A novel ternary mixed-matrix membrane comprising Pebax-1657, [HMIM][NTf2] IL,and Al2O3 nanoparticles for efficient CO2 separation

An innovative technique to efficiently remove CO₂ involves introducing a third component with a positive affinity with CO₂ into a binary mixed-matrix membrane (MMM) and eliminating interfacial defects in its structure. In this research, novel ternary MMMs (TMMMs) were synthesized by embedding 1–Hexyl–3–methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][NTf₂]) ionic liquid (IL) and aluminum oxide (γ–Al₂O₃) nanoparticles into poly (ether-block-amide) (Pebax-1657) matrix for enhancing CO₂ removal from light gases. FESEM, DSC, ATR-FTIR, and XRD analyses were used to evaluate the fabricated MMMs structurally. The permeation tests of gases (CH₄, N₂, and CO₂) through prepared membranes were conducted at 25°C and 4, 6, 8, and 10 bar pressures. In accordance with the permeation outcomes, the ternary MMMs exhibited enhanced CO₂ separation performances compared to the unloaded polymeric membrane. Also, the optimized MMM comprising 10 wt.% of the IL and 6 wt.% of the nanoparticles obtained a CO₂ permeability of 173.90 Barrer, as well as CO₂/N₂ and CO₂/CH₄ selectivities of 77.98 and 24.29 at 10 bar and 25°C, which are higher by about 51%, 23%, and 22%, respectively than those of the pristine polymeric membrane. Based on these results, the prepared membrane appears to be a promising choice for separating CO₂ from light gases.     

STUDY ON THE ACETYLENE HYDROGENATION PROCESS FOR ETHYLENE PRODUCTION: SIMULATION,MODIFICATION, AND OPTIMIZATION

In this study, an industrial acetylene hydrogenation unit is simulated utilizing three available kinetic models. The results are compared against six-day experimental data and the best model is selected. Effects of feed temperature and the amount of injected hydrogen on ethylene selectivity are also studied. According to the simulation results, the unit is not working under its optimum conditions. Furthermore, by reduction of the hydrogen flow rate to 52 kg/h, process selectivity is increased. In addition, a new approach is proposed to modify the hydrogenation process and reduce undesired by-products. In the simulation of the modified process, hydrogenation reactors temperature, hydrogen flow rate, and H-1/H-2 ratio were regulated as adjustable parameters for the process optimization. The simulation shows that ethylene selectivity increases by 12%, while acetylene concentration and hydrogenation reactor temperature remains within acceptable ranges. Such selectivity could be achieved at the hydrogen flow rate of 50 kg/h with H-1/H-2 ratio of 0.1/0.9.     

Influence of structure on release profile of acyclovir loaded polyurethane nanofibers: Monolithic and core/shell structures

In this study, monolithic and core/shell polyurethane (PU) nanofibers were fabricated by single and coaxial electrospinning techniques, respectively. An antivirus drug, Acyclovir (ACY), was loaded on PU nanofibers. The physical condition and interaction of the loaded ACY within these nanofibers were studied by FTIR, XRD, DSC, SEM, and TEM. In vitro tests exhibited an obvious difference in the release pattern between monolithic and core/shell nanofibers and burst release in monolithic nanofibers could be controlled by core/shell structure. Release profile was found to follow Korsmeyere‐Peppas model with Fickian diffusion mechanism. Our study demonstrated that the ACY‐loaded core/shell nanofibers might serve as a device for drug delivery systems. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44073.     

Biodiesel Production: Effects of the Feeding Process on Biomass and Lipid Productivity

Large‐scale biomass production and sewage refining for use in landscaping by employing Chlorella vulgaris were investigated. The effects of the concentrations of carbon, nitrogen, and phosphorus as nutrients in the process were optimized by central composite design. In general, the results revealed that higher amounts of biomass can be obtained by varying the feed concentration; both the N and P concentrations have an effective role in improving the biomass dry weight. The amount of lipid productivity varied from 12 % to 55 %, and one of the photobioreactors tested showed the best conditions for lipid productivity. Also, this process can decrease the greenhouse gas emissions in wastewater treatment.     

Effects of parameters on yield for sub-critical R134a extraction of palm oil

Extraction of palm oil from its palm mesocarp using sub-critical 1,1,1,2-tetrafluoroethane (R134a) as an alternative solvent to supercritical CO₂ was studied. The effects of pressure, temperature, flowrate and sample pre-treatment method on extraction yield were examined. Dynamic method was used to determine palm oil solubility at flowrate between 0.5 and 5.0 ml/min. Extraction was performed at pressures between 45 and 100 bar which was lower than those required by CO₂ solvent, and at temperatures between 40° and 80 °C. The results show that extraction yields using R134a increased with pressure and temperature, and that temperature effect (p-value = 0.0000) on palm oil solubility prevailed over that of pressure (p-value = 0.0087). The maximum yield of 66.06 w/w% was obtained at 100 bar and 80 °C which was the best pressure and temperature. Substantial oil yields at relatively lower pressure proved that sub-critical R134a is a viable alternative to CO₂ for extraction of palm oil.     

Optimized and decentralized pulse control of seismically excited steel structures

The idea of decomposing a centralized complicated system into several synchronous decentralized subsystems has been resulted into the development of decentralized control methods. In this study, a decentralized pulse control scheme is presented based on the theory of Inclusion Principle for steel systems comprising a multi-overlapping structure. The proposed control algorithm is basically an active control system that generates corrective pulses at each moment when the displacement or acceleration exceeds the predefined threshold. In order to evaluate the performance of proposed control system, a numerical study is conducted. The control system is implemented for two linear structural models of five- and twenty-story steel buildings. An optimization algorithm (PSO) is also used to determine the locations of required control inputs in the 20-story building. The results show that the proposed algorithm can substantially mitigate the structural response under different earthquake records (for 5-story model) and different subsystem configurations (for 20-story model).     

An investigation on the correlation between rheology and morphology of nanocomposite foams based on low‐density polyethylene and ethylene vinyl acetate blends

This article presents the correlation between rheology and morphology of nanocomposite foams of low‐density polyethylene (LDPE), ethylene vinyl acetate (EVA), and their blends. LDPE/EVA nanocomposites were prepared via melt mixing and then foamed using batch foaming method. To assess the rheological behavior of polymer melts, frequency sweep and creep recovery tests were done. Morphology of the samples was also studied by scanning electron microscopy and X‐ray diffraction. The results showed that with increase in clay content, storage modulus, complex and zero shear viscosities will be increased, which affect the foam morphology. In addition, elasticity plays an important role in foaming process, in a way that samples with more elasticity percentage have the highest cell density and the lowest cell size. POLYM. COMPOS., 31:1808–1816, 2010. © 2010 Society of Plastics Engineers.