Search results for "Chemical engineering"
showing 10 items of 5892 documents
Studies of Reversible Hydrogen Binding in Nano- Sized Materials
2015
Experimental review of materials suitable for reversible hydrogen binding in nanoporous and nanosized structures of materials, based on natural zeolite (clinoptilolite) and graphene (exfoliated electrochemically from raw graphite), were analyzed. Characterization of materials with SEM, XRD, EDS and Raman spectroscopy methods and aspects of synthesis of a nanostructured zeolite and a few-layer graphite material was done in this work. It was established from gas analyzer results that hydrogen mass fraction in natural zeolite ranged from 1.1 % to 1.4 %, but in the few-layer graphite material − from 0.39 % to 0.46 %.
Modelling the influence of nanoparticles in the phase behaviour of an epoxy/polystyrene mixture
2007
Abstract The cloud point temperatures of four series of epoxy/polystyrene blends have been experimentally determined as a function of polymer mass and system composition. The phase diagrams show an UCST behaviour, increasing incompatibility as the molar mass increases. The Flory–Huggins theory with a concentration-dependent interaction parameter has been developed to study the compatibility of two polymers in presence of spherical nanoparticles. This theory has been first compared with the experimental cloud point curve in absence of nanoparticles, and secondly it has been used to predict the thermodynamic behaviour in presence of different volume fraction of nanoparticles. Nanoparticles co…
Preparation, characterization and hydrolytic degradation of PLA/PCL co-mingled nanofibrous mats prepared via dual-jet electrospinning
2017
Abstract PLA/PCL co-mingled nanofibrous mats were prepared via multi-jet electrospinning. The concentration of PLA and PCL in the co-mingled mats were controlled by changing the flow rate of the two polymer solutions. The amount of PLA and PCL in the co-mingled nanofibrous mats was monitored by UV–Vis measurements through a colored dye added to PLA and by FTIR-ATR analysis. Morphology and mechanical properties of the nanofibrous mats were respectively examined by scanning electron microscopy (SEM) and tensile tests. Water contact angles measurements were also carried out in order to investigate the wettability of the materials. Finally, the hydrolytic degradation of the mats in buffer solut…
Experimental analysis of bubble size distributions in 2D gas fluidized beds
2010
Abstract The present work focuses on the development of a novel statistical approach for the analysis of the behavior of a 2D fluidized bed operating under bubbling and slugging conditions. Experimental data were collected by means of a purposely built lab-scale 2D fluidized bed and an original digital image analysis technique (DIAT), allowing the acquisition of a number of data sufficient to perform a statistical analysis of bubble dynamics. In particular, measurements of bubble size distributions (BSD) along the bed were performed. The analysis allowed to characterize the shape of BSD for different particle systems and fluidization gas velocities; interestingly a bimodal shape of BSD is o…
Improving Separation of Oil and Water With a Novel Coalescing Centrifugal Pump
2018
Summary A novel centrifugal pump that increases oil-droplet sizes in produced water has been developed. This paper investigates a concept of pumping-pressure optimization, with respect to downstream separation efficiency, for the new pump. The investigation shows that the coalescing centrifugal pump always increased the separation efficiency of a downstream hydrocyclone. Furthermore, it is shown that the pumping pressure can be adjusted to maximize the improvement. Experimental results demonstrate how pumping conditions that minimize the volume fraction of droplets with a diameter smaller than the cut size of the hydrocyclone maximize the separation efficiency. Finally, it is demonstrated h…
Morphology of PEO/PDMS blends during shear: Coexistence of two droplet/matrix structures and additive effects
2005
Abstract The morphologies of blends of polyethyleneoxide (PEO 37) and poly(dimethylsiloxane)s (PDSM), with viscosity ratios, λ , of approximately one (PDMS 230) or 2.8 (PDMS 314, being the component of higher viscosity) and interfacial tensions on the order of 10 mN/m, were investigated at 70 °C as a function of shear rate (up to 10 s −1 ) and of time. For the system PEO 37/PDMS 230 we have also studied the influence of the compatibilizer dimethyl–ethyleneoxide–copolymer (PDMS- co -PEO), which is only reasonably soluble in PEO. To investigate the morphologies we have used an optical shear cell in combination with a light microscope. The most important observation consists in the formation o…
EFFECT OF SURFACTANT AND SUBSTRATE TEMPERATURE ON THE GROWTH OF Ag FILMS ON A SAPPHIRE SURFACE
1997
The possibility of modification of the thin film growth on an insulating (sapphire) substrate by using a Ga monolayer as a "surfactant" was studied. We found that the films grown in this way are electrically conducting and can emit photoelectrons at much lower thickness than those deposited on a pure substrate. The surfactant stabilizes the positions of Ag atoms on the substrate surface and inhibits the coalescence of small nuclei into bigger islands, even when the film is annealed to 450 K. This fact may be very important for thin metal film technology.
Automatic Operation and Control of a Novel Coalescing Centrifugal Pump for Improved Oil/Water Separation
2019
Summary In this paper we present the development and implementation of automatic operation and control for a pump/hydrocyclone produced-water-treatment system to maximize oil/water-separation efficiency. A so-called perturb-and-observe (P&O) algorithm is adapted for a novel centrifugal pump to continuously optimize the point of operation. The novel pump coalesces and increases the size of oil droplets in the produced water, resulting in a unique relationship between the coalescing effect and the point of operation, and allowing for the successful implementation of the P&O algorithm. The algorithm was implemented in two different setups, one measuring the droplet-size distribution be…
Properties of treated papers and plastic film influencing ethyl ester transfer
2008
Abstract The objective of this work was to compare and understand the aroma compound barrier property of two impregnated–supercalendered papers, with or without surface coating, and one plastic film (BOPP) in standard conditions of temperature (25 °C) and relative humidity gradient (50%) for foodstuff storage. For that purpose, solubility, diffusivity and permeability coefficients were determined for a homologous series of ethyl esters with a range of physico-chemical properties and vapor concentrations. Whatever the aroma compound and its vapor concentration, the non-coated paper was the more permeable; the coated paper and BOPP presenting close and lower permeability values. The transfer …
Effect of environmental humidity and coating on aroma transfer through treated papers
2012
Abstract Coupled transfers of aroma compounds and water vapour were investigated by varying the relative humidity gradient of storage (50% or 90%) of two paper packaging at 25 °C. These papers differed in their coating surface: both were identically impregnated then supercalendered, and only one was twice coated on both sides with a synthetic barrier substance. Permeability and solubility coefficients were determined. The coating treatment was more effective to decrease the permeabilities of water vapour and ethyl ester than the effect of RH. On the contrary, the RH modified the water content of the treated papers and affected more strongly their permeability and solubility to cis-3-hexenol…