Concentration Of Silica Nanoparticles Research Articles

Reducing surfactant adsorption on rock by silica nanoparticles for enhanced oil recovery

This paper aims at making a thorough investigation on surfactant adsorption on rock under the influence of silica nanoparticles (SNP). The results showed that SNP can reduce surfactant adsorption effectively. With SNP concentration of 0.1, 0.2 and 0.3wt%, static adsorption experiments showed that sodium dodecyl sulfate (SDS) adsorption can be significantly reduced to 2.57, 2.12, and 1.73 from 2.84mg/g, and the dynamic adsorption of SDS decreased to 0.92, 0.77, and 0.66 from 1.16mg/g, respectively. Our subsequent tests conformed a 4.68% growth of oil recovery by the injection of SNP - surfactant solution compared to the normal surfactant solution. The mechanism of the enhanced oil recovery is assumed to be the inhibition of surfactant adsorption and the profile control capability of silica nanoparticles. This study proves the SNP - surfactant flooding is a cost-effective way for enhanced oil recovery.

Interaction of toughening mechanisms in ternary nanocomposites

Silica nanoparticles (SNP) and core‐shell‐rubber (CSR) nanoparticles were added to a lightly crosslinked epoxy in an effort to improve fracture toughness. Properties such as the glass transition temperature, tensile modulus, and yield strength were also measured. Toughening mechanisms were studied by inspecting the fracture surfaces with scanning electron microscope and exploring subsurface damage using both transmission optical microscope and transmission electron microscope. Ternary nanocomposities with a fracture energy five times that of the unmodified epoxy resin were obtained with no discernible drop in the tensile modulus. The increase in stiffness due to the presence of SNP and the increase in compliance due to the presence of CSR were accurately predicted using the Mori‐Tanaka micromechanical model. Unfortunately, the use of SNP did not result in the retention of strength in the ternary nanocomposites. Maximum toughness was observed when the SNP content was 4 vol% and the CSR content was 7 vol%. This combination of particles also resulted in the largest damage zone (subsurface), which agrees well with fracture toughness results. The interaction of toughening mechanisms in rubber‐SNP‐epoxy systems was found to be affected by the interparticle distance between rubber particles. The non‐debonding SNPs between rubber particles could act as shear band stoppers and/or ductility suppressors, which suppressed the toughening performance of rubber particles. On the other hand, the SNPs induce more shear bands between SNPs to increase the toughening performance. The total toughening performance depends on the rubber interparticle distance. POLYM. COMPOS., 39:3482–3496, 2018. © 2017 Society of Plastics Engineers

Strong cellulose nanofibre–nanosilica composites with controllable pore structure

Flexible nanocellulose composites with silica nanoparticle loading from 5 to 77 wt% and tunable pore size were made and characterised. The pore structure of the new composites can be controlled (100–1000 nm to 10–60 nm) by adjusting the silica nanoparticle content. Composites were prepared by first complexing nanoparticles with a cationic dimethylaminoethyl methacrylate polyacrylamide, followed by retaining this complex in a nanocellulose fibre network. High retention of nanoparticles resulted. The structural changes and pore size distribution of the composites were characterised through scanning electron microscopy (SEM) and mercury porosimetry analysis, respectively. The heavily loaded composites formed packed bed structures of nanoparticles. Film thickness was approximately constant for composites with low loading, indicating that nanoparticles filled gaps created by nanocellulose fibres without altering their structure. Film thickness increased drastically for high loading because of the new packed bed structure. Unexpectedly, within the investigated loading range, the level of the tensile index on nanocellulose mass basis remained constant, showing that the silica nanoparticles did not significantly interfere with the bonding between the cellulose nanofibres. This hierarchically engineered material remains flexible at all loadings, and its unique packing enables use in applications requiring nanocellulose composites with controlled pore structure and high surface area.

High strength sustainable concrete using silica nanoparticles

This study deals with the effect of silica nanoparticles (SNPs) in high volume fly ash (40% replacement) cement paste, mortar and concrete. The content of SNPs (0.5–3.0%) was added by the weight of binder and w/b ratio (0.23, 0.25 & 3.0) was optimized in paste and mortar system. The calorimetric results reveal that the hydration process was accelerated as a result of SNPs incorporation and the dormant period was shortening by 4h with 2% SNPs as compared to the control. The effect of optimum dosages of SNPs addition on concrete in terms of mechanical and durability properties was studied at 0.25w/b ratio. The compressive strength results of SNPs added mixtures showed an improvement of 61% at 3days and 25% at 28days of hydration as compared to control. The durability studies at 28day showed that, with the incorporation of SNPs, the porosity, sorptivity and water absorption reduced up to 25–40% and densify the interfacial transition zone (ITZ).

New findings of silica nanoparticles induced ER autophagy in human colon cancer cell

Nanoparticle-induced autophagy has been extensively studied, however, real time information about the endoplasmic reticulum involved autophagic process (ER autophagy) induced by nanomaterials remains unknown. In this work, silica nanoparticles (SNPs) were synthesized with characteristics of low toxicity, good biocompatibility and excellent water dispersibility to treat cells. Results show that either low concentration (10 μg/mL) or high concentration (200 μg/mL) of SNPs could increase the quantity of processing from microtubule-associated protein 1-light chain 3-I (LC3-I) to the other variant of LC3 (LC3-II). Interestingly, the level of autophagy induced by the SNPs is associated with the treated time but not the concentrations of SNPs. Importantly, for the first time, SNP accumulation in ER was discovered through co-localization analysis, which incurs ER autophagy. These new findings about SNPs-induced ER autophagy could open an effective way for securely designing silica-based nanoparticles and enable us to know more about ER autophagy.

Silica nanofluid flooding for enhanced oil recovery in sandstone rocks

Enhanced oil recovery is proposed as a solution for declining oil production. One of the advanced trends in the petroleum industry is the application of nanotechnology for enhanced oil recovery. Silica nanoparticles (SiNPs) are believed to have the ability to improve oil production, while being environmentally friendly and of natural composition to sandstone oil reservoirs.In our work, we investigated the effect of silica nanoparticles flooding on the amount of oil recovered. Experiments were carried using commercial silica of approximately 20nm in size. We used sandstone cores in the core flooding experiments. For one of the cores tertiary recovery is applied where brine imbibition was followed by nanofluid imbibition. While in the other cores secondary recovery was applied where primary drainage is directly followed by nanofluid imbibition. We investigated the effect of concentration of nanofluid on recovery; in addition, residual oil saturation was obtained to get the displacement efficiency. Silica nanofluid of concentration 0.01wt%, 0.05wt%, 0.1wt% and 0.5wt% were studied.The recovery factor improved with increasing the silica nanofluid concentration until optimum concentration was reached. The maximum oil recovery was achieved at optimum silica nanoparticles concentration of 0.1wt%. The ultimate recovery of initial oil in place increased by 13.28% when using tertiary flooding of silica nanofluid compared to the recovery achieved by water flooding alone. Based on our experimental study, permeability impairment was investigated by studying the silica nanoparticles concentration, and the silica nanofluid injection rate. The permeability was measured before and after nanofluid injection. This helped us to understand the behavior of the silica nanoparticles in porous media. Results showed that silica nanofluid flooding is a potential tertiary enhanced oil recovery method after water flooding has ceased.

Removal of methylene blue from its aqueous solution by froth flotation: hydrophobic silica nanoparticle as a collector

Dye pollution has been a severe problem faced by worldwide environmentalists. The use of nanoparticles as adsorbents has attracted widespread interests for effectively removing dyes, while the separation of them from an aqueous solution is a difficult and important subject. For achieving the simultaneous removal of methylene blue (MB) and nanoadsorbents, this work utilized a commercial hydrophobic silica nanoparticle (SNP) (200.0 ± 10.0 nm in average particle size) as a collector and then developed a novel froth flotation technology without using any surfactants. Under the suitable conditions of anhydrous ethanol dosage of 8 mL, pH of 9.0, SNP concentration of 600 mg/L, and flotation column height of 600 mm, the removal efficiencies of MB and SNPs and the volume ratio reached 91.1 ± 4.6%, 93.9 ± 4.7%, and 10.5 ± 0.5, respectively. Subsequently, the recovered MB-adsorbed SNPs in the foamate were separated by free setting due to their high concentration and massive agglomeration. After free setting, MB could be effectively separated from the recovered MB-adsorbed SNPs by using ethanol at pH 2.0 and repeating five cycles of washing-centrifugation. Additionally, the regenerated SNPs could be reused for removing MB up to five times. Overall, this work had a significant meaning for the treatment of dye-contaminated wastewaters.

Structure and Interaction in the pH-Dependent Phase Behavior of Nanoparticle–Protein Systems

The pH-dependent structure and interaction of anionic silica nanoparticles (diameter 18 nm) with two globular model proteins, lysozyme and bovine serum albumin (BSA), have been studied. Cationic lysozyme adsorbs strongly on the nanoparticles, and the adsorption follows exponential growth as a function of lysozyme concentration, where the saturation value increases as pH approaches the isoelectric point (IEP) of lysozyme. By contrast, irrespective of pH, anionic BSA does not show any adsorption. Despite having a different nature of interactions, both proteins render a similar phase behavior where nanoparticle-protein systems transform from being one-phase (clear) to two-phase (turbid) above a critical protein concentration (CPC). The measurements have been carried out for a fixed concentration of silica nanoparticles (1 wt %) with varying protein concentrations (0-5 wt %). The CPC is found to be much higher for BSA than for lysozyme and increases for lysozyme but decreases for BSA as pH approaches their respective IEPs. The structure and interaction in these systems have been examined using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The effective hydrodynamic size of the nanoparticles measured using DLS increases with protein concentration and is related to the aggregation of the nanoparticles above the CPC. The propensity of the nanoparticles to aggregate is suppressed for lysozyme and enhanced for BSA as pH approached their respective IEPs. This behavior is understood from SANS data through the interaction potential determined by the interplay of electrostatic repulsion with a short-range attraction for lysozyme and long-range attraction for BSA. The nanoparticle aggregation is caused by charge neutralization by the oppositely charged lysozyme and through depletion for similarly charged BSA. Lysozyme-mediated attractive interaction decreases as pH approaches the IEP because of a decrease in the charge on the protein. In the case of BSA, a decrease in the BSA-BSA repulsion enhances the depletion attraction between the nanoparticles as pH is shifted toward the IEP. The morphology of the nanoparticle aggregates is found to be mass fractal.

Reinforcement of a PMMA resin for interim fixed prostheses with silica nanoparticles

PurposeFractures in long span provisional/interim restorations are a common complication. Adequate fracture toughness is necessary to resist occlusal forces and crack propagation, so these restorations should be constructed with materials of improved mechanical properties. The aim of this study was to investigate the possible reinforcement of neat silica nanoparticles and trietoxyvinylsilane-modified silica nanoparticles in a PMMA resin for fixed interim restorations. Materials and methodsComposite PMMA-Silica nanoparticles powders were mixed with PMMA liquid and compact bar shaped specimens were fabricated according to the British standard BS EN ISO 127337:2005. The single-edge notched method was used to evaluate fracture toughness (three-point bending test), while the dynamic thermomechanical properties (Storage Modulus, Loss Modulus, tanδ) of a series of nanocomposites with different amounts of nanoparticles (0.25%, 0.50%, 0.75%, 1% w.t.) were evaluated. Statistical analysis was performed and the statistically significant level was set to p<0.05. ResultsThe fracture toughness of all experimental composites was remarkably higher compared to control. There was a tendency to decrease of fracture toughness, by increasing the concentration of the filler. No statistically significant differences were detected among the modified/unmodified silica nanoparticles. Dynamic mechanical properties were also affected. By increasing the silica nanoparticles content an increase in Storage Modulus was recorded, while Glass Transition Temperature was shifted at higher temperatures. ConclusionsUnder the limitations of this in-vitro study, it can be suggested that both neat silica nanoparticles and trietoxyvinylsilane-modified silica nanoparticles, especially at low concentrations, may enhance the overall performance of fixed interim prostheses, as can effectively increase the fracture toughness, the elastic modulus and the Glass Transition Temperature of PMMA resins used in fixed provisional restorations.

Fabrication of Self-Cleaning and Anti-Icing Durable Surface on Glass

Ice accumulation on insulators affected the safety of power system and may inflict serious consequences such as insulator flashover accidents and power failure. This article reported a simple method to prepare anti-icing polydimethylsiloxane superhydrophobic surface on glass by utilizing nano-particle filling method. The effect of concentration of silica nanoparticles on superhydrophobicity of the samples was investigated. The wettability, surface morphology and anti-icing property of the as-prepared superhydrophobic surface were characterized by corresponding methods. Results show that the as-prepared surface with addition amount of 7 g silica nanoparticles exhibited self-cleaning property and excellent superhydrophobicity with a contact angle of 165.7 ± 2.4° and a sliding angle of 3.8°. It was found that the ice formation was delayed for 29 min at −5 °C. Moreover, the as-prepared superhydrophobic surface showed superhydrophobicity in the pH range of 1–13 and exhibited excellent drop impact stability. The as-prepared superhydrophobic surface may be suitable for applications in cold regions owing to its flexibility, durability and anti-icing property.

Role of Silica Nanoparticles on Structural, Optical and Morphological Properties of Poly(Vinyl Chloride-co-Vinyl Acetate-co-2- Hydroxypropyl Acrylate) Copolymer

Pure silica nanoparticles (SNPs) have been successfully obtained by thermal treatment of rice husk through a sol-gel surfactant free technique. Different concentrations of SNPs were embedded within the poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate) (PVVH) copolymer matrix via a solvent casting method. X-ray diffraction analysis (XRD) confirmed the amorphous nature for PVVH combined with an increase in the amorphous regions after addition of SNPs. Fourier transform infrared (FTIR) and ultraviolet/visible (UV/Vis.) spectroscopy revealed the induced changes in chemical structure and optical parameters (i.e. optical energy gap Eg, refractive index n) for PVVH/SNPs composites. Scanning electron microscopy (SEM) was performed to study the surface morphology and homogeneity of the prepared samples.

Preparation and Properties of Soluble, Thermally Stable Poly(Silyl ether amide)s and Related Silica Nanocomposites

ABSTRACTSoluble poly(silyl ether amide)s and related nanocomposites with improved thermally stability was prepared. For this, a diamine was prepared through reaction of para-aminophenol with dichlorodiphenylsilane. Structure of diamine was confirmed with conventional spectroscopic methods. Poly(silyl ether amide)s was synthesized through polycondensation of diamine with different diacid chlorides. Properties of poly(silyl ether amide)s comprising thermal behavior, thermal stability, solubility, solution viscosity, and morphology were studied. Polymers showed high thermal stability and good solubility in organic solvents due to their unique structures. Related nanocomposites with different contents of silica nanoparticles (10–40 wt%) were prepared and their properties compared with pristine polyamides.

Analysis of morphological behaviour and electro-optical properties of silica nanoparticles doped polymer dispersed liquid crystal composites

We have prepared silica nanoparticles (SNPs) doped polymer dispersed liquid crystal (PDLC) composites by using varying concentrations of SNPs. The varying concentration of SNPs has a profound impact on the morphology and electro-optical properties of PDLC. The polarizing optical microscopy (POM) studies revealed a substantial non- homogeneity/dual sized droplet morphology in the LC droplet size induced by the SNPs. The relative transmission was enhanced in the SNP-PDLC composites as compared to the undoped PDLC. The threshold voltage (Vth) of the doped composites decreased as compared to the undoped PDLC but increasing SNP concentration had a slight impact on the threshold voltage (Vth) as well as transmission. The effect of SNPs on nematic-isotropic transition temperature (TN-I) and ionic conductivity was also clarified.

A biology research of collagen/silica composite nerve scaffolds in vitro

Objective To discuss the effect of collagen/silicon composite scaffolds in the peripheral nerve regeneration, and evaluate the adhesion and proliferation of Schwann cells within the scaffolds. Methods In this study, from March, 2013 to May, 2014, the collagen/silicon composite scaffolds with 5, 10, 25, 50 and 100 μg/ml were made by freeze-drying technology, and the single collagen scaffold without silica nanoparticles was made with the same method as a control group. The diameter and size of the silica nanoparticles were measured by light scattering, and the morphology of silica nanoparticles were scanned by electron microscope. The cellular compatibility of composite scaffolds was inspected by cultivating Schwann cells on the scaffolds in vitro. The morphology of the Schwann cells in different sample were observed under optical microscope. The adhesion and proliferation effect of the Schwann cells on the scaffolds were determined by MTT. The DNA content of the cells were measured by fluorescence spectrophotometer. Experimental data were expressed by mean ± standard deviation (SD) values. Data were analyzed using One-way ANOVA followed by Bonferroni’s post hoc comparison tests. Statistics with a value of P < 0.05 indicated statistical significance. Results The average diameter of the nanoparticles mainly distributed from 150 to 190 nm and showed a spheric morphology. Morphologically, all the cultured cells were observed to be in healthy state in most scaffolds except for the scaffolds with 100 μg/ml silica nanoparticles. Whereas all the cells on other samples displayed spindle shape with axons spreading, and there was no obvious morphology difference for the cells on these samples. The results of cytocompatibility of the collagen/silica composite scaffolds using MTT assay showed that both the viability and proliferation of Schwann cells increased firstly and then decreased with the increasing concentration of silica nanoparticles. And the cells showed much better viability and proliferation when the concentration of silica nonoparticles was 25 μg/ml compared with other samples. While the cell viability was significantly decreased when the concentration of silica nonoparticles was larger than 50 μg/ml, which was consistent with the morphology results. The DNA contents of Schwann cells in scaffolds also increased firstly and then decreased with the increment of silica nanoparticles concentratin, and the cells in the composite scaffolds with 25 μg/ml silica nanoparticles showed the largest DNA contents. Conclusion The collagen/silica composite scaffold with 25 μg/ml may contribute to the regeneration of peripheral nerve in the future. Key words: Silica nanoparticles; Collagen; Nerve scaffold; Schwann cell

Understanding functionalized silica nanoparticles incorporation in thin film composite membranes: Interactions and desalination performance

Incorporation of functional nanoparticles in polymer membranes is a promising approach for the development of advanced thin film nanocomposite (TFN) membranes with improved desalination performance. This study was aimed to fabricate TFN membranes incorporated with functionalized silica nanoparticles (SNs), which were synthesized with different sizes (~50 and ~100nm) and surface functionalities (hydroxyl, epoxy and amine). Research focused on getting a better understanding of the interfacial interactions between SNs and polymer matrix and structure-property correlation of the TFN membranes. The physicochemical properties of the functionalized SNs and the TFN membranes were characterized using ATR-FTIR, TGA, DLS, SEM, TEM, XPS, tensiometer and streaming potential analysis. The results confirm successful incorporation of the surface functionalized SNs into the polymer membranes. The concentration, size and surface functionality of SNs were found to have strong impact on the surface hydrophilicity, morphology and chemistry of the TFN membranes. The SNs hybridized TFN members showed increased permeate flux and insignificant change in salt rejection. The surface functionalization of SNs with amine and epoxy moieties could facilitate the chemical interaction between SNs and polymer monomers, resulting in stabilizing the TFN membranes. Our research outcomes have provided new insight into the structure-performance correlation of TFN membranes and can be beneficial for fabrication of a wide range of nanoparticle incorporated membranes.

Low density polyethylene/silica nanocomposite foams. Relationship between chemical composition, particle dispersion, cellular structure and physical properties

This paper presents the production and characterization of polymeric nanocomposite foams based on low density polyethylene (LDPE) and different contents of silica nanoparticles. The properties of these foamed materials are conditioned by the properties of the polymer matrix and by the characteristics of the cellular structure. In general, when adding nanoparticles several improvements are obtained in both the solid nanocomposite and the cellular structure. However, the achievement of these potential improvements is conditioned by the level of filler dispersion and by the compatibilization degree between the particles and the polymer. This work analyzes the effects on the dispersion and compatibilization levels of adding, or not, a compatibilizer agent (linear low density polyethylene grafted with maleic anhydride, LLDPE-g-MA), with the aim of understanding the structure and properties of the foamed materials produced from these composites. A modified version of the pressure quench method was used to produce the foamed samples. This method allows obtaining net-shaped foams adequate for analyzing both their microstructure and mechanical properties. Results show that for this particular system, the incorporation of the LLDPE-g-MA compatibilizer does not promote a better dispersion but implies significant differences in terms of nucleating efficiency and reinforcing effect of the nanoparticles. While for solid nanocomposites the higher degree of bonding polymer/nanoparticle promoted by the presence of the compatibilizer translates into a positive mechanical reinforcing effect, for foamed nanocomposites, such high level of compatiblization mitigates the nucleating effect of the nanoparticles. This translates into poorer mechanical properties in the foamed samples containing the compatibilizer agent.

Structure and stability of decontamination foam in concentrated nitric acid and silica nanoparticles by image analysis

The structure and stability of decontamination foam containing chemical reagents were investigated by image analysis, for silica nanoparticle (NP) concentrations varying from 0 to 5wt.%. The decontamination foam that contained 1% v/v non-ionic surfactant and 1M HNO3 as the chemical reagents at extremely low pH, was stable for 60min when the silica NP content was greater than 3wt.%. The foam structure was analyzed in terms of bubble size distribution and bubble count to clarify the enhancing effect of silica NPs on the foam stability. Image analysis showed that as the addition amount of silica NPs increased, the total number of formulated bubbles increased while the bubble size decreased. The amount of silica NPs attached to the bubbles increased with the addition of silica NPs, indicating that silica NPs present in the liquid film around the bubbles effectively inhibit bubble breakage. In bubble structure, the thickness of liquid film in silica NPs was higher than that without silica NPs. The measurements of liquid volume in foam confirmed that the chemical reagent increased in the increase of the liquid film. The decontamination efficiency, in terms of weight loss of the corroded specimen, increased in the addition of silica NPs due to the increase of chemical reagents in thicker liquid film. This study provides a new insight into the role of silica NPs in decontamination foam.

Influence of colloidal silica nanoparticles on pullulan-coated BOPP film

Abstract The influence of two different types of colloidal silica (CS) nanoparticles in a main pullulan coating on bi-oriented polypropylene (BOPP) was evaluated in this work with the goal of exploring new and more advantageous applications in the food packaging sector. It was observed that the addition of the nanoparticles did not affect the friction properties of the pristine pullulan coating, with the static and kinetic coefficient mean values being 0.35 and 0.22, respectively. An improvement in the barrier properties against O2 and CO2 was observed for all the tested nanocomposite coatings. The best performance was provided by the particles with the highest surface area (750 m2 g−1) (O2TR ∼30 mL m−2 24 h−1 and CO2TR ∼80 mL m−2 24 h−1 at 23 °C under dry conditions) compared to the pristine pullulan-coated BOPP (O2TR ∼480 mL m−2 24 h−1 and CO2TR ∼1245 mL m−2 24 h−1). Noteworthy, the change in the permeability properties ultimately yielded a decrease of the CO2/O2 selectivity towards 1. The addition of CS nanoparticles did not modify the optical attributes of the pullulan coating, with the final haze values being approximately 1.5% for all nanocomposite layers. The wettability of the final coatings was influenced by the addition of the CS nanoparticles, with a remarkable decrease of the water contact angle to ∼19° for the formulation loaded with the lowest concentration of silica nanoparticles that have the smallest size and the highest surface area. The potential application of the pullulan-CS coatings for MAP-packaged fruit and vegetables is suggested.

Spray Application and Release of Microalgae from Water-in-Oil Emulsions

Background: This study was completed as part of a larger effort to develop emulsions that have high stability for long-term algal cell storage and that release cells rapidly when applied to a pond surface as inoculum. Past research has shown that including silica nanoparticles in the oil phase yields stable emulsions but that cell release upon application takes place on the order of days. Methods: Water-in-oil (W/O) emulsions were prepared with Chlorella sorokiniana and brilliant sulfoflavine (BSF) in the internal phase to investigate the effects of oil phase thickeners on BSF and cell release upon spray application of the emulsion to a water surface. Three oil phase thickeners: Aerosil R974, Bentone 38, and Bentone 150, were tested at concentrations ranging from 0.25-1% (w/w) in the oil phase. Results: The oil phase thickeners had a modest impact on the release of BSF but no significant effect on cell release. In particular, emulsions with Bentone 150 had significantly faster release of BSF than other thickeners. Spray application of the emulsion onto a water surface, however, had a dramatic effect on cell release rate without negatively affecting cell viability. Average spray droplet size was found to be ~45 μm and nearly 100% release of both cells and BSF could be achieved within ~30 minutes. Conclusion: Spray application resulted in rapid release of algae and dye even for emulsions with a high concentration of silica nanoparticles. The fact that thickeners affected the release rate of soluble BSF but not cells suggests the potential to design emulsions with differential release rates of cells and compounds upon spray application. Keywords: Chlorella, controlled release, emulsion, oil phase thickener, silica nanoparticles, spray application.

Electrodialysis heterogeneous ion exchange membranes modified by SiO2 nanoparticles: fabrication and electrochemical characterization.

In the current study mixed matrix heterogeneous cation exchange membranes were prepared by solution casting technique. The effect of SiO(2) nanoparticles in the polymeric solution on the physicochemical properties of prepared membranes was studied. Scanning optical microscope images showed uniform particle distribution and relatively uniform surfaces for the prepared membranes. The membrane water content was reduced by silica nanoparticles in the membranes' matrix. The membrane ion exchange capacity, membrane potential, transport number and selectivity were improved initially by an increase of SiO(2) nanoparticles concentration up to 1%wt in prepared membranes and then showed a decreasing trend with a further increase in additive ratio from 1 to 4%wt. The ionic permeability and flux were also decreased initially by an increase of silica nanoparticles concentration up to 0.5%wt in the membrane matrix and then increased again with a further increase in nanoparticles concentration from 0.5 to 4%wt. Moreover, the results exhibited that using silica nanoparticles in the membrane matrix caused an obvious decrease in areal electrical resistance. The opposite trend was found for membrane mechanical strength using SiO(2) nanoparticles.