Use Of Silica Nanoparticles Research Articles

Role of physicochemical properties in silica nanoparticle-mediated immunostimulation

Immunostimulation caused by nanoparticles may be beneficial or adverse depending on their intended application. Activation of immune cells is beneficial for indications targeting the immune system for therapeutic purposes, such as tumor microenvironment reprogramming, immunotherapy, and vaccines. When it is unwanted, however, immunostimulation may lead to excessive inflammation, cytokine storm, and hypersensitivity reactions. The increasing use of silica nanoparticles (SiNPs) for the delivery of drugs, imaging agents, and antigens warrants preclinical studies aimed at understanding carrier-mediated effects on the number, activation status, and function of immune cell subsets. Herein, we present an in vitro study utilizing primary human peripheral blood mononuclear cells (PBMC) to investigate the proinflammatory properties of four types of SiNPs varying in size and porosity. Cytokine analysis was performed in resting and LPS-primed PBMC cultures to understand the ability of silica nanoparticles to induce de novo and exaggerate preexisting inflammation, respectively. Changes in the number and activation status of lymphoid and myeloid cells were studied by flow cytometry to gain further insight into SiNP-mediated immunostimulation. Nonporous SiNPs were found to be more proinflammatory than mesoporous SiNPs, and larger-sized particles induced greater cytokine response. LPS-primed PBMC resulted in increased susceptibility to SiNPs. Immunophenotyping analysis of SiNP-treated PBMC resulted in T and B lymphocyte, natural killer cell, and dendritic cell activation. Additionally, a loss of regulatory T cells and an increase in γδ TCR T cell population were observed with all particles. These findings have implications for the utility of SiNPs for the delivery of drugs and imaging agents.

Silica nanoparticles in medicine: overcoming pathologies through advanced drug delivery, diagnostics, and therapeutic strategies.

Over the last decades, silica nanoparticles (SiNPs) have been studied for their applications in biomedicine as an alternative used for conventional diagnostics and treatments. Since their properties can be modified and adjusted for the desired use, they have many different potential applications in medicine: they can be used in diagnosis because of their ability to be loaded with dyes and their increased selectivity and sensitivity, which can improve the quality of the diagnostic process. SiNPs can be functionalized by targeting ligands or molecules to detect certain cellular processes or biomarkers with better precision. Targeted delivery is another fundamental use of SiNPs. They could be used as drug delivery systems (DDS) since their structure allows the loading of therapeutic agents or other compounds, and studies have demonstrated their biocompatibility. When SiNPs are used as DDS, the drug's toxicity and the off-target effects are reduced significantly, and they can be used to treat conditions like cancer and neurological diseases and even aid in regenerative processes, such as wound healing or bone repair. However, safety concerns must be considered before SiNPs can be used extensively in clinical practice because NPs can cause toxicity in certain conditions and accumulate at undesired locations. Therefore, an overview of the potential applications that SiNPs could have in medicine, as well as their safety concerns, will be covered in this review paper.

Nanotechnology Applications in Enhanced Oil Recovery (EOR)

Enhanced Oil Recovery (EOR) techniques are crucial for maximizing crude oil extraction from reservoirs, especially when traditional methods leave significant amounts of oil untapped. Recent advancements in nanotechnology have introduced innovative solutions to longstanding challenges in the oil industry. This research paper explores the application of nanotechnology in EOR, emphasizing the unique properties of nanoparticles that make them highly effective in this context. Nanoparticles, defined by their nanometer-scale dimensions, exhibit high surface area to volume ratios, quantum effects, and enhanced reactivity. These properties enable various mechanisms in EOR, including improved wettability, reduction in interfacial tension, enhanced thermal stability, selective plugging and fluid diversion, and catalytic effects. The study details how silica and titanium dioxide nanoparticles can modify rock surface properties, leading to better water imbibition and oil displacement. It also discusses how surfactant-coated nanoparticles can reduce the interfacial tension between oil and water, facilitating easier oil flow. Furthermore, the research highlights the role of metal oxide nanoparticles, such as aluminum oxide and zinc oxide, in enhancing thermal conductivity and stability during thermal EOR methods like steam flooding. The ability of polymer-coated nanoparticles to selectively plug high-permeability zones and redirect injection fluids is examined, demonstrating how this can lead to a more uniform sweep and higher oil recovery. The catalytic properties of certain nanoparticles, such as iron oxide, are also explored for their potential to promote in-situ chemical reactions that generate gases aiding oil displacement. Field applications and case studies underscore the practical benefits of nanotechnology in EOR. Examples include the use of silica nanoparticles in Middle Eastern oil fields, polymer-coated nanoparticles in Canadian heavy oil reservoirs, and iron oxide nanoparticles in Indian oil fields. These case studies have shown significant increases in oil recovery rates and operational efficiencies. However, the research also identifies several challenges that must be addressed for the widespread adoption of nanotechnology in EOR. These include the high costs and scalability issues associated with nanoparticle production and deployment, potential environmental and health risks, and the need for customized solutions to cater to the unique conditions of different reservoirs. In conclusion, while nanotechnology presents promising advancements in EOR through various mechanisms, overcoming challenges related to cost, scalability, and environmental impact is crucial. As research progresses, nanotechnology is poised to play a vital role in enhancing oil recovery and meeting global energy demands.

Development of a Vanadium Redox Flow Battery Operating with Thin Membrane Coupled with a Highly Selective and Stable Silica‐Based Barrier Layer

Vanadium redox flow battery (VRFB) is a very promising solution for large‐scale energy storage, but some technical issues need to be addressed. Crossover, i.e., the undesired permeation of vanadium ions through the cell separator, causes capacity loss and self‐discharge. Low‐cost and highly selective separators are thus required to improve the competitiveness of this technology. This work investigates the use of silica nanoparticles in an innovative selective layer to improve membrane selectivity and reduce its thickness. 1.5 μm thick barrier layers composed of 1100EW Nafion ionomer with silica (≈3–13 nm diameter) and Vulcan XC‐72R (≈40 nm) nanoparticles in different proportions are directly deposited on 50 μm thick Nafion membranes. The barrier layer composed only of silica nanoparticles reduces the self‐discharge due to crossover by 5 times and increases the average efficiency of the battery. Finally, during more than 1000 h of operation, the barrier layer on a 25 μm Nafion membrane demonstrates excellent stability, working with a constant coulombic efficiency higher than 99% and a capacity decay rate comparable with a thicker Nafion membrane, thus enabling the use of thinner membranes in VRFB, allowing an estimated 8% stack costs reduction with respect to NR212.

Comparative analysis of germination performance from several species of seeds under influence of silica nanoparticles

The first and most critical phase in growing crops is seed germination. Failure and slower germination process may have an impact on productivity. As a result, numerous strategies are needed to hasten germination and improving the quality of the seedlings. One possible strategy is the use of nanoparticles. This present study used colloidal silica nanoparticles (8 - 10 nm) with concentrations of 0 (control), 100, and 1000 mg/L. Seeds from six different species were used (Capsicum annuum, Capsicum frutescens, Cucumis sativus, Solanum melongena, Solanum lycopersicum, and Daucus carota). Seeds were germinated in dark condition for eight consecutive days. The result showed that the use of silica nanoparticles may shorten the germination time while increasing the germination index and coefficient of velocity of germination in C. annuum, C. frutescens, C. sativus, and S. lycopersicum. However, the observed effect was not very strong compared to the control. This could be due to the seeds utilized were not in dormant stage and had rather high viability. On the other hand, we found that silica nanoparticles could alter the structure of the seed coat, allowing for easier water imbibition for germination.

Engineered Silica Nanoparticles for Nucleic Acid Delivery.

The development of nucleic acid-based drugs holds great promise for therapeutic applications, but their effective delivery into cells is hindered by poor cellular membrane permeability and inherent instability. To overcome these challenges, delivery vehicles are required to protect and deliver nucleic acids efficiently. Silica nanoparticles (SiNPs) have emerged as promising nanovectors and recently bioregulators for gene delivery due to their unique advantages. In this review, a summary of recent advancements in the design of SiNPs for nucleic acid delivery and their applications is provided, mainly according to the specific type of nucleic acids. First, the structural characteristics and working mechanisms of various types of nucleic acids are introduced and classified according to their functions. Subsequently, for each nucleic acid type, the use of SiNPs for enhancing delivery performance and their biomedical applications are summarized. The tailored design of SiNPs for selected type of nucleic acid delivery will be highlighted considering the characteristics of nucleic acids. Lastly, the limitations in current research and personal perspectives on future directions in this field are presented. It is expected this opportune review will provide insights into a burgeoning research area for the development of next-generation SiNP-based nucleic acid delivery systems.

Long-term exposure to small-sized silica nanoparticles (SiO2-NPs) induces oxidative stress and impairs reproductive performance in adult zebrafish (Danio rerio)

The widespread use of silica nanoparticles (SiO2-NPs) in various industries, including chemical polishing, cosmetics, varnishes, medical, and food products, has increased the risk of their release into aquatic ecosystems. The toxic effects of small-size SiO2-NPs on the reproductive performance of zebrafish (Danio rerio) have yet to be widely studied. This study aimed to investigate the impact of chronic exposure to small-sized (35 ± 6 nm) SiO2-NPs on adult zebrafish through waterborne exposure to concentrations of 5 (SNP5), 10 (SNP10), 15 (SNP15), and 20 (SNP20) μg/L of SiO2-NPs for 28 days. Our results showed that SiO2-NPs significantly impacted several biochemical parameters, including cholesterol, triglycerides, LDL, HDL, total protein, albumin, urea levels, and alkaline phosphatase and aspartate aminotransferase activity. Cortisol and glucose levels in the SNP20 group significantly differed from the control group. All the exposed groups, apart from SNP5, experienced a significant increase in their total immunoglobulin levels and lysozyme activity. While there was a considerable increase in the activity of catalase and superoxide dismutase in all exposed groups, the expression of antioxidant genes did not appear to be affected. Furthermore, the expression level of il8 was significantly higher in SNP5 and SNP10 than in other treatments. Exposure to SiO2-NPs caused a decrease in gonad weight, absolute fecundity, and larval survival rate, particularly in the SNP20 group. The present study indicates that SiO2-NPs can harm zebrafish and thus further research is necessary to assess their health and environmental risks.

Tailoring the shape memory properties of silica nanoparticle infused photopolymer composites for 4D printing applications: A Taguchi analysis

The study aims to optimize the shape change response of the Shape Memory Photopolymer Composites (SMPPCs) through the use of the Taguchi method. The SMPPCs were created by blending of Soft Photopolymer Resin (SPPR) with Hard Photopolymer Resin (HPPR) in various weight fractions and reinforcing with Silica Nanoparticles (SNPs) at different weight percentages using a Masked Stereolithography (MSLA). The researchers measured the ability of the material to change its shape by determining its shape recovery time (T), fixity ratio (Rf), recovery ratio (Rr), and recovery rate (Vr). The results indicated that the fastest T was observed in unreinforced Blended Photopolymer Resin (BPPR) with 75 wt% SPPR and 25 wt% HPPR. However, when the BPPR was reinforced with 0.3 wt% SNPs, the T was slower. The use of SNPs as reinforcement resulted in excellent Rf, whereas higher weight percentages of SPPR led to better Rr. The weight percentage of SPPR was found to be the primary contributor to T, Rr, and Vr, while the weight percentage of SNPs played a significant role in Rf. The optimum parameters for T and Vr were A1/B3/C1, for Rf were A3/B1/C1, and for Rr were A2/B2/C1. The research findings indicate that reinforced BPPR has outstanding fixity ratios and it is more appropriate for applications that necessitate lengthier recovery and slower recovery rate. The inclusion of SNPs in BPPR increases the T and prolongs the temporary shape retention of the specimen. The generated regression models were validated through confirmation experiments, which yielded strong agreement.

Experimental Investigation of the Effects of the Sizes and Concentrations of SiO2 Nanoparticles on Wettability Alteration and Oil Recovery

The use of silica nanoparticles for enhanced oil recovery has recently attracted the attention of investigators, and the disjoining pressure has been found to be a promising mechanism for removing residual oil. Previous studies have found that decreasing the particle size and increasing the concentration of nanoparticles improves the disjoining pressure, which enables the oil to be removed more easily. However, these studies were not designed for a reservoir environment. In the present work, our goal is to investigate the effects of the sizes and concentrations of nanoparticles by performing experimental wettability tests and core-flooding tests under reservoir conditions and by calculating the disjoining pressure. Our results demonstrate that both wettability alteration and oil recovery are higher with smaller particle sizes. However, we observed no correlation between wettability alteration and concentration. In contrast, the oil-displacement rate was better in the early stages of oil recovery for increased nanoparticle concentrations, suggesting that the disjoining pressure may be more effective then. These results demonstrate that particle sizes and concentrations are essential parameters for enhanced oil recovery using nanoparticles, even in a reservoir environment.

Scattering of coherent acoustic phonons by silica nanoparticles reveals the 3D-morphology of cells in solution down to nanometer thicknesses

In this work, we show that the use of silica nanoparticles improves the imaging and 3D-morphological measurement down to nanometer thicknesses of fixed cells in solution with picosecond ultrasonics (PU). Synchronized ultrafast fs-laser pulses are used to generate coherent acoustic phonons (CAPs) that evoke the Brillouin light scattering and enable the recording of the time-resolved Brillouin oscillations along with the propagation of the acoustic nanopulses through a thin transparent cell in solution. Silica nanoparticles, whose size matches the phonon wavelength at the frequency of the Brillouin scattering in the solution, are used to strongly scatter the CAPs in the solution. Suppressing the Brillouin signature of the surrounding liquid, this protocol improves significantly the PU imaging and makes it possible to measure the mechanical properties of a transparent cell, including the thin peripheral region where the thickness is less than the Brillouin wavelength, equal to half the probe light wavelength in the cell, and where crucial interaction of the cell with its surroundings occurs. We present experimental evidence of the considerable improvement in the cartography of the entire cell using nanoparticles. The intricate frequency dependence of Brillouin scattering and of resonances for a very thin cell is analyzed using a semi-analytical model leading to the challenging measurement of the 3D-morphology of the immersed cell at thicknesses down to 1 / 9 of the optical wavelength.

Surface Modification of Silica Nanoparticles with Ethyl Oleate for the Purpose of Stabilizing Nanolubricants Used for Tribological Tests

Long-term sustainability and decreasing amount of fossil oil reserves require a partial or complete transformation of traditional lubricating oils. The use of silica nanoparticles as a lubricant additive has a huge tribological potential, which has already been discussed in numerous articles. Nanosized silica shows excellent results in reducing friction and preventing wear, but they quickly aggregate and settle after homogenization in oils. For long-term stable dispersion of lubricating oils containing nanoceramics, the surface of the particles was modified with ethyl oleate. The surface modification, the ethyl oleate applied to the surface of the nanosilica, was confirmed by Fourier-transform infrared spectroscopy. Group III based lubricating oil was prepared using the surface-modified nanosilica. The particle size of the nanoparticles in the lubricating oil dispersion was examined by dynamic light scattering. Oscillating tribometer measurements were performed with different concentrations (0.1; 0.2; 0.3 wt%) of nanolubricants. Based on the tribological results, the friction coefficient of the surface-modified nanosilica is more stable, its wear is 15% lower compared to the reference. There is no significant change in the magnitude of the friction coefficient. It can be concluded that the ethyl oleate surface modification method may be suitable for tribological investigations of the acting mechanisms of nanoparticles.

Suppression of Membrane Degradation Accompanied with Increased Output Performance in Fuel Cells by Use of Silica-Containing Anode Catalyst Layers.

Polymer electrolyte membranes (PEMs) for fuel cells are chemically degraded by the attack of ·OH radicals generated from the decomposition of H2O2, which is predominantly produced at the Pt/C hydrogen anode. The incorporation of conventional radical scavengers into the PEM suffers from a decrease in the output performance. We, for the first time, demonstrate that the addition of hygroscopic silica nanoparticles (NPs) to the Pt/C anode catalyst layer provides a remarkably prolonged (ca. 4 times) lifetime of a Nafion membrane in an accelerated stress test and open circuit voltage (OCV) holding at 90 °C, accompanied by improved output (I-E) performances at low relative humidity. It has been found that the use of silica NPs decreases H2O2 formation rate from the OCV to a practical H2 oxidation potential in a half-cell using 0.1 M HClO4 at 90 °C and provides reduced ohmic resistance (increase in water content) and effective utilization of Pt cathode catalyst in a single cell, by which the improvement of the durability of the PEM and increased output performance are explained rationally.

NANOPARTÍCULAS DE SÍLICA (NPSiO2) UTILIZADAS PARA O TRATAMENTO DE DISTÚRBIOS ASSOCIADOS AO SISTEMA NERVOSO CENTRAL (SNC)

SILICA NANOPARTICLES (SiO2NP) USED FOR THE TREATMENT OF DISORDERS ASSOCIATED WITH THE CENTRAL NERVOUS SYSTEM (CNS). In the last decade, nanomedicine has investigated the potential use of silica nanoparticles for drug delivery due to the favorable physicochemical properties of these systems as carriers. Specifically, a few studies have focused on applying silica-based nanosystems to deliver drugs into the central nervous system to treat neurological disorders. The present review aimed to evaluate the properties of silica nanoparticles, such as size, zeta potential, surface area, entrapment efficiency, drug loading, and release profile, exclusively applied for the treatment of central nervous system disorders as well as to describe the correlation between biological outcomes and physicochemical properties. Furthermore, the main processes related to the development of silica nanoparticles, such as preparation and characterization methods, were covered in this review to aid the systematic development of silica-based nanoparticles. In the articles reviewed, silica nanocarriers used in neurological disorders did not exhibit physicochemical similarities. Thus, attempts to prospect relations between physicochemical properties and biological effects are still inefficient when silica nanoparticles are used as drug delivery systems in neurological disorders. Therefore, each silica-based nanocarrier must be fully physicochemical and biologically characterized to comprehend how the structural features of silica nanoparticles affect biological systems.

Evaluation of the Efficacy of Oxymatrine, Emamectin Benzoate and Silica and Zinc Nanoparticles for Controlling the Adults of Trogoderma granarium (Evert) Under Laboratory Conditions.

Yahya, E.E. and M.T. Mohammadali. 2023. Evaluation of the Efficacy of Oxymatrine, Emamectin Benzoate and Silica and Zinc Nanoparticles for Controlling the Adults of Trogoderma granarium (Evert) Under Laboratory Conditions. Arab Journal of Plant Protection, 41(2): 168-172. https://doi.org/10.22268/AJPP-41.2.168172 This study was conducted to evaluate the efficiency of Oxymatrine, Emamectin benzoate, and silica and zinc nanoparticles against the adults of Khapra beetle, Trogoderma granarium (Evert) under laboratory conditions. Results revealed that Oxymatrine gave the highest mortality rate, reaching 100% at a concentration of 2.5 ml/L water 7 days after treatment, compared with 63.33% for Emamectin benzoate, at a concentration of 1.25 ml/L following the same period after treatment. The results obtained indicated that the use of silica nanoparticles achieved a high mortality rate of 37.11% at the concentration of 300 mg/kg seeds compared with 23.11% for zinc nanoparticles 7 days after treatment. The combination of Oxymatrine and silica nanoparticles at a concentration of 1 ml/L and 300 mg/kg seeds, respectively, gave the highest mortality rate of 100%, 5 days after treatment. Keywords: Trogoderma granarium, oxymatrine, emamectine benzoate, nanoparticals

The Effect of Nanosilica Incorporation on the Properties of Cement-Based Materials with and Without other Supplementary Admixtures – A Literature Review

The development of nanotechnology has made it possible to design new materials and improve existing ones. Regarding new supplementary admixtures for cement-based materials, nanosilica is more advantageous than any other nanomaterial. This is due to its high pozzolanic reactivity, besides its filling and seeding effects, which are a consequence of the higher and more reactive specific surface area of the nanosilica and its amorphous structure. Nonetheless, when used improperly or in an inadequate dosage, such a nanomaterial may negatively affect the cement admixture, compromising both fresh and hardened properties. Hence, it is fundamental to understand the nanosilica’s behavior inside the cementitious medium. This review paper is based on recent literature about the incorporation of nanosilica in cementitious materials. The analyses showed that, once incorporated in the cement matrix, nanosilica tends to agglomerate. The behavior of such agglomerates influences both the pozzolanic filling and seeding effects. Therefore, a suitable dispersion of the nanoparticles must be achieved. In this sense, third-generation superplasticizers are used, usually up to 3% of cement mass. The mechanical properties of cement-based materials with nanosilica depend on the amount of nanomaterial and on its specific surface area. There is not an agreement on the optimum dosage of nanosilica, however, percentages up to 5% in cement mass seem to provide a better performance, when compared to greater ones. It is not worthy to use nanosilicas with excessive specific surface area values, because they tend to form large agglomerates, reducing fluidity and compressive strength. Particles with surface areas up to 300 m2/g usually present good performance. Nanosilica improves the early age strength and contributes to the pore refinement of cement-based materials. The combination of nanosilica with other nanomaterials or industrial by-products can improve the mixture’s performance. Nonetheless, the use of silica nanoparticles with agricultural wastes negatively affects the mechanical properties at early ages.

Interfacial engineering of epoxy/silica nanocomposites by amino-rich polyethyleneimine towards simultaneously enhanced rheological and thermal-mechanical performance for electronic packaging application

As electronic devices move toward miniaturization and high-degree integration, it becomes imperative to use nano-sized silica as a reinforcing filler for epoxy resin in modern electronics packaging industries. However, the use of silica nanoparticles (SNPs) brings about new challenges in filler dispersion and in the balance between the rheology and thermal mechanical performance of epoxy nanocomposites. This study presents a novel strategy aiming to address the above challenges by interface engineering with amino-rich branched polyethyleneimine (PEI) polymer molecules through a facile self-assembly process. This not only enables a considerable decrease (by 79.7%) in viscosity accompanied by a significant improvement in viscosity stability (only 2.7 times increase after 24 h) but also leads to a further CTE reduction of 4.8 ppm/°C (equivalent to the effects of around 10 wt% SNPs) relative to the SNPs. This work offers a new direction and efficient approach to develop high-performance epoxy composites for electrical packaging applications as well as provides some fresh insights into the interface-property relationships.

The Role of Silica Nanoparticle in Fingerprint Visualization Studies

Fingerprints are the most important evidence that allows the criminal to be profiled in a crime scene investigation. A fingerprint is considered evidence due to its unique characteristics. Fingerprints are not visible and therefore need to be visualized after being recovered from the scene. Many methods are used for visualization purposes. The most commonly used methods are dusting, Ninhydrin, DFO, Super Glue, etc. the methods are not. In addition to these methods, other chemicals, physical and optical methods have recently been uncovered. Due to technological developments affecting the field of Forensic Sciences, new dimensions have also been introduced to fingerprint studies. The use of nanoparticles has gained momentum, especially in fingerprint visualization studies. In the use of nanoparticles, silica nanoparticles are used in studies. Objective: this study, it was aimed to determine the level of use of silica nanoparticles in fingerprint visualization studies. Based on the data obtained for this purpose, which silica nanoparticle is most used, which method is most used in silica nanoparticle synthesis, what are the dimensions of the resulting molecules, which technique is most preferred for visualization, etc. it is aimed to provide researchers with up-to-date information by determining the parameters? Method: In this study, the systematic literature review was preferred to collect research data. The level of use of silica nanoparticles has been investigated in fingerprint visualization studies between 2016 and 2020. Data collection was obtained through scientific studies. Parameters such as silica nanoparticle molecules, synthesis methods, absorbent values, surface types used, imaging types were compared in the obtained publications.

Experimental investigation of silica nanoparticle assisted Surfactant and polymer systems for enhanced oil recovery

Enhanced oil recovery techniques are commonly used today in oil fields to boost oil production. The objective of the present study is to investigate the use of silica nanoparticles (NPs) with surfactants and polymers to increase the oil recovery from oil fields. Synergistic effects of surfactant, polymer, and nanoparticles on interfacial tension (IFT) reduction, wettability alteration, emulsification, and viscosity improvement are reported in this study. Core flooding experiments were performed in cores with different permeabilities to screen the reservoir on basis of rock properties. The dispersion of NPs in the aqueous solution of surfactant and polymer was characterized by stability analysis, Turbiscan analysis, dynamic light scattering (DLS), and zeta-potential measurements. The nanoparticles were able to further reduce the IFT between the surfactant solution and crude oil. The stability of nanofluids was increased when surfactant was added as evidenced by a higher zeta potential value (−39.6 mV). The addition of polymer led to even higher stability of the nanofluids as observed by the Turbiscan analyzer. A synergistic effect of NPs, surfactant, and polymer was observed in the core flooding experiments. The nanofluid system provided higher incremental oil recovery in high permeability core as compared to low permeability core. Different recovery mechanisms responsible for oil recovery by nanofluids like wettability alteration, disjoining pressure, log jamming, and pore channel plugging phenomena are discussed. The flooding results indicate that the injection of the designed slug increases the oil recovery up to 28% of the original oil in place after conventional water flooding. Therefore, the findings of this study can help for a better understanding of the use of silica NPs with surfactant and polymer as a chemical EOR agent. The result also helps in the screening of sandstone reservoirs where nanofluid could be employed.

The impact of salinity, alkalinity and nanoparticle concentration on zeta-potential of sand minerals and their implication on sand production

The effect of brine salinity, cation type, pH, and produced sand on zeta potential (ZP) measurements with and without the presence of silica nanoparticles is investigated through pH measurement, static tests for sand and ZP measurements as well as Field Emission Scanning Electron Microscope (FESEM) analyses. Three important factors were investigated: composition of the injected brine, surface charge and pH. Their influence on stability of nanoparticles in the injected brine and amount of sand segregation was determined and the analysis of the new outcomes based on rock/brine ZP measurements was reported. The results show that the use of silica nanoparticles with high pH helps in preventing sand production and that pH has a main effect on the surface charge of the sand particle released, affecting the ZP of the solution. Nanoparticles can be active as a coating on sand grains and prevent sand segregation during water flooding. Divalent cations have been found to acquire a more substantial impact on neutralizing the negative charge of the sand particles than monovalent cations at the same concentration and pH conditions at 25 ℃. The value of ZP becomes of higher negative value with the decrease of brine salinity. The effectiveness of SiO2 nanoparticles is quite different for soft water and smart water. For soft water, the nanoparticles work more effective at pH higher than 8; and for smart water, the nanoparticles perform better at pH lower than 8. To reduce sand production with the use of silica nanoparticles, it is highly suggested to increase pH, as pH and sand production mechanisms were observed to be inversely related.

Evaluating two nanosilica dimensional range for the consolidation of degraded silicate stones

The application of silica nanoparticles strengthening agents in conservation of monumental and architectural heritage field is currently a challenge of particular interest. Some commercial products are already on the market and several studies highlighted the related strength and weakness. In order to contribute to the knowledge of the interaction between nanoparticles and stone materials as well as to provide key elements to improve the approach to conservative treatments, two silica nanoparticles products for the consolidation of silicate stones were developed in the laboratory. Bianco Sardo granite, Firenzuola and Muggia sandstones were selected as substrates for the experimentation after a laboratory investigation of their open porosity. Silica nanoparticles having two different particles size, both compatible with the porosimetric features of the selected stones, were synthesized and dispersed in an ethanol–water solution. The carrier was specifically studied for avoiding the agglomeration of silica nanoparticles and facilitating the penetration of the products in the stone substrates. Sound and artificially aged specimens were impregnated by capillary absorption method and the effectiveness of the treatment was evaluated through morphological and physical analyses. Microscopic observations, colorimetric analyses, sponge tests, ultrasound velocity determinations and porosimetric measurements showed positive results, which encourage, on one hand, the use of silica nanoparticles for consolidating silicate stones, on the other hand, further researches aimed to improve the synthesized products by reaching a deeper penetration and the reduction of water absorption.