Types Of Silica Nanoparticles Research Articles

Epoxy–Silica Functionally Graded Materials: A Review

This article provides an overview of the studies that have been conducted on the characteristics of epoxy resins containing various types of silica nanoparticles and microparticles, as well as their performance in the industrial application of functionally graded materials (FGMs). Silica nanoparticles and microparticles are used to create epoxy resins in order to improve various properties, such as thermal stability, adhesiveness, electrical conductivity, strength, modulus, and toughness. This review examines the literature that has been published in the last decade, compares the results, focuses on the mechanical and thermal properties, and discusses the changes that have resulted in improvements in those properties. Previous experimental findings are presented and contrasted to demonstrate the extent to which silica filler content contributes to improving the properties of composite materials. The findings reveal that the characteristics of epoxy compounds can be improved by adding a particular amount of silica particles. There is a correlation between an increase in the silica amount and an increase in the Young modulus of epoxy compounds, this correlation becomes stronger as the silica amount increases. Additionally, the tensile strength of epoxy compounds increases to a certain limit as the amount of silica nanoparticles increases. In contrast, the hardness of the material increases as the silica amount increases. The density of the material also increases steadily as the silica amount in the material increases. According to thermal analysis results from calorimetric research on epoxy–silica systems, the glass transition temperature increases as the silica amount increases.

Seed nano-priming using silica nanoparticles: effects in seed germination and physiological properties of Stevia Rebaudiana Bertoni

BackgroundThis study aimed to assess the effects of different concentrations of silicon (Si) nutrient sources, including bulk silicon dioxide (bSiO2) and two types of silica nanoparticles, nSiO2 (I) and nSiO2 (II) at different concentrations of 1, 5, 10, 25, 50, and 100 ppm in the germination process of stevia. The priming experiment was conducted using a completely randomized design with three replicates to ensure the reliability of the results.ResultsAll stevia seedlings subjected to nano-priming significantly improved the germination parameters. The germination percentage increased by 106%, reaching 68% in nano-primed seedlings. Similarly, the germination rate showed a remarkable increase of 128.12% at 7.3 day−1. Additionally, the root, shoot, and seedling dry weight increased by 283%, 168.9%, and 220% and determined 0.092, 0.078, and 0.17 g plant−1, respectively, compared to the control. Furthermore, seed priming with nSiO2 (I) at a concentration of 10 ppm resulted in an increased catalase (CAT) activity (36.15 Umg−1 protein) and peroxidase (POX) activity (approximately 0.057 U.mg−1 protein). Also, the highest sucrose amount was observed in the root (equal to 160.4 μg g−1 DW) and shoot (equal to 247 μg g−1 DW) of seedlings primed with 10 ppm of nSiO2 (I). However, it should be noted that nano-priming at the highest concentration led to oxidative damage indicated by an increase in H2O2 concentration. Conversely, bSiO2 demonstrated a lesser effect on improving germination, seedling growth, antioxidant activities, and biochemical attributes compared to nSiO2 (I), and nSiO2 (II).ConclusionsThis study established that seed priming with nSiO2 (I) at a concentration of 10 ppm was the most effective in enhancing germination percentage and rate, root/shoot/dry weight, biochemical attributes, and enzyme activities (such as α-amylase, CAT, and POX). The results suggested that seed priming with nSiO2 (I) at the optimal concentration could improve the seed germination by enhancing the antioxidant system, starch metabolism, and ultimately protecting plants from oxidative damage.Graphical

Rheological and adhesive properties of nanocomposite bitumen binders based on hydrophilic or hydrophobic silica and modified with bio-oil

Improved adhesive and cohesive properties of bitumen blends with bio-oil and two types of silica nanoparticles having either hydrophilic or hydrophobic surface were studied. The morphology of the modified bitumen and its rheological properties at normal and elevated temperatures were also investigated in detail. The addition of 5–20 wt% bio-oil leads to the appearance of a small yield stress in the bitumen melt and a reduction in the loss tangent for the cooled mixture. At the same time, the addition of 5% bio-oil is the most optimal, as it results in an increase of the thermodynamic work of adhesion and the measured adhesive strength of the bitumen binder to the silicate surface by 16–21%. The addition of silica nanoparticles in quantities up to 15 wt% causes a more significant increase in the yield stress as well as an even greater improvement in the stiffness and elasticity of the bitumen binder at normal temperature. Moreover, the nanoparticles increase the cohesive strength of the bitumen binder up to 60% and bidirectionally change its adhesion characteristics, depending on the nature of their surface. At a concentration of 15 wt%, the hydrophobic silica doubles the adhesion of the binder to steel, whereas the hydrophilic one conversely halves it.

Granulometric effect of silica nanoparticles on hydration kinetics and microstructure of cement based materials

Effect of particle size of two types of silica nanoparticles (SNPs) on hydration kinetics of tricalcium silicate (C3S) and Portland cement was investigated. Two different types of SNPs were used in the present study, first one is the synthesized by sol-gel method (SNPs-sg) having particle size 30–70 nm, while the second one is the synthesized by Flame Spray Pyrolysis method (SNPs-fsp) having particle size <10 nm. The dosages of SNPs used in this study varied from 1–10% and water/binder ratio used for the hydration was 0.4. Rietveld analysis of XRD results show that at 4 h of hydration, the unhydrated content in control samples at 4 h hydration was ∼88% and in presence 1% SNPs-sg, it was ∼75%, however, in presence of SNPs-fsp, the content of unhydrated C3S was ∼60%. Further, FTIR results reveal that in case of control samples at 1 h of hydration, the characteristic peaks of C3S at 850 cm−1 and 940 cm−1 are present, while, with 1% SNPs-sg addition, reduction in the intensity C3S peaks were observed showing acceleration in dissolution rate and a broader peak is observed at ∼1110 cm−1 with 1% SNPs-fsp samples indicating the starting of polymerization in silicate chain of C-S-H gel.

Nonlinear charge regulation for the deposition of silica nanoparticles on polystyrene spherical surfaces

HypothesisWe describe the deposition behavior of monodispersed silica nanoparticles on polystyrene spherical particles by using modified pairwise DLVO (Derjaguin-Landau-Verwey-Overbeek) interaction force profiles at pH values between two and twelve. Our modified model contains a new nonlinear charge regulation parameter that considers redistribution of ions, which allows us to realistically express the electrical double layer (EDL) interaction forces. ExperimentsSilanol-terminated silica nanoparticles (7.6 ± 0.4 nm), l-lysine-covered silica nanoparticles (7.8 ± 0.4 nm), and polyallylamine hydrochloride-covered polystyrene (PAH/PS) particles (348 ± 1 nm) were synthesized. Then, each type of silica nanoparticle was deposited on the PAH/PS particles at a range of pH values. FindingsOur new regulation parameter describes the realistic redistribution of charges governed by pH, total salt concentration, ionic strength of solution, and separation distance of particles. We find that this regulation parameter can be roughly approximated from the absolute values of theoretically calculated surface charge density and potential distributions, as well as experimentally measured ζ-potentials. Morphological analysis using electron microscopy of the experimental systems shows that the modified pairwise DLVO interaction forces exceptionally describe the deposition behavior of the silica nanoparticles physically adsorbed on the PAH/PS particle substrates.

Effect of (3-aminopropyl)triethoxysilane on dissolution of silica nanoparticles synthesized via reverse micro emulsion.

Silica nanomaterials have been studied based on their potential applications in a variety of fields, including biomedicine and agriculture. A number of different molecules have been condensed onto silica nanoparticles' surfaces to present the surface chemistry needed for a given application. Among those molecules, (3-aminopropyl)triethoxysilane (APS) is one of the most commonly applied silanes used for nanoparticle surface functionalization to achieve charge reversal as well as to enable cargo loading. However, the colloidal stability of APS-functionalized silica nanoparticles has not been thoroughly studied, which can be problematic when the high reactivity of amine groups is considered. In this study, four different types of silica nanoparticles with varied location of added APS have been prepared via a reverse micro emulsion process, and their colloidal stability and dissolution behavior have been investigated. Systematic characterization has been accomplished using transmission electron microscopy (TEM), silicomolybdic acid (SMA) spectrophotometric assay, nitrogen adsorption-desorption surface area measurement, and aerosol ion mobility-mass spectrometry to track the nanoparticles' physical and chemical changes during dissolution. We find that when APS is on the interior of the silica nanoparticle, it facilitates dissolution, but when APS is condensed both on the interior and exterior, only the exterior siloxane bonds experience catalytic hydrolysis, and the interior dissolution is dramatically suppressed. The observation and analyses that silica nanoparticles show different hydrolysis behaviors dependent on the location of the functional group will be important in future design of silica nanoparticles for specific biomedical and agricultural applications.

Nanocarriers for Biomedicine: From Lipid Formulations to Inorganic and Hybrid Nanoparticles.

Encapsulation of cargoes in nanocontainers is widely used in different fields to solve the problems of their solubility, homogeneity, stability, protection from unwanted chemical and biological destructive effects, and functional activity improvement. This approach is of special importance in biomedicine, since this makes it possible to reduce the limitations of drug delivery related to the toxicity and side effects of therapeutics, their low bioavailability and biocompatibility. This review highlights current progress in the use of lipid systems to deliver active substances to the human body. Various lipid compositions modified with amphiphilic open-chain and macrocyclic compounds, peptide molecules and alternative target ligands are discussed. Liposome modification also evolves by creating new hybrid structures consisting of organic and inorganic parts. Such nanohybrid platforms include cerasomes, which are considered as alternative nanocarriers allowing to reduce inherent limitations of lipid nanoparticles. Compositions based on mesoporous silica are beginning to acquire no less relevance due to their unique features, such as advanced porous properties, well-proven drug delivery efficiency and their versatility for creating highly efficient nanomaterials. The types of silica nanoparticles, their efficacy in biomedical applications and hybrid inorganic-polymer platforms are the subject of discussion in this review, with current challenges emphasized.

Modeling of water-in-oil Pickering emulsion nanofiltration - Influence of temperature

Recently, the feasibility of Pickering emulsion membrane filtration has been shown to be a promising procedure for efficient catalyst recovery in continuous liquid/liquid multiphase catalysis. In this work, the impact of temperature on the permeation of the pure solvent 1-dodecene as well as on the filtration of water-in-oil Pickering emulsions stabilized with two different types of silica nanoparticles (differing in particle hydrophobicity) using an organic solvent nanofiltration membrane was experimentally investigated. While a temperature increase led to an increase in flux, the influence of the particle type was negligible. Furthermore, for the first time, a mathematical model to describe Pickering emulsion filtration was successfully developed. The flux of solvent through the membrane could be predicted via the solution-diffusion model including an Arrhenius-type relationship to describe the temperature dependency of the diffusion coefficient. Implementing this into a resistance in series model the Pickering emulsion filtration behavior could be predicted with high accuracy. These results are indispensable for the optimal process design for Pickering emulsion application in catalytic multiphase systems.

A novel imaging tool; fluorescent organosilica nanoparticles

The novel type of silica nanoparticles, organosilica nanoparticles, has been developed by Nakamura and colleagues. The nanoparticles can be synthesized in a few of simple reactions and have a good size and dispersibility. Organosilica nanoparticles have SH groups on their surface, which makes it possible to conjugate them with antibodies and other protein molecules. We synthesized organosilica nanoparticles with a diameter of 100 nm, containing fluorescein isothiocyanate (FITC) or Rhodamine B, which resulted in high fluorescence intensity. These nanoparticles were tested in various biochemical applications and in this study, we focused on their use in flow cytometry. We found that the application of these nanoparticles with antibodies could efficiently detect specific cells in a flow cytometer. We also discuss cell tracking methods using these nanoparticles.

Stability of particle dispersion and heterogeneous interfacial layers in polymer nanocomposites

In a groundbreaking study, Akcora group has shown that poly(ethylene oxide), PEO, nanocomposites with dynamically asymmetric, heterogeneous interfaces present a unique and reversible thermal-stiffening behavior above the glass transition temperature of the adsorbed polymer (Senses, E. et al., ACS Appl. Mater. Interfaces2015, 7, 14682–14689.). However, chemically heterogeneous interfaces can be fragile under severe shear fields that are common in continuous polymer processes. The current study is inspired by the work done in Akcora group on thermally-stiffening polymer nanocomposites and is aimed at understanding the effect of continuous processing operations such as extrusion on the structure and properties of thermally-stiffening nanocomposites. The effect of processing on nanocomposites of PEO and colloidal silica, SiO2, were investigated via thermogravimetric analysis (TGA), scanning electron microscopy (SEM), small and wide angle X-ray scattering, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and rheometry. Three types of silica nanoparticles were employed in the current study (while keeping the average silica nanoparticle size and concentration constant: 40–50 nm diameter and 30% by weight): bare silica, silica adsorbed with polycarbonate (PC), and silica adsorbed with poly(2–vinyl pyridine), P2VP. The adsorption of PC and P2VP onto silica creates a dynamically asymmetric, heterogeneous interface that is quite different compared to homogeneous interfaces where either nanoparticle surfaces are chemically modified with small chemical groups or with long grafted chains. The results indicated that upon extrusion, the average size of secondary agglomerates either remained unchanged or decreased slightly but the amount of agglomeration increased leading to deterioration of silica nanoparticle dispersion and viscoelastic properties (at temperatures below the glass transition temperature of the adsorbed polymer). Among the three systems studied, P2VP-adsorbed silica containing samples showed the largest degradation of viscoelastic properties upon extrusion, which was attributed to the desorption and disentanglement within the heterogeneous interface or to agglomeration leading to breaking of the percolated structure formed by nanoparticles and polymer bridges.

Comparative Study of the Impact Wedge-Peel Performance of Epoxy Structural Adhesives Modified with Functionalized Silica Nanoparticles

Epoxy structural adhesives have strong adhesion, minimal shrinkage and high thermal and chemical resistance. However, despite these excellent properties, their high-energy impact resistance should be improved to satisfy the increasing demands of the automotive industry. For this reason, we used four types of silica nanoparticles with different surface groups, such as polydimethylsiloxane (PDMS), hydroxyl, epoxy and amine groups, as toughening agents and examined their effect on the glass transition temperature (Tg), crosslinking density and phase separation of epoxy structural adhesives. High-energy impact resistance, mode I fracture toughness and lap shear strength were also measured to explain the effect of surface functional groups. Silica nanoparticles with reactive functional groups increased the mode I fracture toughness of epoxy structural adhesives without sacrificing the crosslinking density. Although the mode I fracture toughness of epoxy structural adhesives could not clearly show the effect of surface functional groups, the dynamic resistance to cleavage obtained by impact wedge-peel tests showed quite different values. At a 0.3 vol% content, epoxy-functionalized silica nanoparticles induced the highest value (40.2 N/mm) compared to PDMS (34.1 N/m), hydroxyl (34.9 N/mm), and amine (36.1 N/m). All of these values were significantly higher than those of pristine epoxy structural adhesive (27.7 N/mm).

The synergistic role of silica nanoparticle and anionic surfactant on the static and dynamic CO2 foam stability for enhanced heavy oil recovery: An experimental study

CO2 foam is a promising candidate in enhanced oil recovery and reducing anthropogenic CO2 emission through geo-sequestration due to its CO2 mobility control ability. However, instability of CO2 foam stabilized solely by surfactant strongly retards its application. Here, two types of silica nanoparticles (NPs) with varied hydrophobicity are used with sodium bis(2-ethylhexyl) sulfosuccinate (AOT) to increase CO2 foam stability. Through foamability and foam stability experiments, together with complementary experiments such as measurements of CO2-water interfacial tensions, particle zeta potential, and adsorption isotherm of surfactant, the stabilization mechanisms of AOT-NPs aqueous dispersions on the CO2 foam films are revealed. Oil recovery experiments are performed in an oil-wet micromodel where high permeability channels are included to mimic wormholes in unconsolidated sandstone reservoirs during sand production. Results show that the nanoparticle surface hydrophobicity strongly influences the interactions between particles and AOT. Partially hydrophobic NPs (NPB) are much more efficient in generating and stabilizing CO2 foam than hydrophilic NPs (NPA) when mixed with AOT in a proportion of 1: 0.16 (wt%/wt%). AOT-NPB dispersions improve the recovery in two aspects: First, the synergistic interactions between AOT and NPB leads to the adsorption of AOT on particle surfaces, thus enhancing mechanical strength of bubbles. High quality foam encompasses a fine foam texture and provides higher resistance to the gas flow, leading to a more uniform sweep. Second, AOT-NPB dispersions reduces oil/water IFT, promotes emulsification forming oil in water (O/W) emulsions, and alters glass surface wettability, leading to substantial incremental oil recovery.

Critical flocculation concentration for polyvalent ions using silica nanoparticles; a new version of Schulze-Hardy rule

Critical Flocculation Concentration (CFC) is an important quantity because allows to know the optimal amount of flocculant required to remove (adsorb) specific quantities of metal ions in aqueous solution allowing to reduce both, the flocculation time and the excess of unreacted flocculant; this unreacted material produces, by itself, an additional contamination. The results reported here show that the standard Schulze-Hardy-Rule (SHR), based only in the valence z, is not longer valid to obtain the right values of CFC. In this work it is reported a correct determination of CFC for di- and tri-valent ions using different types of silica nanoparticles. Both, the initial pH slope (-pHo) and the valence z are required to determine correctly the CFC. The proposed modified version for CFC is CFC ∝ [(-pHo)z]−1.

Interactions between functionalised silica nanoparticles and Pseudomonas fluorescens biofilm matrix: A focus on the protein corona.

Biofilms are microbial communities embedded in an extracellular polymeric matrix and display an enhanced tolerance to the action of antimicrobials. The emergence of novel functionalised nanoparticles is considered a promising avenue for the development of biofilm-specific antimicrobial technologies. However, there is a gap in the understanding of interactions between nanoparticles and the biofilm matrix. Particularly, questions are raised on how nanoparticle charge and surface groups play a role in aggregation when in contact with biofilm components. Herein we present the synthesis of four types of silica nanoparticles and undertake an analysis of their interactions with Pseudomonas fluorescens biofilm matrix. The effect of the biofilm matrix components on the charge and aggregation of the nanoparticles was assessed. Additionally, the study focused on the role of matrix proteins, with the in-depth characterisation of the protein corona of each nanoparticle by Liquid Chromatography with Tandem Mass Spectrometry experiments. The protein corona composition is dependent on the nanoparticle type; non-functionalised nanoparticles show less protein selectivity, whereas carboxylate-functionalised nanoparticles prefer proteins with a higher isoelectric point. These outcomes provide insights into the field of biofilm-nanoparticle interactions that can be valuable for the design of new nano-based targeting systems in future anti-biofilm applications.

A novel design of silica-based completion nanofluids for heavy oil reservoirs

The main objective of this manuscript is the design of completion nanofluids (NanoCF) using silica nanoparticles based on the impact on the capillary number for being applied in heavy crude oil reservoirs. Six types of silica nanoparticles with different chemical nature were characterized by dynamic light scattering (DLS), point of zero charge (pHpzc), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), surface area (SBET), X-ray diffraction (XRD) and total surface acidity through temperature-programmed desorption of NH3 (TPD-NH3). Adsorption isotherms were constructed for understanding the non-ionic surfactant interaction with nanoparticles and rock surfaces, showing that a high adsorption affinity of the surfactant onto the rock surface, leaving less than 24% of free surfactant molecules able to migrate to the water/oil interface. Nevertheless, nanoparticle addition onto completion fluids (CF) could reduce the adsorbed surfactant onto the rock surface by 75%, which means more molecules of surfactant at the interface due to the nature of the obtained nanoparticles (NPS). The nanoparticles were selected based on the capillary number, showing that the best material reduced the interfacial tension between heavy crude oil and CF more than 76% and have the capacity to modify an initial oil-wet state to a water-wet rock surface. Finally, a coreflooding test was carried out at reservoir conditions (158 °F and 6.89 MPa) for evaluating the best completion nanofluid design based on the static tests, showing an increase of the oil effective permeability of 37% and incremental oil recovery of 3% in comparison to the completion fluid without nanoparticles. For the first time, novel completion nanofluids could allow stimulating the well from the beginning of the productive life.

A novel imaging tool; fluorescent organosilica nanoparticles

The new type of silica nanoparticles as a novel imaging tool, organosilica nanoparticles, has been developed by Nakamura and colleagues. The nanoparticles can be synthesized in a few of simple reactions and have a good size and dispersibility. Organosilica nanoparticles contain fluorescent dyes and are superior in fluorescence intensity to the conventional dye. These nanoparticles have SH groups on their surface, which makes it possible to conjugate them with antibodies and other protein molecules. We synthesized organosilica nanoparticles whose diameter is 100 nm including fluorescein isothiocyanate (FITC) or Rhodamine B and then conjugate these nanoparticles with an anti‐mouse IgG antibody and so on. We applied these conjugated antibodies to immunofluorescence staining to mouse brain sections. We also discuss this novel imaging tool to detect many biomolecules.

The Membrane Interactions of Nano-Silica and Its Potential Application in Animal Nutrition.

Simple SummarySilicon dioxide nanostructures, due to good biocompatibility, low toxicity and high synthetic availability, are promising materials for various biological and industrial applications. Interest in using silicon dioxide nanostructures arises not only from their special interactions with cell membranes, but also from an ease in manipulating their particle size, shape and porosity, allowing one to make a material with the desired physicochemical properties. Despite that, there is still little known about the possible use of silicon dioxide and other nanostructures in animal nutrition. The aim of the present paper was to describe the properties of silica nanostructures, demonstrating potential applications and achievable benefits of using nanostructures as a feed additive. Based on the literature, it seems that diet supplementation with nanoparticles leads to improved performance and immunity in animals, which might be, at least partially, related to changes in the composition of gut microbiota. These unique features make nanoparticles interesting candidates as feed additives used in animal nutrition.Nanoparticles are increasingly popular in numerous fields including electronics, optics and medicine (vaccines, tissue engineering, microsurgery, genomics and cancer therapies). The most widely used nanoparticles in biomedical applications are those designed by man. Scientists have obtained many types of silica nanoparticles with defined shape and chemical composition, but different properties and applications. Nanoparticles include particles with at least one dimension ranging from 1–100 nm. Silica nanoparticles (Sn), reaching values from several dozen to several hundred m2/g, have unique physicochemical properties due to their porous structure and well-developed specific surface. Currently, the use of Sn in animal nutrition, with a focus on gastrointestinal tract function, is of great interest.

Silica-based nanosystems for therapeuticapplications in the skin.

Aging, exposure to oxidants, infectious pathogens, inflammogens, ultraviolet radiation and other environmental and genetic factors can result in the development of various skin disorders. Despite immense progress being made in dermatological treatments, many skin-associated problems still remain difficult to treat and various therapies have limitations. Progress in silica-based nanomaterials research provides an opportunity to overcome these drawbacks and improve therapies and is a promising tool for inclusion in clinical practice to treat skin diseases. This review focuses on the use of various types of silica nanoparticles with therapeutic applications in various skin disorders. These nanosystems improve treatment efficacy by maintaining or enhancing the effect of several drugs and are useful tools for nanomedicine, pharmaceutical sciences and future clinical applications.

Study of Nanoparticle-Stabilized Foams in Harsh Reservoir Conditions

Many oil reservoirs are at high temperatures and contain brines of high salinity and hardness. The focus of this work is to develop robust foams stabilized by a mixture of nanoparticles and surfactants for such reservoirs. Two types of silica nanoparticles (Si-NP1, Si-NP2) with different grafted low molecular weight ligands/polymers were used. First, aqueous stability analysis of these nanoparticle dispersions were conducted at high-temperature (80 °C) and high-salinity conditions (API Brine; 8 wt% NaCl and 2 wt% CaCl2). The screened nanoparticles were used in combination with an anionic surfactant. Second, bulk foam and emulsion stability tests were performed to investigate their performance in stabilizing the air–water and oil–water interface, respectively. Third, foam flow experiments in the absence of oil were performed to characterize the foam rheology. Finally, oil displacement experiments were conducted in an in-house, custom-built 2D sand pack with flow visualization. The sand pack had two layers of different mesh size silica sand which yielded a permeability contrast of 6:1. Brine floods followed by foam floods (80% quality) were conducted, and foam flow dynamics were monitored. The grafting of low molecular weight polymers/ligands on silica nanoparticle surfaces resulted in steric stabilization under high-temperature and high-salinity conditions. Foam flow experiments revealed a synergy between Si-NP2 and surfactant in stabilizing foam in the absence of crude oil. In the oil displacement experiments in the layered sand packs, the waterflood recoveries were low (~ 33% original oil in place) due to channeling in the top high-permeability zone, leaving the bottom low-permeability zone completely unswept. Foam flooding with just the surfactant leads to a drastic improvement in sweep efficiency. It resulted in an incremental oil recovery as high as 43.3% OOIP. Different cross-flow behaviors were observed during foam flooding. Significant cross-flow of oil from low-permeability zone to high-permeability zone was observed for the case of surfactant. Conversely, the Si-NP2-surfactant blend resulted in no cross-flow from the low-permeability region with complete blocking of the high-permeability region due to the formation of in situ emulsion. Such selective plugging of high-perm zones using nanoparticles with tailored surface coating and concentration has significant potential in recovering oil from heterogeneous reservoirs.

A highly efficient decontamination foam stabilized by well-dispersed mesoporous silica nanoparticles

A foam with high stability for the efficient decontamination of radioactive materials has been prepared by using well-dispersed mesoporous silica nanoparticles (NPs). Three different types of silica NPs were tested: solvent-extracted mesoporous silica (SMS) NPs, calcined mesoporous silica (CMS) NPs, and commercial silica (M-5) NPs. The stability and decontamination efficiency of the foam prepared using SMS NPs was higher than those using other silica NPs. The liquid volume in the foam with the SMS NPs are 10–25 times greater than those containing the CMS and M-5 NPs. The stability of the decontamination foam consisting of SMS NPs is higher because of its higher viscosity; the SMS NPs sample contains a larger number of particles per unit volume and has smaller particle sizes than the CMS and M-5 NPs samples. To investigate the dispersion-agglomeration properties of the silica NPs, the size distributions of the silica NPs in the decontamination foam solutions were determined by using dynamic light scattering. The SMS NPs are smaller than the CMS and M-5 NPs in the decontamination foam solution. For stainless steel 304 and carbon steel specimens corroded with the radionuclide 60Co, decontamination foams containing SMS NPs were found to exhibit a decontamination efficiency 20–40% greater than those of the foams containing the other silica NPs. This superior efficiency arises because the foams prepared with SMS NPs exhibit improved stability and their liquid component can hold larger amounts of the decontamination agent.