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RISS 인기검색어
- 검색키워드
- 저자 : Azizi Navid (검색결과 5 건)
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Navid Azizi,Mehran Arzani,Hamid Reza Mahdavi,Toraj Mohammadi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.9
One of the effective techniques for improving separation properties of polymeric membranes is incorporation of suitable nanoparticles into their matrices. This study presents the preparation of three types of nanocomposite membranes comprising three grades of poly (ether-block-amide) (Pebax 1074, Pebax 1657 and Pebax 2533) and modified multi-walled carbon nanotubes (MWCNTs) with different loadings (1, 1.5, 2 and 2.5 wt%). The prepared membranes were characterized by field emission scanning electron microscopy (FESEM), attenuated total reflection-Fourier transfer infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD). Permeation of CO2 and CH4 gases through the prepared membranes was measured at the pressure range of 2-8 bars and 25 oC. The results showed that the incorporation of MWCNTs into the polymers matrices improves CO2/CH4 selectivity. Further, Pebax 1074/MWCNT nanocomposite membrane exhibits better performance for CO2/CH4 separation compared to the neat Pebax and the two other nanocomposite membranes.
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Azizi Navid,Jahanmahin Omid,Homayoon Reza,Khajouei Mohammad 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.6
Mixed-matrix membranes (MMMs) composed of suitable CO2-philic polymers and fillers can be attractive candidates for CO2/CH4 and CO2/N2 separation due to their high CO2 permeability, good thermochemical stability, low fabrication cost, and fast production process. In this research, a novel ternary MMM was fabricated via the blending of poly (amide 12-b-ethylene oxide) (PEBAX-1074) with polyethylene glycol (PEG-200) and magnesium oxide (MgO) nanoparticles mixture. The effects of various loadings of the fillers on CO2, N2, and CH4 permeability values through the membranes were studied. Permeation of CO2, N2, and CH4 gases through the resultant membranes at pressures of 2, 4, 6, 8, and 10 bar and temperatures of 25, 35, 45, and 55 °C revealed the superiority of the MMMs for CO2/CH4 and CO2/N2 separation in comparison with the pristine membranes. Particularly, at 25 °C and 2 bar, the CO2 permeability, as well as ideal CO2/CH4 and CO2/N2 selectivity of the optimized MMM containing 40 wt% of PEG-200 and 8 wt% of MgO nanoparticles, rose to 210.1 Barrer, 24.9 and 60.9, corresponding to enhancement of around 225%, 23% and 24% of the CO2 permeability and selectivity compared to the neat membrane, respectively. Thus, the fabricated MMM has a satisfying potential to separate CO2 from N2.
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Fereidoun Azizi,Navid Saadat,Mir Alireza Takyar,Hengameh Abdi,Ladan Mehran,Atieh Amouzegar 대한내분비학회 2022 Endocrinology and metabolism Vol.37 No.6
Background: This study compared the degree of sustained control of hyperthyroidism in patients with toxic multinodular goiter(TMNG) treated with long-term methimazole (LT-MMI) or radioactive iodine (RAI). Methods: In this clinical trial, 130 untreated patients with TMNG were randomized to either LT-MMI or RAI treatment. Bothgroups were followed for 108 to 148 months, with median follow-up durations of 120 and 132 months in the LT-MMI and RAIgroups, respectively. Both groups of patients were followed every 1 to 3 months in the first year and every 6 months thereafter. Results: After excluding patients in whom the treatment modality was changed and those who were lost to follow-up, 53 patients inthe LT-MMI group and 54 in the RAI group completed the study. At the end of the study period, 50 (96%) and 25 (46%) patientswere euthyroid, and two (4%) and 25 (46%) were hypothyroid in LT-MMI and RAI groups, respectively. In the RAI group, four(8%) patients had subclinical hyperthyroidism. The mean time to euthyroidism was 4.3±1.3 months in LT-MMI patients and 16.3±15.0 months in RAI recipients (P<0.001). Patients treated with LT-MMI spent 95.8%±5.9% of the 12-year study period in a euthyroid state, whereas this proportion was 72.4%±14.8% in the RAI-treated patients (P<0.001). No major treatment-related adverseevents were observed in either group. Conclusion: In patients with TMNG, LT-MMI therapy is superior to RAI treatment, as shown by the earlier achievement of euthyroidism and the longer duration of sustained normal serum thyrotropin.
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Maryam Ariazadeh,Zahra Farashi,Navid Azizi,Mohammad Khajouei 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2
Silica (SiO2) nanoparticles were first functionalized using (3-aminopropyl) triethoxysilane (APTES) and then utilized as filler for the preparation of poly (ether-block-amide) (Pebax®-1074) based mixed-matrix membranes (MMMs). To characterize the modified nanoparticles and the prepared membranes, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were conducted. The influences of the pure and amine-modified nanoparticles content, and feed temperature and pressure on CO2 and CH4 permeability and ideal CO2/CH4 selectivity values of the membranes were studied. The permeation experiments exhibited that the incorporation of 12.5 wt% of amine-functionalized SiO2 nanoparticles into the Pebax matrix raises the CO2 permeability and ideal CO2/CH4 selectivity about 100 and 32%, respectively.
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Seyed Mohammad Ali Ahmadi,Toraj Mohammadi,Navid Azizi 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.1
Mixed-matrix gas separation membranes were prepared by embedding various content of halloysite nanotubes (HNTs) (0, 0.5, 1, 1.5, and 2 wt%) within poly (ether-block-amide) matrix. XRD, FT-IR, TGA, and SEM analyses were conducted to study crystal structure, chemical bonds changes, thermal resistance, and cross-sectional morphology of the resultant membranes, respectively. Permeability values of pure CH4 and CO2 gases through the synthesized neat and mixed-matrix membranes (MMMs) were experimentally determined at constant temperature (25 oC) and several pressures (4, 6, 8, and 10 bar). The obtained results exhibited improved CO2 permeability of the MMMs comparing with the pristine Pebax membrane. As an example, at a pressure of 4 bar, raising the incorporated HNTs loading from 0 to 2wt% enhanced the permeability of CO2 from 76.50 to 101.23 Barrer.
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