Hydrophilic Nanoparticles Research Articles

Wetting of porous thin films exhibiting large contact angles.

Porous solid films that promote large apparent contact angles are interesting systems since their wetting properties are dependent on both the surface structure and water penetration into the film. In this study, a parahydrophobic coating is made by sequential dip coating of titanium dioxide nanoparticles and stearic acid on polished copper substrates. The apparent contact angles are determined using the tilted plate method, and it is found that the liquid-vapor interaction decreases and water droplets are more likely to move off the film when the number of coated layers increases. Interestingly, it is found that under some conditions, the front contact angle can be smaller than the back contact angle. Scanning electron microscopy observations demonstrate that the coating process led to the formation of hydrophilic TiO2 nanoparticle domains and hydrophobic stearic acid flakes that allows heterogeneous wetting. By monitoring the electrical current through the water droplet to the copper substrate, it is found that the water drops penetrate the coating layer to make direct contact with the copper surface with a time delay and magnitude that depends on the coating thickness. This additional penetration of water into the porous film enhances the adhesion of the droplet to the film and provides a clue to understand the contact angle hysteresis.

Dynamic Wetting Properties of Silica-Poly (Acrylic Acid) Superhydrophilic Coatings.

Superhydrophilic coatings based on a hydrophilic silica nanoparticle suspension and Poly (acrylic acid) (PAA) were prepared by dip coating. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to examine the morphology of the coating. The effect of surface morphology on the dynamic wetting behavior of the superhydrophilic coatings was studied by changing the silica suspension concentration from 0.5% wt. to 3.2% wt. while keeping the silica concentration in the dry coating constant. The droplet base diameter and dynamic contact angle with respect to time were measured using a high-speed camera. A power law was found to describe the relationship between the droplet diameter and time. A significantly low experimental power law index was obtained for all the coatings. Both roughness and volume loss during spreading were suggested to be responsible for the low index values. The water adsorption of the coatings was found to be the reason for the volume loss during spreading. The coatings exhibited good adherence to the substrates and retention of hydrophilic properties under mild abrasion.

Self-Healing of Biocompatible Superhydrophobic Coatings: The Interplay of the Size and Loading of Particles.

The broad application potential of superhydrophobic coatings is limited by the usage of environment-threatening materials and poor durability. The nature-inspired design and fabrication of self-healing coatings is a promising approach for addressing these issues. In this study, we report a fluorine-free and biocompatible superhydrophobic coating that can be thermally healed after abrasion. The coating is composed of silica nanoparticles and carnauba wax, and the self-healing is based on surface enrichment of wax in analogy to the wax secretion in plant leaves. The coating not only exhibits fast self-healing, just in 1 min under moderate heating, but also displays increased water repellency and thermal stability after healing. The rapid self-healing ability of the coating is attributed to the relatively low melting point of carnauba wax and its migration to the surface of the hydrophilic silica nanoparticles. The dependence of self-healing on the size and loading of particles provides insights into the process. Furthermore, the coating exhibits high levels of biocompatibility where the viability of fibroblast L929 cells was ∼90%. The presented approach and insights provide valuable guidelines in the design and fabrication of self-healing superhydrophobic coatings.

Highly Hydrophilic Oleylamine-Modified Superparamagnetic Iron Oxide Nanoparticles for Biomedical Applications

Superparamagnetic iron oxide nanoparticles (SPIONs) are becoming important vehicles for biomedical applications. This study demonstrates a new strategy based on a “haircut” reaction, aiming at the design of highly hydrophilic and functional nanoparticles. The as-synthesized SPIONs have a diameter of ∼4 nm and reveal super-organophilic behavior due to their surface modification by oleylamine molecules present on their surface (o-SPIONs). The “trimming”, which is applied on the oleylamine molecule double bond, produces shorter chains terminated by carboxyl groups, with the resulting nanoparticles exhibiting high hydrophilicity, dispersibility in water, and functionality (h-SPIONs). The biological behavior of h-SPIONs is studied against three different cell lines and reveals a selective cytotoxic effect against cancer cells. This novel method of engineering the surface properties of nanoparticles can lead to the development of a new generation of functional nanomaterials. In addition, h-SPIONs can evolve into a new and expanding family of magnetic nanomaterials in future biomedical systems.

Experimental investigation of hydrophobic and hydrophilic silica nanoparticles on extended surfactant properties: Micro-emulsion, viscosity, and adsorption behaviors

The novel applications of nanoparticles and surfactants are of interest for improving chemical oil recovery performance. In this study, two types of hydrophobic and hydrophilic SiO2 nanoparticles (NPs) were used in conjunction with a binary surfactant system (extended Carboxylate and Dioctyl sulfosuccinate (AOT) surfactants at the ratio of 0.6:0.4 by volume). An extensive series of experiments were performed in the presence of API brine containing NaCl: CaCl2 at the 8:2 wt ratio to study microemulsion phase behavior, interfacial tension (IFT), surfactant adsorption onto NP surfaces, solution and microemulsion viscosity, and oil recovery. The results indicate that the microemulsion phase behavior, optimum salinity (S*), and IFT were influenced by the concentrations and surface characteristics of the NPs. Hydrophobic or hydrophilic NPs at 500 ppm in the binary surfactant system could form Type III microemulsion and decrease the S* from 2 to 1.75 wt%. When the NP concentration reached 1000 ppm, the S* reduced to 1.5 wt%. The IFT value of the neat binary surfactant system at the S* was obtained in an ultralow range (0.0013 mN/m), and the IFT value of the hydrophobic NPs exhibited a more significant reduction than the hydrophilic NP systems. The adsorption result demonstrates that Carboxylate surfactant had lower adsorption onto hydrophilic NP than AOT. COSMO σ-profile and screened charge density illustrated that the low coverage of Carboxylate surfactant was from hydrogen bonding interaction, making the surfactant lie flat on the surface. The viscosity of the NP-surfactant solution was affected by the capacity of the surfactant adsorption onto the NP surface. In this regard, adding the hydrophobic NPs at 1000 ppm provided the highest solution viscosity over the entire shear rate and temperature range. The viscosity of the microemulsion formulated by hydrophobic NPs was higher than that of the microemulsion formulated by the hydrophilic NPs. The system with the lower NP concentration had higher microemulsion viscosity than the system with the higher NP concentration. The oil recovery results indicate that the appropriate NP type and concentration in the surfactant system could increase the displacing viscosity and decrease the microemulsion viscosity compared with the neat surfactant flooding system. The success in improving oil recovery was achieved with recovery efficiency of 88% original oil in place (OOIP).

Curcumin-encapsulated hydrophilic gelatin nanoparticle to stabilize fish oil-loaded Pickering emulsion

Herein, pH-cycle method was explored to prepare curcumin-encapsulated hydrophilic bovine bone gelatin (BBG/Cur) nanoparticle and then the obtained nanoparticle was applied to stabilize fish oil-loaded Pickering emulsion. The nanoparticle had a high encapsulation efficiency (93.9 ± 0.5 %) and loading capacity (9.4 ± 0.1 %) for curcumin. The nanoparticle-stabilized emulsion had higher emulsifying activity index (25.1 ± 0.9 m2/g) and lower emulsifying stability index (161.5 ± 18.8 min) than BBG-stabilized emulsion. The pH affected the initial droplet sizes and creaming index values of the Pickering emulsions: pH 11.0 < pH 5.0 ≈ pH 7.0 ≈ pH 9.0 < pH 3.0. Curcumin provided obvious antioxidant effect for the emulsions, which was also dependent on pH. The work suggested pH-cycle method could be used to prepare hydrophobic antioxidant-encapsulated hydrophilic protein nanoparticle. It also provided basic information on the development of protein nanoparticles for Pickering emulsion stabilization.

Effect of Janus Nanoparticles on Foam Stability

The foam properties of different surfactants were evaluated by the stirring method. The synergistic foam stabilizing effect was formed by the combination of lauryl glucoside and hydrophilic nanoparticles, but the result was feeble. The blend of Janus nanoparticles and surfactants significantly improves foam stability, and the two have a strong synergistic effect on foam stability. The compound system has a specific temperature resistance. Kruss dynamic surface tensiometer and surface dilatation rheometer were used to measure the gas-liquid interface properties of the hydrophilic nanoparticles compound system, Janus nanoparticles compound system, and surfactant system, respectively. The effects of Janus nanoparticles on the surface tension and surface dilatation modulus of the compound system were analyzed, which were correlated with the stability of the foam.

Resveratrol Analogs and Prodrugs Differently Affect the Survival of Breast Cancer Cells Impairing Estrogen/Estrogen Receptor α/Neuroglobin Pathway.

Breast cancer is the first leading tumor in women in terms of incidence worldwide. Seventy percent of cases are estrogen receptor (ER) α-positive. In these malignancies, 17β-estradiol (E2) via ERα increases the levels of neuroglobin (NGB), a compensatory protein that protects cancer cells from stress-induced apoptosis, including chemotherapeutic drug treatment. Our previous data indicate that resveratrol (RSV), a plant-derived polyphenol, prevents E2/ERα-induced NGB accumulation in this cellular context, making E2-dependent breast cancer cells more prone to apoptosis. Unfortunately, RSV is readily metabolized, thus preventing its effectiveness. Here, four different RSV analogs have been developed, and their effect on the ERα/NGB pathway has been compared with RSV conjugated with highly hydrophilic gold nanoparticles as prodrug to evaluate if RSV derivatives maintain the breast cancer cells' susceptibility to the chemotherapeutic drug paclitaxel as the original compound. Results demonstrate that RSV conjugation with gold nanoparticles increases RSV efficacy, with respect to RSV analogues, reducing NGB levels and enhancing the pro-apoptotic action of paclitaxel, even preventing the anti-apoptotic action exerted by E2 treatment on these cells. Overall, RSV conjugation with gold nanoparticles makes this complex a promising agent for medical application in breast cancer treatment.

Magnetic composite membrane roll column for rapid and high efficiency separation of antibodies

The increase in upstream titers of monoclonal antibodies puts enormous pressure on downstream processes, therefore new purification technology is desired. In this study, magnetic composite membrane roll columns based on “membrane sandwiched magnetism” strategy was proposed in order to overcome the drawbacks of conventional Protein A based methods. The composite membrane material consisted of high-density vinylimidazole (VIM) polymer brush modified hydrophilic membrane and Fe3O4 magnetic nanoparticles (MNPs, 5 mg). The resultant roll columns possess high permeability and hydrophilicity, excellent anti-non-specific adsorption ability, and good mechanical strength. Thanks to the “membrane sandwiched magnetism” strategy, the novel composite material also exhibited higher enrichment capacity (582.7 mg/g) for antibodies, faster processing (only 14.5 min), easier scaling up, and more convenient multiple circulation in comparison to the previously reported technologies. Therefore, the MNPs composite membrane (MNPs-M) roll column can rapidly and effectively enrich the target antibody, such as trastuzumab, bevacizumab, infliximab, rituximab, anti-PD-1 mAb, or hIgG from various biological matrices with good selectivity, recovery (>91.2 %), and purity (>98.4 %). Finally, in order to investigate the high-throughput separation ability, an automated antibody purification platform was established using a VIM polymer brush modified membrane roll column combined with a protein purification instrument. With a flow rate of 8 mL/min, the platform can rapidly process 10 mL of cell culture medium containing 0.5 mg/mL trastuzumab within only 10 min. In a word, a purification process was established in lab-scale and enlarged afterwards, and the novel composite material exhibits outstanding enrichment performance for antibody purification.

Ultrasmall porphyrin-silica core-shell dots for enhanced fluorescence imaging-guided cancer photodynamic therapy.

Clinically used small-molecular photosensitizers (PSs) for photodynamic therapy (PDT) share similar disadvantages, such as the lack of selectivity towards cancer cells, short blood circulation time, life-threatening phototoxicity, and low physiological solubility. To overcome such limitations, the present study capitalizes on the synthesis of ultra-small hydrophilic porphyrin-based silica nanoparticles (core-shell porphyrin-silica dots; PSDs) to enhance the treatment outcomes of cancer via PDT. These ultra-small PSDs, with a hydrodynamic diameter less than 7 nm, have an excellent aqueous solubility in water (porphyrin; TPPS3-NH2) and enhanced tumor accumulation therefore exhibiting enhanced fluorescence imaging-guided PDT in breast cancer cells. Besides ultra-small size, such PSDs also displayed an excellent biocompatibility and negligible dark cytotoxicity in vitro. Moreover, PSDs were also found to be stable in other physiological solutions as a function of time. The fluorescence imaging of porphyrin revealed a prolonged residence time of PSDs in tumor regions, reduced accumulation in vital organs, and rapid renal clearance upon intravenous injection. The in vivo study further revealed reduced tumor growth in 4T1 tumor-bearing bulb mice after laser irradiation explaining the excellent photodynamic therapeutic efficacy of ultra-small PSDs. Thus, ultrasmall hydrophilic PSDs combined with excellent imaging-guided therapeutic abilities and renal clearance behavior represent a promising platform for cancer imaging and therapy.

Amphiphilic interaction-mediated ordering of nanoparticles in Pickering emulsion droplets.

For various industrial processes, the stabilization of an oil phase is crucial and demands a proper balance of complex interactions in an emulsion system. In Pickering emulsions, this is achieved by introducing nanoparticles, which become organized at the oil-water interface. The influence of interparticle interactions towards the formation of a stable emulsion and the ordering of the stabilizing nanoparticles is intriguing and needs attention. In this work, the role of amphiphilic interactions between hydrophilic silica nanoparticles and the Pluronic F127 tri-block co-polymer towards the spontaneous formation of a fairly stable Pickering emulsion has been studied using small-angle X-ray scattering. Unlike the usual random arrangements of the nanoparticles in a conventional Pickering emulsion, we observed highly organized silica nanoparticles at the oil-water interface. The established standard raspberry structural model of the Pickering emulsion fails to explain such strong ordering as observed in the present case. A plausible formation mechanism of the present Pickering emulsion with a high on-surface silica correlation is elucidated on the basis of the combined interactions of the block co-polymer and silica particles. A computer model is developed to elucidate the effects of size and distribution of the surface-decorating nanoparticles and their positional correlation.

Mechanochemical Synthesis of Hydrophilic Sulfur Nanoparticles in Aqueous Surfactant Solutions and Their Antibacterial Activity and Acute Toxicity in Mice

Mechanochemical Synthesis of Hydrophilic Sulfur Nanoparticles in Aqueous Surfactant Solutions and Their Antibacterial Activity and Acute Toxicity in Mice

A general method for endowing hydrophobic nanoparticles with water dispersion abilities.

Inorganic nanoparticles with long-chain ligands are usually hydrophobic. However, simple and practical methods for converting hydrophobic nanoparticles to hydrophilic nanoparticles are still lacking. Herein, we developed a general method involving using dimercaptosuccinic acid (DMSA) for endowing hydrophobic nanoparticles with water dispersion abilities. By mixing a tetrahydrofuran solution of DMSA with a cyclohexane solution of hydrophobic nanoparticles, the long-chain ligands were replaced with DMSA, with the replacement due to the strong and broad-spectrum coordination abilities of sulphydryls and carboxyls. Four representative kinds of hydrophobic nanoparticles, namely Ag, NaGdF4, TiO2, and ZnS nanoparticles, were selected for verifying the performance of this DMSA-based modification method. Meanwhile, this method can also widen the applications of hydrophobic nanoparticles and facilitate their being subjected to further graft modifications. We hope that our research will increase the chances for applications of nanomaterials to be made.

Graphene Based Membrane Modified Silica Nanoparticles for Seawater Desalination and Wastewater Treatment: Salt Rejection and Dyes

The clean water crisis in Indonesia is increasing every year, and waste from the textile industry sector can also add to this problem. There are various water treatment processes to deal with the clean water crisis, one of which is the desalination process using graphene oxide. With the addition of hydrophilic nanoparticles, graphene oxide (GO) membranes can increase roughness and have good mechanical strength. SiO2 nanoparticles also have a high specific surface to absorb water or are hydrophilic. This study aims to determine the ability of the GO-SiO2/Psf membrane to reject salt (NaCl solution) and filtering of methylene blue solutions. Membrane prepared by variations of Tetraethyl orthosilicate (TEOS) 0.6; 0.8; 1.0; and 1.2 ml for GO/SiO2 composite synthesis. The results showed that the GO-SiO2/Psf membrane could absorb methylene blue solution. The most optimum absorption value occurred at a TEOS concentration of 0.8 ml and had the most effective salt rejection value for NaCl solution equal to 67.22%.

Hydrophilic Silica Nanoparticles in O/W Emulsion: Insights from Molecular Dynamics Simulation

Previous studies have been carried out on the effect of silica nanoparticles (SNPs) on the stability of oil-water emulsions. However, the combining configuration of SNPs and oil droplets at the molecular level and the effect of SNP content on the coalescence behavior of oil droplets cannot be obtained through experiments. In this paper, molecular dynamics (MD) simulation was performed to investigate the adsorption configuration of hydrophilic SNPs in an O/W emulsion system, and the effect of adsorption of SNPs on coalescence of oil droplets. The simulation results showed: (i) SNPs adsorbed on the surface of oil droplets, and excessive SNPs self-aggregated and connected by hydrogen bonds. (ii) Partially hydrophilic asphaltene and resin molecules formed adsorption configurations with SNPs, which changed the distribution of oil droplet components. Furthermore, compared with hydrophobic asphaltene, the hydrophilic asphaltene was easier to combine with SNPs. (iii) SNPs would extend the oil droplet coalescence time, and the π-π stacking structures were formed between asphaltene and asphaltene or resin molecules to enhance the connection between oil droplets during the oil droplet contact process. (iv) Enough SNPs tightly wrapped around the oil droplet, similar to the formation of a rigid film on the surface of an oil droplet, which hindered the contact and coalescence of components between oil droplets.

Visible-light driven noble metal (Au, Ag) permeated multicomponent Cu2ZnSnS4 nanocrystals: A potential low-cost photocatalyst for textile effluents and heavy metal removal

An exemplary vision to understand the fundamental role of metal-doped multi-components system such as Au/Ag doped CZTS (Cu2ZnSnS4) nanocrystals encourages the non-vacuum approach for the best performing photocatalyst. Hydrophilic nanoparticles (Au/Ag and CZTS) are allowed to amalgamate under NTP atmosphere, eradicating the prerequisite for high-end equipment. The potential of Au and Ag-doped CZTS nanoparticles was speculated using various optical and structural characterizations. The absorption range of CZTS nanoparticles lies in the visible range, while Au/Ag doping slightly red-shifts the absorption range, considered the desirable state for photocatalysis. The synthesized nanoparticles are highly monodispersed with ∼15–35 nm particle size for Ag, Au, and CZTS. Photocatalysis is a discernible scheme for treating wastewater containing dyes, textile effluents, chemicals, and heavy metals. Here, we strive to use these ex-situ synthesized nanomaterials as photocatalysts, where the real textile waste (collected from industrial outlets), dyes, and heavy metal (chromium (VI)) have been photo-reduced after scrutinizing the finest combination of Ag or Au doped CZTS. Au-CZTS shows superior catalytic activity with an efficiency of 99.7% with a rate constant of 0.2 min−1 (while Ag-CZTS shows 90% efficiency with a rate constant of 0.07 min−1); hence, used for real textile waste and heavy metal (Chromium VI) photo-reduction. The maximum efficiency achieved for textile-1, textile-2, and Cr (VI) reductions is 80%, 70%, and 97%, respectively. The nanocrystals are highly stable and recyclable, tested for 15 repeated cycles. These studies pave the way for developing cost-effective, environmentally-friendly, durable, and selective semiconductor-metal (Au/Ag) hybrid heterostructures as visible-light-driven photocatalysts for wastewater remediation.

Pickering Emulsion-Templated Nanocomposite Membranes for Excellent Demulsification and Oil-Water Separation.

A worldwide steady increase in oily wastewater, due to oil spillage and various industrial discharges, requires immediate efforts toward development of an effective strategy and materials to preserve the natural water bodies. Designing a superwettable fibrous membrane of robust structure and anti-fouling property for efficient separation of oil-water mixtures and emulsions is therefore highly demanding. The electrospun fibrous membrane, which possesses porosity and flexibility and properties including superwettability and tunable functionality, can be considered as apposite materials for this cause. In this approach, we combined two strategies, viz., Pickering emulsion and near gel resin (nGR) emulsion electrospinning together to produce a fibrous nanocomposite membrane for efficient oil-water separation and demulsification. nGR Pickering emulsions were stabilized using hydrophilic SiO2 nanoparticles and successfully optimized for fabricating the crosslinked core sheath-structured fibrous membrane. The prepared membrane provided twofold functionality due to the core sheath structure of the fibers. The crosslinked polystyrene core offered high oil adsorption capacity, whereas SiO2-functionalized crosslinked polyvinyl alcohol sheath provided a rough, superhydrophilic surface with underwater oleophobic behavior to the membrane. The optimized SiO2-Pickering emulsion-templated nanocomposite membrane demonstrated excellent underwater anti-oil adhesion behavior (UWOCA ∼148°) with efficient oil-water separation capacity of more than 99% and separation flux up to 3346 ± 91 L m-2 h-1. The membrane was evaluated against various oil-water emulsions and found to have a superior separation efficiency. Moreover, excellent anti-oil adhesion property provided the intact membrane, where consistent separation performance was achieved up to 10 separation cycles without any loss. The membrane was used for separation of hot oil-water emulsions and showed no structural disintegration or loss in separation performance when exposed to elevated temperatures. The developed nanocomposite membranes could efficiently be used for separation and demulsification, and their applications can be explored in various other fields including selective sorption, catalysis, and storage in future.

Separation of n-butanol from aqueous mixtures using TiO2 and h-BN functionalized MIL-101(Cr) incorporated PVDF mixed matrix membranes

In the present work, polyvinylidenefluroide (PVDF) mixed matrix membranes (MMMs) membranes are synthesized for selective separation of n-butanol from an aqueous mixture through organophilic pervaporation (PV). Hydrophobic MIL-101(Cr) surface-modified with TiO2 and h-BN nanoparticles (NPs) are incorporated into the PVDF membrane. The prepared nanocomposites and MMMs are characterized by various analytical techniques: FESEM, AFM, HRTEM with SAED pattern, PXRD, FTIR, XPS, TGA, porosity and water contact angle measurements. The prepared MMMs are applied to recover the 1.5 wt% n-butanol/water mixture. The hydrophobic nature of MIL-101(Cr) enhances the adsorption selectivity for butanol, resulting in enhanced butanol flux and selectivity. Experimental data show that the total flux and selectivity boost with increased feed composition and temperature. The modified membranes show enhancement in total flux and selectivity by 19.03 % and 63.25 % (A2), 80.03 % and 284.72 % (A3), and 90.99 % and 145.13 % (A4), respectively. Incorporating h-BN NPs into the MIL-101(Cr) increases the affinity for water molecules to pass through membranes, reducing the butanol selectivity of the membranes. From the experimental data, it can be concluded that adding hydrophilic nanoparticles such as TiO2 and h-BN into the MIL-101(Cr) enhances each membranes total flux and separation factor. The significant separation results are found for A3 membrane with total flux of 3139.21 g m−2 h−1 and separation factor of 95.04. Also, the A3 membrane shows good long term performance stability of 160 h. Overall, good physiochemical characteristics and separation performance show the practical applicability of the butanol separation for the prepared membranes.

Deterioration effects of SiO2 nanoparticles on the mass transfer in a single drop system with resistance in both phases

In the present study, it has been shown that the very small amount of Nanoparticles(NPs) has very significant effects on mass transfer deterioration. For the first time, the effects of hydrophilic SiO 2 NPs have been investigated in the system with the resistance in both phases (butanol-succinic acid-water. NPs with four-volume concentrations were added to the dispersed phase, and the transient and terminal velocities of drops were reported using an image processing tool. Results showed that the effects of NPs on the transient velocity of circulating /oscillating drops are insignificant. Experimental results also showed that the maximum and average deterioration effects were 54% and 26%, respectively in the presence of NPs. The addition of only 0.0005 vol% of NPs revealed about 20% deteriorating effect, while after the addition of 0.01 vol% of NPs, slight differences were observed. Accumulation of NPs in the interface area and gradual occupation were the main reason for mass transfer reduction, which has been supported by the calculation results in the present study. At the final stage, for the first time, the new overall mass transfer correlation has been proposed based on conjugate mass transfer resistance. This general form of correlation can be used for any liquid-liquid extraction (LLE) system with the dominant mass transfer resistance in the two phases in the presence of NPs. • Investigation of hydrophilic NPs effects on the mass transfer in systems with the resistance in both phases • Reporting the mass transfer deterioration of about 20% in the presence of 0.0005 vol% of NPs • Proposing a general form of mass transfer correlation for systems with resistance in both phases • confirmation of experimental findings with the calculation results

Synergistic improvement of foam stability with SiO2 nanoparticles (SiO2-NPs) and different surfactants

Foam fluids are widely used in petroleum engineering, but long-standing foam stability problems have limited the effectiveness of their use. The study explores the synergistic effects and influencing factors of SiO2 nanoparticles (SiO2-NPs) with different wettability properties and three different surfactants. The paper investigates the foaming performance of different types of surfactants and analyzes and compares the stability of foam after adding hydrophilic and hydrophobic SiO2-NPs from macroscopic as well as microscopic perspectives, and the effects of temperature and inorganic salts on the stability of mixed solutions. The experimental results show that: 1) hydrophilic nanoparticles can significantly enhance the foam stability of amphoteric surfactants, with a small increase in the foam stability of anionic and cationic surfactants; 2) The concentration of nanoparticles did not have a significant effect on the stability of the cationic surfactants and this conclusion was verified in the experimental results of the surface tension measured below;3) The cationic surfactants showed better temperature resistance at temperatures of 50–90 °C. Both amphoteric surfactant solutions with the addition of hydrophilic SiO2-NPs or hydrophobic SiO2-NPs significantly improved the temperature resistance of the foam at high temperatures. The anionic surfactant solution with hydrophobic SiO2-NPs did not enhance the solution temperature resistance; 4) The surface tension of the surfactant solution gradually increases with increasing concentration of hydrophilic or hydrophobic SiO2-NPs and then levels off; 5) the hydrophilic SiO2-NPs had a significant effect on the salt tolerance of the anionic and amphoteric surfactant solutions. The salt tolerance of cationic surfactant solutions with hydrophobic SiO2-NPs was better than that of surfactants with hydrophilic SiO2-NPs.