Simultaneous multi-objective optimization of a new promoted ethylene dimerization catalyst using grey relational analysis and entropy measurement

A hybrid approach between the Taguchi method and grey relational analysis (GRA) with entropy measurement was applied to determine a single optimum setting for reaction factors of the proposed ethylene dimerization catalyst having overall selectivity to 1-butene (S_1-btn (%)) and turnover frequency (TOF (h^-1)) as multiple quality characteristics. Titanium tetrabutoxide (Ti(OC₄H₉)₄) catalyst precursor in combination with triethyl aluminum (TEA) activator, 1,4-dioxane as a suitable modifier, and ethylene dichloride (EDC) as a novel promoter were used in the catalysis. Control factors of temperature, pressure, Al/Ti, 1,4-dioxane/Ti, and EDC/Ti mol ratios were investigated on three levels and their main effects were discussed. The effect of the binary interaction between temperature, pressure, and Al/Ti mol ratio was also examined. Weight of the responses was determined using entropy. Analysis of variance (ANOVA) for data obtained from GRA indicated that EDC/Ti mol ratio with 27.64% contribution had the most profound effect on the multiple quality characteristics. Development of the weighted Grey-Taguchi method used the Taguchi method as its basic structure, adopted GRA to deal with multiple responses, and entropy to enhance the reasonability of the comprehensive index produced by GRA to make the results more objective and accurate. Overall, these combined mathematical techniques improved catalytic performance for 1-butene production.     

The morphology and gas‐separation performance of membranes comprising multiwalled carbon nanotubes/polysulfone–Kapton

The development of desirable chemical structures and properties in nanocomposite membranes involve steps that need to be carefully designed and controlled. This study investigates the effect of adding multiwalled nanotubes (MWNT) on a Kapton–polysulfone composite membrane on the separation of various gas pairs. Data from Fourier transform infrared spectroscopy and scanning electron microscopy confirm that some studies on the Kapton–polysulfone blends are miscible on the molecular level. In fact, the results indicate that the chemical structure of the blend components, the Kapton–polysulfone blend compositions, and the carbon nanotubes play important roles in the transport properties of the resulting membranes. The results of gas permeability tests for the synthesized membranes specify that using a higher percentage of polysulfone (PSF) in blends resulted in membranes with higher ideal selectivity and permeability. Although the addition of nanotubes can increase the permeability of gases, it decreases gas pair selectivity. Furthermore, these outcomes suggest that Kapton–PSF membranes with higher PSF are special candidates for CO₂/CH₄ separation compared to CO₂/N₂ and O₂/N₂ separation. High CH₄, CO₂, N₂, and O₂ permeabilities of 0.35, 6.2, 0.34, and 1.15 bar, respectively, are obtained for the developed Kapton–PSF membranes (25/75%) with the highest percentage of carbon nanotubes (8%), whose values are the highest among all the resultant membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43839.     

Carbon nanotubes growth on sub-surface catalyst layer of Cu–Ni nanoparticles thin film

Cu–Ni nanoparticles (NPs) thin films were prepared by Direct Current (DC) magnetron sputtering with Cu and Ni targets. The products were used as catalysts for Thermal CVD (TCVD) growing of carbon nanotubes (CNTs) from acetylene gas at 825°C. In order to characterize the nano catalysts, X-ray Diffraction (XRD) and Atomic Force Microscopy (AFM) and to study the synthesized CNTs Scanning Electron Microscopy (SEM) and Raman Spectroscopy were applied. A remarkable CNT grown on the sub-surface of catalyst layer compared to its top is deduced from SEM images. Despite the poor catalytic activity of the top-surface, these considerations led us to conclude more catalytic activity of the sub-surface.     

Improving Blood Compatibility of Polyethersulfone Hollow Fiber Membranes via Blending with Sulfonated Polyether Ether Ketone

Appropriate membrane for blood contacting applications requires hemocompatibility and high permeation flux; it should inhibit proteins or platelets adsorption and still possess high permeability. Aiming to improve the polyethersulfone (PES) hollow fiber membrane hemocompatibility, sulfonated polyether ether ketone (SPEEK) is self‐synthesized in the present research and added to PES in different ratios. Scanning electron microscopy images have revealed significant changes in PES membranes structure after addition of SPEEK, which can influence water permeation property of the membranes. Water contact angles of the membranes have reduced from 75° to 50° after addition of 4 wt% SPEEK. Influence of SPEEK addition on hemocompatibility of the PES membranes is evaluated via protein (bovine serum albumin) adsorption, platelet attachment, and coagulation time (APTT and TT) assays. Obtained results reveal that hemocompatibility of the modified hollow fiber membranes is enhanced as a result of emerging repulsive forces between negative charges on the membranes surface and negatively charge blood components.

     

Synthesis of biocompatible and degradable microspheres based on 2‐hydroxyethyl methacrylate via microfluidic method

Monodisperse poly(2‐hydroxyethyl methacrylate), p‐HEMA, microspheres in size ranging from 16 to 340 (μm) were synthesized by in situ emulsion photopolymerization of HEMA monomer with polyethylene glycol diacrylate (p‐EGDA) by means of a three‐dimensional microfluidic flow‐focusing device. An aqueous solution of HEMA, p‐EGDA as chain extender and UV‐photoinitiator serving as dispersed phase formed microdroplets in a continuous oil phase mainly consisting of n‐heptane. A downward coaxial orifices design in the device led to confinement of the reaction admixtures thread to central axis of the microchannels. This design strategy could solve the wetting problem of dispersed phase with the microchannels leading to a successful production of monodisperse microspheres with size variation of less than 4%. The effects of concentration of p‐EGDA, surfactant, and flow rate ratios on microsphere size were examined. It was observed that increasing the concentration of p‐EGDA slightly increases the size whereas increasing the flow rate ratios of continuous to dispersed phase effectively decreases the size of microspheres. The rapid continuous synthesis of p‐HEMA based microspheres via the microfluidic route with reliable control over size, size distribution, and composition opens new doors for mass production of biocompatible and degradable polymeric microspheres for enormous biotechnological applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40925.     

Rheological,crystal structure,barrier, and mechanical properties of PA6 and MXD6 nanocomposite films

In this study, rheological, crystal structure, barrier, and mechanical properties of polyamide 6 (PA6), poly(m‐xylene adipamide) (MXD6) and their in situ polymerized nanocomposites with 4 wt % clay were studied. The extent of intercalation and exfoliation as well as type of crystals, crystallinity, and thermal transitions were investigated using X‐ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. Dynamic rheological measurements revealed that incorporation of nanoclay significantly increases complex viscosity of MXD6 nanocomposites at low frequencies, which was related to the formation of a nanoclay network and exchange reaction between MXD6 chains. The comparative study of dynamic characteristics (G′ (ω) and G″ (ω)) for aliphatic and aromatic polyamide nanocomposites with their neat resins as well as the relaxation spectra for both polymer systems confirmed the possibility of the aforementioned phenomena. Although, the crystallinity of MXD6 films was lower as compared to PA6 films, the permeability to oxygen was more than 5 times better for the former. Incorporating 4 wt% clay enhanced the barrier property, tensile modulus, and yield stress of PA6 and MXD6 nanocomposite films in both machine and transverse directions without sacrificing much puncture and tear resistances. The PA6‐based films showed higher tear and puncture strength as compared to MXD6 films. POLYM. ENG. SCI., 54:2617–2631, 2014. © 2013 Society of Plastics Engineers     

Investigation of well test behavior in gas condensate reservoir using single-phase pseudo-pressure function

Gas condensate reservoirs present complicated thermodynamic behavior when pressure falls below the dew point pressure, due to fluid dropout and change in the fluid composition. Condensate blockage in the near wellbore region reduces the well deliverability. Mixture composition change in the reservoir makes the interpretation of well tests in gas condensate reservoirs a serious challenge. In this study, at first the capillary number effect and Non-Darcy Flow on compositional simulation of gas condensate reservoirs were investigated and then well test analysis was carried out. The main objective of this work was to examine gas condensate well test analysis using single-phase gas pseudo-pressure and radial composite model assuming capillary number effect and Non-Darcy Flow. For this purpose some fluid samples were selected and results compared. Results indicate that estimation of reservoir properties below the dew point is in good agreement with actual input, particularly for lean fluid samples.     

Efficient loading and entrapment of tamoxifen in human serum albumin based nanoparticulate delivery system by a modified desolvation technique

Herein, the poorly water-soluble drug, Tamoxifen (Tmx), was loaded in the amphipathic matrix of human serum albumin (HSA) nanoparticles by a modified desolvation method. In order to enhance the drug loading (DL) and drug entrapment efficiency (DEE) (<2% and 10%, respectively), ultrasonication of Tmx-HSA mixture was performed prior to desolvation process. Tmx loading and entrapment efficiency were optimized by employment of the response surface methodology (RSM)-central composite design (CCD) of experiments. Under the optimum conditions of 1.59 mg Tmx/ml concentration, 7.76 pH and 5 h incubation of HSA-Tmx, the DL of 6.7% and DEE of 74% are achievable. Particles with the average size of 195 nm, zeta potential of −21 mV and polydispersity index of 0.09 were produced under these conditions. A more sustained Tmx release behavior was observed from polyethylene glycol (PEG) conjugated nanoparticles in comparison to the non-PEGylated ones. The short-term stability investigation showed no alteration in physicochemical properties of nanoparticles at 4 and 37 °C, but small increase in nanoparticles size was observed after three months of storage at room temperature. This is the first report for efficient production of a Tmx delivery system based on HSA nanoparticles.     

The use of biomass and stillage recycle in conventional ethanol fermentation

Modifications of the conventional ethanol fermentation process using biomass and stillage recycle were investigated and the advantages of the technique were studied. The biomass recycle method resulted in a reduction in the use of approximately 8% raw material (molasses). The recycle of 15–70% of stillage (dealcoholised) from a previous fermentation was also tested successfully. Generally the results of these experiments revealed 13–47% less water consumption and consequently about 13–47% reduction of stillage volume, which was more economical for further treatments.