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sio2

در نشریات گروه علوم پایه
  • Thanh Liem Pham, Thien Trung Nguyen, Tran Bich Tram Vo, Tan Phat Vu, Van Man Tran, My Loan Phung Le *

    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
  • Mojtaba Vafaee Baghban, Maryam Omidvar *, Rahele Zhiani, Malihe Sadat Hosseiny, Seyed Mohammadmahdi Nouri

    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
  • Mbarka Ouchabi, Ilyasse Loulidi *, Mahfoud Agunaou

    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
  • Majid Ahmadlouydarab *, Sadaf Javadi, Farshad Adel Alijan Darab
    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
  • Rahmat Ghasemi, Mahmoud Naseri *, Dariush Souri, Ahmad Kamalianfar
    The preparation of Co1-xCdxFe2O4/SiO2 nanocomposites with core/ shell structure involved the coating of SiO2 using Stöber method on Co1-xCdxFe2O4 and the use of facile thermal treatment method for synthesizing nanoparticles. The effect of cadmium substitution and SiO2 coating on the degree of crystallinity, samples composition, microstructure, and phase composition were conducted by X-ray diffraction (XRD), energy dispersion X-ray analysis (EDXA), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FT-IR), respectively. Magnetic properties were demonstrated by a vibrating sample magnetometer (VSM) which displayed that Co-Cd ferrite nanoparticles and coated silica samples exhibited magnetic behaviors. In investigating the influence of cadmium substitution and the SiO2 coating on the band gap energy (Eg), a more accurate method was used in evaluating the band gap energy (Eg). The method of evaluation is a recently proposed one known as derivation of absorption spectrum fitting (DASF) which involves the direct absorption spectra of UV-Visible region, without any need for the concentration of powders or solutions.
    Keywords: Nanocomposites, Magnetic properties, Ferrites, SiO2
  • Sofiane Labidi *, Boukoffa Mechati
    Natural quartz mineral was examined as a new sorbent for Hg(II) removal from synthetic wastewater systems. Batch adsorption experiments of Hg(II)  onto quartz mineral were conducted under various conditions such as solution pH, sorbent dosage, contact time, initial Hg(II)  concentration. Adsorption experiments results of Hg(II) by quartz mineral showed good achievement after 180 min with 1.0 g/L sorbent mass at pH of 2.0, agitation speed of 200 rpm and a temperature of 25°C. Moreover, the Hg(II) concentration was directly related to increases the adsorption capacity, the maximum Hg(II) uptake by quartz  sample was 16.52 mg/g for 80 mg/L (C0 (Hg(II)].  Langmuir isotherm and pseudo-second-order kinetics (R2 > 0.99) were found to be the most appropriate models to describe the adsorption of Hg(II) by quartz mineral. The intra-particle diffusion model and the calculated Dubinin–Radushkevich adsorption energy (Eads = 0.78 kJmol-1), confirms a physisorption adsorption reaction occurring in three stages.
    Keywords: SiO2, Hg(II), Wastewater, kinetic, physisorption
  • Elham Mohamadzadeh, Zinat Gordi *
    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
  • Sunil Gaikwad *, Murali Venkata Basavanag Unnamatla
    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
  • Hamed Samadi Mollayousefi, Abdollah Fallah Shojaei, Nosrat Mahmoodi *
    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
  • ساناز سعیدی راد، جمیله سیدیزدی، سیده هدی حکمت آرا*

    در این مقاله، نانولوله کربنی عامل دار (MWCNT-COOH) با لایه هایی از پوشش زیست سازگار دی اکسید سیلیسیوم (سیلیکا) پوشش داده شد. این پوشش به دلیل دارا بودن گروه های هیدروکسیل (OH) متعدد در سطح خود، علاوه بر آنکه از تجمع نانولوله ها جلوگیری می کند، قابلیت گیراندازی و پایدار کردن نانوذرات مختلف را به طور یکنواخت و به اندازه دلخواه روی سطح خود دارد. نانولوله پوشیده با سیلیکا (MWCNT/SiO2) با درصد های مختلفی از نانوذرات مگنتیت (Fe3O4) دوپه شد. نسبت های 1، 2 و 3 برابر Fe3O4 به MWCNT/SiO2 به ترتیب S1، S2 و S3 نامیده شدند. نانوکامپوزیت های حاصل (MWCNT/SiO2/Fe3O4) توسط طیف سنجی پراش پرتو ایکس (XRD)، میکروسکوپ الکترونی روبشی (SEM) مشخصه یابی شد. خاصیت مغناطیسی نمونه ها با استفاده از مغناطش سنج نمونه ارتعاشی (VSM) بررسی شد که نشان دهنده خاصیت سوپرپارامغناطیس نانوکامپوزیت ها بود. به دلیل دارا بودن خاصیت زیست سازگاری، هر سه نمونه از نانوکامپوزیت تهیه شده به عنوان فوتوکاتالیست های قابل بازیافت (به دلیل دارا بودن خاصیت مغناطیسی) برای حذف رنگ متیلن آبی مورد استفاده قرار گرفتند.

    کلید واژگان: SiO2، MWCNT، Fe3O4، خاصیت مغناطیسی، فوتوکاتالیست
    Sanaz Saeedirad, Jamileh Seyedyazdi, Seyyedeh Hoda Hekmatara *

    In this paper, functionalized carbon nanotubes were covered with a biocompatible shell of silica (MWCNT/SiO2). Having a high amount of OH groups, silica shells avoid nanotubes agglomeration and are able to uniformly capture and stabilize arbitrary amounts of nanoparticles on their surface. MWCNT/SiO2 doped with different amounts of Fe3O4 nanoparticles. Three samples of Fe3O4/SiO2/MWCNT nanocomposites prepared by 1, 2, and 3 weight ratio of Fe3O4 to SiO2/MWCNT are labeled S1, S2, and S3, respectively. Then, they were characterized by X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM). The magnetic property of samples was investigated with vibrational sample magnetometer (VSM), which indicated the superparamagnetic property of nanocomposites. Due to their biocompatibility, nanocomposites were used as recyclable photocatalysts to remove methylene blue dye.

    Keywords: SiO2, MWCNT, Fe3O4, magnetic property, photocatalyst
  • Rahul Kamble *, Milind Gaikwad, Manojkumar Tapare, Shrikant Hese, Shuddhodan Kadam, Ajay Ambhore, Bhaskar Dawane
    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
  • Sami Sajjadifar *, Ghobad Mansouri, Issa Amini, Maryam Yari
    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
  • زهره رزم آرا*

    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 هیدروژن
    Zohreh Razmara *

    A 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
  • Ashkan Faridan, Manochehr Bahmaei *, Amirabdolah Mehrdad Sharif
    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
  • Parisa Safaei, Sajad Sepahvand, Fatemeh Hossieni, Shahnaz Ghasemi, Zeinab Sanaee *
    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
  • Majid Saghi *, Mohammad Khazaei Nejad, Ali Arasteh

    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
  • Majid Saghi *, Aref Shokri, Ali Arastehnodeh, Mohammad Khazaeinejad, Atena Nozari
    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
  • Abd Karim Norani, Rokiah Hashim *, Othman Sulaiman, Salim Hiziroglu, Salmiah Ujang, Wan Noor Aidawati Wan Nadhari
    The main objectives of this study were to evaluate the biodegradation behaviour of experimental particleboard bonded with modified 30 % of PVOH, 70 % of Oil palm starch and 3 % of nano silicon dioxide (SiO2). Boric acid at 2 % was also added as a cross-linker to PVOH in modified oil palm starch to enhance decay resistant for the samples. All the particleboards were evaluated by soil burial, borer and fungal strains tests. The samples were then compared with particleboard bonded with native oil palm starch and commercial urea formaldehyde (UF). The results indicated that particleboards bonded with modified PVOH/Oil palm starch were more resistant than particleboard bonded with their native starch and thus can be used as a potential binder for green particleboard in future. The SiO2 also showed a significant effect towards modified oil palm starch as compared to their native oil palm starch and commercial binder.
    Keywords: Oil palm starch, PVOH, SiO2, Biodegradation, Particleboard
  • Thean-Yu Yee, Mohd Omar Fatehah *
    Silicon dioxide (SiO2) in nanoscale had been detected as waste product in river water for the past two decades and it is recently proven to have adverse effects toward human and animal health, the ecosystem and water treatment system. The removal of SiO2 nanoparticles (NPs) from water still remains a challenge due to its small size and unknown interactions within the water body. In this study, dynamic light scattering (DLS) technique was applied to characterize SiO2 in terms of surface charge and particle size as a function of pH within the range of 2 to 11 to analyze the aggregation behavior and significance of the intermolacular interactions in deionized (DI) water and tap water. DLS analysis identified both pH values of the point of zero charge (pHPZC) of SiO2 NPs in DI water and tap water at pH 3.2 and pH 2.8 respectively. The initial pH was discovered at 7.1 in tap water with a mean particle size of 346 nm and an average surface charge value of -27 mV compared to initial pH of DI water which was 5.4 with mean particle size of 295 nm and an average surface charge value of -33 mV. It was found that both in DI water and tap water, SiO2 NPs aggregated and increased in particle size but reduced in surface charge when pH slowly decreased towards their respective pHPZC from the initial pH by adding 0.25M of hydrochloric acid. The mean particle size at pHPZC in DI water is measured at 1750 nm larger compared to the mean particle size in tap water indicating that the presence of other ions in tap water suppressed the aggregation process. In conclusion, results suggests that pH does influence the surface charge of SiO2 NPs and affect the stability behavior and its interaction processes in aqueous suspensions.
    Keywords: SiO2, surface charge, particle size, pH, dynamic light scattering
  • Akbar Eshaghi *, Mohammadreza Mojab
    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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