Enhanced adsorption of perfluorooctanoic acid using functionalized imidazolium iodide ionic liquid-based poly (glycidyl methacrylate)

Per- and polyfluoroalkyl substances (PFASs) are among the emerging pollutants of public health and the environment due to environmental persistence, bioaccumulation, and potential toxicity. Removal of PFAS under mild conditions is a challenge. Therefore, employment of organic functionality immobilized on polymeric sorbents has driven significant attention. Herein, new imidazolium-based ionic liquid (IIL) covalently grafted on poly (glycidyl methacrylate) (PGMA) support was synthesized successfully and characterized by Fourier transform infrared, scanning electron microscope, and thermal gravimetric analysis. The functionalized imidazolium ionic liquid-based PGMA was applied in perfluorooctanoic acid (PFOA) removal from an aqueous solution. The effect of contact time, adsorbent dose, temperature, pH, and counter anions investigated on the extent of adsorption has been investigated. The concentration of PFOA solutions was measured by ethyl violet active substances assay, and equilibrium data were analyzed by Langmuir, Freundlich and Tempkin isotherms. The experimental results have been fitted to Langmuir model at ambient temperature and the maximum monolayer coverage capacity (q_m) was found to be 769.23 mg/g. Also the thermodynamic parameters were obtained, and observed that the adsorption of PFOA onto imidazolium iodide-PGMA was an endothermic and spontaneous process at the temperatures under investigation.     

Novel 0D/1D ZnBi2O4/ZnO S-scheme photocatalyst for hydrogen production and BPA removal

Developing interfacial connections is one of the breakthrough strategies to improve the photocatalytic activity. Herein, ZnBi₂O₄ nanoparticles-ZnO nanorods heterojunction was successfully synthesized and used, as a dual-function photocatalyst, for photocatalytic degradation of Bisphenol A and hydrogen production with improved photocatalytic activity under simulated sunlight irradiation. The highest H₂ production (3.44 mmol g^?1 h^?1) was obtained for ZnO-20 wt% ZnBi₂O₄ sample, which is around 12.7 times higher than pure ZnO. According to the HRTEM result, the intimate interfacial connections are formed between ZnO and ZnBi₂O₄ which could act as trapping centers for charge carriers and results in the boosted photocatalytic activity. Further, a high aspect ratio of 1D ZnO nanorods and small size of 0D ZnBi₂O₄ nanoparticles (~10 nm) increases the number of interfacial contacts and thus the charge carriers’ recombination was suppressed more efficiently. Based on the trapping experiments, ESR and Mott-Schottky analysis, ZnBi₂O₄–ZnO hybrid photocatalyst followed the S-scheme charge transfer mechanism.     

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.     

Elastic analysis of FGM rotating cylindrical pressure vessels

Abstract

In this paper, stresses in isotropic rotating thick‐walled cylindrical pressure vessels made of functionally graded material are obtained as a function of radial direction by using the theory of elasticity. The pressure, inner radius and outer radius are considered constant. Material properties are considered as a function of the radius of the cylinder to a power law function and the Poisson's ratio is assumed as constant. The analytical solution of the Navier equation is obtained for the conditions of plane strain, plane stress and the cylinder with closed ends. Following this, profiles are plotted for different values of the powers of the module of elasticity for the radial displacement, radial stress, and circumferential stress, as a function of radial direction.     

Evaluation of wool nanoparticles incorporation in chitosan/gelatin composite films

The aim of this work was to develop chitosan/gelatin composite films embedded with various amounts of wool nanoparticles, which were produced by an environmental friendly process. Films loaded with wool nanoparticles were subjected to physiochemical, biological, and mechanical characterization. The obtained results showed that incorporation of wool nanoparticles into chitosan/gelatin composite led to a reduction in swelling, moisture content and dissolution degree of the films. In vitro degradation test revealed that the nanoparticles‐embedded composites had a lower degradation rate than that of chitosan/gelatin composite. Besides, composite films containing wool nanoparticles showed an improvement in the stability in phosphate buffered saline. On the other hand, tensile strength and elongation at break decreased upon loading the films with wool nanoparticles. The biocompatibility of the produced composites was also confirmed by MTT test. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40294.     

Brownian Motion Effects on Natural Convection of Alumina–Water Nanofluid in 2‐D Enclosure

This article reports a numerical study of natural convection heat transfer in a differentially heated enclosure filled with a Al₂O₃–water nanofluid. Fluent v6.3 is used to simulate nanofluid flow. Simulations have been carried out for the pertinent parameters in the following ranges: the Rayleigh number, Ra = 10⁶, 10⁷, and the volumetric fraction of alumina nanoparticles, ? = 0 ? 4%. The effect of Brownian motion on the heat transfer is considered and examined. The numerical results show a decrease in heat transfer with an increase in particle volume fraction. Similar to experimental results, the Nusselt number increases with the Rayleigh number in the numerical results. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21121     

Ratcheting behavior of cylindrical pipes based on the Chaboche kinematic hardening rule

In this study, cyclic loading behavior of thick cylindrical pipes are described. Effects of internal pressure level and axial strain amplitude on the ratcheting rate under different types of loading histories are investigated. The kinematic hardening theory based on the Chaboche model is used to predict the plastic behavior of the structures. An iterative method is developed to analyze the structural behavior under cyclic loading conditions based on the Chaboche kinematic hardening model.     

Simulation of deep level traps effects in quantum well transistor laser

In this paper, we present an analytical model to analyze the influence of deep level traps on the static and dynamic responses of transistor laser (TL). Our analyze is based on analytically solving the continuity equation and rate equations including the effect of the deep level trap (DLT), which incorporate the virtual states as a conversion mechanism. The results of simulation show that the main characteristics of laser such as threshold current, quantum efficiency, output power, and modulation bandwidth are affected by total density of traps in the active region.     

RFID-based localization with Non-Blocking tag scanning

The simple and cheap passive RFID tag systems have recently been used for efficient localization of indoor mobile robots, where each RFID tag stores its own absolute position and the mobile robot carrying an RFID reader scans the RFID tags to localize itself. The available localization schemes using passive RFID systems do not consider the scanning delay which may cause location estimation error, especially when the robot moves at a high speed. In this paper, a new Non-Blocking scanning (reading) scheme is proposed to avoid collisions so that the scanning delay, and consequently the localization error, can be reduced. This scheme avoids collisions among tag replies by assigning tag IDs based on the FCA coloring scheme. Theoretical and simulation studies indicate that the new Non-Blocking scheme combined with the new tag arrangement pattern can achieve a good RFID localization performance in terms of both estimation error and scanning delay with reduction of tag/reader required complexities.     

Quasi-classical modeling of molecular quantum-dot cellular automata multidriver gates

ABSTRACT: Molecular quantum-dot cellular automata (mQCA) has received considerable attention in nanoscience. Unlike the current-based molecular switches where the digital data is represented by the on/off states of the switches, in mQCA devices, binary information is encoded in charge configuration within molecular redox centers. The mQCA paradigm allows high device density and ultra-low power consumption. Digital mQCA gates are the building blocks of circuits in this paradigm. Design and analysis of these gates require quantum chemical calculations, which are demanding in computer time and memory. Therefore, developing simple models to probe mQCA gates is of paramount importance. We derive a semi-classical model to study the steady-state output polarization of mQCA multidriver gates, directly from the two-state approximation in electron transfer theory. The accuracy and validity of this model are analyzed using full quantum chemistry calculations. A complete set of logic gates, including inverters and minority voters, are implemented to provide an appropriate test bench in the two-dot mQCA regime. We also briefly discuss how the QCADesigner tool could find its application in simulation of mQCA devices.