فهرست مطالب

Chemical Engineering - Volume:15 Issue: 4, Autumn 2018

Iranian journal of chemical engineering
Volume:15 Issue: 4, Autumn 2018

  • تاریخ انتشار: 1397/09/23
  • تعداد عناوین: 7
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  • M. Baniamer, A. Almasi, Sh. Sharifnia* Pages 3-16
    Pharmaceutical pollutants are one of the most important issues of modern life and their negative effects on the environment and human health are undeniable. In the present work, the effectiveness of the photocatalytic process was studied by two semiconductors (ZnO and V2O5) in order to remove the Diclofenac Sodium completely under solar irradiation. The study examined the impact of parameters such as the high-level range concentration of pharmaceutical, catalyst dosage, pH changes and time on the photodegradation of Diclofenac Sodium in aqueous solution. All the experiments were carried out under solar and UV irradiation to compare between the two circumstances. The optimum conditions obtained for photodegradation of Diclofenac Sodium were: reaction time 180 min, zinc oxide and vanadium pentoxide = 1 g L-1, Diclofenac Sodium concentration = 300 mg L-1 and pH = 4. In addition, chemical oxygen demand removal was investigated for all the conditions and total degradation was observed by V2O5 under optimum conditions. The study of reaction kinetics was carried out at optimum conditions and approximately a pseudo-first order kinetic model was in agreement with experimental results in each case.
    Keywords: Photocatalysis, Pharmaceutical Active Ingredient, Wastewater Treatment, Solar Energy
  • M. Shafiee *, A. Akbari , B. Ghiassimehr Pages 17-26
    At this work, removal of Pb (II) using Lawsonia inermis (Henna) was studied. In recent years, use of low price adsorbent is taken into consideration. Adsorption experiments were performed in batch system at ambient temperature (25℃). The influence of some parameters such as time, initial metal concentration, pH and adsorbent dose were investigated. The optimum conditions was obtained at pH of 6, 10 ppm of initial metal concentration, 80 min of contact time and 0.75 g/L of adsorbent dose. To study the adsorbent morphology, Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) was used before and after adsorption of Pb (II) ions. Sorption of Pb (II) was evaluated by Freundlich and Langmuir isotherms. The results indicate that the Freundlich isotherm model is better described the adsorption of Pb (II) than Langmuir isotherm model. Also, it is observed that, the pseudo-second-order kinetic model well fitted to experimental data .
    Keywords: Adsorption, Pb (II), Henna, Langmuir, Freundlich, Pseudo first-order kinetics model, Pseudo-second-order kinetics model
  • N. Mostafazadeh, A.A. Ghoreyshi*, K. Pirzadeh Pages 27-47
    In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum condition was revealed as solvent: metal ion molar ratio of 4.6:1, ligand: metal ion molar ratio of 318:1 and temperature of 23℃. The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR and FESEM analyses. Effect of adsorption pH, adsorbent dosage, initial concentration and contact time on adsorption process was investigated. Based on the results, the maximum adsorption capacity of Cr(VI) was 26.27 mg/g which was obtained at 35℃, pH= 5, adsorbent dosage of 3 g/l and initial concentration of 107.82 mg/l. The equilibrium time for Cr(VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26.27 mg/g at initial concentration of 107.82 mg/l. The equilibrium data were described better by Langmuir-Freundlich isotherm model than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles and the Cr(VI) adsorption was almost retained after two cycles.
    Keywords: Adsorption, Cr(VI), ZIF-67, solvothermal, regeneration
  • F. Hosseini, M. Rahimi *, O. jafari Pages 48-62
    In this work, extraction of propionic acid from the aqueous phase to the organic phase (1-octanol) was performed in T-junction microchannels and effects of channel diameter and fluid flow rate on the mass transfer characteristics were investigated. The two-phase flow patterns in studied microchannels with 0.4 and 0.8 mm diameters were observed. Weber ‎ number and surface-to-volume ratio were calculated for evaluating flow patterns. Moreover, the effect of volumetric flow rates on the extraction ‎efficiency, volumetric mass transfer coefficient, and pressure drop was examined. Results showed that the pressure drop in the microchannel with 0.4 mm diameter is 2-2.7 times higher than that in the microchannel with 0.8 mm diameter. In both microchannels, with increase in flow rate, the extraction ‎efficiency first increases and then decreases. In addition, at high flow rates (2.4, 4.5 and 6 mL/min), the extraction ‎efficiency in the microchannel with 0.8 mm diameter increased up to the range of 7-14.9 % compared with that in the microchannel with 0.4 mm diameter.
    Keywords: extraction, propionic acid, microfluidic, channel diameter
  • Sh. Biswas, Md. M. Islam, M. M. Hasan, S.H. Rimu, M. N. Khan, P. Haque, M. M. Rahman * Pages 63-80
    This paper reports the evaluation of adsorbing Cr (VI) ions on sorbent prepared from chitosan (CHT), a versatile derivative of chitin, and dodecyl amine modified locally available kaolinite clay (Bijoypur clay) (MC) that has excellent mechanical properties and great resistance to chemical and biological attack. The effect of the initial metal ion concentration, solution pH, contact time, and adsorbent dosages on the adsorption capacity of the composites was investigated. pH 4 is selected for better adsorption by the adsorbents. The adsorption abilities were studied over Cr (VI) ions using different adsorption isotherm such as Langmuir, Freundlich, and Dubinin-Radushkevich respectively. Langmuir isotherm is found better fitted with maximum adsorption capacity of 73 mg/g by composite SB-1. R2 obtained from Langmuir isotherm is 0.999 which indicates a monolayer adsorption on the adsorbent surface. The adsorption kinetics was also well described by the pseudo-second-order equation with a rate constant of 0.000302 g mg−1 min−1 at 25 ppm Cr(VI) concentration. The adsorption of Cr (VI) ions by the adsorbent were confirmed by FT-IR and X-RD analysis of the composites before and after Cr (VI) ion adsorption. The desorption percentage of the metal ion and the second cycle metal adsorption by regenerated (regenerated after the first adsorption by fresh adsorbent) adsorbent processed with 0.01N sulphuric acid shows a value of 78.23% and 68.12% respectively.
    Keywords: Chitosan, Adsorbent, Chromium (VI) ions, Adsorption isotherm, Adsorption kinetics
  • B. Medi *, M., K. Kazi Pages 81-92
    In this work, an improved single-column chromatographic (ISCC) separation process is proposed. The term `improved' refers to both conceptual and physical modifications compared to the available single-column processes, including a novel fraction collection scheme and allowing overlapped peaks from adjacent cycles. Also the fraction collection mechanism was modified in order to facilitate online monitoring. Another advantage of the ISCC process is its large degree of freedom as injection volume, cycle time, solvent flow rate, feed concentration, and fraction-collection intervals can all be decision variables in this process. The experimental implementation and validation is covered in this work. The results indicate successful operation of the ISCC process and accompanying peripherals for the separation of guaifenesin enantiomers. In particular, the tests confirmed the integrity of the online monitoring system and proved the capability of the process for 98% purification of the tested enantiomers with an advantageously shorter cycle time, which results in higher productivity.
    Keywords: Chromatographic separation, process design, monitoring, guaifenesin
  • M. E. Zeynali *, H. Abedini, H. R. Sadri Pages 93-104
    DEB dehydrogenation reaction was conducted to produce divinylbenzene (DVB) and ethylvinylbenzene (EVB). The effects of temperature, catalyst weight and time factor on the performance of the dehydrogenation reactor were investigated experimentally. Temperature was varied from 550º C up to 600 º C. Temperature affect the conversion of DEB to DVB significantly. The mole fraction of DEB in the outlet of the reactor is reducing up to 580 º C, but further increase in temperature up to 600 º C does not decrease the mole fraction of DEB in the outlet of the reactor. Catalyst weight was varied from 10 gr up to 40 gr. The results showed that the trends of EVB+DVB production and DEB consumption are identical at various catalyst weights. To obtain optimum time factor for the DEB dehydrogenation process experiments were conducted at various time factors. The results showed that the optimum time factor for DVB as a desired product is 825 gr/hr.mole. . The data and information provided in this research can be used for scale-up and optimization purposes.
    Keywords: Diehtylbenzene Dehydrogenation, Divinylbenzene, Reactor performance, Time factor