Journal of Applied Research in Chemistry
Year:2018 | Volume:12 | Issue:2 |Papers Count:17

In this study, techniques for heat transfer enhancement reviewed. Application ofnanofluids was studied as a new technique for more energy saving and heat recovery. Transysversion17 simulation was used for prediction of thermal efficiency of water and various nanofluidsin a flat plate solar collector. Nano fluids that were used in this simulation analysis are copperoxide, copper, and alumina. The results show that the heat transfer and thermal efficiency ofcopper nanofluid are greater than other working fluids while the exergy efficiency of alumina isgreater. Gambit 2. 4. 6 was used for our CFD calculation along with the Fluent version17. 2. Weused a model to numerically simulate the heat transfer. The governing equations and correspondingboundary conditions are converted to dimensionless forms and solved numerically by the finiteelement method. The results show that efficiency of copper is 67% and it is greater than aluminaand copper oxide efficiency.

1, 10-Phenanthroline entails several appealing structural and chemical properties: basicity, rigidity, aromaticity, planarity, and chelating capability. This makes it a versatile catalystin organic chemistry. An efficient and environmentally friendly method for the synthesis oftetrahydrobenzo[b]pyrans as important pharmaceutical compounds has been developed usingPhenanthroline (%5 mol) as an organocatalyst. A mixture of an aromatic aldehyde, malononitrile, and 1, 3-dicarbonyl compounds in the presence of the Phenanthroline as homogeneous catalyst at50º in H2O/EtOH resulted in excellent yields of the corresponding products. This new methodologyis of interest due to use of aqueous media as a green solvent system, its short reaction time, highyields, and no further purification.

Para-Nitrophenol (PNP) as a nitroaromatic matter is a hazardous pollutant in industrialwastewaters. In this paper degradation of the pollutant was performed by the catalysts ofCuWO4/CuO, Na0. 01WO3, and WO3 under visible light. The catalysts were synthesized byhydrothermal method and the process was performed in a suspension reactor equipped with a metalhalid lamp (400 W). The synthesized catalysts were characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), and Diffuse reflection spectroscopy(DRS). The effective parameters of pH, reaction temperature, and light intensity have been studied. The results showed that using [Catalyst] = 2000 ppm, [PNP] = 20 ppm, T = 25 ° C, and pH = 12after 240 min, the degradation efficiency for WO3, Na0. 01WO3, and CuWO4/CuO obtained about40%, 42. 3%, and 30%, respectively.

In the present study, attempts have been made for the first time to investigate the influence of leadsulfide (PbS) colloidal quantum dots along with their ligand exchange from long-chain insulating oleic acid(OA) to the short-chain semiconducting methylammonium lead iodide (MA4PbI6), called perovskite, uponthe photon harvesting efficiency and photovoltaic characteristics of bulk heterojunction (BHJ) polymericsolar cell comprising ternary photo active layer based on poly (3-hexyl thiophene)(rrP3HT) as electrondonor and PC61BM as acceptor. According to the photo absorption spectrum obtained within UV-Vis andNIR regions, the ternary cells based on OA and MA4PbI6 capped PbS exhibit enhanced photon harvestingefficiency compared with their binary counterpart cell. The steady state photoluminescence results revealefficient electron transfer from photoexcited P3HT to QDs and hole transfer from photoexcited QDs toP3HT, leading to the improved power conversion efficiency (PCE) of the ternary cells. However, comparedwith OA, the semiconducting perovskite (MA4PbI6) ligand shows to be much more effective in increasingpower conversion efficiency, so that 6% improvement in PCE is seen by the introduction of 6% PbS QDcapped with perovskite ligand unlike PbS QD with OA ligand which had adverse effect on the photovoltaicproperties of P3HT: PC61BM solar cell. This is explained to be due to the insulating characteristic of longchain OA as well as improved charge carrier transport in the case of PbS capped perovskite based ternarysolar cells.

In this research work, sodium dodecyl sulfate (SDS) was deposited on the surfaceof carbon paste electrode by dropping method. Then, the modified carbon paste electrode withSDS containing nickel (Ni/SDS) was prepared by inserting the modified electrode in a solutioncontaining nickel nitrate for 5 minutes and sweeping of the consecutive potential in sodiumhydroxide solution. Also, considering the importance of using ethylene glycohol as a proposedsource instead of hydrogen and because of its slow kinetic on the bare carbon paste electrode, itsoxidation investigated on the above modified electrode. The results showed the electrocatalyticoxidation of ethylene glycol on the surface of carbon paste electrode modified with SDS/Ni. The effect of various parameters on the efficiency of modified electrode was investigated andthe optimal conditions were determined. Finally, the reaction rate constant between the chemicalredox centers at the modified electrode surface and ethylene glycol was calculated. Simplicity, lowcost, and high sensitivity are the outstanding features of the electrode.

Wet air oxidation (WAO) is an efficient way to treat industrial wastewaters. In presentstudy, wet air oxidation process was used for treatment of spent caustic effluents from ethylene unit inthe petrochemical industry. After analysis and determination of wastewater properties, the process wasperformed using an experimental set-up having 1-L reactor in the temperature range of 170-200 ˚ C and 6-9bar partial pressure of oxygen. The effects of parameters including liquid volume, temperature, and pH wereinvestigated. Performing experiments in two liquid volumes of 200 and 400 mL confirmed that requiredoxygen is provided at 190 ˚ C and changing the partial pressure of oxygen has no significant effect on processefficiency due to abundant oxygen in the reactor. The values of reduction in chemical oxygen demands(COD) after 3 h at temperatures of 170, 190, and 200 C were 61, 63, and 67%, respectively. The process at200 ˚ C and pH of 12 and 10 for 3 h could decrease 69 and 82% of COD, respectively. Applying homogenousFe3+ and Cu2+ catalysts could not enhance the performance of the process significantly. Furthermore, thekinetics of two-stage reactions of wet air oxidation process was also studied and the kinetic constants andactivation energies were determined. Since the real sample from a petrochemical unit was used, determinationof optimum operation conditions, investigation on the effect of catalyst, and also determination of kineticdegree of wet air oxidation reaction for spent caustic wastes of petrochemical units might be considered asthe novelties of the current study.

The interaction of Re (I) tricarbonyl-diimine complex ([Re]) with calf thymus DNA(CT-DNA) was investigated by using UV– Vis, fluorescence spectrophotometry, circular dichroism(CD) spectroscopy, thermal denaturation, and cyclic voltammetry (CV) studies. The bindingconstant value Kb of complex [Re] was found to be 5. 47×106 M-1 using UV-Vis spectrophotometrydata. The results show that the [Re] complex has relatively good interaction in comparison to otherSchiff base complexes, indicating that the [Re] complex binds to DNA by electrostatic and partialintercalation modes. In addition, the intercalation mode is dominant via electrostatic interaction, as the most experiments confirm it.

Vanadium is a nonessential mineral of the daily diet that has shown beneficialhealth effects. In the present research, we synthesized and characterized three vanadiumcomplexes, [VOCl(bpy)2]Cl (1), [VOCl(phen)2]Cl (2), and [VO(SO4)(phen)2] (3), from thereaction of VCl3 and VOSO4 salts with 2, 2'-bipyridine(bpy) and 1, 10-phenanthroline (phen)ligands. The mentioned complexes were characterized by FT-IR, Mass and UV-Vis spectroscopy. In absorption spectrum of the synthesized compounds, there is a broad weak peak, above 700nm which is referred to d-d transition of vanadium (IV) center. Moreover, stretching vibration ofV=O is appeared around 973-978 cm-1, in IR spectrum. These results confirm the structure of thecompounds. Cytotoxic properties of the complexes were checked out on a normal cell NIH3T3(Rat embryo fibroblast cell) and against three cancer cell lines including HT29 (colon carcinoma), CacoII (colorectal adenocarcinoma), and T47D (breast cancer cell) by MTT assay and comparedwith cis-platin. The results indicate compound (1) with low toxicity on normal cells and highcytotoxicity on the cancerous cell lines, is capable of selectively killing properties.

Water injection is one of the EOR methods which has shown great potential in recentyears. The water flooding process is more effective when the injected water is enriched by chemicalswhich improves the oil recovery by reducing interfacial tension (IFT) and alternating wettability. In this work four long alkyl chain imidazolium based ionic liquids (ILs) including Octyl, Decyl, Dodecyl, and Tetradecyl methylimidazolium Chloride were synthesized and characterized by1HNMR and elemental analysis. Furthermore, some physicochemical properties were investigatedfor studied ILs as a function of temperature. The synthesized ILs were examined as additivesin injected water to reduce the IFT in water flooding process. The critical micelle concentration(CMC) point and IFT of enriched sea water by ILs/crude oil were measured as a function of ILsconcentration. The results show that ILs can be good candidates for EOR technology due to theirsignificant behavior in IFT reduction and their low consumption. According to obtained results, asthe alkyl chain was longer, the CMC point and IFT values were lower. [C14mim][Cl] was the mosteffective ILs which 50 ppm of this ILs, reduced the IFT values to 0. 65 mN. m-1.

Para-toluene sulfonic acid embedded on nano silica (ρ-TSA@nano SiO2) has beensynthesized via a simple procedure and characterized by fourier transform infrared spectroscopy(FT-IR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM)techniques. The synthesized nanocatalyst has been utilized to accelerate the one-pot multicomponentcondensation reaction of isatins, anilines, and acetone to obtain the corresponding 1'-aryl-2'-(2-oxoindolin-3-yl)spiro[indoline-3, 5'-pyrroline]-2, 3'-diones at water media under reflux conditions. Utilization of H2O as available and green solvent, excellent yields of products, short reactiontimes, avoidance of by-products which could be obtained via Aldol condensation of acetone, easily-handle, inexpensive, non-toxic, and heterogeneous nano acid catalyst are some advantageousof the reported method. The recovery and reusability of the nano catalyst has been examined forfour runs without activity loss.

In this work, the carbon nanotubes/platinum black composite was prepared by easy, efficient, and cheap method and morphology of composite was investigated by using tunnellingelectron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). The TEM imagesshowed that Pt was immobilized like rosary seeds on external walls of carbon nanotubes and thePt in EDX spectra confirmed presence of Pt element in composite. Then catalytic activity of thisnanocomposite was investigated using carbon paste electrode modified with this nanocompositefor hydrogen evolution reaction in acidic media by electrochemical methods such as linear sweepvoltammetry. The linear sweep voltammetry of Pt-CNT/CPE electrode exhibits higher currentdensity and less negative value of potential towards hydrogen evolution reaction than the CPE. Effects of different parameters such as electrolyte type, electrolyte concentration, and platinumblack/carbon nanotubes ratio were studied for electrocatalysis of hydrogen evolution reaction. The results showed that sulphuric acid 0. 1 M and 2: 5 ratio was choice as optimum condition forhydrogen evolution reaction. The deposition of this nanocomposite on the electrode caused onsetpotential of-0. 2 V and the lowest Tafel slope of 4. 0 V-1 dec-1 for hydrogen evolution reaction. Theelectron transfer coefficient and exchange current density for the Pt-CNT/CPE were calculated byTafel plot about 1. 3 and 0. 12 mA cm-2, respectively for hydrogen evolution reaction.

One of the main drawbacks in organometallic-mediated radical polymerization techniques is ahigh amount of catalyst residual in the polymer product, which results in deep colors in polymer mixture. Inthis research, cross linked suspended polyvinyl acetate (SPVAc) was used as catalyst adsorbing agent andits release in cobalt-mediated radical polymerization of vinyl acetate. For this purpose, firstly, the adsorptionprocess of cobalt acetylacetonate on these particles and also the thermodynamics of this process werestudied. SPVAc particles have the capability of the catalyst adsorption at low temperatures and adsorbedcatalyst particles are gradually released by increasing temperature to polymerization reaction temperature. The kinetic studies for vinyl acetate polymerization in the presence of cobalt acetylacetonate adsorbed onthe SPVAc particle is compared with cobalt acetylacetonate mediated polymerization of vinyl acetate in theabsence of SPVAc particle. The results have proved positive effects of these particles on the rate and kineticof reaction. Then, radical polymerization of vinyl acetate without the need for purification of polymer wascarried out successfully through a single reaction in a column packed with alumina and a layer of adsorbedcobalt acetylacetonate catalyst on the SPVAc particles. In this method, the slow adsorption and desorptionof cobalt complex by suspended polyvinyl acetate, were followed by the radical polymerization and the finalseparation step.

In this study, TiO2-MgO mesoporous particles were prepared via evaporationinducedself assembly method using two different copolymers of polyvinylpyridine-polystyrene(PVP-PS) and polyethylene glycol-polypropylene glycol-polyethylene glycol (PEG-PPG-PEO orPEO-PPO-PEO) as structure directing agents. The characteristics of the products were investigatedby X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm (BET-BJH), Fourier transforminfrared spectrometry (FT-IR), and scanning electron microscopy (SEM). The effects of polymertype, different amounts of magnesium, and calcination temperature were studied. The resultsshowed that the use of (PEO-PPO-PEO) copolymer and increasing the amount of magnesiumnitrate increased the surface area of the products. In addition, increasing of calcination temperaturefrom 400 to 550 oC leads to a reduction in surface area of the samples. Simvastatin was loaded onthe prepared samples and drug release was studied in simulated gastrointestinal fluid. The releaseprofile of simvastatin fluid from the TiO2-MgO sample, prepared by using (PEO-PPO-PEO), in thesimulated gastric and intestinal within 20 hours showed 100 and 70%, respectively.

The entrance of heavy metals contaminants into the aqueous environment, due to their toxicity andthe biological damages is hazardous for the human health. So the separation of them from the environment is animportant subject. In this work, adsorption of heavy metals was investigated using biological method. The processof adsorption of copper and manganese using bacterium were done at different conditions (pH, temperature, and adsorbent concentration). Besides, the experimental design of Response Surface Methodology (RSM) wasused to study the interactions between parameters and to draw the surface diagrams, and the estimation of themathematical equation (absorbance versus variables) as a polynomial model. Results showed that increasing ofpH up to 6 increased the bio-sorption of both Mn and Cu. Increment in temperature and adsorbent content had thesame effect. Although the absorbance of Mn was a little higher than Cu, both of them showed the same changes withvariables. The observed increment effects were lower at lower levels of variables and became more considerableat higher levels of variables. In each level of absorbent, with increasing of the temperature, absorbance increasedwhich was greater at higher pH. Also, the incremental effect of pH was more remarkable at the higher bacteriumconcentration. The effect of each variable was influenced by another one. Using RSM, the bio-sorption amountsof both Cu and Mn were formulated versus T, pH, and adsorbent content, with a suitable accuracy and low error. In addition, the interactions between parameters were analyzed considering 3D plots and the coefficients of theachieved equations. Finally, the predicted results from the equations for the new experimental conditions werecompared with the the experimental results, which showed a good agreement.

HCl is always used as precursor in synthesis of γ-alumina granules via oil-drop. Acomparative study was conducted to evaluate the effect of precursor on the catalytic characteristicsand performance of γ-alumina prepared via the oil-drop technique. The synthesized materials werecharacterized by X-ray diffraction (XRD), BET (Brunauer-Emmett-Teller), BJH (Barret-Joyner-Halenda), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmittingelectron microscopy (TEM), and ammonia temperature programmed desorption (NH3-TPD)techniques. As a general trend, the γ-alumina catalyst prepared via oil-drop using HNO3 as theprecursor has the higher surface area, pore volume, pore size, and distribution which are preferredin catalysis. Based on the results, the γ-alumina samples prepared using HNO3 are superior inactivity about two times at 250 ° C due to the differences in crystalline size, morphology, texturalproperties, and acid strength. Moreover, the incorporation of chlorine into γ-alumina structure isresponsible for poisoning of catalysts which is evident by the less activity for the reaction.

Here, we report thermodegradation of poly(methyl methacrylate)/silver nanoparticle(PMMA/AgNP) nanocomposite networks synthesized by in-situ photoiniferter-mediatedphotopolymerization. The nanocomposite networks were prepared in the presence of 0. 5 wt. %of AgNP and various amounts of allyl methacrylate (0, 1, 5, 10 wt. %) as crosslinking agent. Thekinetic studies of thermodegradation of the nanocomposite networks by two isoconversionalmethods, Flynn-Wall-Ozawa and Kissinger– Akahira– Sunose, showed that AgNP had a dual effecton thermal degradation of PMMA networks; at early stages, AgNP promoted the degradationof the nanocomposites while in the subsequent stages maintained the polymer stability againstthermal degradation.