Browsing by Author "Vladisavljevic, Goran T."
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Item Open Access Eco-friendly fabrication of highly selective amide-based polymer for CO2 capture(American Chemical Society, 2019-09-05) Fayemiwo, Kehinde; Chiarasumran, Nutchapon; Nabavi, Seyed Ali; Loponov, Konstantin N.; Manovic, Vasilije; Benyahia, Brahim; Vladisavljevic, Goran T.Porous polymeric adsorbents for CO2 capture (HCP-MAAMs) were fabricated by co-polymerisation of methacrylamide (MAAM) and ethylene glycol dimethacrylate (EGDMA) using acetonitrile and azobisisobutyronitrile as a porogen and initiator, respectively. The X-ray photoelectron and Fourier transform infrared spectra revealed a high density of amide groups in the polymer matrix of HCP-MAAMs, which enabled high selectivity to CO2. The polymers BET surface area and total pore volume was up to 277 m2 g-1 and 0.91 cm3 g-1, respectively. The highest CO2 uptake at 273 K and 1 bar CO2 pressure was 1.45 mmol g-1 and the heat of adsorption was 27-35 kJ mol-1. The polymer with the lowest crosslinking density exhibited unprecedented CO2/N2 selectivity of 394 at 273 K. Life cycle assessment revealed a lower environmental impact of HCP-MAAMs compared to molecularly imprinted polymers. HCP-MAAMs are eco-friendly CO2 adsorbents owing to their low regeneration energy, environmentally benign fabrication process, and high selectivity.Item Open Access Mechanisms and control of single-step microfluidic generation of multi-core double emulsion droplets(Elsevier, 2017-04-04) Nabavi, Seyed Ali; Vladisavljevic, Goran T.; Manovic, VasilijeSingle-step generation of monodisperse multi-core double emulsion drops in three-phase glass capillary microfluidic device was investigated using a micro-particle image velocimetry (micro-PIV) system. Phase diagrams were developed to predict the number of encapsulated inner drops as a function of the capillary numbers of inner, middle and outer fluid. The maximum stable number of inner drops cores in uniform double emulsion drops was six. Starting from core/shell drops, the formation of double emulsion drops with multiple cores was achieved by decreasing the capillary number of the outer fluid and increasing the capillary number of the middle fluid. A stable continuous jet of the middle fluid loaded with inner drops was formed at high capillary numbers of the middle fluid. Empirical correlations predicting the size and generation frequency of inner drops as a function of the capillary numbers and the device geometry were developed. Dual-core double emulsion drops were used as templates for the fabrication of polymeric capsules using “on-the-fly” photopolymerisation. The capsule morphology was controlled by manipulating the stability of the inner drops through adjusting the concentration of the lipophilic surfactant in the middle fluid. At low concentration of the lipophilic surfactant, inner drop coalesced during curing and single compartment capsules with thin shells were produced from dual-core drops. The core/shell capsules produced from multi-core drops were monodispersed and larger than those produced from core/shell drops in the same device.Item Open Access Prediction and control of drop formation modes in microfluidic generation of double emulsions by single-step emulsification(Elsevier, 2017-06-01) Nabavi, Seyed Ali; Vladisavljevic, Goran T.; Bandulasena, Monalie V.; Arjmandi-Tash, Omid; Manovic, VasilijeHypothesis Predicting formation mode of double emulsion drops in microfluidic emulsification is crucial for controlling the drop size and morphology. Experiments and modelling A three-phase Volume of Fluid-Continuum Surface Force (VOF–CSF) model was developed, validated with analytical solutions, and used to investigate drop formation in different regimes. Experimental investigations were done using a glue-free demountable glass capillary device with a true axisymmetric geometry, capable of readjusting the distance between the two inner capillaries during operation. Findings A non-dimensional parameter (ζζ) for prediction of double emulsion formation mode as a function of the capillary numbers of all fluids and device geometry was developed and its critical values were determined using simulation and experimental data. At logζlogζ > 5.7, drops were formed in dripping mode; the widening jetting occurred at 5 < logζlogζ < 5.7; while the narrowing jetting was observed at logζlogζ < 5. The ζζ criterion was correlated with the ratio of the breakup length to drop diameter. The transition from widening to narrowing jetting was achieved by increasing the outer fluid flow rate at the high capillary number of the inner fluid. The drop size was reduced by reducing the distance between the two inner capillaries and the minimum drop size was achieved when the distance between the capillaries was zero.Item Open Access Production of molecularly imprinted polymer particles with amide-decorated cavities for CO2 capture using membrane emulsification/suspension polymerisation(Elsevier, 2016-05-14) Nabavi, Seyed Ali; Vladisavljevic, Goran T.; Wicaksono, Agni; Georgiadou, Stella; Manovic, VasilijeHighly uniform amide-based molecularly imprinted polymer (MIP) particles containing CO2-philic cavities decorated with amide groups were produced using membrane emulsification and subsequent suspension polymerisation. The organic phase containing acrylamide (functional monomer), oxalic acid (dummy template), ethylene glycol dimethacrylate (crosslinker) and azobisisobutyronitrile (initiator) dissolved in a 50/50 mixture (by volume) of acetonitrile and toluene (porogenic solvents) was injected through a microengineered nickel membrane with a pore diameter of 20 μm and a pore spacing of 200 μm into agitated 0.5 wt% aqueous solution of poly(vinyl alcohol) to form droplets that have been polymerised at 60 °C for 3 h. The volume median diameter of the droplets was controlled between 35 and 158 μm by shear stress at the membrane surface. The droplets maintained their physical stability during storage for 4 weeks and their size was independent of the dispersed phase content. The particle size after polymerisation was consistent with the initial droplet size. The particles were stable up to 210 °C and had a specific surface area of 239 m2/g and a CO2 capture capacity of 0.59 mmol/g at 273 K and 0.15 bar CO2 partial pressure.