We have developed an integrated microfluidic platform for producing 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) in continuous flow from a single bolus of radioactive isotope solution, with constant product yields achieved throughout the operation that were comparable to those reported for commercially available vessel-based synthesisers (40-80%). The system would allow researchers to obtain radiopharmaceuticals in a dose-on-demand setting within a few minutes. The flexible architecture of the platform, based on a modular design, can potentially be applied to the synthesis of other radiotracers that require a two-step synthetic approach, and may be adaptable to more complex synthetic routes by implementing additional modules. It can therefore be employed for standard synthesis protocols as well as for research and development of new radiopharmaceuticals.
The phase behavior of ternary water−alkyl methacrylate−alkyl polyglycol ether (C i E j ) systems has been examined. Specifically, using seven different alkyl methacrylates ranging from methyl to hexadecyl methacrylate and C10E6 as surfactant, vertical sections through the phase prism were determined, from which the phase inversion temperature, the upper and lower critical temperature of the three-phase body, and the efficiency of the surfactant and its monomeric solubility in the oil were obtained. Keeping hexyl methacrylate as oil-fixed, 18 different surfactants were applied including short- and long-chain surfactants such as C4E3 and C14E8. The microemulsion systems examined here show the same general patterns as the well-known nonionic microemulsions with alkanes as oil. Notably, the phase inversion temperature is highly dependent on the alkyl chain length of the oil, a fact that is often left out of consideration when choosing a surfactant in emulsion polymerization. For a given oil the phase inversion temperature can be adjusted by appropriate choice of the number of ethylene glycol units of the surfactant. The efficiency of the surfactant systematically depends on the alkyl chain length of both the surfactant and the oil. Interestingly, there is a striking parallel between efficiency of a surfactant and its monomeric solubility in the oil. Finally, in preparation for applying these systems to the synthesis of nanoscaled latexes in microemulsion polymerization the water-rich part of the phase prism was examined. Both the expected shape of the emulsification failure phase boundary and the near-critical phase boundary with its nonmonotonic decay characteristic of branched network structures are delineated. The results of some preliminary polymerizations are briefly discussed.
In this work we demonstrate a continuously operating microfluidic device for solvent removal and exchange for chemical syntheses by means of a supporting gas. The glass device consists of three sections: (i) three merging microchannels to create an annular gas-liquid stream; (ii) a serpentine channel with a heater underneath to allow efficient evaporation of the volatile solvent; (iii) a section with side capillaries to separate the liquid from the gas phase. We demonstrate the performance of the device for the removal of acetonitrile from an acetonitrile-water mixture. We achieved efficient removal of acetonitrile within a few seconds for flow rates of 20-30 mL min 21 and a nitrogen pressure of 1.2 bar. In three steps, acetonitrile was reduced from 50 wt% in the feed solution to 1 wt% in the final solution. We believe that the device can be easily applied to other solvent mixtures.
Microemulsions are thermodynamically stable, macroscopically isotropic mixtures of at least two immiscible components and a surfactant. Their general features, i.e. the complex phase behavior, the ultralow interfacial tensions, and the multifarious nanostructure, have been systematically elucidated in the last century. However, the efficient solubilization of long-chain n-alkanes and waxes, which plays a significant role in enhanced oil recovery, washing, and cosmetics, remains a challenge. Thus, in this work the influence of the n-alkane chain length k on the phase behavior of ternary (symmetric) microemulsions containing equal volumes of water and oil was studied. Using n-alkanes ranging from n-dodecane (C 12 H 26 ) to n-dotriacontane (C 32 H 66 ) and pure n-alkyl polyglycol ether (C i E j ) surfactants, we found that the efficiency of the respective surfactant decreases linearly with increasing k, while the phase inversion temperature (PIT) shows a logarithmic dependence. The influence of a technical wax on the phase behavior was studied by means of the systems H 2 O−SASOLWAX 5805 (Sasol)−C 16 E 6 yielding an equivalent alkane carbon number (EACN (SASOLWAX 5805)) of 30.8. Finally, the pure C i E j surfactants were replaced with technical grade counterparts of the Genapol series (Clariant) finding that the solubilization efficiency of the long-chain Genapol O 080 is comparable to the pure C 16 E 6 surfactant. Using small-angle neutron scattering (SANS) the microstructure of the formulated microemulsions was studied near the so-called optimum (X ̃) point. The scattering curves prove that microemulsions containing long-chain n-alkanes and waxes are also bicontinuously structured at the phase inversion temperature (PIT). Interestingly, a high degree of structural ordering is found reflected by values of the amphiphilicity factor f a ranging between −0.83 and −0.87.
In this work, we report on air/N 2 gasification of a byproduct stream from an industrial fermenter in a tubular microwave plasma reactor to investigate the feasibility of the technology for organic compounds valorization, given the limited number of relevant works in the literature. In this context, an operating window defined by air/N 2 /biomass flow rates and power input has been identified to enable stable and efficient operation. Up to 89% carbon conversion efficiency and 41% cold gas efficiency have been attained with syngas product composition H 2 :CO:CO 2 = 41:53:6, fairly close to the calculated equilibrium composition values in the temperature range 973 K to 2173 K.
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