the precursor. The mass ratios of sodium hydroxide (NaOH) to CGFS range from 0.4 to 1, resulting in varying morphologies and adsorption properties. Specifically, the sample with the NaOH to CGFS ratio of 0.6 (CGFS-0.6) shows the best adsorption performance. The adsorption capacities are 2.87 mmol/g and 8.49 mmol/g at 20 °C with 15 % and 45 % CO2 concentration, respectively. The material is characterized by a well-developed pore structure shaped like a bouquet of flowers, with a specific surface area of 457 m2/g and pore volume reaching 2.34 cm3/g. During the hydrothermal processing, silicate/aluminosilicate entities self-organized into a Si-O-Na/Al network structure, endowing the synthesized adsorbent with optimal internal porosity and silanol functionalities. The adsorption equilibrium is achieved rapidly within 10 min, and CO2 adsorption stability remains robust across 20 successive cycles. All isothermal models of the adsorbents conform to the Sips model. This study offers a promising pathway for the value-enhanced utilization of coal-derived solid wastes.

Thermo and pH-responsive nanocarriers based on mesocellular silica foam and poly(N-vinylcaprolactam-co-methacrylic acid): Synthesis, characterization, and in vitro cytotoxicity assay

Smart hybrid nanocarriers were prepared by grafting poly(N-vinylcaprolactam-co-methacrylic acid) (poly(NVCL-co-MAA)) onto mesocellular silica foams (MCF silica) to evaluate them as controlled delivery systems of doxorubicin (DOX). The development of these nanocarriers began with the synthesis of MCF silica with interconnected porous structures and an average pore diameter of 27 nm. Then, free radical polymerization was used to graft the smart copolymer, and some parameters such as comonomer concentration and reaction time were studied. The DOX was loaded by immersion in an aqueous drug solution, while the in vitro release was investigated at different pHs (7.4, 5.8) and temperatures (25, 37 °C). In addition, the cytotoxicity of nanocarriers was investigated in vitro using the direct contact method with human breast cancer cells (SKBR3). In general, hybrid nanocarriers with copolymer graft percentages ranging from 30 to 60 % were obtained. On the other hand, at higher grafting of poly(NVCL-co-MAA) onto MCF silica, higher drug loading (up to 6.41 × 10−2 mg DOX/mg HN) was observed. Furthermore, in vitro DOX release results suggested that the nanocarriers released up to 52 % at 37 °C and a pH of 5.8. Finally, the in vitro cytotoxicity assay revealed that the DOX-loaded hybrid nanocarriers were cytotoxic to SKBR3 cells, indicating a controlled administration of DOX from the nanocarriers compared to free DOX. These results suggest that nanocarriers could have great potential for use as controlled delivery systems of anticancer drugs.