Surface Of Stainless Steel Fibers Research Articles

Exploring the optimal electropolymerization strategy for the preparation of solid-phase microextraction fibers using pyrrole-dopamine copolymers

In-situ electropolymerization of conductive polymers on the surface of stainless-steel substrates is a well-established but promising procedure for the preparation of solid-phase microextraction (SPME) tools. Herein, different electrochemical methods including constant potential (CP), constant potential pulse (CPP), and cyclic voltammetry (CV) were utilized to fabricate SPME fibers by in-situ electropolymerization of pyrrole-dopamine copolymers (PPY/PDA) on the surface of stainless-steel fibers. The coated fibers were characterized and applied for the direct-immersion SPME (DI-SPME) sampling of ultra-trace amounts of plant hormones including abscisic acid (ABA), gibberellic acid (GA3), and indole acetic acid (IAA) in fruit juices, followed by HPLC-UV determination. The results showed that CV electropolymerization is significantly more efficient than the two other methods. The coatings created by the CV method were satisfactorily uniform, adhesive, and durable and exhibited higher extraction performance compared to the CP and CPP procedures. The important experimental variables of the proposed DI-SPME-HPLC method were evaluated and optimized using response surface methodology with a Box-Behnken design. The developed method showed wide-range linearities, spanning from 0.05 to 20μg mL−1 for GA3, and 0.02 to 20μg mL−1 for ABA and IAA. The limits of detection were obtained 0.01μg mL−1 for GA3, and 0.005μg mL−1 for ABA and IAA. The fiber was successfully employed for the simultaneous DI-SPME-HPLC analysis of plant hormones in fruit juice samples.

Preparation of sulfonic acid functionalized covalent organic framework solid phase microextraction fibers and their application in the analysis of neurotransmitters in the mouse brain

Neurotransmitters (NTs) are essential for intercellular communication and primarily include monoamine, amino acid, and cholinergic NTs. These molecules play important roles in the body's stress response, motor coordination, neuronal communication, and homeostatic functions. Previous studies have shown that abnormal changes in NT levels are associated with various neurological disorders. Therefore, the development of accurate analytical methods for NT detection will enhance the current understanding on complex neuropathophysiology by providing functional knowledge and techniques for early diagnosis, thereby facilitating the development of new therapeutic options for the related diseases. The solid phase microextraction (SPME) technique combines sample preparation, separation, and enrichment in a single step and is minimally invasive, low cost, solvent free, and high throughput. SPME has been successfully applied to the in vivo analysis of target analytes in animal, human, and plant tissues. The coating material plays a significant role in the development of in vivo SPME methods and must meet various analytical requirements, including a suitable geometry for the SPME device, high extraction capacity, excellent selectivity, and wide extraction coverage for the target analytes. Covalent organic frameworks (COFs) are porous crystalline polymers constructed from organic framework units through strong covalent bonds; these materials are characterized with a low density, large specific surface area, permanent porosity, excellent chemical/thermal stability, and easy functionalization.In this study, a sulfonic acid-functionalized COF material (COF-SO3H) with good crystallinity, excellent chemical/thermal stability, strong hydrophobicity, a uniform mesoporous structure, and narrow pore size distribution was prepared using 2,4,6-triformylphloroglucinol and 1,4-diamino-2-nitrobenzene as monomers. Then, the COF-SO3H was coated onto the surface of stainless-steel fibers and used for in vivo enrichment of NTs. The structural properties of COF-SO3H were characterized using various techniques, such as scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), all of which showed that COF-SO3H had a good crystalline structure and uniform mesopore distribution with a specific surface area of 46.17 m2/g. Compared with the SPME fibers of HLB, C18, MCX, amino, and PXC columns, the prepared COF-SO3H fibers showed better extraction efficiency for the target NTs. Next, the factors affecting SPME efficiency were optimized. The optimal desorption solvent was formic acid-methanol-water (0.5∶49.5∶50, v/v/v), and the optimal extraction and desorption times were 15 min. A method for the in vivo analysis of NTs in the brains of mice was established by combining the COF-SO3H fibers with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) under optimal conditions. The NTs were separated on an Acquity UPLC BEH-C18 analytical column (100 mm×2.1 mm, 1.7 μm) with 0.1% formic acid aqueous solution (A) and acetonitrile (B) as the mobile phases. The flow rate was set to 0.2 mL/min, and the gradient elution procedure was as follows: 0-4 min, 5%B-6%B; 4-7 min, 6%B-5%B; 7-11 min, 5%B. Under optimal conditions, the method showed good linearity (r2>0.99). The limits of quantification (S/N≥5) were in the range of 0.003-0.005 μg/mL and 3-5 μg/mL for monoamine and amino acid NTs, respectively, with RSDs of less than 20%. The method showed good precision (0.80%-9.70%) and accuracy (2.08%-17.72%), with absolute matrix effects in the range of 82.22%-117.92%. These values reflect the good purification and enrichment abilities of the proposed fibers for the target analytes. Finally, the established SPME method was combined with UPLC-MS/MS and successfully applied to quantify target NTs in the brains of mice. The proposed strategy provides a practical method for the in vivo detection and quantitative analysis of NTs and expands the applications of functionalized COF materials for the analysis of various targets.

Growth of Carbonaceous Nanoparticles on Steel Fiber from Candle Flame for the Long-Term Preservation of Ultratrace Mercury by Solid-Phase Microextraction.

An extremely simple, cost-effective, and one-step method was developed for the preparation of solid-phase microextraction (SPME) fibers via the in situ synthesis of carbonaceous nanoparticles on the surface of stainless steel fiber from a candle flame. The prepared SPME fiber provided excellent adsorption capability toward Hg2+ derived with sodium tetraethylborate and was explored for the separation, preconcentration, and long-term preservation of ultratrace mercury in natural water samples. Moreover, the SPME fiber was further utilized for the highly sensitive routine analysis and field analysis of mercury with a commercial atomic fluorescence spectrometer (AFS) and a miniature point discharge optical emission spectrometer (μPD-OES), respectively. Under the optimum conditions, detection limits of 0.0005 μg L-1 and 0.007 μg L-1 together with relative standard deviations (RSDs) less than 5.8% were obtained for Hg2+ by headspace SPME-AFS and SPME-μPD-OES, respectively. The practicality of the prepared SPME fiber was validated via the determination of Hg2+ in real water samples with satisfactory recoveries (79-115%). Long-term preservation of mercury at parts per trillion level was undertaken at -20 °C and the sample loss rates were less than 5% after 9 days of storage, respectively, indicating that the storage performances of mercury provided by the proposed method are much better than that obtained by conventional methods. Notably, the extraction performance of the SPME fiber is not decreased obviously even after more than 100 times of operation. Due to its advantages of high sensitivity, high stability, simple operation, low cost, and low energy consumption, this method provides an avenue for the field analysis and long-term preservation of mercury in the field of environmental analytical chemistry.

Headspace solid-phase microextraction of menthol using a sol–gel titania-based coating along with multiwalled carbon nanotubes on the surface of stainless steel fiber

Sol–gel coating technology for the preparation of solid-phase microextraction fibers involves a single-step procedure and allows for in situ creation of chemically bonded coatings which are characterized by high thermal and solvent stabilities. A novel titania sol–gel coating was prepared for the first time on a stainless steel fiber and applied for the headspace solid-phase microextraction (HS-SPME) of menthol with gas chromatography and flame ionization detection. Important parameters influencing the efficiency of SPME process, such as extraction time, extraction temperature and ionic strength, were optimized by central composite design. An extraction time of 40 min at 60 °C gave maximum extraction efficiency, when NaCl (10% w/v) was added to the aqueous sample. The analytical characteristics of the proposed method were comparable with other reported fibers. Under optimized conditions, the linearity was between 0.05 and 100 µg mL− 1. The relative standard deviations (RSDs) determined at 0.5 µg mL− 1 concentration level (n = 5) were as follows: intra-day RSD 7.26%; inter-day RSD 10.87%; fiber-to-fiber RSD 9.05%. The relative recoveries determined after spiking a mint distillate sample at three concentration levels from 0.067 to 50.0 µg mL− 1 varied from 86 to 102%. The proposed method was successfully applied for the analysis of menthol in peppermint samples.

A novel polyaniline/polypyrrole/graphene oxide fiber for the determination of volatile organic compounds in headspace gas of lung cell lines

Exploration of volatile organic compounds (VOCs) generated by lung cell lines is a powerful and non-invasive tool for the detection of potential volatile biomarkers of lung cancer. In this study, a simple and sensitive solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method was developed for the determination of VOCs in the headspace gas of lung cell lines. For the purpose of preconcentration, a novel polyaniline/polypyrrole/graphene oxide (PANI/PPy/GO) coating was prepared on the surface of stainless steel fiber via in-situ electrochemical deposition for the first time. The characteristic properties of the coating were studied and the results revealed that the coating possessed large surface area, high extraction efficiency, excellent thermal and mechanical stability as well as long lifespan. Some parameters affecting the extraction efficiency such as synthesis conditions, extraction and desorption conditions were optimized. Under the optimal conditions, the method displayed relatively wide linear range (three or four orders of magnitude) with correlation coefficients above 0.9916. Low detection limits from 1.0 to 12ngL−1 were obtained. Relative standard deviations ranged from 1.2% to 18.0% indicating good repeatability and reproducibility of the method. This method has been successfully applied to analyze VOCs in the headspace gas of lung adenocarcinoma epithelial cell line (A549) and human embryonic fibroblast cell line (MRC-5).

Catalytic combustion of isopropanol over Co-Mn mixed oxides modified ZSM-5 zeolite membrane catalysts coated on stainless steel fibers

Abstract A novel gradient porous Co-Mn mixed oxides modified ZSM-5 zeolite membrane/PSSF (paper-like stainless steel fibers) catalyst was prepared for catalytic combustion of isopropanol in a membrane reactor. First, the paper-like sintered stainless steel fibers (PSSF) support was fabricated by wet lay-up papermaking method and sintering process. Then, ZSM-5 zeolite membranes were synthesized on the surface of stainless steel fibers by using secondary growth process. Finally, the cobalt and manganese mixed oxides modified ZSM-5 zeolite membrane catalysts were prepared by wet impregnation method. These novel modified membrane catalysts were characterized by using SEM, XRD, N2 adsorption–desorption isotherms and XPS, respectively. The catalytic activity test was carried out over a membrane reactor filled with ZSM-5 zeolite membrane catalysts and granular catalysts, respectively. The experimental results showed that the junctures of stainless steel fibers were completely sintered together to form a three-dimensional network structure and ZSM-5 zeolite membrane was fabricated on the PSSF support with the thickness of 1.78 μm. The cobalt element existed as Co3+and Co2+, maganese element existed as Mn4+ and Mn3+. The results of catalytic activity tests showed that catalytic activity for isopropanol over ZSM-5 zeolite membrane catalyst was superior to that over granular ZMS-5 catalyst, the reaction temperature of 50% and 90% conversion of isopropanol over ZSM-5 zeolite membrane catalyst dramatically decreased. The Co-Mn(1:4)/ZSM-5/PSSF catalysts presented the most excellent catalytic activity for isopropanol combustion, compared with Co/ZSM-5/PSSF and Mn/ZSM-5/PSSF catalysts, respectively.

A powerful approach to graphene/stainless steel web hybrids for large scale electromagnetic shielding applications

Graphene/Stainless Steel web hybrids were fabricated using soaking-annealing method. The microstructure was characterized by field emission scanning electron microscope an X-ray diffraction. The results showed that Graphene uniformly dispersed on the surface of stainless steel fibers which were further prepared to large scale graphene/Stainless steel web. For the as-prepared products a minimum reflection loss (RL) of −42.6 dB was achieved at 8.5 GHz. Moreover, the frequency range with RL peak value below −10 dB was achieved in a broad frequency bandwidth of 9.8 GHz, suggesting the excellent microwave absorption properties.

Catalytic combustion kinetics of isopropanol over novel porous microfibrous‐structured ZSM‐5 coating/PSSF catalyst

Porous thin‐sheet cobalt–copper–manganese mixed oxides modified microfibrous‐structured ZSM‐5 coating/PSSF catalysts were developed by the papermaking/sintering process, secondary growth process, and incipient wetness impregnating method. Paper‐like sintered stainless steel fibers (PSSF) support with sinter‐locked three‐dimensional networks was built by the papermaking/sintering process, and ZSM‐5 coatings were fabricated on the surface of stainless steel fibers by the secondary growth process. Catalytic combustion performances of isopropanol at different concentrations over the microfibrous‐structured Co–Cu–Mn (1:1:1)/ZSM‐5 coating/PSSF catalysts were measured to obtain kinetics data. The catalytic combustion kinetics was investigated using power–rate law model and Mars–Van Krevelen model. It was found that the Mars–Van Krevelen model provided fairly good fits to the kinetic data. The catalytic combustion reaction occurred by interaction between isopropanol molecule and oxygen‐rich centers of modified microfibrous‐structured ZSM‐5 coating/PSSF catalyst. The reaction activation energies for the reduction and oxidation steps are 60.3 and 57.19 kJ/mol, respectively. © 2014 American Institute of Chemical Engineers AIChE J, 61: 620–630, 2015

Fabrication of porous copper/manganese binary oxides modified ZSM-5 membrane catalyst and potential application in the removal of VOCs

Abstract Copper-manganese binary oxides modified ZSM-5 membrane catalysts were synthesized by using incipient wetness impregnating method. Specifically, the PSSF (paper-like sintered stainless steel fibers) support was fabricated by wet lay-up papermaking/sintering process and the ZSM-5 membranes were synthesized on the surface of stainless steel fibers by using secondary growth process. The catalysts were characterized by using scanning electron microscopy (SEM), Energy dispersive X-ray spectrometer (EDS) mapping, X-ray diffraction (XRD), N 2 adsorption–desorption, X-ray photoelectron spectra (XPS) as well as H 2 -TPR (Temperature programmed reduction). The most efficient catalyst was Cu–Mn(1:6)/ZSM-5/PSSF, exhibiting best catalytic activity (% of isopropanol conversion was 210 °C) and excellent reaction rate. It can be also demonstrated that the zeolite membrane reactor performs better for isopropanol oxidation, giving a T 90% that is around 70 °C lower than obtained in the traditional particles fixed bed. The excellent catalytic performance of the Cu–Mn(1:6)/ZSM-5/PSSF catalysts can be attributed to the presence of ZSM-5 zeolite membrane, well dispersion of catalysts actives, reasonable mass/heat transfer efficiency, excellent oxygen storage ability as well as higher contacting efficiency. Furthermore, the Cu–Mn(1:6)/ZSM-5/PSSF catalyst exhibits a high stability after being used at 260 °C for 50 h.

Gradient porous Co–Cu–Mn mixed oxides modified ZSM-5 membranes as high efficiency catalyst for the catalytic oxidation of isopropanol

Novel gradient porous mixed cobalt–copper–manganese mixed oxides modified ZSM-5 membrane catalysts were synthesized by the incipient wetness impregnating method. The paper-like sintered stainless steel fibers (PSSF) support was fabricated by the wet lay-up papermaking/sintering process, and the ZSM-5 membranes were synthesized on the surface of stainless steel fibers by using secondary growth process. These novel modified membrane catalysts have been characterized by a series of techniques including SEM, EDS mapping, XRD, N2 adsorption–desorption, XPS and H2-TPR method. Catalytic performances of isopropanol oxidation over these novel catalysts were investigated. Among the series of catalysts, the as-prepared Co–Cu–Mn (1:1:1)/ZSM-5/PSSF catalysts have exhibited the best catalytic activity, demonstrating by a lowest T90% at 210°C. The gradient porous modified ZSM-5 membrane as high efficiency catalyst can offer a much higher catalytic activity, excellent reaction stability, and higher contact efficiency.

A Novel Sintered Stainless Steel Fiber Felt with Rough Surface Morphologies

A novel sintered stainless steel fiber felt (SSSFF) with rough surface morphologies and high strength as well as high porosity is fabricated by solid-state sintering of stainless steel fibers produced by cutting method. The rough surface morphologies are characterized by laminar and jagged structures formed on the surface of stainless steel fibers. The SSSFF with 85% porosity sintered at 1200°C for 60 min exhibits tensile strength of 19 MPa and yield stress of 10.5 MPa. The influence of sintering parameters on surface morphologies and tensile strength is investigated. The experimental results show that the rough surface structures will disappear gradually when sintering temperature is 1300°C or sintering time is excessive, that is, 240 min when sintering temperature is 1200°C. The SSSFF with high porosity presents high tensile strength when sintering temperature ranges from 1100°C to 1200°C and sintering time is from 60 min to 120 min. In addition, the fracture mechanism of the SSSFF is investigated when subjected to uniaxial tensile load.

Preparation and Characterization of Metolachlor Molecularly Imprinted Polymer Coating on Stainless Steel Fibers for Solid-Phase Microextraction

A molecularly imprinted polymer (MIP) with metolachlor as the template molecule was first coated on the surface of stainless steel fibers through chemical bonding. Despite 12 times repeated coating procedures, a homogenous, porous, and highly cross-linked MIP coating was obtained with thickness of 17.4 µm (RSD of 6.1%). The specific selectivity of MIP coating to metolachlor and three metabolites could be concluded with 4.4, 4.1, 3.9, and 2.9 times higher extraction amounts of metolachlor, hydroxymetolachlor, deschlorometolachlor, and desmethylmetolachlor than that of the NIP coating, respectively, and good extraction capabilities for chloroacetanilide herbicides were found with the MIP-coated SPME stainless steel fiber. For validation, the fiber was applied for the extraction of metolachlor, propisochlor, and butachlor in spiked corn and soybean samples, and the recoveries of 90.7–92.6%, 86.4–87.9, and 85.4–87.5% were obtained, respectively.