Microwave absorption and photocatalytic properties of magnetic nickel nanoparticles/recycled PET nanofibers web

Abstract

The use of nanoparticles in electrospun web has always been of great interest for a wider and easier application especially for microwave absorption and photocatalytic activity. In this work, nickel nanoparticles/recycled poly (ethylene terephthalate) nanofibers web (Ni NPs/RPET NFs web) were electrospun from a homogeneous sonicated RPET solution containing Ni NPs with an average diameter of 32.5?nm synthesizedthrough the chemical reduction method. To study morphologies, crystalline structure, magnetic, wettability, microwave absorption and photocatalytic activities of the web, field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and electromagnetic properties were used. The saturation magnetization of the Ni NPs/RPET NFs web at a nickel concentration of 3% was 0.5?emu/g. In addition, the wettability, the reflection coefficient, the absorption coefficient, the EMI shielding and the photocatalytic activities of the Ni NPs/RPET NFs web were improved compared to the RPET NFs web.     

Effect of Fe3O4 nanoparticles on magnetic electrospun nanofibers

A new simple magnetic electrospinning setup was devised to manufacture partially aligned nanofiber in the paper. Compared with the traditional electrospinning setup, a U-shaped permanent magnet was employed and applied with a slide rheostat. Polyvinyl alcohol (PVA) and PVA/Fe₃O₄ fibers were prepared by the magnetic electrospinning, respectively. The morphology and alignment of the fibers were characterized by the use of scanning electron microscopy (SEM). Results showed that the magnetic field could decrease the diameter of fibers and enhance the crystal conditions of fibers, and the addition of Fe₃O₄ nanoparticles improved the alignment of nanofibers.     

Enhanced magnetic and antifungal characteristics on wool with Fe3O4 nanoparticles and BTCA: a facile synthesis and RSM optimization

A facile route for the synthesis of high-quality Fe₃O₄ nanoparticles (FNPs) has been successfully confirmed by employing a co-precipitation technique and then was stabilized onto wool fabric through a simple “impregnating” process. Here, the synergistic effect of BTCA and synthesized FNPs on magnetic and antifungal characteristics of the wool fabric was investigated. The FNPs was stabilized on the wool surface using BTCA cross-linking agent. The role of both FNPs and BTCA concentrations on magnetic and antifungal properties of samples was optimized using response surface methodology. The magnetization properties and uniform distribution of FNPs on the wool surface were characterized by vibrating sample magnetometry, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The saturation magnetization and antifungal activity against Candida albicans of BTCA/FNPs-optimized wool was 7.8 emu g^?1 and 98.31%, respectively. Subsequently, treated wool fabric with optimum concentration of FNPs and BTCA enhanced magnetic and antifungal properties.     

Fe3O4/木质素基纳米碳纤维复合材料的制备及其微波吸收性能探究

本研究以蔗渣乙酸木质素为原料制备了木质素基实心和中空纳米碳纤维(CNFs和HCNFs),然后采用溶剂热法,将经浓硝酸表面氧化处理后的碳纤维和乙酰丙酮铁共混反应合成了Fe_3O_4/实心和中空纳米碳纤维复合材料(Fe_3O_4/CNFs和Fe_3O_4/HCNFs)。通过傅里叶变换红外光谱仪和拉曼光谱仪分析了碳纤维在浓硝酸氧化处理前后的结构变化,通过扫描电子显微镜能谱仪、X射线衍射仪、比表面积孔径分析仪、振动样品磁强计和矢量网络仪分析并对比了Fe_3O_4/CNFs和Fe_3O_4/HCNFs的形貌结构、磁性能和微波吸收性能。结果表明,Fe_3O_4/CNFs和Fe_3O_4/HCNFs的饱和磁化强度分别为12. 7emu/g和16. 5 emu/g,均表现出了典型的超顺磁性。相较于Fe_3O_4/CNFs,Fe_3O_4/HCNFs在厚度仅为1. 5mm下其最小反射损耗达-11. 8 dB,另外随着吸波体厚度在1. 0～2. 5 mm范围变化,小于-10 dB的吸收频带范围为5. 28～14. 75 GHz,表现出了更优异的微波吸收性能。     

Determination of Estrogens in Milk Samples by Magnetic‐Solid‐Phase Extraction Technique Coupled With High‐Performance Liquid Chromatography

A magnetic‐solid‐phase extraction method coupled with high‐performance liquid chromatography and diode array detection has been developed for simultaneous determination of 3 estrogens in milk samples. In this work, Fe₃O₄ NPs were synthesized by a simple chemical co‐precipitation reaction, and the surface of Fe₃O₄ was modified with cetyltrimethyl ammonium bromide (CTAB; designed as Fe₃O₄@CTAB). The synthesized Fe₃O₄@CTAB NPs were characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy, and transmission electron microscope. Fe₃O₄@CTAB NPs have high binding affinity toward estrone (E1), 17β‐estradiol (17β‐E2), and diethylstilbestrol (DES). Fe₃O₄@CTAB NPs can be easily separated from sample solutions using an external magnet due to the high super‐paramagnetic property. The separation, preconcentration procedure is fast and will be completed in 2 min. Estrogens linear dynamic ranges were achieved in the range of 10 to 1000 ng/mL with regression coefficients (R²) higher than 0.9992. The limits of detection were between 0.26 and 0.61 ng/mL. Parameters influencing the recoveries were investigated and optimized. The proposed method was used for the determination of E1, 17β‐E2, and DES in milk samples, and recoveries were ranged from 91.3% to 105.0%, with the relative standard deviations in the range of 2.7% to 4.0%.     

Treatment of enzymatic wool with Fe3O4 nanoparticles and citric acid to enhance mechanical properties using RSM

In this work, protease enzymatic wool was treated with citric acid and Fe₃O₄ nanoparticles to produce fabric with enhanced tensile strength, elongation, alkali resistance with controllable hydrophilicity/hydrophobicity through a simple ‘impregnating’ method. Protease enzymatic is also one of the most important processes usually carried out in alkali condition to obtain the desirable characteristics, which enhanced the surface activity and nanoparticles adsorption. Mechanical properties such as tensile strength and elongation were reduced as a consequence of alkali enzymatic pretreatment. Here, with the help of citric acid cross-linking agent, Fe₃O₄ nanoparticles were stabilized on the enzymatic wool surface in a way to revenge reduction in the tensile strength, elongation, alkali resistance. In order to create optimum tensile strength, elongation, alkali resistance, lightness and hydrophilicity/hydrophobicity, the appropriate models were obtained based on Design-Expert software. Overall, the results confirmed that the enzymatic wool fabrics could be modified by citric acid and Fe₃O₄ nanoparticles post-treatment. The Fe₃O₄ nanoparticle/citric acid treatment on the protease enzymatic wool improved tensile strength and elongation along with the higher alkali resistance and controllable hydrophilicity/hydrophobicity.     

Amperometric determination of bisphenol A in milk using PAMAM–Fe3O4 modified glassy carbon electrode

A simply and sensitively electroanalytical method for determination of bisphenol A (BPA) using poly(amidoamine) (PAMAM) and Fe₃O₄ magnetic nanoparticles modified glassy carbon electrode (GCE) was presented. Compared with bare electrode, PAMAM–Fe₃O₄ modified electrode not only significantly enhanced the oxidation peak current of BPA, but also lowered the oxidation overpotential, suggesting that the modified electrode can remarkably improve the determining sensitivity of BPA. Factors influencing the detection processes were optimised and kinetic parameters were calculated. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of BPA in the range of 1 × 10⁻⁸–3.07 × 10⁻⁶ M with the correlation coefficient of 0.9996 and the detection limit of 5 × 10⁻⁹ M. The current reached 95% of the steady-state current within about 6 s. The proposed method was successfully applied to determine BPA in milk samples and satisfactory results were obtained.     

Fe3O4@VC磁性纳米粒子对Cr(VI）的吸附性能

通过水热法合成Fe₃O₄@V_C磁性纳米粒子,采用透射电镜、红外光谱和X射线衍射等表征手段对合成的粒子结构进行表征。探讨了pH值、吸附时间、吸附剂用量、溶液初始浓度等因素对六价铬Cr(VI）吸附的影响,并对Cr(VI）的吸附热力学和动力学进行了研究。结果表明,在pH为1.50,25 ℃条件下,磁性纳米粒子对Cr(VI）的饱和吸附量可达39.12 mg/g,吸附率为85%以上。吸附性能试验表明,磁性纳米粒子对Cr(VI）的吸附符合Langmuir热力学模型和HO准二级动力学吸附模型。     

Magnetic Wood-based Superhydrophobic Aerogel for Efficient Oil-Water Separation

The fabrication of directionally driven oil-water separation materials has great significance for the removal of oil spills and organic pollutants. In this study, an oil-water separation aerogel capable of directionally adsorbing oil was designed using an anisotropic wood aerogel with a layered structure and a top-down fabrication strategy. Specifically, a magnetic wood-based superhydrophobic aerogel (methyltrimethoxysilane (MTMS)/Fe₃O₄ wood aerogel) was developed through the in situ co-precipitation of Fe₃O₄ nanoparticles and chemical vapor deposition. Owing to its highly porous structure, lipophilicity, hydrophobicity (water contact angle of 160°), and high compressibility, the MTMS/Fe₃O₄ wood aerogel exhibits excellent oil-water separation performance and compression cycle stability. Additionally, the Fe₃O₄ endows the material with excellent magnetic and photothermal conversion capabilities. These excellent properties make MTMS/Fe₃O₄ wood aerogel a promising recyclable and sustainable oil-water separation material.     

Study on the structural and luminous properties of two kinds self-luminous fibers

Abstract

Reports on the structural and optical characteristics of rare earth luminous fibers have been launched, two kinds of red light emitting luminous fibers: SrAl₂O₄:Eu²⁺,Dy³⁺/light conversion agent-PET as well as SrAl₂O₄:Eu²⁺,Dy³⁺-light conversion agent-PET were artificially manufactured, using rare-earth strontium aluminate SrAl₂O₄:Eu²⁺, Dy³⁺ as the rare-earth luminescent material. Their luminous properties depended on Eu²⁺, Dy³⁺ and fiber-forming polymers, with dispersion agent as a matrix. Herein, studies related to emitting red light of this two kinds of luminous fibers have been widely carried out. The morphology and EDS as well as luminous properties of the resulting samples were characterized. The results showed that the emission spectrum had a broad band from 450 to 590?nm with the two highest excitation intensity located at 520 and 580?nm for SrAl₂O₄:Eu²⁺, Dy³⁺-light conversion agent-PET, and at 520 and 605?nm for SrAl₂O₄:Eu²⁺, Dy³⁺/light conversion agent-PET. The brightness and the afterglow time of SrAl₂O₄:Eu²⁺, Dy³⁺-light conversion agent-PET were lower than that of SrAl₂O₄:Eu²⁺, Dy³⁺/light conversion agent-PET.     

C18/C8-Functionalized Magnetic Silica Nanospheres (Fe3O4@Si-C8/C18) as Capture Probes for Highly Efficient and Rapid Purification of Veterinary Drug Residues

The purpose of this study is to develop a rapid and efficient purification method for determination of veterinary drug based on magnetic silica nanospheres. We have described a scheme for preparing C₁₈/C₈-functionalized magnetic silica nanospheres (Fe₃O₄@Si-C8/C18) for potential use as capture probes in sample pretreatment. The magnetic Fe₃O₄ particles were firstly coated by tetraethyl orthosilicate to form magnetic silica nanospheres, which were then modified by both trimethoxy(octadecyl)silane (C18) and trimethoxy(octyl)silane (C8). The Fe₃O₄@Si-C8/C18 thus prepared could exhibit strong superparamagnetism, highly efficient capture ability, easy-to-use for isolation, and enrichment of veterinary drug residues in food.     

Synthesis,characterisation and analytical application of Fe3O4@SiO2@polyaminoquinoline magnetic nanocomposite for the extraction and pre-concentration of Cd(II) and Pb(II) in food samples

This work describes a novel Fe₃O₄@SiO₂@polyaminoquinoline magnetic nanocomposite and its application in the pre-concentration of Cd(II) and Pb(II) ions. The parameters affecting the pre-concentration procedure were optimised by a Box–Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount and pH) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent, and elution time) were selected as main factors in the optimisation study of the elution step. Following the sorption and elution of analytes, the ions were quantified by flame atomic absorption spectrometry (FASS). The limits of detection were 0.1 and 0.7 ng ml^?1 for Cd(II) and Pb(II) ions, respectively. All the relative standard deviations were less than 7.6%. The sorption capacities of this new sorbent were 57 mg g^?1 for Cd(II) and 73 mg g^?1 for Pb(II). Ultimately, this nanocomposite was successfully applied to the rapid extraction of trace quantities of these heavy metal ions from seafood and agricultural samples and satisfactory results were obtained.     

Preparation and Characterization of Co3O4/Graphene/Cellulose Nanofiber Composite Films

Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability, light weight, flexibility, and environmental friendliness. In this study, Co₃O₄/graphene/cellulose nanofiber (CNF) flexible composite films, in which the CNF acted as a spacer for the graphene, were prepared via a facile and scalable vacuum filtration method. The effects of the CNF on the microstructure, hydrophilicity, thermal stability, tensile strength, surface resistance, and electrochemical performance of the Co₃O₄/graphene/CNF composite films were systematically investigated. The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co₃O₄/graphene/CNF composite films, particularly their hydrophilicity and tensile strength. Meanwhile, Co₃O₄/graphene/CNF composite films with a CNF content of 4% appeared to have the optimal electrochemical performance, with an area specific capacitance of 56 mF/cm² and prominent capacitance retention of 95.6% at a current density of 1 A/g after 1000 cycles. This work demonstrated that the prepared Co₃O₄/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.     

Functional Magnetic Nanoparticles for Highly Efficient Cholesterol Removal

In this study, magnetic nanoparticles functionalized with carboxylated β‐cyclodextrin (CM‐β‐CD; referred to Fe₃O₄@CM‐β‐CD) were synthesized and used for the efficient removal of cholesterol from milk and egg yolk via host–guest interactions. The results of Fourier‐transform infrared, X‐ray photoelectron spectroscopy, and thermogravimetric analysis indicated that the CM‐β‐CD was successfully conjugated to the surface of Fe₃O₄, and the amount of CM‐β‐CD attached on Fe₃O₄@CM‐β‐CD was determined to be 9.164%. The X‐ray diffraction and transmission electron microscopy data revealed that the process of CM‐β‐CD coating did not result in a phase change of the Fe₃O₄, and the Fe₃O₄@CM‐β‐CD nanoparticles were determined to have an average size of about 15 nm. The results of isotherm adsorption and kinetic properties indicated that CM‐β‐CD functionalization increased the cholesterol removal efficiency, and the characteristics of cholesterol adsorption on Fe₃O₄@CM‐β‐CD were fitted well with the Langmuir adsorption model and Lagergren pseudo‐1st‐order kinetic models. Furthermore, compared with the Fe₃O₄ nanoparticles, the functionalized Fe₃O₄@CM‐β‐CD nanoparticles exhibited greater cholesterol removal efficiency, and saponification of the milk and egg yolk was found to be beneficial for the cholesterol removal; using the Fe₃O₄@CM‐β‐CD nanoparticles, 98.8% and 94.6% of the cholesterol was extracted in 1 h from saponified milk and egg yolk, respectively, and the Fe₃O₄@CM‐β‐CD nanoparticles still displayed efficient cholesterol removal after 6 reuses.     

Electrochemical behaviour of Sudan I at Fe3O4 nanoparticles modified glassy carbon electrode and its determination in food samples

In this work, a simple and sensitive electrochemical method was developed to determine Sudan I based on magnetic Fe₃O₄ nanoparticles modified glassy carbon electrode using cyclic voltammetry and differential pulse voltammetry. The sensor exhibited an obviously electrocatalytic activity towards the oxidation of Sudan I, which can be confirmed by the increased oxidation peak current and the decreased oxidation peak potential when compared with the bare GCE. The determination conditions, such as pH, modifier amount, accumulation time and accumulation potential, were optimised. And some kinetic parameters were calculated. Under the optimum experimental conditions, the oxidation current of Sudan I was proportional to its concentration from 0.01 to 1 μM and 1 to 20 μM. The detection limit was estimated to be 0.001 μM (S/N = 3). The developed method was successfully applied to determine Sudan I content in food samples with satisfactory results.     

Magnetic graphene oxide nanocomposites as the adsorbent for extraction and pre-concentration of azo dyes in different food samples followed by high-performance liquid chromatography analysis

ABSTRACT

This work presents a method of magnetic solid-phase extraction (MSPE) combined with high-performance liquid chromatography (HPLC) to analyse five synthetic azo dyes (tartrazine, amaranth, carmine, sunset yellow, allura red) in different food samples. The magnetic graphene oxide nanocomposite (GO@Fe₃O₄) was prepared by a one-step solvothermal method and used as the sorbent for extraction and pre-concentration of azo dyes in food samples. The as-prepared GO@Fe₃O₄ nanocomposite was characterised by transmission electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, vibrating sample magnetometer, and Brunuer-Emmett-Teller analysis. The extraction and desorption parameters were investigated, including the material amount, extraction time, pH of the solution, desorption temperature, and desorption solvents. Under the optimised conditions, the limits of detection (LODs) were 1.14–2.23, 0.36–0.77 and 0.68–1.26 ng/g for candy, jelly, and plum candy, respectively. The limits of quantification (LOQs) were 4.02–7.73, 1.21–2.50 and 2.31–4.20 ng/g for candy, jelly, and plum candy, respectively. For the analysis of spiked jelly, recoveries were between 73.2% and 107.7%, with RSDs lower than 1.34 %. The developed method was successfully applied to the analysis of real samples including jelly, candy and plum candy.     

Dispersed synthesis of uniform Fe3O4 magnetic nanoparticles via in situ decomposition of iron precursor along cotton fibre for Sudan dyes analysis in food samples

ABSTRACT

Fe₃O₄ magnetic nanoparticles, with a negative charge surface, are known to have efficient adsorbent properties, but they tend to be agglomerated into larger aggregates or flocs, which can cause loss of specific area. The addition of cotton fibre, as a stabiliser in preparation of the Fe₃O₄ nanoparticles, is able to efficiently reduce particle aggregation, and thus, effective particle size, resulting in much greater specific surface area and adsorption sites. Fe₃O₄ nanoparticles synthesis was accomplished by in situ high-temperature decomposition of the precursor ferric ion in the presence of cotton fibre and ethylene glycol solvent. The morphology of Fe₃O₄ nanoparticles was characterised by field emission scanning electron microscopy and X-ray diffraction, which confirmed that the magnetic nanoparticles are highly dispersed. These Fe₃O₄ nanoparticles were used for clean-up and pre-concentration of Sudan dyes in chilli and hot red sauces, prior to their determination by capillary liquid chromatography diode array detection. A comparative study of analyte pre-concentration was conducted with magnetic nanoparticles prepared with and without cotton fibre showing that both solid phases adsorb the analytes, but higher recoveries were obtained when using cotton fibre which therefore was selected for extraction of Sudan dyes.     

Magnetic Chitosan Nanocomposite Used as Cleanup Material to Detect Chloramphenicol in Milk by GC-MS

A novel method for determination of chloramphenicol in milk samples was introduced. Magnetic Fe₃O₄@chitosan nanocomposites were synthesized by adding chitosan to the surface of magnetic Fe₃O₄ using glutaraldehyde as cross-linker. Extraction with ethyl acetate, the study used the magnetic Fe₃O₄@CS as cleanup materials, without an additional cleanup step, to detect chloramphenicol in milk samples. To obtain maximal cleanup efficiency, several parameters were investigated including amount of magnetic materials, pH of the solution, purification time, and temperature. Under the optimal conditions (the amount of 100 mg/g of magnetic materials, pH?=?5, 10 min, and 20 °C), the sensitivity of the proposed method had improved about tenfold than that of without magnetic materials. Moreover, the decision limits and detection capability were 0.05 and 0.11 μg/kg, respectively, which were comparable to those measured by most methods. The rapid, simple, solvent-saving, and efficient method was proved to be robust in monitoring [d(?)-theo-2-dichloroacetamido-1-p-nitrophenyl-1,3-propanediol] in milk samples.     

MSPE-GC/MS在造纸废水苯系污染物检测中的应用研究

采用化学共沉淀法合成了磁性多壁碳纳米管材料(Fe3O4@MWSNTs),对该材料进行扫描电子显微镜、X射线衍射、红外光谱、元素分析等表征,并将其作为磁性固相萃取(MSPE)的吸附剂,建立了磁性固相萃取结合气相色谱质谱联用(MSPE-GC/MS)检测造纸废水中苯系污染物的分析方法。结果显示,Fe3O4纳米颗粒较好地附着在多壁碳纳米管的表面,材料C含量为37.45%,Fe3O4纳米颗粒的尺寸在50~200 nm左右,亲水性适中。将该材料用于造纸废水气质联用分析检测的前处理中,能够排除基质干扰并吸附痕量苯系污染物,此外,与普通液液萃取相比具有简单、快速、易于操作、有机溶剂用量少等优点。气质检测结果显示,建立的方法对痕量苯系污染物有很好的检出效果。     

Amperometric Determination of Quercetin in Some Foods by Magnetic Core/Shell Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@ZnO Nanoparticles Modified Glassy Carbon Electrode

In this paper, Fe₃O₄@ZnO core/shell magnetic nanoparticles (MNPs) have been synthesized by a simple method, to modify carbon paste/glassy carbon electrode and improve its efficiency for determination of quercetin. The synthesized MNPs were characterized by X-ray powder diffraction (XRD), transmission electronic microscope (TEM), and scanning electronic microscope (SEM). SEM and TEM results show that the prepared Fe₃O₄@ZnO MNPs are made of the spherical shape particles with an average size of about 15 nm. The electrochemical behavior of quercetin at the surface of modified electrode was investigated. Under the optimal conditions, a linearity range of quercetin was 7.9?×?10^?7 to 6.1?×?10^?5 mol/L (0.24–18.44 mg/L) with detection limit (S/N?=?3) and sensitivity of 0.16 μmol/L (0.048 mg/L) and 0.04 μA/μM, respectively. The validated method was applied successfully for determination of quercetin in some foods and human breast milk.