Modified Silica Nanoparticles Research Articles

Treatment of Olefin plant spent caustic by combination of Fenton-like and foam fractionation methods in a bench scale.

Spent Merox caustic (SMC) is a hazardous waste that is produced during the Merox desulfurization process in the petroleum refinery industry and should be treated before discharging to environment. In the present study, treatment of SMC was investigated by three methods including Fenton-like process, foam fractionation, and a combination of both processes. Immobilized TiO2/Fe0 on modified silica nanoparticles was used as a heterogeneous Fenton-like catalyst. The chemical and physical characteristics of the catalyst were determined using Fourier-transform infrared spectroscopy, X-ray diffraction, diffuse reflectance spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and transmission electron microscopy techniques. The treatment performance of the combined method was measured as a cost-effective method with chemical oxygen demand (COD) removal percentage. The effect of parameters including pH, gas flow rate, surfactant type and concentration of hydrogen peroxide, catalyst, and chelate were investigated. It is found that the prepared heterogeneous catalyst has high activity for the treatment of SMC. In addition, the results showed that the combined method achieved 97.6 ± 0.5% COD removal, while the measured values for Fenton or foam fractionation methods alone did not exceed 85.5 ± 1% and 47.2 ± 0.4%, respectively. The advantage of combination process over foam fractionation was the use of an advanced oxidation process in the separating column to eliminate or reduce the secondary phase contamination load. Besides, the role of the column in the effective contact of contaminants with the rising bubbles improved the degradation performance of the proposed process and reduced the consumption of hydrogen peroxide by 46% compared to the Fenton-like method.

Synthesis of antibiotic-modified silica nanoparticles and their use as a controlled drug release system with antibacterial properties

In this study, monodispersed silica nanoparticles were synthesized using the Stöber method. The synthesized nanoparticles underwent a range of surface modifications and were converted to nanoparticles with drug release and antibacterial features. For modification, firstly –NH2 groups were created on the silica nanoparticle surface using (3-Aminopropyl)triethoxysilane (APTES). In the second stage, hexachlorocyclotriphosphazene (Phz) molecules were bound to the silica nanoparticle surfaces due to these amino groups. In the final stage of modification, the chloride groups in the hexachlorocyclotriphosphazene structure were modified with trimethoprim (TMP) and nanoparticles with antibacterial properties were obtained. The modified silica nanoparticles were characterized with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and Thermogravimetric analysis (TGA). The silica-based nanoparticles were used for release of rhodamine 6G, chosen as a model drug. As a result of the drug release studies, the modified silica nanoparticles were found to abide by the Korsmeyer–Peppas low power model and non-Fickian release mechanism as release model. Additionally, nanoparticles both loaded and not loaded with the model drug were determined to have antibacterial properties against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus bacteria.

Effect of Surface Modification of Silica Nanoparticles with Thiol group on the Shear Thickening Behaviors of the Suspensions of Silica Nanoparticles in polyethylene glycol (PEG)

The Fine-tuning of Shear Thickening Fluids (STFs) by surface modification of silica particles has fascinated scientist’s interest worldwide as it results in performance enhancement of STF based on armor systems. In the current study, surface modified Silica nanoparticles (average diameter of 600 nm) possess thiol functional groups which were attained through a reaction with 3-mercaptopropyl-trimethoxysilane in absolute ethanol at 90 °C. Shear thickening fluid of Thiol functionalized Silica nanoparticles were prepared by sonochemical method in polyethylene glycol (PEG-200). The rheological parameters of STFs (modified and unmodified silica Nano particles) were measured using Rheometer MCR 52, Anton Par, Germany. The shear thickening behavior of thiol-based STF shows shear thickening at a higher shear rate compared to only silica-based STF with the decrease in viscosity maximum.

Investigating the experimental and theoretical treatment of spent caustic effluent from an industrial Olefin plant by combining Fenton-like and foam fractionation methods on the bench scale

ABSTRACT In the present study, the treatment of a typical spent Merox caustic waste (SMC) was investigated by three methods of Fenton-like process, foam fractionation and combination of both methods. Immobilised TiO2/Fe0 nanoparticles on modified silica nanoparticles were used as heterogeneous Fenton-like catalyst. The characterisation of catalyst was carried out using Fourier transform infrared (FT-IR), X‐ray diffraction (XRD), diffuse reflectance spectra (DRS) analysis, thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC) and transmission electron microscopy (TEM). The performance of the combined method was evaluated in terms of chemical oxygen demand (COD) residual parameter. The parameters including pH, gas flow rate to the separator column, concentrations of hydrogen peroxide/catalyst/surfactant/chelate agent, surfactant type, and chelate agent type were investigated to obtain the optimum conditions of the process by response surface methodology (RSM) based on eight-factors central composite design (CCD). Under optimum conditions of combining Fenton-like and foam fractionation methods, the minimum residue of COD was 10.98 ppm, corresponding to a COD removal of 99.7%. However, the measured values for the Fenton-like or foam fractionation methods alone did not exceed 88.9% and 58.4%, respectively. In addition, hydrogen peroxide consumption decreased by 63% compared to the Fenton-like method. Also, another important result shows that the use of cationic surfactants is more effective than anionic and amphoteric for wastewater treatment.

Modification of silica nanoparticles by 2,4-dihydroxybenzaldehyde and 5-bromosalicylaldehyde as new nanocomposites for efficient removal and preconcentration of Cu(ii) and Cd(ii) ions from water, blood, and fish muscles.

Herein, silica nanoparticles were modified by 2,4-dihydroxybenzaldehyde and 5-bromosalicylaldehyde to produce new nanocomposites which were abbreviated as N1 and N2, respectively. The synthesized nanocomposites were used for efficient removal and preconcentration of Cu(ii) and Cd(ii) ions from water, blood, and fish muscles. FE-SEM, FT-IR, XRD, CHN elemental analysis, and nitrogen gas sorption analyzer were used to characterize the new nanocomposites. The XRD proved that the synthesized oxide is cristobalite with an average crystallite size of 54.80 nm. Due to the formation of the C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> N group, the intensity of the XRD peak at 2θ = 21.9° in the N1 and N2 nanocomposites decreased significantly. The FT-IR bands, which appeared at 1603 and 1629 cm−1 in the N1 and N2 nanocomposites, are attributable to the bending vibration of CN and/or OH, respectively. Also, the FE-SEM analysis shows the morphology of the silica nanoparticles which were identified as spherical and rod-like with slight agglomeration while the N1 and N2 nanocomposites have flaky surfaces due to the formation of CN groups. The maximum Cu(ii) ion adsorption capacities of the N1 and N2 nanocomposites are 64.81 and 40.93 mg g−1, respectively. The maximum Cd(ii) ion adsorption capacities of the N1 and N2 nanocomposites are 27.39 and 26.34 mg g−1, respectively. The adsorption of Cu(ii) or Cd(ii) ions using the synthesized nanocomposites is spontaneous, chemical, exothermic, and well-matched with the Langmuir equilibrium isotherm. The recovery findings demonstrate that the preconcentration process is accurate, adaptable, and resulted in quantitative separation because % Recovery is more than 95%. Furthermore, the % RSD was less than 3.5%, indicating good reproducibility.

Role of Modified Silica Nanoparticles in Enhancing the Properties of Flexible Solid Electrolytes

Role of Modified Silica Nanoparticles in Enhancing the Properties of Flexible Solid Electrolytes

Quaternary imidazolium-functionalized reactive silica nanoparticles-containing thiol-ene photocured antibacterial hybrid coatings

The need for antibacterial coatings is increasing day by day. In this study, coating materials that do not contain antibacterial agents but have antibacterial properties have been developed. First, two different quaternary imidazole compounds were synthesized. Then, silica nanoparticles were modified with these quaternary agents. By using 1%, 3% and 5% modified silica nanoparticles, UV cured coating materials were obtained according to the thiol-ene reaction mechanism. Mechanical, thermal, surface, structural, optical and antibacterial analyzes of the obtained coatings were performed. The analyzes revealed that UV cured antibacterial coating materials have been successfully synthesized and can be used as a new and unique coating material for the coating industry.

Facile synthesis of ionic liquid modified silica nanoparticles for fast removal of anionic organic dyes with extremely high adsorption capacity

In this work, SiO2-ionic liquid (SiO2-PIL) composites were synthesized from amino groups containing SiO2 particles and imidazolium [C16VIm+] [Br−] (ionic liquid) by the nucleophilic Michael addition reaction and the utilization of the composites for adsorptive removal of anion dyes was also examined in details. The adsorption performance was greatly improved since the presence of ionic liquid, and the practical maximum adsorption capacity of dye can as high as 243.67 mg/g in a very short timeframe. The results of fitting experimental data illustrate the effects of contact time, solution temperature, dye concentration, and pH. The kinetic and isotherm study confirms the pseudo-second-order model and the Langmuir model, respectively. The maximum monolayer adsorption capacity from Langmuir model can be as high as 2955.99 mg/g. The spontaneity and exothermicity of adsorption process can be also proved by data analysis. The novel method for fabrication of ionic liquid modified composites can be altered for environmental remediation or other practical application fields.

Transparent radiative cooling films containing poly(methylmethacrylate), silica, and silver

Window is the least energy-efficient part of buildings or cars; however radiative cooling, as an efficient energy-zero technology, is rarely used in window films of buildings or cars. Therefore, we in this work fabricated a transparent dual-layer film for daytime radiative cooling, which contained a layer of polymethyl methacrylate (PMMA) uniformly mixed with modified silica nanoparticles (SiO2 NPs) and a layer of silver. The dispersion of the modified SiO2 NPs in PMMA was notably improved through in-site grafting PMMA, which resulted in a high transparency of the radiative cooling film even at a high filling fraction of SiO2 (20 wt%). Owing to the strong broadband IR absorbance/emittance (εAW = 94.3%) and high sunlight reflectance (ρ ≈ 50%), the dual-layer film possessed a high cooling capacity and could achieve an average temperature drop of 1.4 °C than pure PMMA film in the daytime outdoor cooling measurement. In the simulated automotive cooling test, the dual-layer film cooled the interior space up to 6 °C below ambient temperature during peak solar hours. The excellent optical property and cooling capability exhibit a promising application of building and car windows for cooling their interior spaces.

Rapid Microwave-Assisted Synthesis of Organo-Modified Nanostructured Silica Coatings with Tunable Water-Repellence Properties

A simple method to fabricate organo-modified silane coatings for water-repellent surface modification was proposed, by using a microwave sol-gel synthesis of hybrid materials. Low-cost fluorine-free tetraethoxysilane (TEOS) and dodecyltriethoxysilane (DDTES) were used as silane derivatives. The organo-modified silica coatings were prepared by the drop-casting method and were characterized by UV-VIS, FTIR spectroscopy, and AFM and SEM microscopy. The morphology of the film show the existence of submicrometer scale roughness due to the aggregation of modified silica nanoparticles. Contact angles of water and diiodomethane on surfaces modified with as prepared nanostructured film were determined in order to assess the hydrophobic and oleophobic properties. The TEOS/DDTES ratio was proved to be a crucial factor in tuning the wettability properties. The results suggest that significant increase of hydrophobicity could be achieved by using non-fluorinated cost-effective silica nanomaterials produced with a rapid ecofriendly method.

Characterization and antioxidant properties of chitosan film incorporated with modified silica nanoparticles as an active food packaging

In this study, two modified silica nanoparticles (SiO2-GA NPs) were successfully obtained by covalently grafting gallic acid onto silica nanoparticles. The mean particle diameters of their were 112.7 ± 0.55 nm (1-SiO2-GA NPs) and 408.7 ± 3.20 nm (4-SiO2-GA NPs), respectively. Novel antioxidant active packaging composite films were prepared by incorporation of 1-SiO2-GA NPs or 4-SiO2-GA NPs into chitosan. The structure analysis of the composite films showed that intermolecular hydrogen bonds were formed between the two modified silica nanoparticles and chitosan. Compared with the chitosan film, the mechanical properties, water vapor barrier property and UV light barrier ability of the composite films were significantly improved. Moreover, the incorporated of the two modified silica nanoparticles significantly increased antioxidant activity of the composite films. This study indicates that composite films incorporated with modified silica nanoparticles, especially the incorporation of 1-SiO2-GA NPs can be used as novel antioxidant food packaging composite films.

Antimicrobial potentiality of green synthesized iron oxide nanoparticles by Penicillium roqueforti

The invasion of foodborne pathogens remains a serious problem for researchers and regulators in the food industry. The introduction of a new type of potent antibacterial agent is of great importance for controlling bacteria and fungi. This study aimed to investigate a novel antimicrobial agent, such as iron oxide nanoparticles (IONPs), which are biosynthesized by a simple, fast, eco-friendly, and efficient method using Penicillium roqueforti MK805460.1. The obtained iron oxide nanoparticles were covered by SiO2 layer using stober method. The biosynthesized nanoparticles were characterized by UV-Vis spectroscopy, energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Antibacterial activity of the nanoparticles with different concentrations of 50, 100, 150, and 200 μg/ml was examined against Gram-positive bacteria (Staphylococcus aureus ATCC 25923 and bacillus subtilis ATCC 6633) and Gram-negative bacteria (Salmonella typhimurium ATCC 14028 and Escherichia coli ATCC 8739) by agar well diffusion and kinetic bacterial growth methods. While, the antifungal activity of nanoparticles was tested against Aspergillus niger, Aspergillus fumigatus, and Aspergillus flavus using the dry weight mycelial method. According to UV-Vis spectroscopic study, the wavelength band observed in the region 204–266 nm, indicating the formation of iron oxide nanoparticles. In addition, spheres of 5–16 nm-sized iron oxide nanoparticles were confirmed via TEM. Also, the results showed that the modified silica nanoparticles had more significant antimicrobial activity than the iron oxide nanoparticles.

Nano-silica/polymer composite as filtrate reducer in water-based drilling fluids

Wellbore instability and reservoir damage caused by filtrate of water-based drilling fluids (WDFs) invading the formation are extremely problematic issues in the process of oil excavation. Herein, we reported a novel polymer with core-shell structure based on modified silica nanoparticles as a filtrate reducer (NS-DA) in WDFs. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (NMR) results revealed that the target product NS-DA had been gained. The results of thermogravimetric analysis (TGA) showed that the thermal decomposition temperature of NS-DA occurred after 293 °C. Meanwhile, NS-DA exhibited the most outstanding filtration loss reduction ability compared to three commercially filtrate reducer (Driscal D. PAC-Lv and CMC) in the filtration loss test prescribed by the American Petroleum Institute. Specifically, the filtration loss of Driscal D/WDFs, PAC-Lv/WDFs and CMC/WDFs were 16.2 mL, 18.4 mL and 19.8 mL after hot rolling at 180 °C for 16 h, respectively, while the filtration loss of NS-DA/WDFs was only 5.6 mL. The mechanism of NS-DA in controlling filtration loss was investigated by Zeta potential measurements, particle size distribution analysis and mud cake analysis. The results showed that NS-DA molecular chains were firmly adsorbed on the surface of clay particles through hydrogen and ionic bonds, which reduced the zeta potential and the average particle size of clay particles, diminished the mud cake permeability, and thus enhanced the stability of the WDFs colloidal system. This work indicates that NS-DA has great potential for future oil excavation.

Hybrid EuIII Coordination Luminophore Standing on Two Legs on Silica Nanoparticles for Enhanced Luminescence.

In this study, we have demonstrated a two-legged, upright molecular design method for monochromatic and bright red luminescent LnIII -silica nanomaterials. A novel EuIII -silica hybrid nanoparticle was developed by using a doubly binding TPPO-Si(OEt)3 (TPPO: triphenyl phosphine oxide) linker. The TPPO-Si(OEt)3 was confirmed by 1 H, 31 P, 29 Si NMR spectroscopy and single-crystal X-ray analysis. Luminescent Eu(hfa)3 and Eu(tfc)3 moieties (hfa: hexafluoroacetylacetonate, tfc: 3-(trifluoromethylhydroxymethylene)camphorate) were fixed onto TPPO-Si(OEt)3 -modified silica nanoparticles, producing Eu(hfa)3 (TPPO-Si)2 -SiO2 and Eu(tfc)3 (TPPO-Si)2 -SiO2 , respectively. Eu(hfa)3 (TPPO-Si)2 -SiO2 exhibited the higher intrinsic luminescence quantum yield (93 %) and longer emission lifetime (0.98 ms), which is much larger than those of previously reported EuIII -based hybrid materials. Eu(tfc)3 (TPPO-Si)2 -SiO2 showed an extra-large intrinsic emission quantum yield (54 %), although the emission quantum yield for the precursor Eu(tfc)3 (TPPO-Si(OEt)3 )2 was found to be 39 %. These results confirmed that the TPPO-Si(OEt)3 linker is a promising candidate for development of EuIII -based luminescent materials.

A new nanoparticle-reinforced silicone rubber composite integrating high strength and strong adhesion

A bulk modification method is developed in this paper to achieve a new nanoparticle-reinforced silicone rubber composite with high strength and strong adhesion. Different from existing modification methods, an adhesion promoter is added in order to improve the adhesive property in addition to the surface modified silica nanoparticle. Furthermore, the adhesion promoter also exhibits an excellent compatibility with the silicone rubber. The tensile strength and shear adhesive strength of the new composite can reach up to 10.4 MPa and 90 kPa, respectively, both of which are much higher than their counterparts in the popular silicone rubber product Sylgard184. Moreover, the strong adhesion performance of the composite exhibits a good stability in either several-hour use or many attachment/detachment cycles. The present composite shows apparent advantages over existing silicone rubber products in not only the direct use as an adhesive material, but also potential applications for manufacturing advanced adhesive devices such as wearable electronics.

Cover Image, Volume 138, Issue 47

The cover image by Bishnupada Mandal's team shows an FETEM image representing (3-Aminopropyl) trimethoxysilane (APTMS)-modified silica nanoparticles (AFSNP). The nanoparticle exhibited uniform spherical structure with a narrow particle size distribution. The particle morphology showed no significant change with functionalization of the silica nanoparticles. However, the APTMS modified silica nanoparticles (AFSNP) exhibited slightly rough-edged spherical structures compared to the unfunctionalized silica nanoparticles. This could be attributed to the polymerization of the organic layer on the particle surface. The interconnectivity formed due to the silanol-amine interaction, in this case, ensured efficient enhancement of CO2 separation. DOI: 10.1002/app.51438

UV light triggered self-healing of green epoxy coatings

Numerous studies have been carried out globally to develop polymer coatings that could protect the underlying metal substrates from corrosion. Among these approaches, self-healing bio-based epoxy coating plays a promising role in corrosion protection. In the present study, a dual container self-healing coating system was developed from bio-based epoxy resin, halloysite nanotubes and silica nanoparticles. The halloysite nanotubes (HNTs) were filled with bio-based epoxy resin by vacuum infiltration technique and the silica nanoparticles were modified with a UV initiator by simple mixing. Later the filled halloysite nanotubes and modified silica nanoparticles were mixed with pure bio-based epoxy resin and hardener and cured to obtain self-healing composites. During the scratch/damage of the epoxy coating, the halloysite nanotube ruptures and the bio-based epoxy resin stored inside the nanotube fills the scratch and comes in contact with UV initiator immobilised on the silica nanoparticles, initiating the curing reaction. At 40 wt% of encapsulated HNTs, the scratch on the bio-based epoxy surface is found to undergo complete self-healing in the presence of sunlight. Overall, the composites showed an increased UV-shielding ability, improved thermal stability, and good transparency. Therefore, the developed bio-based epoxy composite is a viable self-healing coating for metals.

Synthesis, Characterization and Biomedical Applications of p(HEMA-co-APTMACI) Hydrogels Crosslinked with Modified Silica Nanoparticles

In this study, a new silica-based crosslinker was successfully synthesized with the reaction between silica nanoparticles modified with amino groups and glycidyl methacrylate (GMA). Using the synthesized silica-based crosslinker, p(HEMA) and p(HEMA-co-APTMACI) hydrogels were synthesized for use as drug carrier systems with the free radical polymerization method. The synthesized silica-based crosslinker and hydrogels were characterized using scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FTIR) devices. The swelling behavior of hydrogels cross-linked with silica was investigated in different physiological media. The hydrogels were loaded with sodium diclofenac (NaDc) as a model drug. Drug release studies from the obtained drug-loaded hydrogels were performed at 37°C in PBS (pH 7.0) media. Additionally, the antibacterial properties of the hydrogels synthesized in the study were investigated against E. coli (gram-negative), B. subtilis, and S. aureus (gram-positive) bacteria using the disk diffusion method. At the end of the study, p(HEMA-co-APTMACI) hydrogels were determined to display a better drug release profile than p(HEMA) hydrogels.

Preparation of silica-decorated graphite oxide and epoxy-modified phenolic resin composites

A multifunctional hybrid curing component (GSD) for epichlorohydrin-modified novolac resin (ENR) was synthesized via grafting poly(amidoamine) (PAMAM)-modified silica nanoparticles (SD) on graphene oxide (GO) using a ring opening reaction. SD and GSD, as two different curing components, were also used in different contents as reinforcing fillers of ENR matrix. Fourier-transform infrared spectroscopy and thermal gravimetric analysis (TGA) results proved amine-decoration of silica nanoparticles and also successful preparation of GSD. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy results were utilized to investigate structure of the SD and GSD multifunctional curing components and also the resulted composites. XRD pattern of GSD shows two peaks at 10.1 and 21.8° which belong to characteristic peaks of GO and silica nanoparticles, respectively, with weak intensities due to grafting of SD on the GO surface. Thermal investigation of the prepared composites by TGA showed that curing ENR with higher contents of GSD was resulted in higher thermal properties. The ENR composite cured with 5 wt% of GSD presented the highest char residue of 20.5% among the other hybrid composites.

The synthesis and characterization of polyorganosiloxane nanoparticles from 3-mercaptopropyltrimethoxysilane for preparation of nanocomposite films via photoinitiated thiol-ene polymerization.

This article describes the synthesis of modified silica nanoparticles (SiO2-MPTMS) via the condensation reaction carried out between silanol moieties of silica nanoparticles and the trialkoxy silyl groups of (3-mercaptopropyl) trimethoxysilane (MPTMS). Then, SiO2-MPTMS nanoparticles in certain amounts (0.5 wt %, 1 wt %, 2.5 wt % and 5 wt %) were incorporated into thiol-ene resins consisting of bisphenol A glycerolate dimethacrylate and trimethylolpropane tris(3-mercaptopropionate) to prepare nanocomposite films via the photoinitiated thiol-ene polymerization in presence of 2,2-Dimethoxy-2-phenylacetophenone 99% as a photoinitiator. Fourier transform infrared spectroscopy, dynamic light scattering, scanning transmission electron microscopy, thermal gravimetric analyzer, and X-ray photoelectron spectrometer were employed to characterize SiO2-MPTMS nanoparticles. It was revealed that the nanosilica surface was successfully grafted by MPTMS with the grafting ratio of 22.9%. Properties of the nanocomposite films such as decomposition temperature, thermal glass transition temperature, tensile strength, hardness, and particle distribution were investigated and the results were compared with each other and neat film. The addition of MPTMS-modified silica particles did not improve the thermal stability of the films. In scanning electron microscopy study, it was seen that 2.5 wt % of these nanoparticles used as additives were about 200 nm in size and dispersed homogeneously in the polymer matrix. The increase in tensile strength of nanocomposite films compared to the neat film was measured as 77.3% maximum.