Showing papers by "Shahab Shariati published in 2019"

Removal of cationic dye methylene blue (MB) from aqueous solution by Coffee and Peanut husk Modified with Magnetite Iron Oxide Nanoparticles

Abstract: . This study was focused on the adsorption of methylene blue (MB) as a cationic dye on magnetite nanoparticles loaded with coffee (MNLC) and magnetite nanoparticles loaded with peanut husk (MNLPH) as naturally cheap sources of adsorbent. Coffee and Peanut husk were magnetically modified by contact with water-based magnetic fluid. These new type of magnetically natural materials can be easily separated by means of magnetic separators. They were characterized with Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) instruments. Different parameters affecting MB removal efficiency such as contact time, pH of solution and amount of adsorbents were studied and optimized. Dye adsorption process was studied from both kinetic and equilibrium point. The studies of MB sorption kinetic showed rapid dynamic sorption with second-order kinetic model, suggesting chemisorption mechanism with R2 = 0.9988, qeq=10.28 mg g-1 and R2=0.9967, qeq=128.20 mg g-1, respectively. Equilibrium data were fitted well to the Langmuir isotherm more than Freundlich and Temkin isotherm. The modified adsorbents showed MB removal with 88.49 and 74.62 mg g-1 sorption capacity for MNLC and MNLPH, respectively. This study showed a simple, efficient and reliable method for removal of MB from aqueous solutions with MNLC and MNLPH as efficient adsorbents. Resumen. Este estudio se centro en la adsorcion de azul de metileno (MB) como un colorante cationico en nanoparticulas de magnetita cargadas con cafe (MNLC) y nanoparticulas de magnetita cargadas con cascara de cacahuete (MNLPH) como fuentes de adsorbente naturalmente economicas. El cafe y la cascara de mani se modificaron magneticamente por contacto con un fluido magnetico a base de agua. Este nuevo tipo de materiales magneticamente naturales se puede separar facilmente mediante separadores magneticos. Se caracterizaron con espectroscopia infrarroja de transformada de Fourier (FT-IR), difraccion de rayos X en polvo (DRX) y microscopia electronica de barrido (SEM). Se estudiaron y optimizaron diferentes parametros que afectan la eficiencia de eliminacion de MB, como el tiempo de contacto, el pH de la solucion y la cantidad de adsorbentes. Se estudio el proceso de adsorcion de tinte desde el punto de equilibrio y cinetico. Los estudios de cinetica de absorcion de MB mostraron una absorcion dinamica rapida con un modelo cinetico de segundo orden, lo que sugiere un mecanismo de quimiosorcion con R2= 0.9988, qeq= 10.28 mg g-1 y R2= 0.9967, qeq= 128.20 mg g-1, respectivamente. Los datos de equilibrio se ajustaron bien a la isoterma de Langmuir mas que a la isoterma de Freundlich y Temkin. Los adsorbentes modificados mostraron eliminacion de MB con 88.49 y 74.62 mg g-1 de capacidad de absorcion para MNLC y MNLPH, respectivamente. Este estudio mostro un metodo simple, eficiente y confiable para la eliminacion de MB de soluciones acuosas con MNLC y MNLPH como adsorbentes eficientes.

Synthesis and characterization of epoxy/graphite/nano-copper nanocomposite for the fabrication of bipolar plate for PEMFCs

Abstract: In this research, the synthesis of a suitable nanocomposite in terms of properties and economics for use in bipolar plates in proton-exchange membrane fuel cells (PEMFCs) has been carried out successfully. Nowadays, bipolar plates play a significant role in fuel cells which is absolutely important in renewable energy industry. So, epoxy/graphite/nano-copper nanocomposite bipolar plates are prepared by bulk molding compound process. Graphite and nano-copper were added as primary and secondary fillers to the composite, respectively. Epoxy resin was selected since fabrication bulk molding can be done with ease and also because of its lower cost compared to other materials. Although graphite could increase conductive characteristics, it is not sufficient for bipolar plates. Therefore, we boost the conductive properties by increasing nano-copper. Due to the small size of nanoscale copper, it can be well dispersed in polymer and graphite matrix; nano-copper can release conductive properties perfectly throughout the composite. Different percentages of nano-copper, graphite and constant percentage of epoxy are used for this purpose. The electrical resistance, flexural strength, and density of composites were measured according to the applicable standards. The morphology of the prepared plate was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) found that fillers disperse well in the matrix. Innovations in this work include improving properties and increasing the efficiency of the nanocomposite by adding metal nanoparticles (copper).

Sulfonic Acid Functionalized SBA-3 Silica Mesoporous Magnetite Nanocomposite for Safranin O Dye Removal

Abstract: At the present study, sulfonic acid functionalized SBA-3 silica mesoporous magnetite nanocomposite (Fe3O4@SiO2@SBA-3- SO3H) was synthesized and its adsorption ability for removing Safranin O dye from aqueous samples was investigated. X-ray diffraction analysis (XRD), vibrating sample magnetometer (VSM), energy dispersive X-ray spectroscopy analysis (EDX), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the adsorbent. The FESEM images confirmed the synthesis of nanocomposites with good morphology and size below 30 nm. The experimental variables affecting the removal efficiency were optimized by Taguchi orthogonal array experimental design method (L16 array). At the optimal conditions (pH = 6, ionic strength = 0.005 mol L− 1, sample volume = 25 mL, adsorbent weight = 0.12 g and contact time = 15 min) the efficiency for Safranin O removal was obtained as higher than 91%. The pseudo-first-order, pseudo-second-order, intra particle and Elovich kinetic models were investigated, and the kinetic data followed the pseudo-second-order kinetic model (R2 = 0.9999). Also, the study of three isotherm models (Langmuir, Freundlich and Temkin) showed that Freundlich isotherm was suitable for describing Safranin O adsorption (R2 = 0.9941, n = 1.428). The reusability experiments showed high removal efficiency of Safranin O after 9 cycles of usage. Finally, the results of Safranin O removal from the aqueous real samples showed the applicability of this nanocomposite for Safranin O removal applications.

Synthesis of Ultrafine Silver Nanoparticles on the Surface of Fe3O4@SiO2@KIT-6-NH2 Nanocomposite and Their Application as a Highly Efficient and Reusable Catalyst for Reduction of Nitrofurazone and Aromatic Nitro Compounds Under Mild Conditions

Abstract: Uniform dispersion of ultrafine spherical silver nanoparticles (NPs) was obtained over the surface of Fe3O4@SiO2@KIT-6 core–shell support via functionalization of the mesoporous KIT-6 shell by aminopropyltriethoxysilane, followed by coordination of Ag+ ions and in situ chemical reduction with sodium borohydride. The obtained hybrid material, Fe3O4@SiO2@KIT-6-Ag nanocomposite, was fully characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and used as an efficient catalyst for selective reduction of nitroaromatic compounds in aqueous solution at ambient temperature and neutral pH [nine examples, apparent rate constants at 25 °C, k (min−1), 0.112–0.628]. As a non-aromatic example, nitrofurazone which is a cytotoxic antibiotic was also reduced selectively at nitro group without reduction of other functionalities. Fe3O4@SiO2@KIT-6-Ag NPs also showed potential ability to act as catalyst for reduction of nitromethane in aqueous solution which can provide a colorimetric method for detection of nitromethane in solution down to 0.9 × 10−4 mol L−1. Fe3O4@SiO2@KIT-6-Ag nanocomposite was also screened for its antibacterial activity, and satisfactory results were obtained in comparison with drug references including Tetracycline, Chloramphenicol and Cefotaxime as positive controls, on gram negative Escherichia coli and Pseudomonas aeroginosa. Ease of recycling of the Fe3O4@SiO2@KIT-6-Ag is another benefit of this nanocatalyst. Under the optimized conditions, the recycled catalyst showed 15% loss of efficiency after five successive runs.

Evaluation of methanol content of illegal beverages using GC and an easier modified Chromotropic acid method; a cross sectional study.

Abstract: Methanol is highly toxic to human beings and naturally exists in some beverages. Having access to an easy and cheap method for its determination is of great importance to increase the safety of use of these beverages. Our main aim is to evaluate methanol concentration of some alcoholic beverages in Iran black market and compare it with the European and US standards. Also, we evaluated the efficacy of a newly designed and produced chemical kit in determining the risk of methanol toxicity by drinking of such samples compared to gas chromatography method. Methanol content of suspected alcoholic beverages referred to forensic toxicology laboratory, Guilan province, Iran was measured using gas chromatography and a recently designed kit based on modified colorimetric chromotropic acid method. Of 1221 samples, 145 (11.9%) had no ethanol content, while in three samples (0.25%), methanol was high enough (700,000; 870,000; 920,000 mg/L) to cause severe methanol toxicity. Median [IQR] ethanol content of the suspected samples was 9% [3.7, 32.75]. Methanol was detected in 128 (10.48%) samples using gas chromatography method and 160 samples (13.1%) with designed kit with 100% sensitivity, 97.07% specificity, and 100% negative-predictive-value. Alcoholic beverages produced in local black market in Iran are not safe at all. The application of the new method is practical, rapid, easy, and accurate to evaluate the risk of methanol toxicity in suspected alcoholic drinks.

Synthesis of novel spiro[chromeno[4′,3′:3,4]pyrazolo[1,2-b]phthalazine-7,3′-indoline]-2′,6,9,14-tetraone

Abstract: Fe3O4@Cys–SO3H magnetic nanocatalyst has been used as an effective and reusable solid acid catalyst for the one pot synthesis of novel spiro[chromeno[4′,3′:3,4]pyrazolo[1,2-b]phthalazine-7,3′-indoline]-2′,6,9,14-tetraone via a three-component reaction of phthalhydrazide, 4-hydroxycoumarin and isatin derivatives. Easy separation of catalyst, good yields of reaction and synthesis of novel heterocyclic compound are some advantages of this procedure.

Predictive Artificial Neural Network Model for Solvation Enthalpy of Organic Compounds in N , N -Dimethylformamide

Abstract: A quantitative structure-property relationship (QSPR) strategy was followed for prediction of the solvation enthalpy (ΔHsolv) values for 116 organic compounds in N,N-dimethylformamide. At first, a three-parameter multiple linear regression (MLR) model including the hydrophilic factor (Hy), sum of Kier–Hall electrotopological states (Ss) and 3D-MoRSE signal 15 weighted by atomic van der waals volumes (Mor15v) was generated for the enthalpy data. The model showed a standard error of 5.49 and R2 = 0.9220. The descriptors were then employed to develop an artificial neural network (ANN) model for estimating the solvation enthalpies. The developed ANN with 3-6-1 topology resulted in the R2 values of 0.9914, 0.9765, and 0.9796 for the training, validation and test sets, respectively. Relative importances of Ss, Mor15v and Hy were found to be 48.86, 32.08, and 19.06%, respectively. The findings proved the significant role of molecular topology, electron density and hydrophilicity as the structural features determining ΔHsolv values of the organic compounds in N,N-dimethylformamide.

Electrospun polystyrene nanofiber adsorbent for solid phase extraction of phenol as its quinoid derivative from aqueous solutions

Abstract: In the present study, polystyrene nanofibers (PS NFs) were synthesized by electrospinning method and used as adsorbents in solid phase extraction of phenol from aqueous solutions. Phenol was reacted with 4-aminoantipyrine (4-AAP) reagent in presence of potassium hexacyanoferrate (III). The coloured product was extracted by solid phase extraction using electrospun synthesized polystyrene nanofibers and determined by UV-Vis spectrophotometer. At certain conditions of electrospinning process, the variables affecting the solid phase extraction efficiency were studied and optimized. Under the optimized conditions, (sorbent mass: 0.025 g PS NF, sample flow rate: 2.5 mL min−1, eluent: acetone: NaOH 0.1 M (1:1 v/v)), the linear dynamic range (LDR) and limit of detection (LOD as 3 Sb/m) for extraction of phenol from 50 mL of aqueous solutions were determined as 15-2500 µg L-1 and 10 µg L-1, respectively. The precision (as RSD %) of the extraction method using the proposed adsorbent was lower than 7.6%. Finally, the applicability of the proposed method for the extraction of phenol from industrial aqueous samples was examined and satisfactory results were obtained.