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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Polyolefins Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Response surface methodology,Membrane,morphology,thermally induced phase separation,MBR,polypropylene grafted maleic anhydride
- چکیده:
- چکیده انگلیسی: In this study, the response surface methodology (RSM) based on the central composite design (CCD) was used to optimize the preparation condition of polypropylene-grafted maleic anhydride (PP-g-MA) microporous membrane by thermally-induced phase separation (TIPS) method. A mixture of dibutyl phthalate (DBP) and dioctyl phthalate (DOP) was used as diluent. The effect of polymer composition and quenching bath temperature on the morphology and performance of the fabricated microporous membranes was investigated by using RSM. Analysis of variance (ANOVA) was used to determine which variables and interactions between variables had a significant effect on our responses. The ANOVA revealed that the bath temperature was the most significant variable associated with porosity and pure water flux responses and the polymer concentration was the most significant variable associated with tensile response. The obtained results also showed that with increasing the polymer concentration and decreasing the quenching bath temperature, the membrane porosity and pure water flux decreased, whereas the membrane tensile increased. The regression equations were reasonably validated and used to predict and optimize the performance of PP-g-MA membranes within the limits of the variables. Finally, the maximum responses (flux of 115.6 L/m2h, porosity of 62% and tensile of 1.6 MPa) were obtained under the following conditions: polymer concentration of 28.5 wt% and temperature of 329 K. Further, comparison of laboratory-made and commercial membranes in a membrane bioreactor (MBR) system showed that the rate of membrane fouling was decreased by 4.2 times.
- انتشار مقاله: 27-04-1396
- نویسندگان: Hossein Hazrati,Nader Jahanbakhshi,Mohammad Rostamizadeh
- مشاهده
- جایگاه : پژوهشی
- مجله: Polyolefins Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: ZSM-5,Desilication,Hierarchical zeolites,nanocatalyst, MTO
- چکیده:
- چکیده انگلیسی: Highly siliceous ZSM-5 nanocatalysts can dehydrate methanol to a wide range of hydrocarbons. In this study, the development of hierarchical H-ZSM-5 nanocatalysts (Si/Al=200) were reported for the methanol-toolefins (MTO) reaction. The nanocatalysts were prepared through a hydrothermal technique and treated by NaOH desilication. The parent and desilicated nanocatalysts were characterized using FE-SEM, XRD, FTIR, NH3-TPD and N2 adsorption-desorption techniques. The mesoporosity increased five times without significant collapse of the crystalline framework as a result of the appropriate desilication of H-ZSM-5 nanocatalyst. For the nanocatalyst, a high surface area of 189.5 m2 g-1, mesopore volume of 0.35 cm3 g-1 and well-adjusted strong acidity of 0.16 mmol NH3 g-1 resulted in a high methanol conversion of 100%, high propylene selectivity of 43% and low light paraffins selectivity of <8% in the MTO reaction. A broad mesopore size of 2-10 nm suppressed coke deposition and provided a long catalytic life time of 75 h. The developed high silica nanocatalyst showed a high potential for industrial applications due to its stable performance.
- انتشار مقاله: 26-04-1396
- نویسندگان: Mohammad Rostamizadeh,Fereydoon Yaripour,Hossein Hazrati
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Applied Research in Water and Wastewater
- نوع مقاله: Journal Article
- کلمات کلیدی: Membrane fouling,Wastewater,MBR,ZSM-5 nano- adsorbent,SRT,Cake properties
- چکیده:
- چکیده انگلیسی: In this paper, the effect of different sludge retention times (SRTs) on membrane fouling of membrane bioreactor (MBR) systems including synthesized ZSM-5 nano-adsorbent was investigated. Three MBRs including nano-adsorbent were applied in SRTs of 10, 50 and 100 d during six months for wastewater treatment. Soluble microbial products (SMP) and extracellular polymeric substance (EPS) concentration analyses were conducted on the sludge of the bioreactors. Particle size distribution (PSD), Fourier-transform infrared (FTIR) spectroscopy, excitation- emission matrix (EEM) fluorescence spectroscopy, gel permission chromatography (GPC) were performed for determining the properties of the formed cake. Based on GPC test, at SRT of 10 d, organic compounds with varied molecular weights had the low concentration, while compounds with lower molecular weight were found more at SRTs of 50 and 100 d. FTIR and EEM analyses also revealed high concentration of protein compounds in MBR. Consequently, the membrane fouling was decreased in MBR at SRT of 10 d compared to SRTs of 50 and 100 d. In fact, transmembrane pressure (TMP) was 15, 21 and 25 kPa for SRTs of 10, 50 and 100 d, respectively. The EEM results showed that in addition to reduction of proteins by nano-adsorbent in SRTs of 10 and 50 d, the humic compounds were also reduced. The results showed the high efficiency of ZSM-5 nano-adsorbent for reducing of membrane fouling at the low SRT.
- انتشار مقاله: 28-12-1397
- نویسندگان: Hossein Hazrati,Zahra Sadat Sajadian,Nader Jahanbakhshi,Mohammad Rostamizadeh
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Applied Research in Water and Wastewater
- نوع مقاله: Journal Article
- کلمات کلیدی: Membrane fouling,Wastewater,MBR,ZSM-5 nano- adsorbent,SRT,Cake properties
- چکیده:
- چکیده انگلیسی: In this paper, the effect of different sludge retention times (SRTs) on membrane fouling of membrane bioreactor (MBR) systems including synthesized ZSM-5 nano-adsorbent was investigated. Three MBRs including nano-adsorbent were applied in SRTs of 10, 50 and 100 d during six months for wastewater treatment. Soluble microbial products (SMP) and extracellular polymeric substance (EPS) concentration analyses were conducted on the sludge of the bioreactors. Particle size distribution (PSD), Fourier-transform infrared (FTIR) spectroscopy, excitation- emission matrix (EEM) fluorescence spectroscopy, gel permission chromatography (GPC) were performed for determining the properties of the formed cake. Based on GPC test, at SRT of 10 d, organic compounds with varied molecular weights had the low concentration, while compounds with lower molecular weight were found more at SRTs of 50 and 100 d. FTIR and EEM analyses also revealed high concentration of protein compounds in MBR. Consequently, the membrane fouling was decreased in MBR at SRT of 10 d compared to SRTs of 50 and 100 d. In fact, transmembrane pressure (TMP) was 15, 21 and 25 kPa for SRTs of 10, 50 and 100 d, respectively. The EEM results showed that in addition to reduction of proteins by nano-adsorbent in SRTs of 10 and 50 d, the humic compounds were also reduced. The results showed the high efficiency of ZSM-5 nano-adsorbent for reducing of membrane fouling at the low SRT.
- انتشار مقاله: 28-12-1397
- نویسندگان: Hossein Hazrati,Zahra Sadat Sajadian,Nader Jahanbakhshi,Mohammad Rostamizadeh
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Environmental Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Biokinetic coefficient,Hydraulic retention time,Solid retention time,Volatile organic compounds
- چکیده:
- چکیده انگلیسی: In this study, a lab-scale membrane bioreactor (MBR) was operated for a period of more than 10 months to determine the biokinetic coefficients of the system under the hydraulic retention times (HRT) of 20, 15 and 10 hrs and sludge retention times (SRT) of 5-20 days. The results revealed that the biological removal efficiency of styrene and ethylbenzene at a solid retention time of 20 day and a hydraulic retention time of 15 hr was higher compared to a SRT of 10 day and at the same HRT. The results also showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) for styrene and ethylbenzene as substrate were 0.60 and 0.60 mg/mg, 0.25 and 0.25 day−1, 0.188 and 0.363 h-1, and 0.146 and 2.82 mg /l, respectively. Furthermore, ethylbenzene was more appropriate as a source of carbon to activated sludge in the membrane bioreactor than the styrene which had a lower μmax than ethylbenzene.
- انتشار مقاله: 26-10-1395
- نویسندگان: Seyed Mojtaba Seyedi,Hossein Hazrati,Jalal Shayegan
- مشاهده