Temperature/salt tolerance and oil recovery of xanthan gum solution enhanced by surface-modified nanosilicas

Amide-and alkyl-modified nanosilicas(AANPs)were synthesized and introduced into Xanthan gum(XG)solution,aiming to improve the temperature/salt tolerance and oil recovery.The rheological behaviors of XG/AANP hybrid dispersions were systematically studied at different concentrations,temperatures and inorganic salts.At high temperature(75C)and high salinity(10,000 mg,L1 NaCl),AANPs increase the apparent viscosity and dynamic modulus of the XG solution,and XG/AANP hybrid dispersion exhibits elastic-dominant properties.The most effective concentrations of XG and AANP interacting with each other are 1750 mg·L^(-1) and 0.74 wt%,respectively.The temperature tolerance of XG solution is not satisfactory,and high temperature further weakens the salt tolerance of XG.However,the AANPs significantly enhance the viscoelasticity the XG solution through hydrogen bonds and hydrophobic effect.Under reservoir conditions,XG/AANP hybrid recovers approximately 18.5%more OOIP(original oil in place)than AANP and 11.3%more OOIP than XG.The enhanced oil recovery mechanism of the XG/AANP hybrid is mainly increasing the sweep coefficient,the contribution from the reduction of oil-water interfacial tension is less.

The geomechanical properties of soils treated with nanosilica particles

This study examines the effect of nanosilica(NS)additive to improve the mechanical properties of clay,clayey sand,and sand.The engineering properties of the soils were investigated through Atterberg limits,compaction,unconfined compression,ultrasonic pulse velocity(UPV),freeze-thaw,and direct shear tests.The NS content varied from 0%to 0.7%and cement content was 5%and 10%by the dry weight of the soil.The curing period varied from 7 d to 150 d.The consistency,compaction,and strength properties of the soils were affected by the presence of NS and cement.The optimum NS contents in clay specimens with 5%and 10%cement were 0.5%and 0.7%,respectively.It was 0.7%in sand specimens with both cement ratios,as well as 0.3%and 0.7%in clayey sand specimens with 5%and 10%cement,respectively.In terms of freeze-thaw resistance,clayey sand specimens containing 0.5%NS and 10%cement had the minimum strength loss.Exponential relationships existed between the ultrasonic pulse velocity(UPV)and the unconfined compressive strength(UCS)of soil specimens having the same curing period.The shear strength parameters of the soils also improved with the addition of NS.Scanning electron microscope(SEM)images demonstrated that cement and NS contributed to the improvement of the soils by producing a denser and more uniform structure.It was concluded that the minor addition of NS could potentially improve the geomechanical properties of the soils.

Microstructure characteristics of cement-stabilized sandy soil using nanosilica

An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy soil.Cement agent included Portland cement type II.Cement content was 6% by weight of the sandy soil.Nanosilica was added in percentages of 0%,4%,8% and 12% by weight of cement.Cylindrical samples were prepared with relative density of 80% and optimum water content and cured for 7 d,28 d and 90 d.Microstructure characteristics of cementnanosilica-sand mixtures after 90 d of curing have been explored using atomic force microscopy(AFM),scanning electron microscopy(SEM) and X-ray diffraction(XRD) tests.Effects of curing time on microstructure properties of cemented sandy soil samples with 0% and 8% nanosilica have been investigated using SEM test.Unconfined compression test(for all curing times) and compaction test were also performed.The SEM and AFM tests results showed that nanosilica contributes to enhancement of cemented sandy soil through yielding denser,more uniform structure.The XRD test demonstrated that the inclusion of nanosilica in the cemented soil increases the intensity of the calcium silicate hydrate(CSH) peak and decreases the intensity of the calcium hydroxide(CH) peak.The results showed that adding optimum percentages of nanosilica to cement-stabilized sandy soil enhances its mechanical and microstructure properties.

Preparation of polypyrrole/nanosilica composite for solid-phase microextraction of bisphenol and phthalates migrated from containers to eye drops and injection solutions

This paper describes the electrodeposition of polyphosphate-doped polypyrrole/nanosilica nano-composite coating on steel wire for direct solid-phase microextraction of bisphenol A and five phthalates. We optimized influencing parameters on the extraction efficiency and morphology of the nanocomposite such as deposition potential, concentration of pyrrole and polyphosphate, deposition time and the nanosilica amount. Under the optimized conditions, characterization of the nanocomposite was inves-tigated by scanning electron microscopy and Fourier transform infra-red spectroscopy. Also, the factors related to the solid-phase microextraction method including desorption temperature and time, extrac-tion temperature and time, ionic strength and pH were studied in detail. Subsequently, the proposed method was validated by gas chromatography-mass spectrometry by thermal desorption and acceptable figures of merit were obtained. The linearity of the calibration curves was between 0.01 and 50 ng/mL with acceptable correlation coefficients (0.9956-0.9987) and limits of detection were in the range 0.002-0.01 ng/mL. Relative standard deviations in terms of intra-day and inter-day by five replicate analyses from aqueous solutions containing 0.1 ng/mL of target analytes were in the range 3.3%-5.4% and 5%-7.1%, respectively. Fiber-to-fiber reproducibilities were measured for three different fibers prepared in the same conditions and the results were between 7.3% and 9.8%. Also, extraction recoveries at two different concentrations were ≥96%. Finally, the suitability of the proposed method was demonstrated through its application to the analysis of some eye drops and injection solutions.

Influence of colloidal nanosilica on hydration kinetics and properties of CaO/CaSO_(4)-activated slag binder

To solve the energy consumption and CO_(2) emission during cement production,the new binders must be developed as an alternative to cement.CaO/CaSO_(4)-activated slag binder is an eco-friendly and safe cementitious material;however,its low strength during initial stages limits its applications.In this study,colloidal nanosilica(CNS)was employed as an additive to improve the strength of CaO/CaSO_(4)-activated slag binder,and the effects of CNS on the workability,hydration kinetics,hydration products(type,quantity,and polymerization degree),and binder microstructure were thoroughly investigated.A moderate CNS content,through its nucleation effect,significantly increased the hydration rate of the nucleation and crystal growth(NG),phase boundary interaction(I)and diffusion(D)processes,which generated large quantities of calcium aluminosilicate hydrate(C-A-S-H)gel in the initial hydration stage.Meanwhile,the addition of CNS improved the polymerization degree of C-A-S-H gel.This amorphous reactant well-filled the pore space between slag particles and yielded a compact microstructure,consequently enhancing the binder strength.Considering the reduction in fluidity and the increase in production cost,the CNS mass fraction was controlled as3%,and the binder reached the satisfactory strengths of 3.87,24.47,31.43,and 41.78 MPa at 1,3,7,and 28 d,respectively.

Induction of Anthracnose Disease Resistance on Chili Fruit by Treatment of Oligochitosan—Nanosilica Hybrid Material

Oligochitosan (OC) with molecular weight Mw of 5000 g/mol was prepared by gamma Co-60 ray irradiation of chitosan solution. Nanosilica (nSiO2) with the size of 10 - 30 nm was synthesized by calcination of acid treated rice husk. The mixture of 1% OC - 1% nSiO2 was prepared by dispersion of nSiO2 in OC solution. The morphology of nSiO2 in the mixture of OC-nSiO2 was measured from images of transmission electron microscopy (TEM). The effect of foliar application of the mixture of OC-nSiO2 on the induction of resistance against anthracnose disease caused by Colletotrichum gloeosporioides fungus on chili fruits was investigated. Results indicated that foliar application of OC-nSiO2 with the concentration of 60 mg/l - 60 mg/l was found to be as the optimal treatment that reduced the disease severity on chili fruits to 22.2% compared with 90.0% of the control. Thus, OC-nSiO2 hybrid material could be considered as an effective biotic elicitor to prevent anthracnose disease infection for chili fruits. Furthermore, the prepared OC-nSiO2 hybrid material can also be used as an environmentally friendly agrochemical product for sustainable development of agriculture.

Resistance of Epoxypolymer with 2 - 5 wt% Nanosilica in Aggressive Acid Medium

The swelling dynamic and epoxy resin structure changes of nanosilica (NS) with different specific surface in concentrated nitric acid were studied. It is established that with increasing of specific surface area of unmodified NS swelling degree decreases and stability of the composite in the acid goes up. Resistance of NS to the HNO3 can be achieved by choosing the optimal concentration and modifications of NS’s surface. According to electron microscopy and X-ray diffraction, the structure of composite can be changed due to appearance of ordered structural zones.

A novel responsive stabilizing Janus nanosilica as a nanoplugging agent in water-based drilling fluids for exploiting hostile shale environments

Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.

Enhanced consolidation efficacy and durability of highly porous calcareous building stones enabled by nanosilica-based treatments

Outdoor building stones are suffering from serious degradation.To restore internal cohesion and to alleviate the disintegration of decayed stones,consolidation treatment is necessary and significant.Up to date,no fully satisfactory consolidation agent and its application methodology are available,mainly due to the limited penetration depth of consolidants,low compatibility,or poor durability in environmental conditions.Herein,in this study,aiming to design an effective and enduring method for the consolidation of highly porous calcareous stones,nanosilica-based consolidation treatments were tested and compared with traditional compounds(tetraethoxysilane,alkylalkoxysilane,barium hydroxide).In order to evaluate their performance and compatibility,a series of standard tests,including the Drilling Resistance Measurement System(DRMS)test,surface color measurement,vapor diffusivity measurement,and peeling test,were carried out.Besides,the penetration depth and distribution profiles of consolidants were estimated by exploiting elemental raster scanning of SEM-EDS analysis performed throughout the thickness of samples.More importantly,by employing a climatic chamber,the artificial ageing test was also conducted by simulating harsh atmospheric conditions.After accelerated ageing,the performance of all consolidants was assessed again.Results demonstrated that the application of nanosilica(<10 nm in dimension)by cellulose poultice,followed by adding tetraethoxysilane with the classical method“wet on wet”,is the best consolidation approach,in terms of in-depth consolidation efficacy,compatibility with the stone substrate,surface cohesion strength and performance durability in environmental conditions.Moreover,the treated surface is not hydrophobic,which allows further grouting and adhesion operations usually required for the restoration of historic buildings.

A robust and transparent nanosilica-filled silicone rubber coating with synergistically enhanced mechanical properties and barrier performance

Implantable electronic devices(IEDs)are widely used by human beings to achieve medical treatment and diagnosis nowadays.However,ideal encapsulation of IEDs is still far from perfect as full prevention of body fluid diffusion into the coating remains unsolved.Herein,we develop a high-performance composite coating for IED encapsulation by introducing SiO_(2) nanoparticles into silicone rubber,which synergistically enhances mechanical properties and improves barrier performance.By fabricating composite coatings with different nanosilica contents,3%nanosilica is proved to be an optimal additive content with an excellent combination of improved fracture strength(from 2.5 MPa to 4.5 MPa),increased coating resistance(from 10^(4) to 10^(9) cm^(2))and ideal coating uniformity.Mechanical and electrochemical characterizations subsequently confirm substantially enhanced mechanical properties and barrier performance of the composite coating,which effectively resist crack propagation and impede penetrations of water and chloride ions through the coating.Theoretical calculations further uncover that modified SiO_(2) particles with enriched methyl groups endow a strong bridging effect to interact with silicone rubber monomer,which,together with anti-agglomeration property of methyl groups,contributes to a pronounced improvement in mechanical performance of nanosilica-filled silicone rubber.Benefitting from the enhanced mechanical and barrier properties,the as-fabricated nanosilica-filled silicone rubber demonstrates superior protection for the encapsulated circuits with a significantly improved lifetime(709.1 h)compared to that of circuits coated by pure silicone rubber(472.8 h)and bare circuit boards(1 h),which offers great values for packaging material design in future IED encapsulation.

小麦低聚肽-纳米二氧化硅蛋白冠复合物的制备及其性能研究

采用表面羧基化修饰后的纳米二氧化硅(Si O_(2)nanoparticles,Si O_(2)NPs)与小麦低聚肽(wheat oligopeptide,WOP)进行超声复合,使小麦低聚肽在纳米二氧化硅表面形成蛋白冠(protein corona,PC),制备出小麦低聚肽-纳米二氧化硅蛋白冠复合物(wheat oligopeptide-nanosilica protein corona complex,WOP-Si O_(2)PC)。研究不同反应条件对纳米二氧化硅与小麦低聚肽复合率的影响,并对小麦低聚肽-纳米二氧化硅蛋白冠复合物的抗氧化性、起泡性及乳化性进行测定。研究结果表明,小麦低聚肽-纳米二氧化硅蛋白冠复合物制备的最优条件为:超声波时间20 min,超声波温度65℃,Si O_(2)NPs质量分数0.75%。小麦低聚肽-纳米二氧化硅蛋白冠复合物的DPPH自由基、ABTS阳离子自由基清除率达到38.35%、55.12%。起泡性、起泡稳定性达到103.51%、15.21%;持水性、持油性达到423.67%、442.79%;乳化性、乳化稳定性达到16.81 m^(2)/g、65.21%。

Synthesis and electrochemical performance of hierarchical porous carbons with 3D open-cell structure based on nanosilica-embedded emulsion-templated polymerization

A novel synthesis of hierarchical porous carbons （HPCs）with 3D open-cell structure based on nanosilica- embedded emulsion-templated polymerization was reported. An oil-in-water emulsion containing SiO2 colloids was fabricated using liquid paraffin as an oil phase, resorcinol/formaldehyde and silica sol as an aqueous phase, and Span 80/Tween 80 as emulsifiers. HPCs with macropore cores, open meso/ macropore windows, and abundant micropores were synthesized by the polymerization and carbonization of the emulsion, followed by scaffold removal and further KOH activation. A typical HPCs sample as supercapacitor electrode shows the charge/discharge capability under large loading current density （30 A/g） coupling with a reasonable electrochemical capacitance in KOH electrolyte solution.

“Nanospace engineering”by the growth of nano metal-organic framework on dendritic fibrous nanosilica(DFNS)and DFNS/gold hybrids

Advanced hybrid nanomaterials(nanohybrids)with unique tailored morphologies and compositions have been used for the target-oriented catalysts due to the structural or supportive properties of each moiety and the synergistic properties of the individual components.The rational design and development of nanohybrids by integrating highly porous silica into a nano metal-organic framework(NMOF)are expected to enable unique nanospace engineering in the resulting systems to optimize their utility in the target areas.Herein,we report the design and fabrication of advanced nanohybrids composed of dendritic fibrous nanosilica(DFNS)and DFNS/gold(DFNS/Au)hybrids as the core and zinc-based NMOF(Zn-NMOF)as the shell(DFNS@Zn-NMOF)through a solution-based approach.The combined fibrous morphology of DFNS and micropores of NMOF can be directly employed for nanospace engineering in the resulting multi-compositional and hierarchical systems in a controllable manner.The DFNS/Au dots@Zn-NMOF nanohybrid shows improved catalytic performance in the Knoevenagel condensation reaction,attributed mainly to the cooperative effect stemming from the suitably organized configurations of each component.

A Novel Ternary Composite of Polyurethane/Polyaniline/Nanosilica with Antistatic Property and Excellent Mechanical Strength:Preparation and Mechanism

Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments.Herein,polyurethane was composited with polyaniline and nanosilica based on in situ synthesis of polymer and physical mixing of these fillers to reach desired antistatic and mechanical properties.Chemical,morphological and thermal properties of the polyurethane/polyaniline/nanosilica composites were studied.The electrical resistivity of the composite decreased from 1.1×10^(6)MΩto 7.6×10^(4)MΩas a result of the addition of 4%polyaniline.The tensile strength and elongation at break of the polyurethane composites improved by nearly 300%and100%,respectively,when compared with those of the neat polyurethane.The electronic resistance of PU/PANI/NS ternary is low enough for its antistatic property and decreases with the increase of the added nanosilica,which is unexpectedly and rather significant.Our results would shed light on the development of antistatic PU with excellent mechanical performance.

A nanosilica/exfoliated graphene composite film-modified electrode for sensitive detection of methyl parathion

Graphene nanosheets （GS） were easily prepared through liquid-phase exfoliation of graphite powder in N,N-dimethylformamide （DMF） with the assistance of sodium citrate. Then, GS was coated onto a glassy carbon electrode （GCE） surface by drop to fabricate a GS]GCE nanointerface. Subsequently, by using tetraethylorthosilicate sol as precursor, nanosilica was electrochemically deposited onto the GS]GCE surface to produce a nanocomposite film electrode （nanosilicaJGSJGCE）. Electrochemical behaviors of methyl parathion （MP） on the nanosilica/GS/GCE surface were investigated thoroughly. It was found that the nanosilicaJGS nanocomposites can improve the redox peak currents of MP significantly due to the synergetic effect. The oxidation peak current was linearly related to MP concentration in the range from 0.0005 μmol/L to 5.6 μmol/L. The detection limit was calculated to be 0.07 nmol/L （SJN = 3）. The developed method was used to determine MP in real samples. The recoveries were in the range from 95.4% to 104.2%, demonstrating satisfactory results.

A methodology to improve nanosilica based cements used in CO2 sequestration sites

Attempts to reduce the amount of greenhouse gases released into the atmosphere in recent years have led to the development of Carbon Capture and Sequestration(CCS)technology.However,there have been many studies reporting leakages form CO2 storage sites as a result of cement degradation induced by generation of an acidic environment in the storage site.Although there are a number of approaches proposed to enhance the efficiency of the cement,the degradation issue has not been totally resolved yet perhaps due to the excessive corrosives nature of carbonic acid and supercritical CO2.The aim of this study is to propose a methodology to improve the physical and mechanical characteristics of the cement by nanomodification such that a consistent rheology,constant density and a good strength development can be achieved.A new dispersion technique was proposed to ensure that the cement formulation gives a consistent result.The results obtained indicated that unlike the literature mixing,cement slurries prepared by the new mixing technique are very consistent in their rheology,regardless of the sonication parameters chosen.The measurements of the compressive strength performed at the reservoir condition revealed that nanosilica contributes in the strength development up to a certain point.Thermogravimetric Analysis(TGA)conducted at the last stage indicated that the amount of Portlandite left in the cement by adding nanosilica is decreased due to the pozzolanic reaction,which would help the cement to have a higher chance of survival in a storage site.However,cautions must be taken to maintain a certain amount of Portlandite in the cement for slowing down the carbonation rate,as otherwise the matrix of the cement is attacked directly and the cement will be degraded very fast.

复合混凝土材料及不同蜂窝夹芯结构的力学性能综述

为全面开展复合混凝土材料制备蜂窝夹芯板的研究,综述了国内外关于稻草秸秆纤维与纳米二氧化硅复合混凝土材料及蜂窝夹芯结构的研究,分析了各种检测方法,概述了稻草秸秆纤维与纳米二氧化硅复合混凝土材料及不同蜂窝夹芯结构的力学性能,对复合混凝土材料蜂窝夹芯板研究及应用趋势进行总结。

Effects of Nanosilica on Crystallization and Thermal Ageing Behaviors of Polyethylene Terephthalate

The effects of nanosilica（SiO2） on crystallization and thermal aging behaviors of polyethylene terephthalate（PET） have been studied using differential scanning calorimetry（DSC） and polarized optical microscopy（POM）, viscometry, tensile testing and scanning electron microscopy（SEM）. For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 ℃, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.

纳米二氧化硅改性及其在提高采收率中的应用

对改性纳米二氧化硅及其在提高采收率中的应用现状及发展趋势进行了总结,对纳米二氧化硅的物理改性方法及包含胺类化合物改性、硅烷偶联剂改性、醇脂类改性、枝接聚合物改性、原位改性等在内的化学改性方法进行了综述,对于这几种纳米二氧化硅改性方法的优缺点进行论述和评估,重点讨论了改性后的纳米二氧化硅在油气田中降压增注、降低油水界面张力及改变岩石表面润湿性方面的应用和机理。总结了改性纳米二氧化硅在提高采收率方面的优势和不足,对其发展趋势进行了展望,为改性纳米二氧化硅提高采收率技术的进一步研究提供了参考和建议。