Effects of poly (vinyl alcohol) (PVA) content on preparation of novel thiol-functionalized mesoporous PVA/SiO2 composite nanofiber membranes and their application for adsorption of heavy metal ions from aqueous solution

Thiol-functionalized mesoporous poly (vinyl alcohol)/SiO₂ composite nanofiber membranes and pure PVA nanofiber membranes were synthesized by electrospinning. The results of Fourier transform infrared (FTIR) indicated that the PVA/SiO₂ composite nanofibers were functionalized by mercapto groups via the hydrolysis polycondensation. The surface areas of the PVA/SiO₂ composite nanofiber membranes were >290 m²/g. The surface areas, pore diameters and pore volumes of PVA/SiO₂ composite nanofibers decreased as the PVA content increased. The adsorption capacities of the thiol-functionalized mesoporous PVA/SiO₂ composite nanofiber membranes were greater than the pure PVA nanofiber membranes. The largest adsorption capacity was 489.12 mg/g at 303 K. The mesoporous PVA/SiO₂ composite nanofiber membranes exhibited higher Cu²⁺ ion adsorption capacity than other reported nanofiber membranes. Furthermore, the adsorption capacity of the PVA/SiO₂ composite nanofiber membranes was maintained through six recycling processes. Consequently, these membranes can be promising materials for removing, and recovering, heavy metal ions in water.     

Electrospun hydrophilic fumed silica/polyacrylonitrile nanofiber-based composite electrolyte membranes

Hydrophilic fumed silica (SiO₂)/polyacrylonitrile (PAN) composite electrolyte membranes were prepared by electrospinning composite solutions of SiO₂ and PAN in N,N-dimethylformamide (DMF). Among electrospinning solutions with various SiO₂ contents, the 12 wt% SiO₂ in PAN solution has highest zeta potential (−40.82 mV), and exhibits the best dispersibility of SiO₂ particles. The resultant 12 wt% SiO₂/PAN nanofiber membrane has the smallest average fiber diameter, highest porosity, and largest specific surface area. In addition, this membrane has a three-dimensional network structure, which is fully interconnected with combined mesopores and macropores because of a good SiO₂ dispersion. Composite electrolyte membranes were prepared by soaking these porous nanofiber membranes in 1 M lithium hexafluorophosphate (LiPF₆) in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 vol%). It is found that 12 wt% SiO₂/PAN electrolyte membrane has the highest conductivity (1.1 × 10⁻² S cm⁻¹) due to the large liquid electrolyte uptake (about 490%). In addition, the electrochemical performance of composite electrolyte membranes is also improved after the introduction of SiO₂. For initial cycle, 12 wt% SiO₂/PAN composite electrolyte membrane delivers the discharge capacity of 139 mAh g⁻¹ as 98% of theoretical value, and still retains a high value of 127 mAh g⁻¹ as 89% at 150th cycle, which is significantly higher that of pure PAN nanofiber-based electrolyte membranes.     

Solution-blow spun PLA/SiO2 nanofiber membranes toward high efficiency oil/water separation

With the ever frequent of industrial organic solvent emissions and oil spillages, the development of high efficiency oil/water separation materials has attracted extensive attention. Here, PLA-based nanofiber membranes modified with metal oxides (SiO₂, TiO₂, Al₂O₃, and CeO₂) are fabricated through blow spinning the mixed solution of polylactic acid (PLA) and metal oxide nanoparticles (NPs). Results shows that the addition of SiO₂ NPs significantly increases the hydrophobicity of the membranes, while maintaining the excellent superoleophilicity. The PLA/SiO₂ nanofiber membranes demonstrate a higher separation performance than pure PLA, PLA/TiO₂, PLA/Al₂O₃, and PLA/CeO₂ nanofiber membranes with high separation efficiency (~100%) and permeation flux (17,800 L m⁻² h⁻¹ for n-heptane), as well as prominent oil adsorption capacity (19.9 g/g for n-hexane). The successful fabrication of metal oxides modified PLA nanofiber membranes with high separation and adsorption ability, and excellent durability hold great application potential in the field of oily wastewater treatment.     

Plasma-assisted preparation of Fe-Cu bimetal catalyst for higher alcohols synthesis from carbon monoxide hydrogenation

Plasma-assisted Fe-Cu/SiO₂ catalysts were prepared by impregnation technique and characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption isotherms, X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (H₂-TPR) techniques. Catalytic performances for carbon monoxide hydrogenation to higher alcohols were carried out in a fixed-bed reactor at the conditions of T = 300 °C, P = 5 MPa, H₂/CO = 2, GHSV = 6000 ml/g_cat h. Plasma-promoted Fe-Cu bimetal catalyst (FeCuSi-PC) possessed much better catalytic performances than those of conventional sample in the selective hydrogenation of carbon monoxide. XRD and XPS analysis suggested that the plasma assistance in the catalyst preparation remarkably diminished the particle size, improved the catalyst dispersion, and issued an exposure of more copper and iron species on the catalyst surface. The mechanism of plasma on catalyst crystallize size was also discussed.     

Adsorption of Pt(cod)me2 onto organic aerogels from supercritical solutions for the synthesis of supported platinum nanoparticles

The thermodynamics and kinetics of adsorption of Pt(cod)me₂ onto resorcinol-formaldehyde aerogel (RFA) from supercritical carbon dioxide (scCO₂) was investigated by using high performance liquid chromatography (HPLC) to measure Pt(cod)me₂ concentrations in the fluid phase. It was found that the adsorption isotherms of Pt(cod)me₂ at 35 °C for different CO₂ pressures could be represented by modified Langmuir isotherms. The kinetics of adsorption was determined by following the Pt(cod)me₂ uptake of the RFA spheres; these data correspond closely to the behavior from a mass transfer model based on diffusion within the pore volume with the assumption of local equilibrium at the solid-fluid interface. The adsorbed Pt(cod)me₂ molecules were reduced at atmospheric pressure under flowing hydrogen at 200 °C. The resultant Pt nanoparticles were distributed uniformly on the surface and had narrow size distributions. The average particle size of the nanoparticles increased with platinum loading from 2.0 nm at 10 wt.% to 3.3 nm at 34 wt.%. The Pt nanoparticles in an RFA pellet had a uniform radial size distribution, even though the pellet was impregnated with Pt(cod)me₂ for too short a short period of time for the system to reach adsorption equilibrium. The high mobility of the atomic Pt evolved during the reduction process is believed to be responsible for this phenomenon. Performing the adsorption of Pt(cod)me₂ onto RFA at 80 °C led to concurrent reduction and Pt nanoparticle growth.     

Nano-size LiAlO2 ceramic filler incorporated porous PVDF-co-HFP electrolyte for lithium-ion battery applications

The optimized composition of PVdF-co-HFP-LiAlO₂ based micro-porous nano-composite polymer electrolyte membranes (MPNCPEMs) was prepared with a preferential polymer dissolution process. Nitrogen adsorption isotherms and SEM micrographs showed that the enhanced ionic conductivity of polymer electrolyte was due to increase in pore-size, surface area and pore density, results an increase in the electrolyte uptake. The ac-impedance spectroscopy showed that the room temperature ionic conductivity of PVdF-co-HFP-LiAlO₂ based polymer electrolyte membranes increased with the removal of PVA content and attained the maximum ionic conductivity of 8.12 × 10⁻³ S cm⁻¹. The prepared MPNCPEM of high ionic conductivity was subjected into LSV study. Finally, the electrode/electrolyte interfacial resistance was evaluated by monitoring the impedance response at different time intervals.     

Stable oxygen-selective sorbents for air separation

Commercial sorption-based air separation is usually done using nitrogen selective zeolites in pressure swing adsorption (PSA) systems. Separation of air by adsorption of less abundant oxygen is more desirable. In this study we have developed some stable oxygen selective sorbents with silver and cerium salts. AgCl, AgBr, AgI and CeCl₃ all showed stable adsorption characteristics with pure component selectivity of O₂/N₂∼2.0-3.0 at 1 atm. For these salts heat of adsorption of oxygen was found to be slightly higher than that of nitrogen, which was also predicted by ab initio molecular orbital calculations by Chen and Yang (Ind. Eng. Chem. Res. 35 (1996) 4020). The adsorption capacity of these salts was increased by thermal dispersion on high surface area SiO₂ support. AgBr thermally spread on SiO₂ is the best sorbent obtained in this study. AgBr/SiO₂ (1.0 g/g) showed a pure component oxygen selectivity of ∼3 at 1 atm and ∼5 at 7 atm. PSA simulations were used to show the feasibility of nitrogen production using AgBr/SiO₂.     

Developing the properties of new blue phosphors: TiO2-doped Zn2SiO4

2ZnO + SiO₂ + X mol% TiO₂ (Zn₂SiO₄-X-TiO₂, 1 ≤ X ≤ 3) and 2ZnO + SiO₂ + 3 mol% MnO₂ (Zn₂SiO₄-3-TiO₂) compositions were prepared using nanoscale ZnO, SiO₂, TiO₂, and MnO₂ particles. The mixing powders were calcined between 1000 °C and 1300 °C in a N₂ atmosphere. Zn₂SiO₄ was the only phase in the calcined Zn₂SiO₄-X-TiO₂ phosphors. We found that the photoluminescence (PL) properties of synthesized Zn₂SiO₄-X-TiO₂ phosphors revealed these to be blue rather than green. The effects of TiO₂ content and calcining temperature on the PL properties of Zn₂SiO₄-X-TiO₂ phosphors were rigorously investigated.     

Influences of polyacrylic acid adsorption and temperature on the alumina suspension stability

The temperature influence on the alumina (Al₂O₃) suspension stability in the absence and presence of polyacrylic acid (PAA) was studied. The investigated temperature range was 15-35 °C. Stability measurements were carried out by the use of Turbiscan Lab^Expert with a thermostatic system. Additionally, at 25 °C the suspension stability was determined from the spectrophotometric data.The obtained data and calculated values of Turbiscan Stability Indexes (TSI) suggest that for the alumina suspensions without polymer, the values of TSI and the rates of solid particles settling as well as the thickness of sediment were the lowest at all investigated temperatures. Moreover the PAA adsorption causes pronounced decrease of system stability at 15 and 35 °C while at 25 °C polyacrylic acid adsorption slightly improves the alumina stability. The conformational changes of adsorbed polymer macromolecules are responsible for such behaviour of the investigated systems. At all investigated temperatures the solid suspension is not stable in the presence of PAA. In the case of PAA 2 000 the coagulation by charge neutralization takes place, whereas in the case of PAA 240 000 the bridging flocculation is the most probable process. The destabilization of systems by the adsorbed polymer occurs with the lowest effectiveness at 25 °C.     

Double phase separation in preparing polyimide/silica hybrid films by sol-gel method

In this paper, the phase separation process of the polyimide/silica hybrid films made from polyamic acid (PAA) and precursor (TEOS-A) hydrolyzed tetraethoxysilane under acidic condition in N-methyl-2-pyrrolidone (NMP) through sol-gel method was investigated by the scanning electron microscope (SEM). A double phase separation was discovered for the preparation of the hybrid films. With evaporation of the solvent NMP at lower than 100 °C, the component miscibility of TEOS-A and PAA decreases so that the first phase separation took place and a larger particle phase of TEOS-A precursor with size around 2.0 μm was formed. The second phase separation from the matrix phase appeared, as PAA was imidized at elevated temperature, which destroyed the interaction between carboxyl group of PAA and hydroxyl group of TEOS-A, and a nanoscale SiO₂ particle phase formed. The formation mechanism of the double phase separation was explained by the “capture-release” model. According to the model, the second phase separation can be controlled by synthesizing amic acid-imide copolymer with different contents of carboxyl group.     

Electrochemical enhancement of adsorption capacity of activated carbon fibers and their surface physicochemical characterizations

The adsorption of activated carbon fibers (ACFs) and their surface characteristics were investigated before and after electrochemical polarization. The adsorption kinetics of m-cresol showed the dependence on polarized potential, and the adsorption rate constant increased by 77.1%, from 6.38 × 10⁻³ min⁻¹ at open-circuit (OC) to 1.13 × 10⁻² min⁻¹ at polarization of 600 mV. The adsorption isotherms at different potentials were in good agreement with Langmuir isotherm model, and the maximum adsorption capacity increased from 2.28 mmol g⁻¹ at OC to 3.67 mmol g⁻¹ at polarized potential of 600 mV. These indicated that electrochemical polarization could effectively improve the adsorption rate and capacity of ACFs. The surface characteristics of ACFs before and after electrochemical polarization were evaluated by N₂ adsorption-desorption isotherms, scanning electron microscope (SEM), zeta potential and Fourier transform infrared spectroscopy (FTIR). The results showed that the BET specific surface area and pore size increased as the potential rose. However, the surface chemical properties of ACFs hardly changed under electrochemical polarization of less than 600 mV. This study was beneficial to understand the mechanism of electrochemically enhanced adsorption.     

Adsorption characteristics of sericite for cesium ions from an aqueous solution

To efficiently remove cesium ions from aqueous solution, sericite was used as a novel adsorbent. The silanol (SiO₂) and aluminol (Al₂O₃) groups in sericite are likely to play an important role in adsorption process. The maximum adsorption capacity (q_m) and adsorption constant (K_L) for cesium ions obtained from the Langmuir isotherm model were 6.68 mg/g and 0.227 L/mg, respectively and regression curve fit well with the experimental data as the 0.965 of correlation coefficients (r²). However, when the Freundlich isotherm model was used correlation coefficient (r²) was 0.973. Therefore, it was concluded that Freundlich model fits equilibrium data better than Langmuir model. When the 6.0 g/L of sericie concentration was added to aqueous solution, cesium ions were removed by about 80% and the increase was not happened above 6.0 g/L of sericite concentration any more. The process was determined as exothermic reaction because the removal efficiency of cesium ions decreased as temperature increased. Furthermore, all adsorption was completed in 120 min and comparing the pseudo first and second-order kinetic models indicates that the adsorption of cesium ions using sericite follows well the pseudo-second-order kinetics.     

Hybrid inorganic-organic proton conducting membranes based on Nafion, SiO2 and triethylammonium trifluoromethanesulfonate ionic liquid

New hybrid inorganic-organic nanocomposite proton conducting membranes based on Nafion, SiO₂ and triethylammonium trifluoromethanesulfonate (TEATF), a protic ionic liquid, were prepared in two steps. First, various [Nafion/(SiO₂)_ψ] membranes with a SiO₂ weight percentage ranging from 0 to 15 wt.% were prepared by a solvent-casting protocol from DMF solutions. Second, the resulting hybrid membranes were neutralized with triethylammine (TEA) and then impregnated with triethylammonium trifluoromethanesulfonate (TEATF). The structure of the bulk hybrid materials and the interactions occurring between their components were investigated by vibrational spectroscopy (FT-IR ATR and FT-Raman). These latter studies allowed to determine that: (a) the fluorocarbon domains of Nafion consist of a mixture of helical chains with 10₃ and 15₇ helical conformations; (b) interactions take place between the components of the hydrophilic domains, which give rise to micelle-like nanoparticles where a SiO₂ core is covered by a shell of solvating TEATF molecules. The thermal, mechanical and electrical properties of the proposed materials were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC) measurements, by dynamical mechanical analyses (DMA) and by broadband dielectric spectroscopy (BDS), respectively. The electric measurements indicated that [Nafion/(SiO₂)_ψ(TEA)]_3.67/(TEATF)_1.2 exhibits a σ_dc of 4.7 × 10⁻³ S cm⁻¹ at T = 105 °C and a SRC of 5 < T < 135 °C. These results classified this membrane as a very promising material for application in fuel cells.     

Characterisation of a re-cast composite Nafion 1100 series of proton exchange membranes incorporating inert inorganic oxide particles

A series of cation exchange membranes was produced by impregnating and coating both sides of a quartz web with a Nafion^® solution (1100 EW, 10%wt in water). Inert filler particles (SiO₂, ZrO₂ or TiO₂; 5-20%wt) were incorporated into the aqueous Nafion^® solution to produce robust, composite membranes. Ion-exchange capacity/equivalent weight, water take-up, thickness change on hydration and ionic and electrical conductivity were measured in 1 mol dm⁻³ sulfuric acid at 298 K. The TiO₂ filler significantly impacted on these properties, producing higher water take-up and increased conductivity. Such membranes may be beneficial for proton exchange membrane (PEM) fuel cell operation at low humidification. The PEM fuel cell performance of the composite membranes containing SiO₂ fillers was examined in a Ballard Mark 5E unit cell. While the use of composite membranes offers a cost reduction, the unit cell performance was reduced, in practice, due to drying of the ionomer at the cathode.     

Photopolymerization synthesis of polyacrylic acid dispersant with methoxysilicon end groups and its application in a nano‐SiO2 aqueous system

In order to improve the dispersity and stability of the nano‐SiO₂ aqueous system with high solid content, a kind of polyacrylic acid dispersant with methoxysilicon end groups (KH590‐PAA) was synthesized by photopolymerization of acrylic acid (AA) initiated with (3‐mercaptopropyl)trimethoxysilane (KH590). After adding KH590‐PAA into the nano‐SiO₂ aqueous dispersion system (20 wt% solid content), the viscosity and the curing time of the system were measured with a rotational viscometer and the inverted bottle method. Moreover, the dispersion mechanism of KH590‐PAA for the nano‐SiO₂ aqueous system was researched by measuring the adsorption capacity, the particle size and the zeta potential of the nanoparticles with a conductivity meter, dynamic light scattering, SEM and TEM, respectively. The results showed that the methoxysilicon groups in KH590‐PAA could react with hydroxyl groups on the surface of nano‐SiO₂ in the process of stirring, which enhanced the adsorption capacity of the dispersant and then increased the surface charge of the particles. Therefore, electrostatic repulsion and steric hindrance effects between the SiO₂ nanoparticles could be further enhanced by adding the KH590‐PAA dispersant, and then the nano‐SiO₂ aqueous system exhibited better dispersity and stability. Besides, the dispersion properties of SiO₂ nanoparticles in water were closely related to the addition amount and the molecular weight of the KH590‐PAA dispersant. © 2018 Society of Chemical Industry     

Adsorption kinetics and equilibrium of copper from ethanol fuel on silica-gel functionalized with amino-terminated dendrimer-like polyamidoamine polymers

The adsorption kinetics and equilibrium of silica-gel functionalized with amino-terminated dendrimer-like polyamidoamine (PAMAM) polymers SiO₂-G1.0, SiO₂-G2.0 and SiO₂-G3.0 for Cu²⁺ in ethanol fuel were investigated by using batch method. The results indicated that the all the adsorptions of the three adsorbents followed well the pseudo second-order model. The adsorption isotherms were fitted by Langmuir model, Freundlich model and Dubinin–Radushkevich (D–R) model. The results showed that Langmuir model was more suitable to describe the equilibrium data than the Freundlich model. From the D–R isotherm model, the mean free energy E calculated of the three adsorbents showed that the adsorptions were taken place by physical processes. Thermodynamic parameters, ΔG⁰, ΔH⁰ and ΔS⁰ indicated the Cu²⁺ adsorption to be endothermic and spontaneous with decreased randomness at the solid-solution interface, resulting in their higher adsorption capacities at higher temperature. The effect of generation number of PAMAM polymers loaded on silica-gel, contact time, initial concentration and temperatures on the adsorption capabilities were studied in detail. Moreover, the adsorption mechanism of copper from ethanol fuel was also presumed.     

Study of the adsorption of phenol by two soils based on kinetic and isotherm modeling analyses

Various natural adsorbents, which have been in used for removal of pollutants, in general, and phenol, in particular, are mostly directed towards improving the adsorption capacity of the adsorbents by various pretreatments (chemical, thermal or biological), which necessarily lead to increase in the cost as well as in the level of difficulties in regeneration/disposal of the adsorbent. The present studies, on the other hand, are aimed towards evaluating the feasibility of using two common soils as potential low-cost adsorbents for the removal of phenol from its aqueous solution, in their natural forms (i.e., without any pretreatment). Accordingly, experiments were carried out (in batch mode) for optimization of the adsorption parameters (such as pH, contact time, equilibrium time and adsorbent dosage), for varying initial phenol concentrations. The results showed that the maximum phenol adsorption capacity was found at pH ~6, under a constant temperature of 30 ± 2 °C (at 6-hour equilibrium period). Several kinetic models (viz. Lagergren first-order, pseudo-second-order, Elovich and intra-particle diffusion) as well as isotherm models (Langmuir, Freundlich, Redlich and Peterson and Sip) were applied to the experimental data. The pseudo-second-order model was found to be the most suitable model describing the adsorption of phenol by two soils (which indicated this adsorption as a chemisorption process). On analysis of equilibrium isotherms for the adsorption of phenol by two soils, Redlich-Peterson and Sip isotherms were found to be the best representative for phenol-sorption on two selected, soil adsorbents.     

Adsorption of N2, CH4, CO and CO2 gases in single walled carbon nanotubes: A combined experimental and Monte Carlo molecular simulation study

In this study, the adsorption capacity of single-wall carbon nanotubes (SWCNTs) bundles with regard to the pure CH₄, N₂, CO and CO₂ gases at 298 K and pressure range from 0.01 up to 2.0 MPa has been investigated experimentally and computationally. Experimental work refers to gravimetric surface excess adsorption measurements of each gas studied in this nanomaterial. Commercial samples of pristine SWCNTs, systematically prepared and characterized at first, were used for the evaluation of their adsorption capacity. A Langmuir type equation was adopted to estimate the total adsorption isotherm based on the experimental surface excess adsorption data for each system studied. Computational work refers to Monte Carlo (MC) simulation of each adsorbed gas on a SWCNTs model of the type (9, 9) in the grand canonical (GC) ensemble at the same conditions with experiment using Scienomics’ MAPS platform software simulation packages such as Towhee. The GCMC simulation technique was employed to obtain the uptake wt% of each adsorbed gas by considering a SWCNTs model of arrays with parallel tubes exhibiting open-ended cylindrical structures as in experiment. Both experimental and simulation adsorption data concerning these gases within the examined carbon material are presented and discussed in terms of the adsorbate fluid molecular characteristics and corresponding interactions among adsorbate species and adsorbent material. The adsorption isotherms obtained exhibited type I (Langmuir) behavior, providing enhanced gas-substrate interactions. We found that both the experimental as well as the simulated adsorption uptake of the examined SWCNTs at these conditions with regard to the aforementioned fluids and in comparison with adsorbate H₂ on the same material increase similarly and in the following order: H₂ ? N₂ ≈ CH₄ < CO ? CO₂. Furthermore, for each adsorbate fluid the calculations exhibit somewhat greater gas uptake with pressure compared to the corresponding experiment. The difference in the absolute uptake values between experiment and simulation has been discussed and ascribed to the following implicit factors: (i) to the employed model calculations, (ii) to the remained carbonaceous impurities in the sample, and (iii) to a proportion of close ended tubes, contained in the experimental sample even after preparation.     

Activated carbon/CoFe2O4 composites: Facile synthesis,magnetic performance and their potential application for the removal of malachite green from water

Activated carbon/CoFe₂O₄ composite (AC/CFO) was synthesized by a simple one-step refluxing route and was used as adsorbent for the removal of malachite green (MG) dye from water. The structure, morphology and magnetic properties of as-prepared composite were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The results indicated that CoFe₂O₄ particles deposited on the surface of activated carbon in the composite were uniform with the particle size in the range of 14–20 nm. The composite adsorbents exhibited a clearly hysteretic behavior under applied magnetic field, which allowed their magnetic separation from water. Batch experiments were carried out to investigate adsorption isotherms and kinetics of MG onto the composite. The experimental data fitted well with the Langmuir model with a monolayer adsorption capacity of 89.29 mg g^?1. The adsorption kinetics was found to follow pseudo-second-order kinetic model. It was indicated that the as-prepared composite could be used as a promising and effective adsorbent for the removal of MG from water.     

Influence of silica nanoparticles added to an organosilane film on carbon steel electrochemical and tribological behaviour

The electrochemical behaviour and tribological properties of carbon steel coated with bis-[trimethoxysilylpropyl]amine (BTSPA) filled with SiO₂ were evaluated. The silane film filled with SiO₂ was prepared by adding different SiO₂ concentrations. The electrochemical behaviour of the coated steel was mainly evaluated by means of open-circuit potential (E_OC), electrochemical impedance spectroscopy (EIS) and polarization curves, in 0.1 mol L⁻¹ NaCl solution. Structural and morphological characterizations were made by optical, electron and atomic force microscopy (AFM). E_OC and EIS data showed that sample filled with 300 ppm SiO₂ presented the highest E_OC and total impedance value. AFM measurements showed a homogeneous particle distribution of SiO₂ particles. Nanohardness measurements showed SiO₂ promoted an increase of the hardness mean value (1.70 ± 0.11 GPa to non-filled BTSPA and 2.21 ± 0.05 GPa for sample filled with 300 ppm SiO₂). Silane films when filled with SiO₂ particles improved the corrosion resistance of the steel substrate. The optimum SiO₂ particles concentration in silane solution is 300 ppm SiO₂. Incorporation of an extra amount of silica into BTSPA film led to degradation of the corrosion protection of the film to the substrate.