nano-SiO2 Concentration Research Articles

Preparation of SiO2-polydimethylsiloxane-octadecyltrichlorosilane superhydrophobic coating and its self-healing performance

The self-healing performance of superhydrophobic coatings is an important property to enhance the durability and self-cleaning character, which has been a focus of surface modification in recent years. In this work, a simple method was proposed for preparing the superhydrophobic coatings with self-healing properties on slides using nano-SiO2, octadecyltrichlorosilane, and polydimethylsiloxane. The hydrophobic properties, morphologies, compositions, structures, stability, and self-healing properties were respectively investigated via various characterizations and tests. The results indicated that the self-healing properties of the coatings were induced by the Si-O-Si bonds through X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The best self-healing property and hydrophobicity after healing were obtained when the content of polydimethylsiloxane was 35% (wt.), and the contact angle of water would arrive at 160.98° when the concentration of nano-SiO2 was 3% (wt.). The contact angle of each coating surface remained stable and thermally stable when the temperature was increased from 100 to 300 °C ( Tg), and the coatings remained stable under natural acidic and alkaline environments as well as mechanical shocks. So superhydrophobic coatings with self-healing performance have potential applications for the development of durable surfaces.

Effects of Nano-SiO2 grafting on improving the interfacial and mechanical properties of concrete with rice straw fibers

As a green and clean product, plant fiber has become a hot spot in the research of concrete. However, the weak interfacial properties of plant fibers with cement matrix restricted the development of plant fiber reinforced concrete. This study intends to prepare rice straw fiber reinforced concrete (RSFRC) grafting by Nano-SiO2 on the surface of rice straw fibers. The interface properties of silica grafted on straw fibers with cement were evaluated by the pull-out test of a single fiber from the cementitious matrix. The mechanical properties and fatigue resistance of RSFRC were investigated and a two-parameter Weibull probability fatigue equation of RSFRC was established. The enhancement mechanism of ITZ was revealed by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) tests. Results show that straw fibers grafted with Nano-SiO2 can momentously improve the mechanical and fatigue properties of RSFRC. The compressive strength, flexural strength, and abrasion resistance of RSFRC were increased by 14.6%, 22.3%, and 87.1%, compared with ordinary RSFRC after 28 days of curing. The specimens with 3% Nano-SiO2 concentration and the addition of 2% rice straw fiber to the cement weight exhibited the best flexural fatigue performance. From the microstructure analysis, Nano-SiO2 can enhance the interfacial properties of straw fibers in cement matrix, decrease the presence of calcium hydroxide and facilitate the formation of calcium silicate hydrate(C-S-H) gel. Beyond that, this research has a positive environmental impact on lowering the carbon footprint in concrete from using agriculture-based waste materials to extend the service life of infrastructures.

Nano-Silica/Urea-Formaldehyde Resin-Modified Fast-Growing Lumber Performance Study

To promote the performance of fast-growing poplar wood for furniture applications, this study proposes and investigates the feasibility of modifying fast-growing poplar wood with a urea-formaldehyde resin impregnating agent by adding nano-SiO2 as a way to improve its physical and mechanical properties. By observing the solubility of nano-SiO2 addition in urea-formaldehyde resin, determine the optimal ratio of nano-SiO2 addition to the solid content of the urea-formaldehyde resin solution. After the fast-growing poplar specimens were treated with nano-SiO2/UF resin, the water absorption, wet swelling, dry shrinkage, nail grip, flexural strength, and modulus of flexural elasticity of the fast-growing poplar specimens were compared and analyzed to determine the effect of impregnation modification and the optimal impregnation ratio. The results showed that the physical and mechanical properties of fast-growing poplar wood were significantly improved by impregnating the fast-growing poplar wood with urea-formaldehyde resin with SiO2, and the impregnation modification was beneficial to reducing the wet swelling and dry shrinkage of poplar wood, increasing its dimensional stability, improve the grip nail strength, and increase the flexural strength and flexural modulus of elasticity with the increase in nano-SiO2 concentration.

Effect of nano-SiO2 modified recycled coarse aggregate on the mechanical properties of recycled concrete

Improving the performance of the interface between old mortar and recycled coarse aggregate (RCA) is a hot topic and important to enhance the properties of recycled aggregate concrete (RAC). In this paper, the RCA was soaked by nano-SiO2 (NS-RCA) then the water absorption and crushing index of NS-RCA were investigated. The mechanical properties, such as compressive strength, flexural strength, and elastic modulus of RAC prepared by NS-RCA (NS-RAC) were studied. The Thermogravimetric and Differential Thermal Analysis (TG-DTA) and scanning electron microscopy (SEM) were applied to analyze the properties of the interface transition zone (ITZ) around unmodified RAC and NS-RAC. A modified stress–strain model of NS-RAC was proposed considering the concentration of nano-SiO2 and soaking time. The testing results showed that the concentration of nano-SiO2 and soaking time had significant effects on the strength and durability of RCA and the mechanical properties of RAC. The 2% concentration of nano-SiO2 and 48 h soaking time had the best modification effect on RCA. The compressive strength, flexural strength, and elastic modulus of NS-RAC with best modification were 31.8%, 33.2%, and 89.6% higher than those of unmodified RAC respectively. The TG-DTA and SEM analyses indicated that NS-RAC had the denser microstructure of ITZ. This study is conducive to enrich the knowledge about using NS-RAC and supplying guidance for its mix design.

Effects of Multi-Walled Carbon Nanotubes and Nano-Silica on Root Development, Leaf Photosynthesis, Active Oxygen and Nitrogen Metabolism in Maize.

Carbon nanotubes (MWCNTs) and nano-silica (nano-SiO2) are widely used in the field of life science because of their special physical and chemical properties. In this study, the effects of different concentrations of MWCNTs (0 mg·L-1, 200 mg·L-1, 400 mg·L-1, 800 mg·L-1 and 1200 mg·L-1) and nano-SiO2 (0 mg·L-1, 150 mg·L-1, 800 mg·L-1, 1500 mg·L-1 and 2500 mg·L-1) on maize seedling growth and relative mechanisms were explored. The main results are as follows: MWCNTs and nano-SiO2 can promote the growth of maize seedlings, and promote plant height, root length, the dry and fresh weight of seedlings, root-shoot ratio and so on. The ability to accumulate dry matter increased, the relative water content of leaves increased, the electrical conductivity of leaves decreased, the stability of cell membranes improved and the water metabolism ability of maize seedlings increased. The treatment of MWCNTs with 800 mg·L-1 and nano-SiO2 with 1500 mg·L-1 had the best effect on seedling growth. MWCNTs and nano-SiO2 can promote the development of root morphology, increase root length, root surface area, average diameter, root volume and total root tip number and improve root activity, so as to improve the absorption capacity of roots to water and nutrition. After MWCNT and nano-SiO2 treatment, compared with the control, the contents of O2·- and H2O2 decreased, and the damage of reactive oxygen free radicals to cells decreased. MWCNTs and nano-SiO2 can promote the clearance of reactive oxygen species and maintain the complete structure of cells, so as to slow down plant aging. The promoting effect of MWCNTs treated with 800 mg·L-1 and nano-SiO2 treated with 1500 mg·L-1 had the best effect. After treatment with MWCNTs and nano-SiO2, the activities of key photosynthesis enzymes PEPC, Rubisco, NADP-ME, NADP-MDH and PPDK of maize seedlings increased, which promoted the opening of stomata, improved the fixation efficiency of CO2, improved the photosynthetic process of maize plants and promoted plant growth. The promoting effect was the best when the concentration of MWCNTs was 800 mg·L-1 and the concentration of nano-SiO2 was 1500 mg·L-1. MWCNTs and nano-SiO2 can increase the activities of the enzymes GS, GOGAT, GAD and GDH related to nitrogen metabolism in maize leaves and roots, and can increase the content of pyruvate, so as to promote the synthesis of carbohydrates and the utilization of nitrogen and promote plant growth.

Effect of nano-SiO2 on the flowback-flooding integrated performance of water-based fracturing fluids

Nanomaterials have the characteristics of reducing water molecular clusters and improving surface properties. Therefore, it can effectively enhance the oil displacement (or imbibition) effect while developing low permeability and unconventional reservoirs. Volume fracturing based on horizontal wells has become the primary technology in developing unconventional reservoirs. In this paper, we investigated the effect of nano-SiO2 on the rheology, flowback, and subsequent oil displacement performance of fracturing fluid. Results showed that nano-SiO2 had little impact on the swelling and dispersion properties of the two thickeners (i.e., guar gum and emulsion polymer). The apparent viscosity of these two thickener solutions decreased by less than 15% after aging for 24 h. Nevertheless, nano-SiO2 particularly influenced the rheological properties of guar gum based fracturing fluid. That is to say, the increase in the amount of nano-SiO2 gradually reduced the temperature and shear resistance of the fracturing fluid. When the concentration of nano-SiO2 reached 5%, the temperature and shear resistance of fracturing fluid decreased by 40%–60% in the temperature range of 80 to 100 °C. However, nano-SiO2 had little effect on the fracturing fluid's breaking time and the solution's viscosity after breaking, and the surface tension of the solution slightly increased after breaking. The fracturing fluid added with nano-SiO2 improved the performance of inhibiting clay swelling after the gel was broken. In addition, the solution after gel breaking had an excellent demulsification effect on emulsified crude oil when the concentration of nano-SiO2 was less than 0.2%. While the concentration of nano-SiO2 was greater than 0.5%, the increase in nano-SiO2 concentration gradually strengthened the emulsification between crude oil and gel-breaking fluid. Nano-SiO2 also had an excellent oil displacement effect, and it increased the recovery efficiency of primary water flooding by 9.99–13.34 percentage points. IThe field test of nanoparticle flooding and fracturing integrated technology was carried out for two wells in the Mahu tight oil reservoir of Xinjiang Oilfield, NW China. The pilot tests of the two wells were very successful, and the cumulative oil production on the 180th day after the fracturing operation was 20–50% higher than that of the comparison well.

Carbonation Resistance of Marine Concrete Containing Nano-SiO2 under the Action of Bending Load

In order to study the influence of nanomaterials on the carbonation resistance of marine concrete under bending loads, an appropriate amount of nano-SiO2 was added to plain concrete, and a self-developed carbonation box and bending loading device were used to conduct a coupling test. Four different stress levels were set to measure the carbonation depth of nano-concrete at different ages. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the concrete interfacial transition zone. The carbonation depth was used as the test index to evaluate the durability of nano-SiO2-based concrete under the combined action of bending load and carbonation. The test results showed that the compressive and flexural strengths of concrete remarkably improved when the nano-SiO2 concentration was 2%. Compared with regular concrete, the compressive and flexural strengths of nano-SiO2 based concrete improved by 15.5% and 15.3%, respectively. When the stress level was 0.15 and 0.6, the carbonation depths of NS20 were 20.5 and 18.4% lower than those of PC in the tensile zone and 18.9 and 23.7% lower than those of PC in the compression zone. The carbonation depth of the NS20 tensile zone was lower by 31 and 18.4% at 3 and 28 days than that of PC. Compared with PC, the carbonation depth in the compression zone of NS20 decreased by 50 and 23.7%, and the carbonation depth of nano-concrete was significantly lower than that of conventional concrete under the same stress level and age. When the stress level is constant, the carbonation depth of the tension zone and compression zone increases gradually with the increase in age, and the carbonation depth of the concrete in the first 7 d was 50% that at 28 days. Under the same age, the carbonation depth in the tension zone increased with increasing stress levels, while the carbonation depth in the compression zone decreased with increasing stress levels. When the stress level was 0.3–0.45, the slope of the carbonation depth curve significantly increased. SEM and XRD analysis results revealed that nano-SiO2 significantly improved the internal structure of concrete by reducing the width of the microcracks, the number of pores, and the number of microcracks. The number of C3S/C2S and CaCO3 crystals in nano-SiO2 based concrete was significantly less than that in plain concrete, and the amount of C-S-H gel was more than that in plain concrete. Under bending loads, the nano-SiO2 significantly improved the carbonation resistance of concrete. When the dosage of nano-SiO2 was 2%, its improvement effect was the most significant.

Tribological of Eu-doped WO3 coated with SiO2 transfer film formation on sliding surface

ABSTRACT Europium nitrate, ammonium tungstate and hexadecyl trimethyl ammonium bromide were used, and Eu-doped WO3 (WO3:Eu3+) nanopowder was synthesized by the micro-emulsion method. Tetraethyl silicate was hydrolysed into SiO2 and WO3:Eu3+ nanopowder coated with SiO2 (SiO2/WO3:Eu3+) was obtained. The microstructure and morphology of the prepared nano-SiO2/WO3:Eu3+ powders were characterized by XRD, SEM, TEM and HRTEM. Results showed that the prepared nano-SiO2/WO3:Eu3+ powders composed of WO3 of monoclinic and SiO2 of amorphous, which was spherical and granular, and the grain size reaches 50 nm. The tribological behaviour of nano-SiO2/WO3:Eu3+ as extreme pressure and anti-wear additive in the water-based fluid was studied by a four-ball machine. The results demonstrate that nano-SiO2/WO3:Eu3+ exhibits superior load-bearing capacity, anti-wear and anti-friction performance in water-based fluid, especially when the optimal concentration of nano-SiO2/WO3:Eu3+ is 0.4 wt-%. WSD, COF and wear volume of the nano-SiO2/WO3:Eu3+ decreased by 62.43%, 30.20% and 67.34%, respectively, compared with that of the water-based fluid.

Antifungal Activities and Some Surface Characteristics of Denture Soft Liners Containing Silicon Dioxide Nanoparticles.

ABSTRACTObjective:This study aimed at determining the influence of adding silicon dioxide nanoparticles (nano-SiO2) to soft relining materials on C. albicans adhesion, surface roughness, and contact angle.Materials and Methods:Eighty heat-polymerized acrylic resin disks were constructed and relined by using auto-polymerized acrylic soft liners (COE-SOFT, GC Co., Tokyo, Japan). The specimens were categorized into two groups according to the tests conducted. Group A was composed of 40 specimens for evaluating antifungal activity, and Group B was composed of 40 specimens for testing surface roughness and contact angle. Each group was subcategorized into four subgroups (n = 10) according to the concentration of nano-SiO2 added to the soft-liner powder: control, 0.25%, 0.5%, and 1.0% by weight. The colony forming unit (CFU) was used to assess C. albicans count. A profilometer was used to measure the surface roughness values (Ra; μm). The sessile drop method was used to evaluate the contact angle (o) by using a goniometer. Analysis of variance and Tukey’s post hoc tests (α = 0.05) were used for the data analysis.Results:In comparison with the unmodified group, the 0.25% and the 0.5% nano-SiO2 groups exhibited significantly lower C. albicans counts (P < 0.001), surface roughness (P < 0.001), and contact angles (P < 0.001). The exception was the 1% group, which exhibited higher C. albicans count, surface roughness, and contact angles than lower-concentration nano-SiO2 groups; however, these values in the 1% group were still less than their respective values in the control group.Conclusion:The addition of 0.25% and 0.5% nano-SiO2 to an auto-polymerized acrylic soft liner decreased C. albicans adhesion, surface roughness, and contact angle.

Increase of Solid Polymer Electrolyte Ionic Conductivity Using Nano-SiO2 Synthesized from Sugarcane Bagasse as Filler.

The synthesize of solid polymer electrolyte (SPE) based on polyethylene oxide (PEO), NaClO4 and nano-SiO2 was carried out by solution cast technique. Nano-SiO2 was synthesized from sugarcane bagasse using sol-gel method. FTIR analysis was carried out to investigate the bonding between nano-SiO2 and PEO/NaClO4. The morphology of the SPE was characterized using SEM. XRD and DSC analysis showed that SPE crystallinity decreased as nano-SiO2 concentration was increased. Mechanical analyses were conducted to characterize the SPE tensile strength and elongation at break. EIS analysis was conducted to measure SPE ionic conductivity. The PEO/NaClO4 SPE with the addition of 5% nano-SiO2 from sugarcane bagasse at 60 °C produced SPE with the highest ionic conductivity, 1.18 × 10−6 S/cm. It was concluded that the addition of nano-SiO2 increased ionic conductivity and interface stability at the solid polymer electrolyte-PEO/NaClO4.

Nano-SiO2 for efficiency of geotechnical properties of fine soils in mining and civil engineering

Taking into account the decreased number of available lands, the construction of structures on soft soil leads towards the development of soil stabilizing models. This study is aimed at studying the decrement of land resources available, and the design of civil engineering structures on soft soils that will develop the soil impact of nano-SiO2 in the use of clay soil with low liquid limit, in particular shear resistance and unconfined compression. A novel nano-soil stabilizer has been created in this investigation by use of nano-SiO2 activity and ultrafine features that have enabled cement-based stabilizers to increase their characteristics in broad application possibilities. This research aims to examine the influence on soil engineering, particularly the shear strength of clay soil with a low liquid limit to the effect of adding nano-SiO2. Nano-SiO2 has 3 different percentages combined with soil (i.e., 0.5, 0.7 percent by weight of the parent soil), A direct shear test was used to evaluate the shear strength of the specimen, and then the results were analyzed by Artificial Neural Network (ANN) to increase the accuracy of outcomes. Increased nano-SiO2 concentration was shown to lead to an increased internal friction angle and cohesiveness on clay soil. The optimal content for nano-SiO2 is 0.7%. ANN could accurately demonstrate the shear strength percentages in nano-SiO2 content.

Antifungal Efficacy and Physical Properties of Poly(methylmethacrylate) Denture Base Material Reinforced with SiO2 Nanoparticles.

To evaluate the effect of the addition of low concentration of silicon-dioxide nanoparticles (nano-SiO2 ) to poly(methylmethacrylate) (PMMA) denture base material on Candida albicans adhesion, surface roughness, contact angle, hardness, and translucency. A total of 150 acrylic disks were fabricated from heat-polymerized acrylic resin and specimens were divided into 3 groups of 50 per test. They were further subdivided into 5 subgroups (n = 10) according to the concentration of nano-SiO2 : control (no addition) and four tested groups modified with 0.05, 0.25, 0.5, and 1.0 wt% nano-SiO2 of acrylic powder. Slide count and direct culture methods were used to measure C. albicans count (CFU/mL). The surface roughness values (Ra ; μm) were determined using a profilometer. The contact angle (o ) measurement was performed by a goniometer using the sessile drop method. Vickers hardness was used to analyze surface hardness. Translucency was measured using a spectrophotometer. Data analysis was conducted through analysis of variance and Tukey's post hoc tests (α = 0.05). Compared to the control group, direct culture and slide count methods illustrated a significant decrease in C. albicans count (p ˂ 0.001) with the addition of nano-SiO2 , and this decrease was correlated with the concentration of nano-SiO2 . The addition of nano-SiO2 significantly decreased the contact angle (p ˂ 0.001), whereas hardness and surface roughness significantly increased (p ˂ 0.001). The addition of nano-SiO2 significantly decreased translucency (p ˂ 0.001), and this decrease was concentration dependent. Addition of low concentration of nano-SiO2 decreased C. albicans adhesion to PMMA denture base resin. Also, low additions of nano-SiO2 have positive effects on contact angle and hardness, whereas surface roughness and translucency were adversely affected at high concentrations.

Lipidomic analysis of diatoms cultivated with silica nanoparticles

Polar lipids from the diatoms Diadesmis gallica and Navicula atomus were separated and their structures were determined using high resolution tandem MS HILIC-LC/ESI. This method allowed us to identify 34 classes of lipids, each containing dozens of molecular species, including regioisomers. The largest differences were found in two sulfur-containing lipids, sulfoquinovosyldiacylglycerol and phosphatidylsulfocholine caused probably by the remodeling of lipid species. These diatoms have been found to use several mechanisms to resolve growth in extreme environments, i.e. silica starvation. The presence of insoluble nano-SiO2 leads to the replacement of cellular phospholipids with sulfolipids. Regioisomer ratios also vary depending on the concentration of nano-SiO2 in the culture medium, i.e. the biosynthesis of polar lipids via the prokaryotic (plastidial) and/or eukaryotic (explastidial) pathways. Complex analyses of polar lipids using high resolution HILIC-LC/ESI-tandem, as used for diatoms, can also be used for other photosynthetic microorganisms.

Effect of SiO2 Nanoparticles Addition on the Flexural Strength of Repaired Acrylic Denture Base.

Objective The objective of this study was to evaluate the effect of nano-SiO 2 addition on the flexural strength (FS) of repaired acrylic denture base. Materials and Methods Heat-polymerized acrylic resin specimens were fabricated in dimensions of (65 × 10 × 2.5 ± 0.1 mm 3 ) and then sectioned and prepared, creating repair gap with butt (90 degrees) and bevel (45 degrees) repair surface designs forming two main groups according to joint design. Further subdivision was done into four groups ( n = 10) according to nano-SiO 2 concentration: one unmodified group and three modified groups (0.25, 0.5, and 0.75 wt %) in the autopolymerized repair resin. Each pair of a specimen was assembled in a mold and repaired according to manufacturer’s recommendations. Statistical Analysis Three-point bending test was done to measure FS, followed by scanning electron microscope (SEM) examination for fracture surface analysis. Data were analyzed using ANOVA and Tukey’s post hoc test (α = 0.05). Results The addition of nano-SiO 2 significantly improved FS of repaired acrylic resin in comparison to the unmodified group ( p ˂ 0.05). For butt joint, significant differences between nano-SiO 2 reinforced groups were noticed ( p ˂ 0.05), while reinforced beveled groups did not differ significantly ( p ˃ 0.05). Bevel design remarkably increased FS compared with butt design per respective filler concentration. From the SEM images, improved FS was presented with a homogeneous distribution of nano-SiO 2 within polymethyl methacrylate. Conclusion Nano-SiO 2 addition to repair resin and 45 degree-beveled repair surface increased FS of repaired acrylic resin.

Effects of Nano-SiO2 Addition in Drilling Fluid on Wear Behavior of 2Cr13 Steel Casing

This work studied the effects of nano-SiO2 addition in drilling fluid on the wear behavior of casing. The disc specimens and pin specimens were made of 2Cr13 steel and G105 steel, respectively, and the water-based drilling fluids added with different amount of nano-SiO2 were tested, based on which, the wear rate, surface morphology, surface profile, and composition of the wear product were analyzed. Results showed that, the main wear mechanism of 2Cr13 steel casing in the drilling fluid is abrasive–corrosive wear. Adding nano-SiO2 to the drilling fluid can significantly reduce the casing wear. As the nano-SiO2 concentration increases, the wear rate and mean friction coefficient both increase first and then decrease. Drilling fluid shows best lubrication performance when the nano-SiO2 concentration is 2%. The shielding effect of nano-SiO2 can slow down the vicious cycle of “oxidation–destruction–reoxidation” during the wear process. Microhardness of tribofilms increases when adding more nano-SiO2 into drilling fluid, which increases the wear resistance of disc surfaces. However, the excessive addition of nano-SiO2 on a 2% concentration basis can lead to the decrease in bonding strength between tribofilms and matrix, leading to large delamination on the disc surface and therefore reducing the shielding effect of nano-SiO2.

The Mechanical Properties of Poly (Urea-Formaldehyde) Incorporated with Nano-SiO2 by Molecular Dynamics Simulation.

Self-healing materials can promote the sustainable reuse of resources. Poly (urea-formaldehyde) (PUF) microcapsules can be incorporated into dielectric materials for self-healing. However, the mechanical properties of PUF microcapsules need to be improved due to insufficient hardness. In this paper, PUF models incorporated with nano-SiO2 of different filler concentrations (0, 2.6, 3.7, 5.3, 6.7, 7.9 wt.%) were designed. The density, the fractional free volume, and the mechanical properties of the PUF-SiO2 models were analyzed at an atomic level based on molecular dynamics simulation. The interfacial interaction model of PUF on the SiO2 surface was also constructed to further investigate the interaction mechanisms. The results showed that the incorporation of nano-SiO2 had a significant effect on the mechanical properties of PUF. Density increased, fractional free volume decreased, and mechanical properties of the PUF materials were gradually enhanced with the increase of nano-SiO2 concentration. This trend was also confirmed by experimental tests. By analyzing the internal mechanism of the PUF–SiO2 interfacial interaction, it was found that hydrogen bonds play a major role in the interaction between PUF and nano-SiO2. Moreover, hydrogen bonds can be formed between the polar atoms of the PUF chain and the hydroxyl groups (–OH) as well as O atoms on the surface of SiO2. Hydrogen bonds interactions are involved in adsorption of PUF chains on the SiO2 surface, reducing the distance between PUF chains and making the system denser, thus enhancing the mechanical properties of PUF materials.

Optimization of konjac glucomannan/carrageenan/nano-SiO2 coatings for extending the shelf-life of Agaricus bisporus

Nano-SiO2 was inserted into konjac glucomannan (KGM)/carrageenan (KC) coatings to improve the properties of the coating. The optimization of the concentrations of the nano-SiO2, KGM, and KC of the coatings was investigated using a response surface method. The coatings were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and ultraviolet-visible (UV–vis) spectroscopy. The effect of the nano-SiO2/KGM/KC coatings on the postharvest quality of the white mushrooms stored at 4 ± 1 °C was determined. The results showed that the nano-SiO2/KGM/KC coatings exhibited the optimal properties at a nano-SiO2 concentration of 0.3%, a KC concentration of 0.6%, and a KGM concentration of 0.48%. The water vapor transmission rate, transparency, tensile strength, oxygen transmission rate, and carbon dioxide transmission rate were 62.31 g/(m2·d), 83.41%, 323.16 N, 0.015 g/(m2·d), 0.18 g/(m2·d) respectively. The nano-SiO2 decreased the gas permeability of the coatings. It demonstrated that the incorporation of the nano-SiO2 delayed the effect of the UV light on the food quality because it increased the absorbance of the UV light (300 nm) by the KGM/KC three fold. The application of the nano-SiO2/KGM/KC coatings represents a feasible and effective technique for extending the storage time of white mushrooms.

Mechanical, thermal, and water vapor barrier properties of regenerated cellulose/nano-SiO2 composite films

Bionanocomposite films were fabricated by reinforcing regenerated cellulose (RC) with 3-aminopropyl-functionalized silica nanoparticles (nano-SiO2). The composite films were prepared by dissolving cotton linter RC in a 7% NaOH/12% urea solution followed by the addition of nano-SiO2 and 5% H2SO4 solution. The effects of nano-SiO2 concentration (1–5 wt% with respect to RC) on the morphology, water vapor permeability (WVP), thermal properties, and mechanical properties of the RC/nano-SiO2 composite films were evaluated. Morphological studies indicated uniform dispersions of the low-concentration nano-SiO2 particles in the RC matrix. The tensile strength and modulus were increased by 26% and 15%, respectively, in the presence of 2 wt% of nano-SiO2 relative to the values of neat RC film. The WVP of the RC/nano-SiO2 composite films decreased by 22% after reinforcement with 2 wt% nano-SiO2. The results revealed that there is a potential interaction between RC and nano-SiO2, resulting in improved thermal and mechanical properties of the RC/nano-SiO2 composite films compared to those of neat RC film. Bionanocomposite films were fabricated by reinforcing regenerated cellulose (RC) with 3-amino propyl functionalized silica nanoparticles (nano-SiO2). The effects of nano-SiO2 (1–5 wt% with respect to RC) on the morphology, water vapor permeability (WVP), and thermal and mechanical properties of the RC/nano-SiO2 composite films were evaluated. This study highlights the potential of organically modified nano-SiO2 to enhance the properties of RC owing to the ability of nano-SiO2 to interact with the RC matrix at very low concentrations (2 wt%).

Effect of SiO2 nanoparticle on the physical and chemical properties of eco-friendly agar/sodium alginate nanocomposite film

Agar/sodium alginate (AG/SA) nanocomposite films were prepared using solution casting method in presence of various concentrations of nano-SiO2 (2.5, 5, 7.5, and 10 wt%). The effect of nano-SiO2 concentration on the nanocomposite film was investigated. The result of Fourier transform infrared (FTIR) illustrated the formation of hydrogen bonding between nano-SiO2 and polysaccharide. As nano-SiO2 concentration rose from 0 to 10 wt%, the tensile strength and elongation at break all increased up to maximum, respectively. The tensile strength and elongation at break of film containing 10 wt% nano-SiO2 increased by 65.29% and 60.38% respectively when compared to those of film prepared without nano-SiO2. The reason for enhancing in tensile strength might be related to the formation of molecular interaction. The film containing 2.5 wt% nano-SiO2 had maximum water contact angle and minimum water vapor permeability among those of all films prepared in this work. However, the film containing 10 wt% nano-SiO2 had minimum swelling degree and water solubility, further demonstrating the formation of strong interaction. The addition of nano-SiO2 improved the properties of film against UV light and thermal stability. Overall, the addition of nano-SiO2 enhanced the mechanical properties, water resistance and thermal stability of polysaccharide film.

Synthesis of konjac glucomannan-silica hybrid materials with honeycomb structure and its application as activated carbon support for Cu(II) adsorption

Hybrid organic-inorganic materials are of interest for a wide range of applications in fields of biotechnology, medical science, and green chemistry. In this study, we illustrated the principles of synthesis, the structure, and the functions of a novel konjac glucomannan (KGM) based biopolymer-silica hybrid materials. Nano-silicon dioxide (SiO2) was applied as composites, combined with KGM, to form a highly porous structure by using a simple and versatile route – freeze drying. We systematically varied the Nano-SiO2 concentration and solution pH value, the as-prepared organic-inorganic porous materials are highly ordered and highly strengthened with an average porous diameter of 100 μm, with honeycomb structure, tailored mechanical properties, and excellent support capacity. Activated carbon (AC)-loaded porous materials (CKNSi) exhibited a high Cu(II) adsorption capacity.