VOLUME 39, NO3, JUNE-2017
123
 
Precipitation from Solid Solutions

Iqra Zubair Awan and Abdul Qadeer Khan

Precipitation from solid solutions and supersaturated solutions is a very important process as it plays an important role in the structure and properties of metals/alloys. This process is used widely in the metallurgical engineering to obtain desired mechanical properties. The phenomena under discussion has great practical significance, for they make possible the precipitation or age hardening of metals, an extremely important way of hardening of metals, especially in commercial strengthening of non-ferrous alloys, e.g. aluminum and magnesium alloys. This review discusses precipitation and its effects on hardening in solid solutions and saturated solid solutions.
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Adsorption of Methyl Orange from Aqueous Solution by Polymer of Intrinsic Microporosity: Isotherms and Kinetics Study

Muhammad Shakeel, Khalid Mehmood, Muhammad Waseem, Wajid Rehman, Khizar Hussain Shah and Mohsan Nawaz

In this work the adsorption and kinetics studies of methyl orange (MO) on polymer of intrinsic microporosity (PIM 1) was investigated. The results showed that adsorption of MO increases with temperature, suggesting the endothermic nature of sorption process. The adsorption data was found well fitted to the Langmuir model as compared to Freundlich and Temkin models. The kinetics data was described by first order, second order, pseudo first order, pseudo second order, Elovich equation, film diffusion and particle diffusion models. The kinetic data confirmed that the adsorption of methyl orange on PIM-1 follows particle and film diffusion models along with Lagergren pseudo first order and Elovich equations, indicating the sorption as a mixed diffusional process. The activation energy values for the particle and film diffusion processes were 13.09 k J/mol and 13.12 k J/mol respectively whereas, it was 14.11k J/mol according to pseudo first order equation. The low value of activation energy (less than 42 k J/mol) indicates that the adsorption of MO on PIM-1 is diffusional and physical in nature. The values of thermodynamic parameters ensure that the adsorption was endothermic and non-spontaneous with increase in entropy.
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Theoretical and Experimental Studies on Thermal Behavior of 3-Methyl, 3-Carboxy, and 3-Nitro Substituted 1H,4H-6-nitro-pyrazolo[4,3-c]pyrazole

Jiao-Qiang Zhang, Ning-Ning Zhao, Hong-Yu Zhou, Hai-Xia Ma, Hong-Xu Gao, Bo-Zhou Wang and Rong-Zu Hu

To evaluate the stability, heat-resistance ability and thermal safety of MNPP(1H,4H-3-methyl-6-nitro-pyrazolo[4,3-c]pyrazole), CNPP (1H,4H-3-carboxy-6 -nitro-pyrazolo[4,3-c]pyrazole), DNPP (1H,4H-3,6-dinitro-pyrazolo [4,3-c] pyrazole), the theoretical investigation on MNPP, CNPP and DNPP was performed by the DFT-B3LYP/6-31G level using Gaussian 09W program. The theoretical density (ρ) of the compounds was obtained by quantum chemical method. The Kamlet-Jacobs formulas were employed to calculate the detonation properties including the detonation velocity (D) and pressure (P). Their thermal behaviors were investigated by Differential Scanning Calorimetry (DSC), Thermogravimetry-Derivative Thermogravimetry (TG-DTG) and in-situ cell thermolysis/Rapid-Scan Fourier Transform Infrared Spectroscopy (RSFT-IR). Results show that (1) using critical temperature of thermal explosion, free energy of activation of decomposition reaction and self-accelerating decomposition temperature as criterions, the thermal stability, heat resistance ability and thermal safety of the three compounds decrease in the order of DNPP > MNPP >CNPP, but using energy gap and total energy as criterions, the thermal stability decreases in the order of DNPP > CNPP > MNPP, therefore, DNPP is the most stable compound among the three compounds; (2) Among of the three compounds, DNPP possesses the maximum theoretical density (1.80 g•cm-3), the fastest detonation velocity (8.49 km•s-1) and the highest detonation pressure (31.96 GPa), suggesting that DNPP has good detonation properties and potential use in energetic material.
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Effect of Electron Beam Irradiation on the Volatile Flavor Profile of Elettaria Cardamomum (L.) Maton., from Pakistan

Naeem Khan, Nargis Jamila, Ji Yeon Choi, Eun Yeong Nho, Muhammad Imran, Iqbal Hussain, In Min Hwang and Kyong Su Kim

This study was aimed to investigate the effects of electron beam irradiation on volatile flavor profile of Elettaria cardamomum (L.) Maton., from Pakistan. The volatile flavor compounds of non-irradiated and 1, 5, 10 and 20 kGy E-beam irradiated samples were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography mass spectrometry (GC-MS). Volatile flavor compounds were slightly changed by E-beam irradiation as some of the components showed a minor increase or decrease in concentration after ionization treatment. A total of 136 (10684.15 mg/kg) volatile flavor compounds were detected in non-irradiated control samples which decreased to 133 for 1 kGy (11068.61 mg/kg), remained the same 136 for 5 kGy (10884.10 mg/kg) and 10 kGy (11762.52 mg/kg), and increased to 137 for 20 kGy (10973.78 mg/kg) E-beam irradiated samples. There was no major change observed in the application of E-beam irradiation treatment of the samples compared to the non-irradiated ones. E-beam irradiation was therefore concluded to have no adverse effect on the volatile flavor of Elettaria cardamomum (L.) Maton and doses up to 20 kGy were declared not to interfere with the flavor perception of consumers.
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Application of Response Surface Optimization Technique to the Preparation of Cathode Electrode for the Molten Carbonate Fuel Cell

Gülay Özkan, Selim Gemici, Cağil Erkay, Erdi Başarir and Göksel Özkan

One of the fuel cells, the molten carbonate fuel cell (MCFC), comes into prominence due to its high energy potential and suitability for industrial applications. Nickel porous structures are used as anodes and cathodes for MCFC. In this study; Green sheets were obtained by means of tape casting method performing on the prepared mixtures. 23% - 37% by weight nickel oxide was used in the mixture for the purpose of synthesizing cathode green sheets. Different slurry were prepared using different ratios of polyethylene glycol (PEG) as plasticizer, polyvinyl butyral (PVB) as binder, glycerol as dispersant and butanol with hexanol as a solvent. The optimum mixture formulation for the tape casting has been determined by measuring, tensile strength on the green tape. Tensile elongation of green tape refers to resistance to dissolution, cracking and breakage for the green tape slurry. Tensile force parameters were evaluated for the green tape’s slurries. Maximum tensile force and thickness of the green tape is critical factor in order to choose the optimum mixture formulation of cathode slurries. Optimum composition was determined as 23% nickel oxide, 3% binder and 3% plasticizer according to analyze two level experimental factorial design and response surface optimization technique.
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QSPR Study of Some Physicochemical Properties of Sulfonamides Using Topological and Quantum Chemical Indices

Fatemeh Shafiei and Abolfazl Saeidifar

QSPR studies on sulfonamides have been made using recently introduced topological methodology. In this study the relationship between the Randic' (1X), Balaban (J), Szeged (Sz), Harary (H), Wiener (W), Hyper-Wiener (WW), Wiener Polarity (WP) and one other descriptor, namely, the LUMO energy (Elumo) to the thermal energy (Eth kJ/mol), heat capacity (CV J/molK) and entropy (S J/molK) of 41 sulfonamides is represented. Physicochemical properties and the quantum chemical parameter are taken from the quantum mechanics methodology with HF level using the ab initio 6-31G basis sets. The multiple linear regressions (MLR) and Back ward methods (with significant at the 0.05 level) were employed to give the QSPR models. The satisfactory obtained results show that combining the three descriptors (J, Elumo, H) are excellent descriptors for predicted (CV)and(S), the three descriptors (1X, J, Elumo) are useful descriptors for predicted (Eth) of the 41 sulfonamides.
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A Thermodynamic Model for Determination of Carbon Dioxide Solubility and Ionic Speciation in Aqueous Alkanolamine Solutions

Humbul Suleman, Abdulhalim Shah Maulud and Zakaria Man

A thermodynamic model for determination of carbon dioxide solubility and liquid phase ionic speciation in aqueous alkanolamine solutions has been presented. The explicit model equation is simple in computation and can be solved using a hand-held calculator, yet its structure is derived from thermodynamic theory. The model predicts liquid phase ionic equilibria (bicarbonate, carbonate, hydrogen and alkanolamine based species) in carbon dioxide loaded aqueous monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) solutions. The model shows good correlation with experimental data points and is valid for carbon dioxide loadings of 0.001 to 0.9 for MDEA and AMP, and 0.002 to 0.48 for MEA and DEA, over a wide range of amine concentration, pressure and temperature. The equilibrium model developed in this work is based on and represents 159 data points for CO2 solubility in MEA solutions with 7.9% AARD, 114 selected data points for CO2 absorption in aqueous DEA solutions with 7.1% AARD, 107 reported values for CO2 solubility in MDEA solutions with 9.9% AARD and 136 data values for CO2 absorption in aqueous AMP solutions with 8.4% AARD.
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Kinetic Modelling of Aqueous Copper (II) Ions Adsorption onto Turmeric Powder: Effect of Temperature

Amtul Qayoom, Syed Arif Kazmi and Saeeda Nadir Ali

Turmeric was found to sequester toxic metal ions from their aqueous solutions but thorough understanding of metal-adsorbent interaction requires assessment of adsorption rates. Therefore, in present work reaction and diffusion based kinetic models were applied on adsorption data to evaluate adsorption efficiency of turmeric. The correlation of coefficient, R2, for linear regression of pseudo second-order and Elovich kinetic models were found to be close to unity indicating that adsorption of aqueous Cu (II) onto turmeric was chemisorption process and its kinetics followed pseudo-second-order and Elovich models. The value of qe (theoretical) calculated from pseudo-second order model and qe (experimental) were also close to each other. On raising temperature from 298K to 313K, initial adsorption rate, ho, increased from 0.0031 to 0.032 gmmol-1min-1 and second-order kinetic constant, k2, increased from 2.74 to 12.27 g mmol-1min-1 indicating that Cu (II) adsorption onto turmeric powder is of endothermic nature. On the other hand, Elovich model parameters α (mmol g-1 min 1) and βE (gmmol-1) initially increased and then decreased on raising temperature from 298K to 313K. Intraparticle diffusion plot showed multi-linearity suggesting involvement of two step diffusion process. The presence of pores on adsorbent surface was confirmed by Scanning Electron Micrograph. The value of activation energy was found to be 75.29 kJ mol-1.On the basis of kinetic parameters determined at different temperatures and value of activation energy, chemisorption can be assumed as rate controlling mechanism for aqueous Cu (II) adsorption onto turmeric surface.
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Synthesis and Characterization of Partially Metallic Chromium Hollow Nanospheres: A Step toward the Tuning of Magnetic Property

Hafiz Rub Nawaz, Barkat Ali Solangi, Kashif Pervez, Farman Ahmed and Hongbin Cao

At present hollow nanostructures have been intensive topics of research due to their superior properties over their solid nano counterparts. In this study uniform size chromium hollow nanospheres were synthesized by polyol method followed by simple corrosion etching using a proper solvent combination strategy. Fourier transform infrared (FTIR) and UV Visible spectroscopy have been applied to follow the conversion of precursor into metal particles and then hollow nanospheres respectively. Particle size and morphology have been characterized by particle size analyzer and Field Emission Scanning Electron microscopy (FE SEM). The crystal structures of chromium species such as CrO2 and Cr2O3 resulted from CrOOH have been determined by X-ray diffraction technique (XRD). X-ray photoelectron spectroscopy (XPS) has been applied to evaluate the surface binding energy of chromium ions. Self arranged hollow nanospheres have shown temperature-dependent magnetization. In this way magnetic property of solid chromium nanospheres has been tuned by converting them into hollow nanospheres.
Pages(391)
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Radiation Degradation and Hemolytic Toxicity Evaluation of Mono Azo Reactive Dyes

Qurat-Ul-Ain Saeed, Ijaz Ahmad Bhatti and Aisha Ashraf

Monoazo reactive dyes have been synthesized and subjected to degradation before their application. Advanced oxidation process has been recognized as a promising radiation technology for the remediation of hazardous organic compounds. Radiation induced degradation of two mono azo reactive dyes have been tried at different absorbed dose, 5 kGy,10 kGy and 15 kGy. Aqueous solutions of these dyes were treated with gamma radiation using Cs 137 radiation source at Nuclear Institute of Agriculture and Biology (NIAB) Faisalabad. Dyes were evaluated spectrophotometrically by UV-visible and fourier transform infra red (FT-IR) spectroscopic techniques before and after irradiation to analyse their percentage decolorization and degradation. Maximum percentage decolorization of 93% and 63% was achieved for mono azo dyes D1 and D2 at 15 kGy absorbed dose. Toxicity study of these dyes was also tested by haemolytic activity assay. Percentage haemolytic activity of untreated dyes was found within permissible limit showing non toxicity of dye solutions.
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