sio2
در نشریات گروه شیمی-
SiO2 is considered a promising candidate for future high-power energy Li-ion batteries thanks to its affordability and accessibility, low discharge potential (0.7 V vs. Li+/Li), and high specific capacity of 1965 mAh g-1. Rice husk naturally contains SiO2 in the form of nanoparticles, making it a reasonably priced anode material with a high silica content. In this study, amorphous and porous SiO2/C anode materials are successfully synthesized by calcinating rice husk with NaOH, an activating agent. The prepared anode materials exhibited a surface area of 210 m2 g-1 with pore sizes ranging from 50 to 100 nm. In addition, SiO2 particles were coated by a 3-5 nm carbon layer to depress volume expansion and thus enhance cycling performance. The SiO2/C anode provided a capacity of 1625.3 mAh g-1 in the 1st cycle and maintained around 645 mAh g-1 in the following 50 cycles. The optimal negative/positive capacity ratios were determined in coin cells and the high-capacity pouch cells (4x6 cm2, 40 mAh) were further assembled to demonstrate a potential application of SiO2/C in high-power Li-ion batteries.
Keywords: Rice Husk, Sio2, C Anode, Pouch Cell, Li-Ion Batteries -
Polyethersulfone membrane modification by placing hydrophilic nanoparticles in the membrane matrix can improve antifouling ability. In this study, the Fe3O4 nanoparticles were modified by immobilizing SiO2, KCC-1, GMSI, and Carnosine. After surface modification, the nanoparticles were brought into polyether sulfone-based nanofiltration membranes to improve the membrane permeability, separation efficiency, and antifouling ability. The effect of nanoparticles on membrane structure and its performance was investigated using Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM), water contact angle, mean pore size and porosity measurements, pure water flux, and wastewater treatment, as well as antifouling ability. Based on the results, increasing the concentration of nanoparticles from 0 to 0.1 wt% developed the membranes to a more porous structure in the sub-layer, higher thickness, increased pure water flux, higher hydrophilicity, and fouling resistance. Consequently, the membrane with 0.1 wt% of nanoparticles endorsed a decreasing contact angle from 76 ±1 to 60.3±0.2, increasing pure water flux from 50.96 L/m2h to 93.42 L/m2h at a pressure of 9 bar, and a relatively high flux recovery ratio of 95.5%. Thus, a considerable performance of the prepared membrane was established in treating the oily wastewater contaminants.
Keywords: Nanofiltration Membrane, Fe3o4, Sio2, KCC-1, GMSI, Carnosine, Nanoparticles, Hydrophilicity, Fouling Resistance, Oily Wastewater -
The molecularly dispersed BiP1-xVxO4/SiO2 supported oxides, with x varying from 0 to 1, were prepared by impregnation of Bismuth, Phosphorus, and Vanadium on silica. Their structures have been characterized by different techniques: X-ray diffraction, Raman spectroscopy, Temperature-Programmed Reduction of catalysts in H2 (H2-TPR), and methanol oxidation reaction. This very sensitive technique provided us with relevant information on the nature of the active sites (acid-base and redox) on the surface of the catalysts. The results of the characterization show the structural evolution of the vanadium species of the isolated crystallites from V2O5 for x =0.3 and x =0.5, to BiVO4, with the disappearance of BiPO4, with the increase of the vanadium content from x=0.5 to x = 1. The oxidation of methanol showed the basic properties of the BiPO4/SiO2 catalyst, by the formation of carbon dioxide as the major product of the reaction. The substitution of phosphorus with vanadium promotes the formation of formaldehyde, confirming the presence of redox sites on these substituted catalysts. These catalysts were examined in the Oxidative dehydrogenation (ODH) of propane. For x ≥ 0.5, the dispersed BiVO4 exhibited significant activity in propane ODH than the BiPO4 and V2O5 crystallites, with good selectivity to propylene and acrolein, consistent with their high reducibility confirmed by H2-TPR, and the presence of redox sites shown by the oxidation of methanol. The catalyst with x = 0 was less selective for propylene due to the favorable combustion of propylene during its formation. Such an understanding of the intrinsic catalytic properties of the BiP1-xVxO4/SiO2 oxides and in particular, the BiPO4 and BiVO4 crystallites provides new information on the structural requirements of the propane ODH reaction, beneficial for the design of more efficient Bi-P-V-O based catalysts for propylene and acrolein production.
Keywords: Oxidative dehydrogenation, Propane, Propylene, Acrolein, BiP1-xVxO4, SiO2 -
Nanotechnology is a promising and practical method for removing volatile organic materials from tile surfaces. Tiles are usually coated at temperatures above 1000 °C. At temperatures above 500 °C, TiO2 cannot maintain its photocatalytic properties due to the anatase to rutile phase transformation, making it difficult to perform the method. One of the main goals of this study is to explore the possibility of producing TiO2 nanostructures through a simple and cost-effective method without requiring any modifications to existing factory production lines. In this experimental study, the nanostructure of TiO2 was doped with nickel and nitrogen ions, prepared based on silica through the sol-gel method, and mixed with a glaze called nanoglaze. The resulting nanostructure was calcined at 1200 °C, where the molecular ratio of silica-based doped TiO2 was changed. The nanoglaze was coated on the blocks and placed under the CFL lamp. SEM, FTIR, XRD, and TGA techniques were used to analyze its nanostructure. The results showed the thermal stability of the nanostructure at 1200 °C. TiO2 shows a photocatalytic effect only in the ultraviolet region. The removal rate of Methylene Blue as a pollutant sample was tested. The removal rate of methylene blue was 44% in the presence of titanium dioxide photocatalyst. According to XRD analysis, the size of the photocatalyst crystal particles was 3.5 nm. Adding TiO2 removes pollutants from water and air. Also, self-cleaning properties appear in these materials. So, photocatalysts can be added to building structures, pavements, paints, cement and plaster.Keywords: photocatalyst, High thermal stability, TiO2, Ni-doping, N-doping, SiO2
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A supported magnetic nanocomposite as a simple, stable, and efficient catalyst was successfully developed for condensation reaction of aldehydes, ammonium acetate, and isatoic anhydride to prepare 2,3-dihydroquinazolin-4(1H)-one derivatives as essential biologically active heterocyclic compounds. Ethanol as a non-toxic solvent under a reflux condition was utilized in the reactions. The Fe3O4/SiO2/CeO2 nanocomposite was prepared as a magnetic and novel catalyst. The value of components of the catalyst composite, including Fe3O4, SiO2, and CeO2, was optimized using experimental design to prepare the best catalyst composite with the highest reaction efficiency. The optimum amounts of Fe3O4, SiO2, and CeO2 in the catalyst composite were 0.37 g, 0.85 mL, and 1.28 g, respectively. The catalyst structure was characterized by FT-IR spectroscopy, vibrating sample magnetometer, Powder X-ray diffraction, and Transmission electron microscope. A sol-gel procedure was utilized to prepare the catalyst, in which chemical bonds between the catalysis components, leading to a high chemical, mechanical, and thermal stability of the catalyst. Several syntheses of 2,3-dihydroquinazolin-4(1H)-ones derivatives were performed using Fe3O4/SiO2/CeO2 (0.1 g) in EtOH (10.0 mL) under reflux for 9-19 min with yield in the range of 89-97%. The method displayed various advantages, including high yields, easy workup, low catalyst consumption, high catalyst reusability, low reaction times, and fast and straightforward catalyst separation using a magnet.Keywords: 2, 3-Dihydroquinazolin-4(1H)-ones, Quinazolin-4(3H)-ones, nanocomposite, Magnetic catalyst, Fe3O4, SiO2, CeO2, Aldehydes
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The one-pot multicomponent efficient and easily operational protocol has been developed for the synthesis of tetrahydropyrano[2,3-c]pyrazole-5-carbonitrile derivatives. The methods work via the multicomponent reaction between 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one , aldehyde and malononitrile catalyzed by the silica-supported dodeca tungstophosphoric acid (DTP/SiO2) catalyst. The protocol is practically green, milder reaction condition, higher yield, with short reaction times and recyclability of the catalyst.Keywords: DTP, SiO2, Greener solvent, one-pot multicomponant, carbazole-3-carbonitrile
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In this work, polyvinylidene fluoride membranes were modified by introducing nanostructure TiO2/SiO2/POM hybrid fibers in the polymeric dope, to endow them with photocatalytic properties. For this purpose, initially, hybrid fibers were synthesized by electrospinning and calcination technique, and then these additives were incorporated into the membrane matrix. FT-IR and XRD analysis were used for the characterization of synthesized compounds. The FESEM manifests that the average diameter of the hybrid composite fibers is about 500 nm, and investigated membrane morphology. The properties of the prepared photocatalytic membrane were examined by several investigations such as pure water flux, contact angle, salt, and heavy metal rejection. Photocatalytic experiments confirm that membranes display a highly efficient and durable activity for the photodegradation of Methylene Bue (MB) and Humic Acid (HA). Experiments show that the prepared membranes have excellent stability under UV irradiation and can be used potentially for the separation of different components from water. The measurement accuracy and repeatability were determined by calculating the Standard Deviation and entered into Tables.Keywords: hybrid nanostructure, Photocatalytic membrane, Polyoxometalate, nanostructure TiO2, SiO2, POM hybrid fibers in the polymeric dope
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An efficient and convenient method has been developed for the synthesis of 2-amino-5-oxo-4-phenyl-4, 5-dihydropyrano[3,2-c]chromene-3-carbonitrile derivatives from one-pot multicomponent reaction between 4-hydroxy-2H-chromen-2-one, aromatic aldehydes and malononitrile catalyzed by DTP/SiO2 as an efficient and reusable heterogeneous catalyst. The current method provides adavtages over reported method viz simple operational procedure, easy isolation and recyclability of the catalyst, environmental benign, reduced reaction time and superior yield.Keywords: DTP, SiO2, Green chemistry, dihydropyrano[3, 2-c]chromene-3-carbonitrile
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Silica supported 1-(2-(sulfooxy)ethyl)pyridin-1-ium chloride has been explored as highly efficient catalyst for reactions under mild and green conditions for the synthesis of quinoxaline derivatives. The green and mild methods offer appealing attributes such as use of a recyclable, use of EtOH as green solvent and 60 °C condition, short reaction times, a simple workup and high yield of the products.Keywords: Silica supported 1-(2-(sulfooxy)ethyl)pyridin-1-ium chloride, Quinoxaline, Solid acid catalyst, SiO2, [SEP]Cl, One-pot reaction
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نشریه شیمی کاربردی روز، پیاپی 56 (پاییز 1399)، صص 327 -344
کمپلکس جدید ناجور هستهCS)) [(Sr (OH2)6Cu (H2O) 4 Sr2 (dipic) 4 (OH2) 2]n.nH2O کهdipic2- عبارتست از پیریدین 2و6- دی کربوکسیلاتو تحت امواج التراسونیک تهیه شد. ساختار کمپلکسCS به طور کامل توسط تجزیه عنصری، طیف سنجی زیر قرمز (FT-IR)،آنالیز وزن سنجی حرارتی (TGA) ،آنالیز حرارتی تفاضلی (DTA) و پراش پرتو X تک بلور (SC-XRD) شناسایی شد. نتایج آنالیز کریستالوگرافی کمپلکس CS نشان داد که این کمپلکس در ساختار تری کلینیک با گروه فضایی P-1 متبلور شده است. همچنین این آنالیز وجود تعداد زیادی پیوند هیدروژنی H-O...O که نقش اساسی در ایجاد شبکه سه بعدی دارند را تایید می کند.سپس کاتالیست Cu-Sr/SiO2 از تجزیه حرارتی کمپلکس CS در دمای Cº600 و در حضور پایه سیلیکا تهیه شد. در ادامه کاتالیست های مرجع Cu-Sr/SiO2 به روش های همرسوبی و تلقیح نیز تهیه شدند و بوسیله روش های طیف سنجی زیر قرمز ، آنالیز پراش پرتو ایکس (XRD) ، میکروسکوپ الکترونی روبشی (SEM) و مساحت سطح ویژه (BET) شناسایی شدند. نتایج حاصل از این مطالعات نشان داد که کاتالیست حاصل از تجزیه حرارتی کمپلکس CS دارای اندازه ذرات کوچکتر و مساحت سطح ویژه بزرگتری نسبت به دو کاتالیست مرجع است . به منظور تولید گاز هیدروژن، واکنش جابجایی آب- گاز (WGS) در محدوده دمایی Cº420-300 بر سطح کاتالیست های Cu-Sr/SiO2 انجام شد. بررسی اثر دما نشان داد که در Cº380 فعالیت کاتالیزوری هر سه کاتالیست در بالاترین مقدار خود قرار دارد. همچنین بالاترین عملکرد کاتالیزوری مربوط به کاتالیستی است که از کمپلکس CS مشتق شده است. این عملکرد کاتالیزوری بالا به خصوصیات فیزیکی و شیمیایی کاتالیست تهیه شده نظیر اندازه ذرات کوچکتر و مساحت سطح ویژه بیشتر نسبت داده شد.
کلید واژگان: کمپلکس Cu-Sr، ساختار بلوری، کاتالیست Cu-Sr، SiO2، واکنش جابجایی آب -گاز، گاز هیدروژنA new hetero-dinuclear complex [(Sr(OH2)6Cu(H2O)4 Sr2 (dipic)4(OH2)2]n.nH2O (CS) that dipic2- is pyridine-2,6-dicarboxylato has been synthesized under ultrasonic irradiation. The structure of the CS complex has been fully characterized by elemental analysis, Fourier transforms infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and single-crystal X-ray diffraction (SC-XRD). The results of crystallography analysis revealed that this complex crystallizes in a triclinic system with space group P -1. It also confirms the large number of H-O ... O hydrogen bonds play a key role in the creation of the 3D network. The Sr-Cu/SiO2 nano-catalyst was prepared by thermal decomposition of CS complex at 600ºC in the presence of silica support. In addition, reference catalysts of Cu-Sr/SiO2 were prepared by co-precipitation and impregnation methods and characterized by FT-IR spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and specific surface area (BET). The results of these studies show that the catalyst obtained by the thermal decomposition of the CS complex has smaller particle size and larger specific surface area than the two reference catalysts. In order to produce hydrogen gas, a water-gas shift reaction (WGS) was performed on the surface of Cu-Sr/SiO2 nanocatalysts in the temperature range of 300-420ºC. Examination of the effect of temperature shows that at 380ºC the catalytic activity of all three catalysts is at its highest. The highest catalytic performance was achieved by nanocatalyst that derived from CS complex. This high catalytic performance can be attributed to the physicochemical properties of this catalyst such as smaller particle size and higher specific surface area.
Keywords: Sr-Cu complex, crystal structure, Catalyst of Sr-Cu, SiO2, Water-gas shift reaction, Hydrogen gas -
In the presented study, CuO-CoO-MnO/SiO2 nanocomposite was synthesis by Cu(II), Co(II), Mn(II), with 1:1:1 mole ratio and Tetraethyl orthosilicate. azo–azomethine 1-(3-imino-4-hydroxophenylazo-4-nitrobenzene)-4-methyl phenol (L) was synthesized and used as a ligand for capturing the metal ions. Also, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide was applied as the ionic liquid in order to increase the conductivity of the electrode. The nanomaterials were investigated using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM); SEM image shows a homogeneous CuO-CoO-MnO/SiO2 nanocomposite, with an average particle size distribution of 40 nm. Also, the electrochemical characterization of L/CuO-CoO-MnO/SiO2/IL/CPE was checked by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The modification of carbon paste electrode applied to determination of some heavy metal ions include Hg(II), Cd(II), Pb(II) and Zn(II) by square wave anodic stripping voltammetry (SWASV), for the first time. The linear range for determination of analytes in optimized condition was obtained as Hg: 0.0007-0.21 and 0.21-27 μM, Cd: 0.0007-0.21 and 0.21-27 μM, Pb: 0.0009-0.23 and 0.23-27 μM, Zn: 0.001-0.25 and 0.25-27 μM. Also, the detection limits for Hg(II), Cd(II), Pb(II) and Zn(II) were calculated to be 3.019×10-4, 3.445×10-4, 2.407×10-4 and 5.134×10-4 μM, respectively. Finally, the sensor was successfully used for the measurement of the analytes in Tap water and River water samples with recoveries ranging between 98.1% and 102.7%. Also, the obtained results accorded very well with those obtained by atomic absorption spectroscopy (AAS) that corroborated the accuracy and validity of the proposed method.Keywords: Electrochemical Determination, Heavy metal ions, sensor, CuO-CoO-MnO, SiO2
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Lithium-Sulfur (Li-S) batteries are considered as one of the promising candidates for next-generation Li batteries in near future. Although, these batteries are suffering from certain drawbacks such as rapid capacity fading during the charge and discharge process due to the dissolution of polysulfides. In this paper, Sulfur/metal oxide (TiO2 and SiO2) yolk–shell structures have been successfully synthesized and utilized to overcome this problem and improve the electrochemical performance of sulfur cahtode material. Prepared materials have been characterized using Scanning Electron Microscopy(SEM), Transmission Electron Microscopy(TEM) and X-ray diffraction (XRD) techniques. The results show significant improvement in the battery performance as a result of using Sulfur-SiO2 and Sulfur-TiO2 yolk–shell structures. The obtained Sulfur-TiO2 electrode delivers a high initial discharge capacity (>2000 mA h g−1) and discharge capacity of 250 mA h g−1 over 8 charging/discharging cycles with Coulombic efficiency of 60%, while initial discharge capacity for Sulfur-SiO2 electrode was lower (>1000 mA h g−1) compared to Sulfur-TiO2. Sulfur-SiO2 electrode shows the discharge capacity of 200 mA h g−1 over 8 charging/discharging cycles with Coulombic efficiency around70%. The obtained galvanostatic ressults demonstrated that Sulfur-TiO2 electrode possess stronger capability to prevent sulfur and its intermediate reaction products from dissolving into the electrolyte.Keywords: Li-S battery, Nanoparticle, SiO2, Sulfur, TiO2
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In the research, spherical α-Fe2O3 NanoParticles (NPs) were synthesized through Forced Hydrolysis and Reflux Condensation (FHRC) process and were supported on the surface of silica sand by Solid-State Dispersion (SSD) method. Characterization of silica and α-Fe2O3/SiO2 catalyst was done using Fourier-Transform InfraRed (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) images, X-Ray Diffraction (XRD) patterns and Brunauer, Emmet and Teller (BET) surface area. The supported α-Fe2O3/SiO2 nanocatalyst with the average crystallite size of 27.5 nm was used for photocatalytic removal of Methylene Blue (MB) from aqueous solutions under Ultra-Violet (UV) light.In order to optimization of effective parameters on MB degradation, the single-variable method was used. The optimal conditions were determined as pH=11, initial concentration of MB=10 ppm, and the mass of catalyst =1.0 g. Degradation efficiency in optimal conditions was 97.32%.
Keywords: Methylene blue, SSD, FHRC, α-Fe2O3, SiO2 -
The Photocatalytic degradation of chemical pollutants such as dyes, especially by Nano catalysts is an effective method to protect the environment and water resources. In this study, through Forced Hydrolysis and Reflux Condensation (FHRC) method the nanospherical α-Fe2O3 particles were synthesized and supported on the surface of silica sand by Solid-State Dispersion (SSD) method with the average crystallite size of 27.5 nm. The characterization of catalyst and catalyst support was done using FTIR spectroscopy, SEM images, XRD patterns and BET surface area.In this paper, α-Fe2O3/SiO2 nano photocatalyst was used for the removal of methyl red (MR) under ultraviolet (UV) light. After running different tests, the effective parameters such as the concentration of MR, pH, and mass of catalyst on pollutant degradation were optimized by single-variable method. The results showed that the optimum conditions for achieving 98.46 % of degradation were pH at 5, initial concentration of MR at 10 mg/l, and 2.0 g of α-Fe2O3/SiO2 nano photo catalyst.Keywords: Methyl red, Solid-State Dispersion (SSD) method, nanophotocatalyst, α-Fe2O3, SiO2
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In this research work, silica nano-porous thin films were deposited on glass substrates by layer by layer method. The thin films were calcinated at various calcination temperatures (200, 300, 400, and 500 °C). The morphology, surface characteristics, surface roughness and hydrophilic properties of the thin films were investigated by field emission scanning electron microscopy, attenuated total reflectance fourier transform infrared spectroscopy, atomic force microscopy and water contact angle analyzer. The surface characteristic showed that silica nano-porous thin film had an amorphous structure. The hydrophilic results indicated that the water contact angle of the glass coated silica nano-porous surface is decreased by increasing the calcinations temperatures to 300 °C and at higher temperature, it is increased. The deposition of silica nano-porous thin film on the glass surface at the optimum calcination temperature (300 °C) decreased water contact angle of the glass surface from 67° to 3°. Therefore, silica nanoporous thin film calcinated at 300 °C showed superhydrophilicity which greatly encourages the antifogging functions of the thin film.Keywords: Hydrophilicity, Nano-Porosity, SiO2, Sol–gel
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In the present study, the extract of the plant of Oenothera biennis was used to green synthesis of silver nanoparticles (Ag NPs) as an environmentally friendly, simple and low cost method. And Additionally, TiO2/SiO2 was prepared via facile sol-gel method using starch as an important, naturally abundant organic polymer as an ideal support. The Ag NPs/TiO2/SiO2 as an effective catalyst was prepared through reduction of Ag+ ions using Oenothera biennis extract as the reducing and stabilizing agent and Ag NPs immobilization on TiO2/SiO2 surface in the absence of any stabilizer or surfactant. Several techniques such as FT-IR spectroscopy, UV-Vis spectroscopy, X-ray Diffraction (XRD), sScanning eElectron mMicroscopy (FE-SEM), Eenergy dDispersive X-ray sSpectroscopy (EDS), and Ttransmission Eelectron Mmicroscopy (TEM) were used to characterize TiO2/SiO2, silver nanoparticles (Ag NPs), and Ag NPs/TiO2/SiO2. Moreover, the catalytic activity of the Ag NPs/ TiO2/SiO2 was investigated in the reduction of 4-nitrophenol (4-NP) at room temperature. On the basis of the results, the Ag NPs/TiO2/SiO2 was found to be high catalytic activity highly active catalyst according to the experimental results in this study. In addition, Ag NPs/TiO2/SiO2 can be recovered and reused several times in the reduction of 4-NP with no significant loss of catalytic activity.Keywords: TiO2, SiO2, Ag Nanoparticles, Oenothera biennis, NaBH4, 4-NP
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International Journal Of Nanoscience and Nanotechnology, Volume:12 Issue: 4, Autumn 2016, PP 269 -275New extension of nanoparticles used in the last two decades and hence, entrance of them to industrial and non-industrial sewage necessitate study of probable effects of these materials in aquatic ecosystems. This research was performed in order to determine the toxicity effect of silica dioxide (Si 2) nano particles on Dunaliella salina green algae in laboratory conditions. SiO2 nanoparticle is one of the best full-used nano particles which have application in industries like production of ceramics, plastics, glass, cosmetics, medicine and paper. Dunaliella algae because of having economic value and different biochemical composition is used as complements with natural origin in food and pharmacology industries. For toxicity determination of this material, the experiment was performed according to O.E.C.D standard method. Experiments on Dunaliella were performed for 72 hours with 7 treatments, two controls and three replicates in each treatment and daily counting of cells in each tube. Counting cell algae population was done by microscope on a Thoma counting slide. For data analysis, probit analysis, Excel software and SPSS21 were used. The 72 hours NOEC, EC90, EC50 and E 10 were calculated. The amounts of 72 hours are EC10 =5.37.10-5 , EC50 = 0.169 , EC90 = 512.86, NOEC = 1.6×10-2 mg/l. Cell compression noticeably decreased (PKeywords: Algae Dunaliella salina, EC50, SiO2, Toxicity, Nanoparticles, Nanotechnology
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به طور معمول برای اکسایش گروه سولفید تیو استامید و تبدیل آن به داروی هدف (مودافینیل) از عامل اکسنده هیدروژن پراکسید %33 در حضور گلاسیال استیک اسید استفاده می شود که در مدت 4 ساعت انجام می گیرد. در این کار پژوهشی نانو کاتالیست جدید 4O3 /Fe2+/SiO3 /NH3VO تهیه و شناسایی شد و از این کاتالیست برای اکسایش سولفید به سولفوکسید در حضور مقدارهای مولی 2O 2H استفاده شد. نتیجه های به دست آمده نشان دهنده افزایش راندمان فراورده ی پایانی و کاهش زمان واکنش به حدود 45 دقیقه می باشد. کاتالیست جدید تهیه شده به دلیل دارا بودن ویژگی های مغناطیسی پس از انجام مرحله سولفوکسایش، توسط میدان مغناطیسی خارجی(آهن ربا) از ظرف واکنش به راحتی خارج شده و پس از شستشو، دوباره در واکنش استفاده شد. کاتالیست ارایه شده توسط فناوری های IR، BET، SEM، VSMو XRD شناسایی شد.کلید واژگان: اکسایش، سولفید، مودافینیل، دی فنیل متیل سولفینیل استامید، نانو کاتالیست، 4O3، Fe2+، SiO3، NH3VONormally for the oxidation of sulfide group thioacetamide and turn it into a target drug (modafinil) of 33% hydrogen peroxide in the presence of glacial acetic acid oxidizing agent is used which is carried out within 4 hours. In this work, new nano-catalyst VO3-/ NH3+SiO2/Fe3O4 were prepared and characterized for the oxidation of sulfide to sulfoxide in the presence of molar quantities of H2O2. The results show an increase in the efficiency of the final product and reduce the reaction time is about 45 minutes. The new proposed catalyst for possessing magnetic properties after the sulfoxidation, by external magnetic fields (magnets) easily removed from the reaction flask and rewashed was used in the reaction. The catalyst provided by techniques of IR, BET, SEM, VSM and XRD were identified.Keywords: Oxidation, Sulfide, Modafinil, Diphenyl methyl sulfonyl acetamide, Nano, catalysts, VO3, NH3+, SiO2, Fe3O4
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In this study the effect of nano sized silica particles (nano-SiO2) on the physical and mechanical properties of rice husk and Old Corrugated Container (OCC)-cement boards was investigated. Modulus Of Rupture (MOR), Modulus Of Elasticity (MOE), Internal Bonding Strength (IB), density, water absorption and thickness swelling after 24 hours immersion in water and hardness were measured. Results showed that rice husk-cement boards with 2% nano SiO2 demonstrated the best physical and mechanical properties. It is related to better distribution and compaction of particles during compression without particles agglomerating. A higher property of 2%-nano-SiO2 content rice-husk-cement boards was confirmed by their higher hydration temperature. Addition of 3% nano-SiO2 to the mixture reduced the density because of both the substitution of denser cement particles by lighter nano-SiO2 particles and air entrapment in the boards. Furthermore, Scanning Electron Microscopy (SEM) analyses showed that the optimum amount of nano-SiO2 (2%) can fill micro pores and make a uniform structure with a rough surface which improves properties of composite boards.Keywords: Cement boards, Nano, SiO2, Rice husk, Old Corrugated Container (OCC), SEM
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In this work firstly ZnO nanoparticles were synthesized via a simple precipitation method. At the second step titanium dioxide and silicon dioxide shell were synthesized on the core. For preparation ZnO-TiO2-SiO2 the sol product was calcinated at 500 ºC for 2h. Properties of the product were examined by X-ray diffraction pattern (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The photo- catalytic behavior of ZnO-SiO2-TiO2 nanocomposite was evaluated using the degradation of a methylene blue aqueous solution under visible light irradiation. The results show that ZnO-SiO2-TiO2 nanocomposites have applicable photo-catalytic performance.Keywords: Sol, gel, ZnO, TiO2, SiO2, Nanocomposites
- نتایج بر اساس تاریخ انتشار مرتب شدهاند.
- کلیدواژه مورد نظر شما تنها در فیلد کلیدواژگان مقالات جستجو شدهاست. به منظور حذف نتایج غیر مرتبط، جستجو تنها در مقالات مجلاتی انجام شده که با مجله ماخذ هم موضوع هستند.
- در صورتی که میخواهید جستجو را در همه موضوعات و با شرایط دیگر تکرار کنید به صفحه جستجوی پیشرفته مجلات مراجعه کنید.