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Advances in Environmental Technology - Volume:1 Issue: 2, Summer 2015

Advances in Environmental Technology
Volume:1 Issue: 2, Summer 2015

  • تاریخ انتشار: 1395/03/29
  • تعداد عناوین: 6
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  • Mojtaba Ahmadi, M. Hamed Ardakani, A.A. Zinati Zadeh Pages 59-68
    The optimization of process conditions for the degradation of acid blue 193 by UV/peroxydisulfate was investigated using response surface methodology (RSM). The effects of four parameters namely initial K2S2O8 concentration, UV irradiation, temperature, and initial dye concentration on two process responses, color removal and the rate constants of the first-order kinetic equations, were investigated using a second-order polynomial multiple regression model. The analysis of variance (ANOVA) explained a high determination coefficient (R2) value of 0927-0967, which ensures a good fit of the second-order regression model with the experimental data. The central composite design (CCD) was used to optimize the process conditions, which showed that an initial K2S2O8 concentration of 5 mM, UV irradiation of 250 W, temperature of 50 °C and the initial dye concentration of 40 mg/L were the best conditions. Under the optimum conditions, the maximum color removal from the wastewater and the rate constants of the first-order kinetic equation were 100 % and 0.086 min-1, respectively.
    Keywords: Potassium peroxydisulfate, Blue dye, Response surface methodology, color removal, Optimization
  • Majid Mahdavian, Araz Tofigh Kouzekonani Pages 69-75
    In the chemical industry, process intensification is needed to meet important goals such as sustainable and eco-friendly processes. For esterification reaction the “produce more with less pollution” objective can be achieved by coupling reaction and separation in a so called integrated process. In this work a model for describing the esterification reaction of ethyl acetate in pervaporation membrane reactor using amberlyst 15 as a heterogeneous catalyst and polydimethylsiloxane (PDMS) membrane, was developed. This earth-friendly method with low pollution and high yield is an alternative to hazardous methods because using pervaporation membrane reactor reduces both waste and energy consumption. The validity of the model was tested by comparing the calculated results with experimental data reported in the literature. It was shown rate of conversion increased by removing ethyl acetate from the reaction mixture. A parametric study was carried out to evaluate the effects of operating conditions on the performance of the pervaporation membrane reactor. Conversion increased by increasing the temperature, molar ratios of reactants and catalyst concentration.
    Keywords: Pervaporation membrane reactor, Esterification, Ethyl acetate, Modeling, Green chemistry
  • Jalal Shayegan, Jamal Alikhani, Hamid Reza Kariminia Pages 77-84
    In this paper, a modeling tool for risk assessment analysis of the movement of hydrocarbon contaminants in the vadose zone and mass flux of contamination release into the groundwater table was developed. Also, advection-diffusion-reaction equations in combination with a three-phase equilibrium state between trapped air, soil humidity, and solid particles of unsaturated soil matrix were numerically solved to obtain a one dimensional concentration change in respect to depth of soil and total mass loading rate of hydrocarbons into the groundwater table. The developed model calibrations by means of sensitivity analysis and model validation via data from a site contaminated with BTEX were performed. Subsequently, the introduced model was applied on the collected hydrocarbon concentration data from a contaminated region of a gas refinery plant in Booshehr, Iran. Four different scenarios representing the role of different risk management policies and natural bio-degradation effects were defined to predict the future contaminant profile as well as the risk of the mass flux of contaminant components seeping into the groundwater table. The comparison between different scenarios showed that bio-degradation plays an important role in the contaminant attenuation rate; where in the scenarios including bio-degradation, the contaminant flux into the ground water table lasted for 50 years with the maximum release rate of around 20 gr per year while in the scenarios without including bio-degradation, 300 years of contaminant release into groundwater table with the maximum rate of 100 gr per year is obtained. Risk assessment analysis strongly suggests a need for bioremediation enhancement in the contaminated zones to reduce the contaminant influx to groundwater.
    Keywords: vadose zone, advection, diffusion, reaction equation, contaminant transport, risk assessment, numerical modeling
  • Mehrdad Farhadian, Najmeh Askari, Amir Razmjou Pages 85-92
    Decolorization of aqueous solutions containing ionic dyes (Reactive Blue 19 and Acid Black 172) by a TFC commercial polyamide nanofilter (NF) in a spiral wound configuration was studied. The effect of operating parameters including feed concentration (60-180 mg/l), pressure (0.5-1.1 MPa) and pH (6-10) on dye removal efficiency was evaluated. The response surface method (RSM) was utilized for the experimental design and statistical analysis to identify the impact of each factor. The results showed that an increase in the dye concentration and pH can significantly enhance the removal efficiency from 88% and 87% up to 95% and 93% for Reactive and Acid dye, respectively. The effect of pressure on the removal efficiency showed different behavior such that by the raise of pressure from 0.5 to 0.8 MPa, the removal efficiency increased to its maximum, then reduction in removal efficiency was observed by further increases in pressure above the optimum range. The maximum dye removal efficiencies which were predicted at the optimum conditions by Design Expert software were 97 % and 94 % for Reactive Blue 19 and Acid Black 172, respectively. According to the results of this study, NF processes can be used at a significantly lower pressure and fouling issue for reuse applications as an alternative to the widely used RO process.
    Keywords: Wastewater treatment, Water Reuse, Nanofiltration, Ionic dye, Textile Wastewater
  • Bahareh Sadeghalvad, Mojtaba Torabzadehkashi, Amir Reza Azadmehr Pages 93-100
    Heavy metals such as Cu(II) and Pb(II) are among the hazardous pollutants that lead to severe ecological problems and have a toxic effect on living organisms. The removal of Cu(II) and Pb(II) by Iranian bentonite experiment were conducted in single component and multi component systems. The bentonite from the Birjand area was characterized by X-ray diffraction pattern and FTIR spectroscopy. The effects of initial Cu(П) and Pb(П) concentration were investigated on the adsorption process. An equilibrium study was performed and followed by five different isotherm models which included two parameter (Langmuir, Frendlich, Temkin and D-R) and three parameter (Khan) models . From the Langmuir isotherm, the equilibrium adsorption capacity for Cu(П) is 21.10 to 22.17 mg/g in single component and multi component systems respectively, and for Pb(П) is 27.80 to 40.49 mg/g in single component and multi component systems respectively. Comparative adsorption of Cu(II) and Pb(II) onto bentonite showed that the affinity for Pb(II) to interact with bentonite is higher than Cu(II). Based on the free energy of adsorption value for Cu(П) and Pb(П), the interaction between these ions and Iranian bentonite is chemical adsorption, that is to say, ion exchange.
    Keywords: Cu(II), Pb(II) removal, Comparative adsorption, Isotherm models
  • Masoume Ghorbani, Seyyed Mostafa Nowee Pages 101-104
    In the current investigation a novel nano hybrid adsorbent MCM-41/N-(3-trimethoxysilyl)-propyl)diethylenetriamine (MCM-41/TMSPDETA) was prepared and was characterized using DLS (Dynamic Light Scattering), Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analytical techniques and Transmission electron microscopy (TEM). The synthesized MCM-41/TMSPDETA adsorbent possessed high surface area (867 m2g−1), narrow pore size distribution (3.6 nm) and pore volume (0.782 cm3g−1). The nano hybrid adsorbent was applied in batch experiments under different controlling factors by varing pH, contact time and solution temperature of Lead (Pb(II)) and Nickel (Ni(II)) ions. Optimum conditions obtained were 20°C, pH=6 and contact time of 120 min. The maximum capacity of the nano-sorbent was obtained to be 58.823 and 20.921 mg g−1 for Pb (II) and Ni (II) ions for an initial concentration range 10-70 mgL-1. Pseudo-first order, pseudo-second order and intraparticle diffusion models were used to analyze the kinetic data. Results showed that the pseudo-second order model can well describe the adsorption kinetic data.
    Keywords: Pb(II), Ni(II) adsorption, MCM, 41, TMSPDETA, Adsorption kinetic, Pseudo, second order model