فهرست مطالب bagha

In recent years, evaluation of deterioration and aging effects on seismic performance assessment of existing reinforced concrete structures has been paid much attention in earthquake and structural engineering community due to economical and safety issues. Corrosion of concrete reinforcement causes changing of nonlinear behaviour of reinforced concrete structures and ignoring these changes may lead to structural damage during the design life time of RC structures. Investigation of reinforcement corrosion effects in concrete structures on nonlinear behaviour of reinforced concrete members is the main subject of this research. In this study, the structural behaviour of the moment-curvature curve was investigated under these corrosion effects. After occurring the corrosion, cross section of the reinforcement is gradually reduced and consequently load bearing capacity of the reinforced concrete members will be reduced significantly. Accordingly, the relationship between corrosion and moment-curvature curve of structural members will be discussed. A two-dimensional frame is considered to investigate the seismic behaviour of structural frame and members, under different scenarios of corrosion in comparison with the approach proposed by Instruction for Seismic Rehabilitation of Existing Buildings (No. 360). Based on these results, to take the corrosion effects into consideration, it is recommended to use a k factor associated to ultimate sectional capacity instead of ductility limit.

Structural development, caused by active tectonics leads to deformation of morphologyfeatures. The Mosha-North Tehran fault zone, located in south edge of the Central Alborz consists of significant tectonic structures. Hence, study on morphotectonic signs is a proper method for evaluation of relative tectonic activities in the area. In this research, six main morphometric indices such as stream length-gradient (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height(Vf), drainage basin shape (Bs), and mountain front sinuosity(Smf)were considered. The computations and probes of these indices indicate three classes of relative tectonic activity in the study area from low to high level. Consequently, the drainage basins with high class of tectonic activity mostly coincide with the main faults in south edge of the Central Alborz.

In this work، the catalytic degradation of C. I. Reactive Red 120 (RR120) using magnetic nanoparticles of cobalt-iron oxide in the presence of hydrogen peroxide was studied. The magnetic nanoparticles of cobalt-iron oxide have been prepared by modified sol-gel method and have been characterized by XRD، TEM and VSM methods. The prepared nanoparticles were nanocrystalline pure single-phase and with particle sizes of 16-21 nm. Values of saturation magnetization، remanent magnetization andcoersivity were found to be 68 emu/g، 31 emu/g and 1824 Oe، respectively. The magnetic nanoparticles of cobalt-iron oxide showed its catalytic effect for dye degradation over a wide range of pH=2-8 with a maximum effect at pH=2-3. The decolorization rate increased by increasing the amount of catalyst، the concentration of hydrogen peroxide and temperature. The optimal condition for complete decolorization of RR120 (50 ppm، 50 ml) was found to be 0. 1 g/l of catalyst، 10 mM hydrogen peroxide at pH=3 and 75°C. The recovered nanoparticles of cobalt-iron oxide showed almost the same catalytic activity as the first time after 6 cycles of recovery and reuse. J. Color Sci. Tech. 6 (2012)، 77-86© Institute for Color Science and Technology.

In this study، the photocatalytic ozonation of Reactive Red 2 (RR2) and Reactive Red 120 (RR120) in aqueous solutions under UV irradiation was investigated using ZnO as a photocatalyst. The effect of operating parameters such as catalyst dosage، pH،initial dye concentration and salt on the decolorization was studied. UV/vis spectrophotometric was used to assess dye decolorization. The results showed that the best pH value and ZnO dosage were 3 and 15 mmol/l، respectively. The dye decolorization enhanced with decreasing initial dye concentration. Sodium sulfate had no significant effect on dye decolorization process but sodium bicarbonate and sodium carbonate increased decolorization time. The results shown that the photocatalytic ozonation process was an effective method to degrade reactive dyes. J. Color Sci. Tech. 6 (2012), 19-25© Institute for Color Science and Technology.

In the present study the treatment efficiency of O3 and UV+O3 processes were compared for the oxidation of simulated dyebath effluent containing a mixture of C.I. Reactive Red 120 (RR-120) and various dye auxiliaries. The color, COD and TOC removalrates were assessed for different processes. The effects of solution pH, initial dye concentration and presence of sodium hydroxide and sodium carbonate on rates of decolorization were studied. The rate of decolorization decreased by increasing of the initial dye concentration and addition of sodium hydroxide. No change in decolorization was observed by addition of sodium carbonate. The experimental results showed that ozonation combined with UV irradiation (9-watt low-pressure mercury lamp) was slightly more efficient than ozonation alone in COD removal with no change in color removal kinetics. At an initial pH of 6.2, bulk temperature of 25°C, ozone dosage of 55 g/m3 and initial dye concentration of 800 mg/L, the TOC removal efficiency of RR-120 reached 27% and 36% after 90 min for O3 and UV+O3 processes respectively. J. Color Sci. Tech. 4(2010), 151-160© Institute for Color Science and Technology.

This study provides information on the application of the Fenton process as an advanced oxidation method for the treatment of wastewater containing an azo reactive dye (C.I. Reactive Red 120). To establish cost-efficient operating conditions for potential application of Fenton oxidation process, the influence of the main operating parameters such as iron sulfate and hydrogen peroxide doses, solution pH, temperature, initial dye concentration and presence different concentrations of sodium chloride and sodium sulfate have been studied systematically in a laboratory scale. The obtained results showed that the best pH value for decolorization of dye solution was 3. The decolorization of RR120 enhanced with the increasing of reaction temperature but decreased as a presence of chloride and sulfate ions. The increase of Fe2+ and H2O2 doses accelerated the color and COD removals until a point where further addition of Fe2+ or H2O2 became inefficient and unnecessary. The result indicated that over 99% color removal and up to 74% COD removal can be obtained by Fenton’s oxidation. J. Color Sci.Tech. 4(2010), 105-114© Institute for Color Science and Technology.

Study of Anticorrosive Behavior of a Gemini Cationic Surfactant and Its Monomeric Counterpart on Mild Steel in Hydrochloric Acid During Immersion Time 1 Department of Surface Coating and Corrosion, Institute for Color Science and Technology, P.O.Box: 16765-654, Tehran, Iran 2 Department of Environmental Research, Institute for Color Science and Technology, P.O.Box: 16765-654, Tehran, Iran Anticorrosive property of a gemini cationic surfactant (12-4-12) and its monomeric counterpart, dodecyl trimethylammonium bromide (DTAB), on mild steel in 1M hydrochloric acid solution was investigated by electrochemical impedance spectroscopy (EIS). The results revealed the corrosion inhibition effect of these two surfactants on mild steel in acidic solution. It was observed that by increasing the immersion time in test solutions, corrosion resistance of mild steel increased, reaching a constant value after 2 h and 4 h immersions for 12-4-12 and DTAB, respectively. The monomeric surfactant, DTAB, had better corrosion inhibition effect compared to 12-4-12. The lower performance of 12-4-12 could be related to steric hindrance of the free head group. J. Color Sci. Tech. 4(2010), 1-7 © Institute for Color Science and Technology.

The solubilization of a monoazo disperse dye based on naphthalimide containing an ester group in the presence of DTAB and two gemini cationic surfactants was investigated. The results showed that the solubilization power of gemini surfactants micelles was greater than that of conventional surfactant micelles (DTAB) for this dye. The nature of the visible absorption spectra in aqueous surfactant solutions above CMC was very similar to those in the ethanol solution. The solubilization power is strongly dependent on the surfactant structure and nature of micelles. The absorption of used disperse dye intopolyester fabrics in the presence of cationic surfactants increased in the order of DTAB>12-4-12>14-414, once again confirming the higher solubilization power for gemini surfactants even at elevated temperatures. J. Color Sci. Tech. 4(2010), 55-64 © Institute for Color Science and Technology.

This study investigated the potential use of a low-cost inorganic powder (Iranian kaolin) for removal of C.I. Basic Yellow 28 (BY28) from aqueous solution. Kaolin was characterized by laser particle size analyzer (PSA), scanning electron microscopy(SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. The effect of adsorbent dosage, dye concentration, contact time, wastewater volume, initial pH and the presence of different electrolytes were studied. Experimental results revealed that kaolin is a very strong and fast adsorbent and the presence of different electrolytes and pH changes do not have a notable effect for cationic dye removal. The experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir. It was found that the adsorption of BY28 on kaolin followed the pseudo-second order equation which indicates that the adsorption process is chemisorption controlled. J. Color Sci. Tech. 3(2009), 145-155 © Institute for Color Science and Technology.

In this work, decolorization of a reactive dye (C.I. Reactive Black 5) by ozonation method was evaluated by UV-Vis spectrophotometry. The effective operational parameters such as ozonation dosages, stirring, pH, temperature, dye concentration, wastewater volume and the electrolytes were studied. Results showed that the ozonation was a very effective method for reactive dye decolorization. Complete decolorization was achived in different dye concentrations, wastewater volume and electrolytes. These parameters just had some effect on rate of decolorization and not the yield. The concentration of ozone stream and mixing rate were two important factors among all other factors. J. Color Sci. Tech. 2(2008), 67-75.© Institute for Colorants, Paint and Coatings.

The retarding effect of gemini cationic surfactants in acrylic dyeing with a cationic dye (methylene blue) was studied by using UV-Vis spectroscopy. The dye adsorption rate increases with increasing temperature. The retarding action of gemini cationic surfactants is much stronger than that of the corresponding monomeric surfactants. In this work, a new empirical kinetic model based on simultaneous first and second order has been proposed. The kinetic of acrylic dyeing with a cationic dye at different temperatures and in the presence of monomeric and gemini cationic surfactants was studied by using different empirical equations. The proposed equation showed a very good correlation withexperimental data in comparison to the previous ones. J. Color Sci. Tech. 1(2008), 73-82. © Institute for Colorants, Paint and Coatings.