جستجوی مقالات مرتبط با کلیدواژه « nanofibers » در نشریات گروه « شیمی »
تکرار جستجوی کلیدواژه «nanofibers» در نشریات گروه «علوم پایه»-
Paclitaxel used to treat malignant tumors of cancer by controlling the release of the drug to the tumor cells at the exact time. Polycaprolactone (PCL) as a semi-crystalline polyester with a glass transition temperature and low melting point used as matrix and cellulose for fibrous layer. This polymer is easily processed at low temperatures, but due to its crystalline nature and strong hydrophobicity, the degradation of PCL is very slow. In this article, the anticancer drug is loaded into single-layer and three-layer cellulose acetate/polycaprolactone nanofibers and the amount of drug uptake, release behavior and release kinetics of the nanofibers are investigated. The resulting nanofibers were fabricated by electrospinning and freeze-drying to evaluate drug release and biocompatibility. Then, scanning electron microscopy (SEM) showed the approximate diameter and length of the nanofibers as 300-400 nm. Functional group and chemical bonds of nanofibers were detected by fourier transform infrared spectroscopy (FT-IR) analysis. Results have shown that the maximum degradation for PCL/CA + 15% D/PCL scaffold is 53% and 43% for the same scaffold by electrospinning method. The percentage of inflation increases as the concentration of PCL/CA in the scaffold increases. For the 5-minute time period, the percentage of inflation ranges from 14.29% for the PCL/CA+5%/PCL sample to 29.77% for the PCL/CA+15%/PCL sample. Similarly, for the 30-minute time period, the percentage of inflation ranges from 20.51% to 34.65% for the respective samples. The obtained results show slow and continuous release of the drug in vitro at 37°C and pH = 5.8, which can be used as a drug carrier in targeted treatment systems for anticancer drugs.Keywords: Paclitaxel, Polycaprolactone (PCL), Cellulose Acetate, Nanofibers, Drug Release, Anticancer Treatment}
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Currently, storing energy in a suitable form that can be converted and released to the desired state is one of the challenges facing modern technologies. Energy storage not only reduces the mismatch between supply and demand, but also increases the efficiency and reliability of energy systems and plays a very important role in reducing energy loss. In this research, the nanofibers of polyethylene glycol as a phase change material and polyamide 6 as a preservative in pipelines have been simulated in different conditions via COMSOL Multiphysics 5.6 software. For this purpose, the oil is placed inside a tube and a cylindrical tank and the container is covered with a thin layer of polyethylene glycol-polyamide nanofibers. In the following, the thermophysical properties of composite nanofibers of phase change materials in different weight percentages were investigated and the effects of changes in temperature, density, viscosity and thermal conductivity on them were compared. The results of the research showed that the most suitable system for heat management is related to the nanoparticles of phase change materials with the highest weight percentage of polyethylene glycol. Also, the use of nanofibers of phase change materials is very effective in improving thermal management and temperature control and can be used as suitable materials for energy storage and transfer. In addition, with the passage of time, more heat is absorbed by polyethylene glycol and energy storage is done better.Keywords: Nanofibers, Phase Change Materials, Energy Storage, Thermal Management, Thermal Conductivity}
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In this research, a Glassy Carbon Electrode (GCE) was modified with glucose oxidase (GOx)/chitosan (CS)/Graphene Oxide (GO) nanofibers for the detection of glucose via the electrospinning method. To do this, GOx was trapped among the two CS/GO nanofibers layers. Concerning electrochemical properties and producing conditions, the optimum amounts for GOx and GO in the deposited layer were 20 mg/mL and 20 % w/w, respectively. An investigation on the effects of pH, time of oxygen dissolving in the test solution, and scan rate on electrochemical behavior revealed that the peak current increased with increasing the oxygen dissolving time up to 20 min and scan rate values. However, the redox processes showed more symmetric anodic and cathodic structures at slow scan rates. Also, the highest current was obtained at a pH of 7.4. The result showed that the electrochemical process of GOx occurs through a two-proton and two-electron transformation. Additionally, the sensor exhibited excellent reproducibility and stability properties. It was concluded that the use of nanofibrous structure and the immobilization of the glucose oxidase among the two CS/GO nanofibers layers enhanced the electrochemical properties significantly due to the penetration of water-soluble glucose molecules in the porous nanofiber layers, which helped efficiently catalyze the oxidation of glucose and facile direct electron transfer for GOx. The resultant modified electrodes exhibited a high sensitivity of 1006.86 μA/mMcm2 and a low detection limit of 0.02 mM with a wide linear range of 0.05–20 mM.Keywords: Graphene, Glucose oxidase, Chitosan, Nanofibers, Cyclic voltammetry, Electrochemical biosensor}
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در این مطالعه نانوکامپوزیت اکسید آهن/ استات سلولز به روش الکتروریسی تهیه و عملکرد آن در حذف آرسنیک مورد ارزیابی قرار گرفت. در اینجا نانوذره اکسید آهن معناطیسی پوشش داده شده با اسید اولئیک به روش هم رسوبی سنتز و در محلول استات سلولز قرار داده شد. این محلول پلیمری برای تشکیل الیاف نانوکامپوزیت الکتروریسی شد. غشای نانوکامپوزیت استات سلولز/اکسید آهن توسط SEM و FTIR مورد بررسی قرار گرفت. خواص مغناطیسی نانوالیاف کامپوزیت با استفاده از آنالیز مغناطیس سنجی نمونه ارتعاشی مشخص شد. این نانوکامپوزیت برای حذف یون های آرسنیک از محلول آبی مورد استفاده قرار گرفت. آزمایش های جذب برای مطالعه رفتار جذب یون های آرسنیک به عنوان تابعی از pH، زمان تماس و غلظت اولیه انجام شد. نتایج تجربی نشان داد که حداکثر ظرفیت غشای نانوکامپوزیت استات سلولز- اکسید آهن برای حذف آرسنیک از 0.36 میلی گرم بر گرم در pH=9 است. برای بررسی بهتر مکانیسم جذب، دو مدل ایزوترم لانگمویر و فروندلیچ مورد بررسی قرار گرفتند. بر اساس نتایج، داده های جذب به خوبی با ایزوترم لانگمویر مطابقت دارد. قابلیت استفاده مجدد از غشای نانوکامپوزیت برای چندین فرآیند جذب و دفع در محیط های اسید و باز مورد بررسی قرار گرفت .کلید واژگان: نانوکامپوزیت, جاذب, نانوالیاف, نانوذره مغناطیسی, حذف آرسنیک}In this study, iron oxide/cellulose acetate nanocomposite was prepared by electrospinning method and its performance was evaluated for removal of arsenic. Here, oleic acid coated magnetite nanoparticle was synthesized by co-precipitation method and was impregnated in cellulose acetate solution. This magnetite impregnated polymer solution, was electrospun to form nanocomposite polymer fiber. The cellulose acetate/iron oxide nanocomposite membrane was characterized by SEM and FTIR. The magnetic properties of composite nanofibers were characterized by using vibrational sample magnetometry analysis. The nanocomposite was used to remove arsenic ions from aqueous solution. Batch adsorption experiments were carried out to study the sorption behavior of arsenic ions as a function of pH, contact time and initial concentration. Experimental results showed that the maximum capacity of the cellulose acetate-iron oxide nanocomposite membrane for removal of arsenic from low concentration is 0.36 mg/g at pH 9. For better investigation of the adsorption mechanism, two isotherm models, Langmuir and Freundlich were tested. Based on the isothermal results, adsorption data were fitted well to Langmuir isotherm. The reusability of the nanocomposite membrane was confirmed for several adsorption and desorption processes by acid-alkali treatment.Keywords: Nanocomposite, Sorbent, nanofibers, Magnetite nanoparticle, Arsenic removal}
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This work aimed to prepare pH-sensitive nanofibrous mats as a drug releasing system using a green method. Gelatin nanofibers were first prepared by electrospinning and then cross-linked with glutaraldehyde. To evaluate the capability of this product as a drug delivery system, vancomycin was loaded into the nanofibrous mats in different doses as a model antibiotic drug. The chemical structure of the prepared material was investigated by (Fourier transform-infrared) FT-IR. Field emission scanning electron microscopy (FE-SEM) observations showed that uniform bead-free nanofibers with an average diameter of 157 nm were successfully fabricated. The drug release studies revealed that the relative rate of drug release in buffer media with pH =2.0 was higher than that in a buffer solution with pH =7.4. The drug release mechanism of samples was determined by Korsmir-Pepas model. Moreover, the incorporation of vancomycin into the nanofibers provided an effective antibacterial activity against Escherichia coli and Staphylococcus aureus microorganisms. The developed antibiotic loaded nanofibrous mats can be considered as a promising novel antimicrobial wound dressing material.Keywords: antibacterial property, Drug delivery, electrospinning, gelatin, nanofibers}
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Tissue engineering benefits from electrospun scaffolds, particularly as drug carriers and reconstructive materials for orthopedic implants, as well as many other uses obtaining a large number of publications in a short period in the region through the production of complex scaffolds, the development of new nanotechnology processes, and improvement of imaging methods. Labeling these materials has become critical to achieving accurate and satisfactory results. This is an excellent method for mimicking the extracellular matrix of bone using biodegradable and biocompatible polymers for bone restoration. In this project, electrospinning of a PMMA: PVA scaffold is used. These composite fibers had a clear and continuous shape when examined under a scanning electron microscope (SEM), and their components were identified using (FTIR). Experiments revealed that this characterization of significant effects in the electrospinning method for biomedical applications plays an important role in producing implant coating materials for bone reconstruction.Keywords: Nanotechnology, Electrospinning, Characterization, PMMA, PVA blend, Nanofibers}
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نشریه کیفیت و ماندگاری تولیدات کشاورزی و مواد غذایی، سال دوم شماره 2 (پیاپی 6، پاییز 1401)، صص 36 -49تحقیقات اخیر نشان داده است نانو الیاف بلند و متخلخل به عنوان یکی از ایمن ترین نانو مواد بدلیل تولید قابل کنترل، داشتن سطح ویژه بالا و ساختار ماتریس پیوسته می تواند انتخاب مناسبی به عنوان میزبان، جهت طیف گسترده ای از تحقیقات باشد. در این پژوهش در ادامه مطالعه پیشین نویسندگان، فازهای ساختاری نانو الیافی که توسط ادغام مواد معدنی به ماتریس پلیمری در محدوده صفر تا 0.5 از ترکیب پلی وینیلیدین فلوراید (PVDF) و نانو ذرات اکسید دوتایی آهن/منگنز (FMBO) سنتز شده بود بررسی و ویژگی های آنها با توجه به ساختار و مشخصات سطح با استفاده از SEM و TEM تعیین شد. با توجه باینکه گزارشهای مربوط به تجزیه و تحلیل فازهای β ،α و γ اغلب بر اساس داده های اندازه گیری شده دارای دیدگاه های متفاوتی است در این تحقیق، با بررسی باندهای ارتعاشی FTIR و مشخصات XRD فازهای ساختاری نانوالیاف الکتروریسی PVDF و PVDF/FMBO ارزیابی و با استفاده از نتایج FTIR به طور خاص با بررسی باندهای 762 و 612، 1275 و 1234 cm-1 و تطابق آن با نتایج XRD و مرور تحقیقات منتشر شده به ترتیب فازهای β ،α و γ متمایز گردید.کلید واژگان: نانو الیاف, پلی وینیلیدن فلوراید, نانوذرات, الکتروریسی, فاز}Journal of Quality and Durability of Agricultural and Food Products, Volume:2 Issue: 2, 2022, PP 36 -49Recent research has shown that long, porous nanofibers are one of the safest nanomaterials due to their controllable production, high specific surface area and continuous matrix structure. In this study, following the previous study of the authors, Structural phases of nanofibers were synthesized from combination of polyvinylidene fluoride (PVDF) and iron/manganese binary oxide nanoparticles (FMBO) were evaluated. Mineral adsorbents were integrated into polymer matrix in the range of zero to 0.5. The properties of nanofibers according to the structure and surface characteristics using SEM and TEM were determined. In this study, structural phases of PVDF and PVDF/FMBO electrospinning nanofibers were distinguished by examining the FTIR vibration bands and analyzing the XRD characteristics due to the different reports on the analysis of α, β and γ phases according to the measured data. The results of FTIR, specifically by examining bands 762 and 612, 1275 and 1234 cm-1 and its compliance with XRD results and reviewing published research the α, β and γ phases were distinguished, respectively.Keywords: Nanofibers, PVDF, nanoparticles, Electrospinning, Phase}
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تحقیقات اخیر نشان داده است نانو الیاف بلند و متخلخل به عنوان یکی از ایمن ترین نانو مواد بدلیل تولید قابل کنترل، داشتن سطح ویژه بالا و ساختار ماتریس پیوسته می تواند انتخاب مناسبی به عنوان میزبان، جهت طیف گسترده ای از تحقیقات باشد. در این پژوهش در ادامه مطالعه پیشین نویسندگان، فازهای ساختاری نانو الیافی که توسط ادغام مواد معدنی به ماتریس پلیمری در محدوده صفر تا 0.5 از ترکیب پلی وینیلیدین فلوراید (PVDF) و نانو ذرات اکسید دوتایی آهن/منگنز (FMBO) سنتز شده بود بررسی و ویژگی های آنها با توجه به ساختار و مشخصات سطح با استفاده از SEM و TEM تعیین شد. با توجه باینکه گزارشهای مربوط به تجزیه و تحلیل فازهای β ،α و γ اغلب بر اساس داده های اندازه گیری شده دارای دیدگاه های متفاوتی است در این تحقیق، با بررسی باندهای ارتعاشی FTIR و مشخصات XRD فازهای ساختاری نانوالیاف الکتروریسی PVDF و PVDF/FMBO ارزیابی و با استفاده از نتایج FTIR به طور خاص با بررسی باندهای 762 و 612، 1275 و 1234 cm-1 و تطابق آن با نتایج XRD و مرور تحقیقات منتشر شده به ترتیب فازهای β ،α و γ متمایز گردید.کلید واژگان: نانو الیاف, پلی وینیلیدن فلوراید, نانوذرات, الکتروریسی, فاز}Journal of Quality and Durability of Agricultural and Food Products, Volume:1 Issue: 4, 2022, PP 51 -63Recent research has shown that long, porous nanofibers are one of the safest nanomaterials due to their controllable production, high specific surface area and continuous matrix structure. In this study, following the previous study of the authors, Structural phases of nanofibers were synthesized from combination of polyvinylidene fluoride (PVDF) and iron/manganese binary oxide nanoparticles (FMBO) were evaluated. Mineral adsorbents were integrated into polymer matrix in the range of zero to 0.5. The properties of nanofibers according to the structure and surface characteristics using SEM and TEM were determined. In this study, structural phases of PVDF and PVDF/FMBO electrospinning nanofibers were distinguished by examining the FTIR vibration bands and analyzing the XRD characteristics due to the different reports on the analysis of α, β and γ phases according to the measured data. The results of FTIR, specifically by examining bands 762 and 612, 1275 and 1234 cm-1 and its compliance with XRD results and reviewing published research the α, β and γ phases were distinguished, respectively.Keywords: Nanofibers, PVDF, nanoparticles, Electrospinning, Phase}
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در این کار، نانوالیاف کبالت استات/پلی وینیل الکل/PVA) 2(Co(OAc) به روش الکتروریسی تهیه شدند. در ادامه، با تیمار دمایی مناسب، نانوالیاف کبالت اکسید (CoxOy NFs) به دست آمدند. ریخت شناسی سطح و قطر نانوالیاف تهیه شده به وسیله میکروسکوپ الکترون روبشی (SEM) مورد بررسی قرار گرفت. نتیجه ها SEM نشان داد که الیاف طویل با قطر متوسط در حدود nm 50 برای CoxOyNFs به دست آمدند. با استفاده از تجزیه وزن سنجی گرمایی (TGA)، دمای مناسب برای تکلیس در حدود C 600 به دست آمد. طیف بینی فروسرخز تبدیل فوریه (FT-IR) نشان داد که همه اجزای آلی نانوالیاف الکتروریسی شده پس از تکلیس، خارج شدند. برای بررسی ساختار بلوری نانوالیاف اکسید فلزی از پراش پرتو ایکس (XRD) استفاده شد. فاز بلوری CoxOyNFs، مکعبی تعیین شد. با استفاده از هم دماهای جذب واجذب نیتروژن، مساحت سطح نانوالیاف g/2m4/4 به دست آمد. رفتار الکتروشیمیایی الکترود خمیرکربن اصلاح شده با CoxOyNFs (CoxOy/CPE) به وسیله روش های ولتامتری چرخه ای، طیف بینی امپدانس الکتروشیمیایی و کرونوآمپرومتری مورد مطالعه قرار گرفت. فعالیت الکتروکاتالیستی الکترود اصلاح شده نسبت به اکسایش اتیلن گلیکول (EG) در محیط قلیایی مورد مطالعه قرار گرفت. نتیجه های به دست آمده نشان داد کهCoxOyNFs/CPE قابلیت الکتروکاتالیز اکسایشEG را دارد.
کلید واژگان: الکتروریسی, نانوالیاف, اکسایش الکتروکاتالیزی, کبالت اکسید, اتیلن گلیکول}In this work, cobalt acetate/polyvinyl alcohol (Co (OAc)2/PVA) nanofibers were prepared by the electrospinning method. In the following, cobalt oxide nanofibers (CoxOy NFs) were obtained by appropriate thermal treatment. The surface morphology and diameter of the synthesized nanofibers were investigated by Scanning Electron Microscopy (SEM). The results showed that long fibers with an average diameter of around 50 nm were obtained for CoxOy NFs. By ThermoGravimetric Analysis (TGA), the appropriate temperature for calcination was obtained at about 600 °C. The Fourier Transform-InfraRed (FT-IR) spectroscopy showed that all the organic constituents of the electrospun nanofibers were removed after calcination. For the investigation of the crystallinity of the metal oxide nanofibers, X-Ray Diffraction (XRD) was used. The crystalline phase of CoxOy nanofibers was determined as cubic. By using adsorption-desorption isotherms, the surface area of the nanofibers was obtained at about 4.4 m2/g The electrochemical behavior of CoxOy NFs modified carbon paste electrode (CoxOy/CPE) was studied by cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry methods. The electrocatalytic activity of the modified electrode was studied towards oxidation of ethylene glycol (EG) in an alkaline medium. The obtained results showed that the CoxOy NFs/CPE has electrocatalytic ability towards the EG oxidation.
Keywords: Electrospinning, Nanofibers, Electrocatalytic oxidation, Cobalt oxide, ethylene glycol} -
Electrospinning has been recognized as an efficient technique for the fabrication of polymernanofibers. Recently, various polymers have successfully been electrospun into ultrafine fibers.Electrospinning is an extremely promising method for the preparation of tissue engineering scaffolds.In this study, nanofibers gelatin was electrospun at 20% v/v optimized content. To produce gelatinnanofibers optimally, production parameters need to be investigated. In the electrospinning, device(voltage and distance) parameters were determined to be effective; as a result, these parameterswere researched and the influences of electrospinning device parameters (voltage & distance)on properties of gelatin nanofibers were evaluated. These parameters affected the diametersize, uniformity, hydrophilicity and thermal degradation of electrospun gelatin nanofibers. All ofthese properties were examined by SEM, FTIR, CA, BET, XRAY and TGA tests and finally optimumgelatin nanofibers can be used in many applications including cell culture, drug delivery and tissueengineering.Keywords: Electrospinning, Gelatin, Morphology, Nanofibers, Tissue Engineering}
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نانوالیاف هسته-پوسته متشکل از دی اکسید تیتانیوم و دی اکسید قلع به روش الکتروریسی، با هدف بالا بردن فعالیت فوتوکاتالیستی، ساخته شد و در ناحیه فرابنفش مورد مطالعه قرار گرفت. مورفولوژی و ریزساختار نانو الیاف تولید شده با استفاده از تصویربرداری میکروسکوپ الکترونی روبشی SEM و میکروسکوپ الکترونی عبوری TEM و پراش اشعه ایکس XRD مورد بررسی قرار گرفتند. بر اساس تصاویر SEMبدست آمده، نمونه های ساخته شده دارای ساختار دو لایه هسته-پوسته TiO2- SnO2 با قطرهایی در محدوده 120-70 نانومتر هستند. آنالیزهای XRD نشان می دهند که نانو ساختارهای سنتز شده بعد از عملیات حرارتی دارای ساختاری با فاز غالب کریستالی است. علاوه بر این، نتایج حاصل از طیف سنجی نوری فرابنفش-مرئی UV-Vis نشان می دهد که تغییرات قله های جذب رنگ های رودامین بی، متیلن آبی و متیل نارنجی مورد آزمایش، در حضور نانو الیاف هسته-پوسته TiO2- SnO2 بطور خیلی محسوسی کاهشی بوده که تاییدی است بر اثر خاصیت فوتوکاتالیستی نانو الیاف تولید شده، بطوریکه در نهایت منجر به کاهش در غلظت رنگ به کار رفته، شده است.
کلید واژگان: نانو ذرات, الکتروریسی, نانو الیاف, ساختار هسته -پوسته, فعالیت فوتوکاتالیستی, TiO2- SnO2}Nano scale, Volume:6 Issue: 3, 2019, PP 52 -60The core-shell nanofibers consist of titanium dioxide and tin dioxide were fabricated by electrospinning method in order to enhance photocatalytic activity under ultraviolet UV irradiation. The morphology and microstructure of the produced nanofibers were investigated using scanning electron microscopy SEM, transition electron microscopy TEM and X-ray diffraction XRD. According to SEM images, the fabricated samples have core-shell TiO2-SnO2 structures with diameters ranging from 120 to 70 nm. The XRD analyzes show that synthesized nanostructures have a crystalline dominant phase after thermal treatment. Furthermore, the results of ultraviolet-visible UV-Vis spectroscopy show that the changes in absorption peaks of Rhodamine b, Methylene blue and Methyl orange have been considerably reduced in presence of core-shell nanofibers TiO2-SnO2. These results confirm that the photocatalytic properties of nanofibers eventually led to a reduction in concentration of the model dye.]]>
Keywords: Nanoparticles, electrospinning, nanofibers, core-shell structures, TiO2-SnO2, photocatalyst activity} -
Magnetic poly (acrylonitrile-co-acrylic acid) (PAN-co-AA) composite nanofibers with different proportions of magnetic nanoparticles (MNPs) were fabricated using electrospinning technique. Electrospinning conditions like polymeric concentration, applied voltage, feeding rate, working distance, and collector type were explored and optimized to produce ultrafine- uniform size and bead free nanofibers. Electrospun nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Brunauer−Emmett−Teller (BET) isotherms, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM). The optimum electrospinning conditions were obtained to be 12wt% concentration, 20 kV voltages, 20 cm tips to collector distance and 0.5 mL/h flow rate. At the optimal operating condition the nanofibers diameter dropped from 359 nm to 74 nm and the specific surface area increased to 12.09 m2g-1 with respect to MNPs content (0 to 40 wt. %). Also, the magnetic property of magnetic nanofibers facilitated the separation of solid phase much easier than nonmagnetic nanofiber.Keywords: Electrospinning, Nanofibers, Poly (acrylonitrile-co-acrylic acid), Magnetic nanoparticle}
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در این پژوهش، نانوالیاف نیکل استات/پلی وینیل الکل (Ni(OAc)2/PVA) به روش الکتروریسی تهیه شدند. در ادامه، با عملیات گرمایی مناسب، نانوالیاف نیکل اکسید (NiO NFs) به دست آمدند. ریخت شناسی سطح و قطر نانوالیاف تهیه شده به وسیله میکروسکوپی الکترون روبشی (SEM) مورد بررسی قرار گرفتند. نتیجه ها نشان دادند که رشته های بسیار بلند با قطر متوسط در حدود nm 90 برای NiO NFs به دست آمدند. با استفاده از تجزیه وزن سنجی گرمایی (TGA)، دمای مناسب برای تکلیس در حدود C 600 به دست آمد. طیف بینی فروسرخ تبدیل فوریه (FT-IR) نشان داد که همه اجزای آلی نانوالیاف الکتروریسی شده پس از تکلیس خارج شدند. برای بررسی ساختار بلوری NiO NFs از پراش پرتو ایکس (XRD) استفاده شد. فاز بلوری نانوالیاف نیکل اکسید، مکعبی تعیین شد. با استفاده از هم دماهای جذب واجذب نیتروژن (BET)، مساحت سطح NiO NFs در حدود m2/g 2/4 تخمین زده شد. رفتار الکتروشیمیایی الکترود خمیرکربن (CPE) اصلاح شده با NiO NFs به وسیله روش های ولتامتری چرخه ای، طیف بینی امپدانس الکتروشیمیایی و کرونوآمپرومتری مورد مطالعه قرار گرفت. فعالیت الکتروکاتالیستی الکترودهای اصلاح شده نسبت به اکسایش اتیلن گلیکول (EG)، اتانول و متانول در محیط قلیایی مورد مطالعه قرار گرفت و نتیجه های به دست آمده نشان داد که چگالی جریان کاتالیستی برای NiO NFs/CPE برای اکسایش EG از الکل های دیگر بیش تر است.
کلید واژگان: نانوالیاف, الکتروریسی, اکسایش الکتروکاتالیستی, نیکل اکسید}In this research, nickel acetate/polyvinyl alcohol (Ni(OAc)2/PVA) nanofibers were prepared by the electrospinning method. In the following, nickel oxide nanofibers (NiO NFs) were obtained by appropriate heat treatment. The surface morphology and diameter of the synthesized nanofibers were investigated by Scanning Electron Microscopy (SEM). The results showed that long fiberswith an average diameter of around 90 nm were obtained for NiO NFs. By using Thermo Gravimetric Analysis (TGA), the appropriate temperature for calcination was obtained at about 600 °C. The Fourier Transform-InfraRed (FT-IR) spectroscopy showed that all the organic constituents of the electro-spun NFs were removed after calcination. For the investigation of the crystallinity of the nickel oxide NFs, X-Ray Diffraction (XRD) was used. The crystalline phase of the NiO NFs was determined as cubic. The surface area of the NiO NFs was estimated at about 4.2 m2 g-1 using adsorption-desorption isotherms (BET). The electrochemical behavior of NiO NFs modified Carbon Paste Electrode (CPE) was studied by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry methods. The electrocatalytic activity of the modified electrodes was studied towards oxidation of ethylene glycol (EG), ethanol and methanol in alkaline medium and the obtained results showed that the catalytic current density for the NiO NFs/CPE towards EG oxidation is more than other alcohols.
Keywords: Nanofibers, Electrospinning, Electro-catalytic oxidation, Nickel oxide} -
Nitrogen oxides (NOx) released in atmosphere by fuels combustion lead to photochemical smog and acidic rains and have negative effects on human`s nervous system. In this research nanocomposite membranes of Poly Vinylidene Fluoride (PVDF)/ Poly Dimethylsiloxane (PDMS) and Titanium Dioxide nanoparticles (TiO2) with different weight percentage of TiO2 (0.5 and 1) for adsorption of NOx were prepared using electrospinning. To investigate the properties of prepared fibers, scanning electron microscopy (SEM) and Attenuated Total Reflectance spectroscopy (ATR) were used. The fibers morphology and particles distribution in polymer were determined by SEM pictures. The composite fibers with 0.5 wt% TiO2 removed 50% nitrogen oxides and fibers with 1 wt% TiO2 removed 100% of nitrogen oxides. Generally, the presence of Titanium Dioxide nanoparticle (anatase phase) in fibers, vapor and ultraviolet ray have removed toxic NOx gas by contribution in photocatalysis. The ATR spectrum of fibers confirmed NOx adsorption by composite nanofibers. TiO2/ polymer composite membrane showed the promising potential for application as a filter to remove Nitrogen Oxides from air.Keywords: Nanofibers, Pollutant Removal, photocatalyst, Nitrogen Oxides (NOx)}
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در این پژوهش، نانوالیاف با استفاده از الکتروریسی محلول پلی استایرن در حلال DMF / THF تولید شد. پارامترهای مهم مانند ولتاژ، فاصله بین تزریق و جمع کننده، سرعت تزریق، غلظت پلی استایرن و سرعت چرخش جمع کننده در روش الکتروریسی بهینه سازی شد. نتیجه ها نشان داد که در بازه ی معین، با افزایش ولتاژ، فاصله الکتروریسی زیاد، شدت جریان تزریق پایین و سرعت بالای جمع کننده، نانو الیافی دارای ساختار زنجیری منظم و قطر کم تر به دست می آید. در شرایط بهینه، الیاف پلی استایرنی دارای قطر میانگین nm 102-70 بودند. جاذب پلی استایرن با دی تیزون اصلاح شد. با انتخاب بهترین شرایط، نانو الیاف پلی استایرن اصلاح شده با قطر میانگین nm 126-73 تولید شد. نانوالیاف پلی استایرنی تولید شده، برای پیش تغلیظ مس در نمونه پساب مورد استفاده قرار گرفت. پارامترهای اثرگذار در استخراج همانند مقدار جاذب، pH، نوع و حجم حلال شوینده و مقدار نمک، به روش تک متغیره بررسی و بهینه شد. با توجه به نتیجه ها، شرایط بهینه عبارتند از: مقدار فاز جامد:g 006/0، 7pH=، حلال شوینده: محلول استونیتریل با حجمmL 7/0، نمک پتاسیم نیترات g3/1. این روش روی نمونه های حقیقی استفاده شد و نتیجه های خوبی به دست آمد. فاکتور تغلیظ بالا و حد تشخیص خیلی خوب این روش از جمله نکته های برجسته آن می باشد.کلید واژگان: الکتروریسی, نانو الیاف, پلی استایرن, اصلاحگر, مس, استخراج فاز جامد}In this work, the Nanofibers were synthesized using electrospun of polystyrene solution in DMF/ THF solvent. The important parameters such as voltage, the distance between injector and collector, speed injection, the concentration of polystyrene and speed rotation of collectors in electrospun technique were optimized. Results showed that, within certain limits, by increasing the voltage, high Electro distance, low injection rate and high speed of the collector, we will get the Nanofibers with diameters less and regular chain structure. In optimal conditions, the average of polystyrene fibers diameter was 70-102 nm. Polystyrene absorbent modified by dithizone. By selecting the best conditions, the modified polystyrene Nanofibers were produced with an average diameter of 73-126 nm. The synthesized polystyrene Nanofibers were used for preconcentration of Copper in wastewater samples. The effective parameter on extraction such as adsorbent amount, pH, type and volume of eluent solvent and salt amount was evaluated and optimized with one at the time method. According to the results, optimum conditions are the solid phase: 0/006 gr, pH = 7, eluent solvent: acetonitrile solution with a volume of 0/7 mL, 1/3 g amount of potassium nitrate salt. This method was applied to real samples and good results were obtained. High enrichment factors and very good detection limit are highlights of this method.Keywords: Electro-Span, Nanofibers, Polystyrene, Modifier, Copper, Solid phase extraction}
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Poly(vinylidene fluoride) (PVDF) nanofibers were prepared via electrospinning process. Several different factors influence on this process and application of experimental design for its optimization is of great importance. The central composite design (CCD) was used for planning and optimizing of the experiments and also, the analysis of variance (ANOVA) was employed for the statistical validation of regression models. In this research, we found optimal condition for the effects of four factors, i.e. PVDF concentration, flow rate, voltage and interval on the fiber diameter. The model indicated that the flow rate (negatively) and solution concentration (positively) influence extremely on the fiber diameter, whereas the voltage and interval influence equally together on the response (negatively).Keywords: Central Composite Design, Electrospinning Process, Expert Design, Nanofibers, Optimization, Poly(vinylidene fluoride)}
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