In this study, several TiO
2
mesoporous nanoparticles with different mol% of niobium and silver were synthesized using the sol–gel method. The crystalline phase, chemical state, photocatalytic and ...optical properties, specific surface area, and morphology of mesoporous nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis reflective spectroscopy (UV–Vis), Brunauer–Emmett–Teller-specific surface area (BET) and field emission scanning electron microscopy (FESEM). With increasing calcination temperature, the photocatalytic activity of the samples gradually increased due to the improvement of crystallization of the anatase and rutile phases. Nb/Ag codoping sample calcined at 550 °C has reduced the band gap energy (3.17 eV to 3.06 eV) and improved the photocatalytic properties of samples under visible light (xenon lamp, 200 W for 1 h and 2 h). Doped TiO
2
mesoporous nanoparticles were shown to have the highest photocatalytic activity as compared with the pure TiO
2
nanoparticles. The best photocatalytic efficiency of codoped TiO
2
mesoporous nanoparticles was observed for the TNA3 sample calcined under 550 °C, containing molar contents of Nb (0.5 mol%) and Ag (1 mol%) dopant ions with 95.60% efficiency.
Synthesis of Nb/Ag-codoped TiO
2
(TNA) nanoparticles by sol–gel method
Highlights
Nb/Ag additive enhanced significantly photocatalytic properties of TiO
2
based nanoparticles for remove of organic compounds (MB).
Structural, optical and surface analysis of samples dependent to dopant concentration.
Nb/Ag codoped TiO
2
nanoparticles is promising for photocatalytic properties in visible light.
Pure and Mg-doped ZnO (3 at. %) nanoparticles were prepared based to sol–gel route under supercritical conditions of ethyl alcohol. The samples were characterized by certain techniques. XRD patterns ...showed the hexagonal wurtzite crystalline structure of ZnO and Mg-doped ZnO nanoparticles. The TEM image demonstrates the hexagonal shape and the nanometric size of the nanostructures. SEM images show the presence of hexagonal like shape nanoparticles and the increase of grain size for the Mg doped sample. The corresponding EDX analysis proves the existence of Mg with low concentrations and shows coherent distribution of high concentrations of Zn and O elements. The UV–Vis–NIR spectroscopy exhibits high absorbance of the prepared samples in the UV range. Thereafter, the effect of doping ZnO by Mg on sensing properties has been investigated. The obtained results outline an enhancement in sensing performances for Mg doped ZnO based sensor, which exhibits, competitive response and recovery times, high and linear response at working temperature 300 °C toward low and high ethanol concentrations with detection limit less than 1 ppm. Long term stability has been also investigated and sensor exhibits after one year, similar and reproducible responses.
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•Pure and Mg (3 at.%) doped ZnO nanoparticles have been synthesized using sol–gel technique.•The TEM observation shows prismatic shape and nanosized particles confirming the XRD results.•3 at% Mg doped ZnO (M3ZO) based gas sensor exhibits high sensitivity and excellent response to ethanol.•M3ZO has highest Response/ppm ratio compared to literature results at 300 °C and 50%RH.•M3ZO sensor Response exhibits, good linear relationship with concentration, and excellent long term stability.
In this paper, we report the experimental results on the synthesis of water glass based silica aerogels, which were dried under ambient pressure. Water glass was hydrolyzed and condensed in water ...using HCl as the catalyst. To minimize shrinkage during drying process, N,N-dimethylformamide (DMF), acting as drying control chemical additive (DCCA), was introduced. Before the ambient pressure drying, solvent exchange and surface modification were completed. In order to get hydrophobic aerogel, trimethylchlorosilane (TMCS) was used to modify the hydrophilic hydrogel surface. Here a large amount of TMCS can be saved compared with that in single step solvent exchange/surface modification method. The effects of DMF on the physical and textural properties of the resulting aerogels were investigated. When the molar ratio of Si in water glass to DMF is 2.23, the synthesized silica aerogels have better properties. Characterized by FT-IR, SEM, BET, etc., the resulting aerogels have well-developed mesoporous structure (mean pore size of ~15nm) with super hydrophobicity (contact angle of 161°) and excellent absorption capacity of organic liquids.
•Min. amount of TMCS was obtained through experiments for complete surface modification.•Optimum volume ratio of H2O to water glass was gotten.•Proper amount of DMF can uniform the PSD of as-prepared silica aerogels.•More than 0.9ml organics (some) can be absorbed by 1cm3 of the silica aerogels.
This study focuses on the synthesis and characterization of Zirconium(IV) Propoxide (ZTP), Colloidal Silica (CS), and Methyltrimethoxysilane (MTMS)-derived non-stick hard coatings prepared via the ...sol–gel method. In the synthetic procedure, two different solutions were prepared separately based on the different hydrolysis rates of the silicon (SolS) and zirconium (SolZ) components. Polydimethoxysilane (PDMS) and Fluoralkylsilane (FAS) were used as hydrophobicity-promoting agents. The solution was applied onto aluminum surface, which was afterward dried and densified at 250 °C. The final solution was characterized by FTIR spectroscopy to determine the Zr–O–Si hetero-bonding and Si–O–Si and Zr–O–Zr homo-bonding. Coatings were analyzed by their hardness, hydrophobicity, and gloss. A homogeneous solution and crack-free hybrid coating was obtained. FTIR results showed that homo- and hetero-bonding between Zr and Si elements were obtained from a precipitation-free solution. Measured contact angles varied between 100° and 112°, and these results were evaluated according to the surface and gel structure.
Highlights
A crack-free, hydrophobic, hard hybrid thin films were synthesized using ZTP, MTMS and CS via sol–gel method.
ZTP increased the contact angle of the film surface.
Precipitation-free SolS solution was obtained due to the reactions between methyl groups in MTMS and the colloidal silica particles.
PDMS and FAS components further increased the wetting angle of the hybrid film up to a specific ratio.
FTIR results showed that Zr–O–Si hetero-bonding and Si–O–Si, Zr–O-Zr homo-bonding were obtained as result of the precipitation-free solution.
Excellent biocompatibility and its similar biological characteristics to bone apatite, extensively expand the hydroxyapatite (HA) usage in bioimplant applications. The crystallite size of HA is one ...of the most administrated parameter for determination of reaction rate at the interface of artificial/natural bones. This study tried to propose a new predictive model by employment of the gene expression programming (GEP), i.e., a powerful soft computing technique, to estimate the crystallite size of HA that were prepared by sol–gel route. Firstly, 37 different reliable experiments were carried out considering the type of phosphor precursor, pH, drying temperature, aging time, temperature and time of calcination as practical parameters as input variables, and HA crystallite size as output variable. Absolute fraction of variance (
R
2
), mean absolute percentage error (MAPE), root relative squared error (RRSE), and mean squared error (MSE) were considered to validate the most appropriate GEP model/s. The experiment results were divided randomly into 29 training sets and 8 testing sets. Finally, the best model was selected in
R
2
= 0.9929, MAPE = 2.8, RRSE = 0.0956, and MSE = 1.7. The results of simulation confirmed the unique features of GEP for the determination of HA crystallite size prepared by sol–gel route.
Predicted vs. experimental HA crystallite size through GEP-3, GEP-8 and GEP-6 models in (
a
) training phase, and (
b
) testing phase.
In this paper, we introduce the synthesis of undoped ZnO and 5 wt % Gd/K co‐doped ZnO compounds to improve photocatalytic activity. Undoped ZnO particles and Gd/K co‐doped ZnO particles were ...synthesized by the sol‐gel method. The samples were studied by X‐ Ray Diffraction (XRD), Scanning Electron Microscopy (SEM)/energy dispersive X‐ray (EDX), Ultraviolet Visible Spectroscopy (UV‐Vis), Brunauer–Emmett–Teller (BET), and particle size analysis. Then tehir photocatalytic activities were tested. SEM micrographs showed that the particle size was in the sub‐micrometer or nanometer range. Particle size analysis revealed that the mean size was closer to the micrometer range. The specific surface area of the powder was obtained quite low in accordance with the larger particle size. The photocatalytic activity of 5% Gd/K co‐doped ZnO was compared with undoped ZnO in the degradation methyl blue. When their photocatalytic activities were examined, Gd/K co‐doped ZnO showed ∼66% degradation at 60 min, while undoped ZnO showed ∼52% degradation at the same time.
Routine geotechnical engineering practice has witnessed a significant increase in the usage of unsaturated soil mechanics principles. Laboratory measurement of the soil-water characteristic curve ...(SWCC) for a soil has been labelled as a primary reason for the improved understanding of unsaturated soil behaviour. Laboratory measurement of the “shrinkage curve” has yielded further insight into the estimation of unsaturated soil property functions (USPFs). The USPFs provide the necessary information for the simultaneous numerical modeling of the saturated and unsaturated portions of the soil profile. This paper presents a state-of-practice summary of the engineering protocols that have emerged amidst the numerous research studies reported over the past couple of decades. It also introduces issues related to hysteresis associated with the SWCC and suggests a pathway forward.
•The sol-gel technique was adopted to prepare the spinel ferrite nanoparticles.•Pure spinel phase structure with cubic symmetry was observed for all samples.•The crystallite size of the prepared ...samples ranges from 35.4-43.6 nm.•FTIR spectra affirm the evacuation of nitrates and citric acid from all samples.•VSM study exhibits soft ferromagnetic nature due to the low coercivity value.
The current work involves the synthesis of MnxCo0.5−xZn0.5Fe2O4 (x = 0.0, 0.1, 0.2, 0.3, and 0.4) by adopting sol-gel auto combustion technique. For all the samples, the single-phase spinel structure with cubic symmetry was assured by the XRD studies. The crystallite size lies in the nanoscale range of 35.4–43.6 nm as estimated by utilizing Debye-Scherrer formula. FTIR spectroscopy affirms the formation of spinel structure due to the appearance of characteristic vibrational bands near 400 and 600 cm−1 which corresponds to the octahedral and tetrahedral sites respectively. FESEM micrographs reveal the presence of non-uniform grain growth which was agglomerated, inhomogenous in size and shape, and having porous morphology. VSM study exhibits soft ferromagnetic nature due to the low coercivity value. There is a decrement in the saturation magnetization with increasing Mn2+ concentration which is due to the decrease in the crystallite size and non-magnetic nature of the Mn2+.
A series of amylases were encapsulated within silica matrices taking into account the nature of the amylase: α-amylase (
Bacillus subtilis
), α-amylase (
Aspergillus oryzae
), and β-amylase (barley), ...and the nature of the organosilane (alkyl-, amine- and mercaptan-based organosilanes). The results for the biocatalytic activity were shown to be dependent on the nature of the encapsulated enzymes and on the nature of the employed organosilane. Organosilanes containing the amine group showed different effects and lower biocatalytic conversions (on average). In general, β-amylase increased in biocatalytic activity after encapsulation. There was a strong correlation between the nature of the organosilane and the resulting porosity of the matrix as well as the reducing sugars produced from the saccharification tests. The lower the particle radius of gyration and the higher degree ramification of the secondary particles, the higher the catalyst bioactivity was. Generally, glucose production during saccharification was favored by the encapsulation of the enzyme.
Highlights
Different organosilanes (7) were employed to modify silica surface.
The organosilanes containing the amine group showed lower bioconversion.
β-amylase increased in biocatalytic activity after encapsulation.
Organosilanes increase the pore diameter.
The magnetic nanosized rare earth iron garnets (R3Fe5O12, where R=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared by an aqueous sol–gel method. Herein we present, that all these garnets can be ...obtained by this effective synthesis method simply by changing the temperature of the final annealing. It was also demonstrated, that a different annealing temperature leads to a different particle size distribution of the final product. The SEM analysis results revealed that the smallest particles were formed in the range of 75–130nm. The phase purity and structure of the rare earth iron garnets were estimated using XRD analysis and Mössbauer spectroscopy. Magnetic properties were determined by magnetization measurements. The relation between the particle size, composition and magnetic properties of the sol-gel derived garnets were also discussed in this study.
•First time series of R3Fe5O12 (R=from Sm to Lu) are prepared by sol–gel process.•Different sintering temperature leads to the different particle size distribution.•Correlation between microstructure, composition and magnetic properties is shown.
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