Experimental investigation of nanofibrous poly(vinylidene fluoride) membranes for desalination through air gap membrane distillation process

Javad Karimi-Sabet,Mojtaba Shariaty-Niassar,Rasoul Moradi,Younes Amini 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.10

A comparative study was conducted to evaluate the performance of two membrane types of electrospun poly(vinylidene fluoride) (PVDF) and commercial ploytetrafluoroethylene (PTFE). The optimized needleless electrospinning technique was used to prepare PVDF membranes. Scanning electron microscopy (SEM), wettability tests, water flux, mechanical strength and liquid entry pressure (LEP) measurements were performed to evaluate the prepared membrane. Air gap membrane distillation (AGMD) experiments were carried out to investigate the salt rejection performance and the durability of membranes. The results show that our nanofibrous PVDF membrane presents higher water permeation flux (>20 kg/m2 h) compared to commonly used PTFE. In addition, the experimental data confirms that competitive salt rejection efficiency (>99.8%) was obtained in this new membrane.

Preparation and characterization of a novel calcium-conducting polymer inclusion membrane: Part I

Reza Darvishi,Javad karimi Sabet,Mohsen Nasr Esfahany 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.10

The preparation and characterization of a novel type of castor oil-based polymer inclusion membrane (PIM) was investigated, focusing on its flux and selective recovery of Ca2+ over competitive ions such as K+, Na+, and Mg2+. The PIM contains a cross-linked high-molecular-weight green polyol (GPO) as a polymer base, benzene-18crown-6 as a carrier, and an ionic liquid called 1-Butyl-3-methylimidazolium chloride as a plasticizer. GPO was first synthesized by a reaction between an epoxidized castor oil and a cellulose acetate, thereafter, cross-linked by isophorene isocyanate. The base polymer and the prepared PIM were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The FTIR results indicate that oxirane groups in the epoxidized castor oil molecules reacted with the primary hydroxyl groups of cellulose acetate chains. The contact angle measurement hints at the hydrophobic characteristics of the prepared membrane. Compared to the PVC-, CA-, and PVDF-based polymer inclusion membrane, the cured GPO-based PIM, showed higher selectivity and flux of calcium ions with the same composition. The greater stability and significantly higher surface roughness are further favorable features of the novel PIM.

Optimization and modification of PVDF dual-layer hollow fiber membrane for direct contact membrane distillation; application of response surface methodology and morphology study

Mehdi Bahrami,Javad karimi Sabet,Ali Hatamnejad,Abolfazl Dastbaz,Mohammad Ali Moosavian 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.11

RSM methodology was applied to present mathematical models for the fabrication of polyvinylidene fluoride (PVDF) dual-layer hollow fibers in membrane distillation process. The design of experiments was used to investigate three main parameters in terms of polymer concentration in both outer and inner layers and the flow rate of dope solutions by the Box-Behnken method. According to obtained results, the optimization was done to present the proper membrane with desirable properties. The characteristics of the optimized membrane (named HF-O) suggested by the Box-Behnken (at the predicted point) showed that the proposed models are strongly valid. Then, a morphology study was done to modify the fiber by a combination of three types of a structure such as macro-void, sponge-like and sharp finger-like. It also improved the hydrophobicity of outer surface from 87 to 113o and the mean pore size of the inner surface from 108.12 to 560.14nm. The DCMD flux of modified fiber (named HF-M) enhanced 62% more than HF-O when it was fabricated by considering both of RSM and morphology study results. Finally, HF-M was conducted for long-term desalination process up to 100hr and showed stable flux and wetting resistance during the test. These stepwise approaches are proposed to easily predict the main properties of PVDF dual-layer hollow fibers by valid models and to effectively modify its structure.

Separation performance investigation of packed distillation columns using simple NEQ approach based on packing multicomponent efficiencies and effective mass transfer coefficients

Hadi Poortalari,Javad karimi Sabet,Farshad Varaminian 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5

A simple non-equilibrium modeling approach is proposed to simulate multicomponent distillation process in packed columns. The real behavior of the column is simply considered by the evaluation of interphase mass transfer rate based on the overall mass transfer coefficient. Two distinct methods are used to calculate this overall coefficient including the effective mass transfer coefficient method and the packing efficiency method. The modelling procedure consists of an iterative segment-wise algorithm implemented in a MATLAB home-code. For verification, the obtained composition profiles from a structured and a random packed column are compared with reported experimental data. Comparisons show that the packing efficiency-based model could acceptably predict the experimental profiles with an average relative deviation of 18% and 25% for structured and random packed columns, respectively. This confirms that our simple non-equilibrium approach is a reliable and robust model for the performance evaluation of packed columns.

Thin film graphene oxide membrane: Challenges and gas separation potential

Fateme Abbasi,Javad Karimi-Sabet,Cyrus Ghotbi,Zeinab Abbasi 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5

Graphene oxide membranes were prepared by vacuum and pressurized ultrafiltration methods on the 12% modified Polyacrylonitrile (12mPAN) substrate to specify challenges, salient features, future directions, and potential of GO membrane for separation fields using characterization techniques and gas separation test (studied gases are CO2, He and N2), which is an efficient tool for better understanding of GO membrane behavior. GO membrane structure was examined over a wide range of parameters, such as pore size range of substrate and its surface properties, pH of GO dispersion, GO content, synthesis pressure, operating pressure and temperature. The results show that the GO content does not hold a linear relationship with the permeance and selectivity. Film thickness, aggregates, synthesis pressure defects and interlayer spacing have significant effects on the gas separation performance of GO membranes which originate from the synthesis method and its conditions.

Performance evaluation of a novel reactor configuration for oxidative dehydrogenation of ethane to ethylene

Hamid Asadi-Saghandi,Javad Karimi-Sabet 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.7

A one-dimensional non-isothermal steady state model was developed to simulate the performance of three-reactor configurations for the oxidative dehydrogenation of ethane (ODHE) to ethylene. These configurations consist of side feeding reactor (SFR), conventional fixed bed reactor (CFBR) and membrane reactor (MR). The performance of these reactors was compared in the terms of C2H6 conversion, C2H4 and CO2 selectivity and temperature profiles. The use of sectional air injections on the wall of SFR with a limited number of injection points showed that the performance of reactor significantly improves and optimum pattern of oxygen consumption is also obtained. Moreover, our SFR with a liquid coolant medium operates in an effectively controlled temperature profile that is comparable with that of the MR, which is cooled by a coolant stream of air. Hence, an enhancement in the level of selectivity is obtained for the SFR configuration. Consequently, the side feeding procedure can decrease the high operating temperature problem and low ethylene selectivity in the ODHE process. According to obtained results, the SFR would be a proper alternative for both the MR and CFBR.

Thermodynamic modeling of PVTx properties for several water/hydrocarbon systems in near-critical and supercritical conditions

Mohammad Reza Mozdianfard,Fatemeh Masoodiyeh,Javad Karimi-Sabet 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.1

Both the equation of state-excess Gibbs energy (EoS/G E) model and the cubic plus association (CPA) equation of state (EoS) are compared in this study with respect to their accuracy in the correlation of PVTx for systems such as water/methanol, water/ethanol, water/benzene, water/toluene, water/methane, water/n-butane, water/n-pentane, water/n-hexane, water/heptane, and water/octane, in supercritical conditions within temperature and pressure ranges of (573-698 K) and (7.0-276.0MPa), respectively. In the proposed EoS/G Emodel, Peng-Robinson (PR) equation of state, linear combination Vidal-Michelsen (LCVM) and Wong-Sandler (WS) mixing rules in conjunction with UNIQUAC activity coefficient model were used. Correlation of both CPA and EoS/G Emodels was evaluated by comparing the results with the experimental data. Average absolute relative deviation (AARD) for WS, LCVM, and CPA was found to be 2.99,11.11 and 5.14%, respectively, indicating better correlation of WS model with the experimental data.