A state-of-the-art review on single drop study in liquid–liquid extraction:Experiments and simulations

The experimental and numerical investigations of single drop in liquid/liquid extraction system have been reviewed with particular focus on experimental techniques and computational fluid dynamic simulation approaches.Comprehensive surveys of available experimental techniques and numerical approaches for single drop rising and falling were given.Subsequently,single drop mass transfer was also reviewed both experimentally and numerically.Additionally,single drop breakage and coalescence process and the influencing factors were summarized and compared,so as to establish sub-models for population balance model.Future directions on single drop mass transfer,drop breakage and coalescence were suggested.It is believed that the single drop is a powerful tool to assist extraction process design from lab-scale to pilot-scale.

Efficient fixation of CO_(2) into propylene carbonate with [BMIM]Br in a continuous-flow microreaction system

Utilization of carbon dioxide(CO_(2)) is of great significance in the development of CO_(2) absorption and the solution of greenhouse gas effect.Highly efficient conversion of CO_(2) into cyclic carbonate with green catalysts is essential for the more sustainable expansion of CO_(2) fixation.Traditional batch reactor is limited by low efficiency, high cost and low security. Meanwhile, continuous flow system showcased a myriad of virtues, including shortening the residence time from hours to seconds, and decreasing reaction temperature, and possessing the nature of easy industrial scale-up. In this paper, a continuous-flow microreaction system was developed to synthesis propylene carbonate(PC) from propylene oxide(PO) and CO_(2) using 1-butyl-3-methylimidazolium bromide([BMIM]Br) as catalyst. By observing the flow patterns inside microreaction system, the effects of reaction temperature, molar fraction of catalyst, operating pressure, residence time, molar ratio of CO_(2)/PO as well as recycling performance of catalyst on the overall performances were comprehensively evaluated into details. Under different reaction conditions,the flow patterns were set to vary between slug flow and annular flow. The results showed that the yield of propylene carbonate(PC) can reach99.7% at 140℃ and 3.0 MPa with the residence time of 166 s, while the recycling performance of the designed system greatly conforms the future trend of green chemistry.

Precipitation study of CO2-loaded glycinate solution with the introduction of ethanol as an antisolvent

Focused beam reflectance measurement(FBRM)and 13C nuclear magnetic resonance(13C NMR)analysis were used to study the precipitation process of CO2-loaded potassium glycinate(KGLY)solutions at different CO2 loadings,during the addition of ethanol as an antisolvent at a rate of 10 mL·min−1.The volume ratio of ethanol added to the KGLY solution(3.0 mol·L−1,340 mL)ranged from 0 to 3.0.Three solid-liquid-liquid phases were formed during the precipitation process.The FBRM results showed that the number of particles formed increased with CO2 loading and ethanol addition for CO2-unsaturated KGLY solutions,whilst for CO2-saturated KGLY solution it first increased then decreased to a stable value with ethanol addition.13C NMR spectroscopic analysis showed that the crystals precipitated from the CO2-unsaturated KGLY solutions consisted of glycine only,and the quantity crystallised increased with CO2 loading and ethanol addition.However,a complex mixture containing glycine,carbamate and potassium bicarbonate was precipitated from CO2-saturated KGLY solution with the maximum precipitation percentages of 94.3%,31.4%and 89.6%,respectively,at the ethanol volume fractions of 1.6,2.5 and 2.3.