Nitrogen-rich hyper-crosslinked polymers for low-pressure CO2 capture

A series of poly[methacrylamide-co-(ethylene glycol dimethacrylate)] (poly(MAAM-co-EGDMA)) porous polymeric particles with high CO2-philicity, referred to as HCP-MAAMs, were synthesised for CO2 capture. The polymers with a MAAM-to-EGDMA molar ratio from 0.3 to 0.9 were inherently nitrogen-enriched and exhibited a high affinity towards selective CO2 capture at low pressures. A techno-economic model based on a 580 MWel supercritical coal-fired power plant scenario was developed to evaluate the performance of the synthesised adsorbents. The presence and density of NH2 moieties within the polymer network were determined using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The thermogravimetric analysis (TGA) showed that the polymers were thermally stable up to 515–532 K. The maximum CO2 adsorption capacity at 273 K was 1.56 mmol/g and the isosteric heat of adsorption was 28–35 kJ/mol. An increase in the density of amide groups within the polymer network resulted in a higher affinity towards CO2 at low pressure. At a CO2:N2 ratio of 15:85, CO2/N2 selectivity at 273 K was 52 at 1 bar and reached 104 at ultra-low CO2 partial pressure. The techno-economic analysis revealed that retrofitting a HCP-MAAM-based CO2 capture system led to a net energy penalty of 7.7–8.0%HHV points, which was noticeably lower than that reported for MEA or chilled ammonia scrubbing capture systems. The specific heat requirement was superior to the majority of conventional solvents such as MDEA-PZ and K2CO3. Importantly, the economic performance of the HCP-MAAM retrofit scenario was found to be competitive to chemical solvent scrubbing scenarios

Continuous Membrane Emulsification with Pulsed (Oscillatory) Flow

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial and Engineering Chemistry Research, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: http://dx.doi.org/10.1021/ie3020457Tubular micrometer pore sized sieve type membranes with internal diameter of 14 mm and length of 60 mm containing uniform pores of diameter 10 and 20 μm were used to generate emulsions of sunflower oil dispersed in water and stabilized by Tween 20 using oscillatory flow of the continuous phase. Drop diameters between 30 and 300 μm could be produced, in a controllable way and with span values of down to 0.4. By using pulsed flow it was possible to provide dispersed phase concentrations of up to 45% v/v in a single pass over the membrane, that is, without the need to recirculate the continuous phase through the membrane tube. It was possible to correlate the drop size produced with the shear conditions at the membrane surface using the wave shear stress equation. The oscillatory Reynolds number indicated flow varying from laminar to substantially turbulent, but the change in flow conditions did not show a notable influence on the drop diameters produced, over what is predicted by the varying wall shear stress applied to the wave equation. However, the 20 μm pore sized sieve type membrane appeared to allow the passage of the pressure pulse through the membrane pores, under certain operating conditions, which did lead to finer drop sizes produced than would be predicted. These through-membrane pulsations could be suppressed by changes in operating conditions: a higher dispersed phase injection rate or more viscous continuous phase, and they did not occur under similar operating conditions used with the 10 μm pore sized sieve type of membrane. Generating emulsions of this size using pulsed continuous phase flow provides opportunities for combining drop generation at high dispersed phase concentration, by membrane emulsification, with downstream processing such as reaction in plug flow reactors

Visual metaphor and authoritarianism in Serbian political cartoons

This article examines how political cartoons reflected and mobilized resistance to growing authoritarianism and the personalization of power in contemporary Serbia. The focus is on the work of Dušan Petričić, the most influential political cartoonist in Serbia, which was published in daily Politika and weekly NIN between 2012 and 2017. Petričić’s cartoons offer interesting insights into a dramatic decline of press freedom and the rise of authoritarian personalist rule in terms of both their content and political impact. The authors draw on quantitative content analysis and qualitative multimodal analysis to examine the key representational and stylistic features of Petričić’s cartoons, both as a way to understand the relationship between his aesthetics and his political statements, and in order to critically assess some of the ways in which democratization conflicts may be expressed visually. Their analysis also draws on evidence from an in-depth interview with the author. In combining a systematic analysis of key visual patterns across a sample of cartoons with a comprehensive evaluation of how both visual and linguistic features work together to promote anti-authoritarian ideals and resistance, the article offers a framework to understand the political import of aesthetics in Serbia’s democratization process

Stirred cell membrane emulsification for multiple emulsions containing unrefined pumpkin seed oil with uniform droplet size

Stirred cell membrane emulsification was used to create double water-in-oil-in-water emulsions at the dispersed phase flux of up to 3200 L m(-2) h(-1). The oil phase was unrefined pumpkin seed oil or sunflower oil containing 30% by volume of internal water phase and the external water phase was 2% Tween 20 (polyoxyethylene sorbitan monolaurate) or 2% Pluronic F-68 (polyoxyethylene-polyoxypropylen copolymer). Using microengineered nickel membranes with pore sizes between 15 and 40 mu m, median drop sizes of double emulsion droplets were in the range between 100 and 430 mu m, depending mainly on the shear at the membrane surface and dispersed phase injection rate. In most cases the drops were very uniform, with span (i.e. 90% drop size minus 10% drop size divided by median size) values of around 0.5. This data is similar to what was obtained previously for simple O/W emulsions of the same materials. Hence, the internal water phase, and internal surfactant, 5% PGPR (polyglycerol polyricinoleate), did not adversely influence the emulsification process. A marker material, copper sulfate, was added to the internal water phase and the release of copper was monitored with respect to time. For both lipid systems, at the larger droplet size, there was a significant period of no copper release, followed by almost linear release with time. This initial period was absent when the drop size was close to 100 mu m. The initial entrapment efficiency of the copper, in all experiments, was higher than 94%. (C) 2011 Elsevier B. V. All rights reserved

Composite Norland Optical Adhesive (NOA)/silicon flow focusing devices for colloidal particle manipulation and synthesis

Microfluidic flow focusing devices are widely used to generate steep chemical concentration gradients at the interface between miscible or partially miscible streams. In this study, first we present an optimised protocol for the manufacturing of composite flow focusing devices, consisting of a micropatterned layer of Norland Optical Adhesive (NOA) glue bound to flat or microgrooved silicon substrates. Then, three different applications of these devices are demonstrated, namely (i) particle spreading and focusing in continuous flows past flat substrates, (ii) particle accumulation within the dead-end cavities of microgrooved substrates and (iii) synthesis of nano-sized liposomes. Colloidal particle spreading, focusing and accumulation were achieved through diffusiophoresis transport induced by salt concentration gradients at the interface between electrolyte streams. Epi-fluorescence microscopy was adopted to characterise the spatio-temporal distribution of silica and polystyrene nanoparticles in the devices with flat or microgrooved surfaces. The effects of particle zeta potential and groove thickness on particle dynamics were investigated. 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine (DOPC) liposomes were generated by hydrodynamic focusing and characterised via dynamic light scattering. Liposome populations with controlled narrow size distributions could be achieved by adjusting the flow rate conditions in the devices. This work demonstrates that composite NOA/silicon flow junction devices offer a competitive alternative to conventional PDMS chips and can support a wide range of microfluidic applications, including nanoparticle synthesis, characterisation and filtration, drug encapsulation and biochemical analysis

Controlled production of oil-in-water emulsions containing unrefined pumpkin seed oil using stirred cell membrane emulsification

Membrane emulsification of unrefined pumpkin seed oil was performed using microengineered flat disc membranes on top of which a paddle blade stirrer was operated to induce surface shear. The membranes used were fabricated by galvanic deposition of nickel onto a photolithographic template and contained hexagonal arrays of uniform cylindrical pores with a diameter of 19 or 40 mu m and a pore spacing of 140 mu m. The uniformly sized pumpkin seed oil drops with span values less than 0.4 were obtained at oil fluxes up to 640 L m(-2) h(-1) using 2 wt.% Tween 20 (polyoxyethylene sorbitan monolaurate) or 2-10 wt.% Pluronic F-68 (polyoxyethylene-polyoxypropylen copolymer) as an aqueous surfactant solution. Pumpkin seed oil is rich in surface active ingredients that can be adsorbed on the membrane surface, such as free fatty acids, phospholipids, and chlorophyll. The adsorption of these components on the membrane surface gradually led to membrane wetting by the oil phase and the formation of uniform drops was achieved only for dispersed phase contents less than 10 vol.% At high oil fluxes, Pluronic F-68 molecules present at a concentration of 2 wt.% could not adsorb fast enough, on the newly formed oil drops, to stabilise the expanding inter-face. (c) 2008 Elsevier B.V. All rights reserved