Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as well as economic...Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as well as economic pressures associated with VOCs. Solvents that are derived from biomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over con- ventional VOCs, such as low toxicity, biodegradability and renewability. This review aims to summarize the use of bio-derived solvents in solvent extraction applications, with special emphasis given to utilization of biodiesels and terpenes. Compared with the conventional VOCs, the overall performance of these bio-derived solvents is comparable in terms of extraction yields and selectivity for natural product extraction and no difference was found for metal extraction. To date most researchers have focused on laboratory scale thermodynamics studies. Future work is required to develop and test new bio-derived solvents and understand the kinetic performance as well as solvent extraction nilnt nlant studies.展开更多
The emission of large amounts of carbon dioxide is of major concern with regard to increasing the risk of climate change. Carbon capture, utilisation and storage (CCUS) has been proposed as an important pathway for sl...The emission of large amounts of carbon dioxide is of major concern with regard to increasing the risk of climate change. Carbon capture, utilisation and storage (CCUS) has been proposed as an important pathway for slowing the rate of these emissions. Solvent absorption of CO_2 using amino acid solvents has drawn much attention over the last few years due to advantages including their ionic nature, low evaporation rate, low toxicity, high absorption rate and high biodegradation potential, compared to traditional amine solvents. In this review, recent progress on the absorption kinetics of amino acids is summarised, and the engineering potential of using amino acids as carbon capture solvents is discussed. The reaction orders between amino acids and carbon dioxide are typ- ically between 1 and 2. Glycine exhibits a reaction order of 1, whilst, by comparison, lysine, proline and sarcosine have the largest reaction constants with carbon dioxide which is much larger than that of the benchmark solvent monoethanolamine (MEA). Ionic strength, p H and cations such as sodium and potassium have been shown to be important factors influencing the reactivity of amino acids. Corrosivity and reactivity with impurities such as SOx and NOxare not considered to be significant problems for amino acids solvents. The precipitation of CO_2 loaded amino acid salts is thought to be a good pathway for increasing CO_2loading capacity and cutting desorption energy costs if well-controlled. It is recommended that more detailed research on amino acid degradation and overall process energy costs is conducted. Overall, amino acid solvents are recognised as promising potential solvents for car- bon dioxide capture.展开更多
Using experimental data from a number of pulsed disc and doughnut solvent extraction columns, a unified correla- tion for the prediction of dispersed phase holdup that considers the effects of mass transfer is present...Using experimental data from a number of pulsed disc and doughnut solvent extraction columns, a unified correla- tion for the prediction of dispersed phase holdup that considers the effects of mass transfer is presented. Pulsed disc and doughnut solvent extraction columns （PDDC） have been used for a range of important applications such as ura- nium extraction and nuclear fuel recycling. Although the dispersed phase holdup in a PDDC has been presented by some researchers, there is still the need to develop a robust correlation that can predict the experimental dispersed phase holdup over a range of operating conditions including the effects of mass transfer direction. In this study, dis- persed phase holdup data from different literature sources for a PDDC were used to refit constants for the correlation presented by Kumar and Hartland lind. Eng. Chem. Res.,27 （1988）,131-138] which did not consider the effect of col- umn geometry. In order to incorporate the characteristic length of the PDDC （i.e. the plate spacing）, the unified cor- relation for holdup proposed by Kumar and Hartland based on data from eight different types of columns [Ind. Eng. Chem. Res.,34 （1995） 3925-3940] was refitted to the PDDC data. New constants have been presented for each hold- up correlation for a PDDC based on regression analysis using published holdup data from PDDCs that cover a range of onerating conditions and nhwical nronerties and consider the direction of mass transfer.展开更多
The fully developed mixed convection hybrid nanofluid flow in a vertical microchannel is examined in detail.The simplified hybrid model that omits the nonlinear terms due to the interaction of different nanoparticle v...The fully developed mixed convection hybrid nanofluid flow in a vertical microchannel is examined in detail.The simplified hybrid model that omits the nonlinear terms due to the interaction of different nanoparticle volumetric fractions is derived and compared with the existing one.The generalized model describing hybrid nanofluid suspended with multiple kinds of solid particles is suggested.The argument that the corresponding nanofluid solutions obtained by the homogenous model can be recovered from the results of the regular problems through simple arithmetic operations is checked.Solutions in similarity form for this flow problem are formulated by means of a set of similarity variables.The effects of various parameters on important physical quantities are analyzed and discussed.展开更多
The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process mo...The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process model utilised the Electrolyte Non-Random Two Liquid(ENRTL) thermodynamic model and various packing correlations. The results from the ACM equilibrium model shows good agreement with an inbuilt Aspen Plus?model when using the same input conditions. By further introducing a Murphree efficiency which is related to mass transfer and packing hydraulics, the equilibrium model can validate the experimental results from a pilot plant within a deviation of 10%. A more rigorous rate based model included mass and energy flux across the interface and the enhancement effect resulting from chemical reactions. The rate based model was validated using experimental data from pilot plants and was shown to predict the results to within 10%. A parametric sensitivity analysis showed that inlet flue gas flowrate and K2 CO3 concentration in the lean solvent has significant impact on CO_2 recovery. Although both models can provide reasonable predictions based on pilot plant results, the rate based model is more advanced as it can explain mass and heat transfer, transport phenomena and chemical reactions occurring inside the absorber without introducing an empirical Murphree efficiency.展开更多
We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boun...We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boundary condition, for instance, the zero electrostatic potential in the middle of the channel. Using the similarity transformation, we employ the homotopy analysis method （HAM） to get the analytical solution of the model. In our approach, the unknown pressure constant and the integral constant related to the electric potential are solved spontaneously by using the proper boundary conditions on the channel walls, which makes our model consistent with the commonly accepted models in the field of fluid mechanics. It is expected that our model can offer a general and proper way to study the flow phenomena in microchannels.展开更多
Knowledge of the rheological behavior of saturated particulate networks is crucial for every process in which a particulate network is built-up,dewatered,or transported,as in a decanter centrifuge.However,difficulties...Knowledge of the rheological behavior of saturated particulate networks is crucial for every process in which a particulate network is built-up,dewatered,or transported,as in a decanter centrifuge.However,difficulties arise as to how to characterize the material properties.Thus far,no standardized method or measurement device has prevailed.In this work,the requirements for a useful device are discussed,followed by the design of a modified shear cell for a Schulze ring shear tester RST-01.pc and its measurement procedure.Shear experiments under normal load with different sediments consisting of inorganic and organic particles whose material properties strongly affect the rheological behavior were performed.The results demonstrate the potential of the modified shear cell.Furthermore,current challenges in characterization are discussed.The characterization possibilities of the developed shear cell are a further step toward understanding the theological behavior of liquid-saturated particulate networks.展开更多
Currently, a large proportion of global fossil fuel emissions originate from large point sources such as power generation or industrial processes. This trend is expected to continue until the year 2030 and beyond. Car...Currently, a large proportion of global fossil fuel emissions originate from large point sources such as power generation or industrial processes. This trend is expected to continue until the year 2030 and beyond. Carbon capture and storage （CCS）, a straightforward and effective carbon reduction approach, will play a significant role in reducing emissions from these sources into the future if atmospheric carbon dioxide （CO2） emissions are to be stabilized and global warming limited below a threshold of 2 ℃. This review provides an update on the status of large scale integrated CCS technologies using solvent absorption for CO2 capture and provides an insight into the development of new solvents, including advanced amine solvents, amino acid salts, carbonate systems, aqueous ammonia, immiscible liquids and ionic liquids. These proposed new solvents aim to reduce the overall cost CO2 capture by improving the CO2 absorption rate, CO2 capture capacity, thereby reducing equipment size and decreasing the energy required for solvent regeneration.展开更多
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,dur...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.展开更多
Solvent extraction is now finding applications in a broader range of fields than the past. Many of these applications require process equipment with shorter contact times, and in some cases to the point where the trad...Solvent extraction is now finding applications in a broader range of fields than the past. Many of these applications require process equipment with shorter contact times, and in some cases to the point where the traditional equilibrium stage approach is not a good model for predicting performance. In addition, feed streams are becoming lower in concentration of the solute. This means greater feed to solvent flow ratios are being used and so loss of organics as entrainment in the feed is more of a concern both economically and environmentally. These trends mean that a greater emphasis is being placed on the kinetics of extraction and stripping in models to predict performance and on formation and coalescence of drops to control entrainment. This paper reviews recent advances in the tools for investigating kinetics and coalescence in solvent extraction processes and some of the insights that are being uncovered in these fundamental processes in solvent extraction technology.展开更多
基金Support from the Australian Research Council (project ID:LP140100650)
文摘Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as well as economic pressures associated with VOCs. Solvents that are derived from biomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over con- ventional VOCs, such as low toxicity, biodegradability and renewability. This review aims to summarize the use of bio-derived solvents in solvent extraction applications, with special emphasis given to utilization of biodiesels and terpenes. Compared with the conventional VOCs, the overall performance of these bio-derived solvents is comparable in terms of extraction yields and selectivity for natural product extraction and no difference was found for metal extraction. To date most researchers have focused on laboratory scale thermodynamics studies. Future work is required to develop and test new bio-derived solvents and understand the kinetic performance as well as solvent extraction nilnt nlant studies.
文摘The emission of large amounts of carbon dioxide is of major concern with regard to increasing the risk of climate change. Carbon capture, utilisation and storage (CCUS) has been proposed as an important pathway for slowing the rate of these emissions. Solvent absorption of CO_2 using amino acid solvents has drawn much attention over the last few years due to advantages including their ionic nature, low evaporation rate, low toxicity, high absorption rate and high biodegradation potential, compared to traditional amine solvents. In this review, recent progress on the absorption kinetics of amino acids is summarised, and the engineering potential of using amino acids as carbon capture solvents is discussed. The reaction orders between amino acids and carbon dioxide are typ- ically between 1 and 2. Glycine exhibits a reaction order of 1, whilst, by comparison, lysine, proline and sarcosine have the largest reaction constants with carbon dioxide which is much larger than that of the benchmark solvent monoethanolamine (MEA). Ionic strength, p H and cations such as sodium and potassium have been shown to be important factors influencing the reactivity of amino acids. Corrosivity and reactivity with impurities such as SOx and NOxare not considered to be significant problems for amino acids solvents. The precipitation of CO_2 loaded amino acid salts is thought to be a good pathway for increasing CO_2loading capacity and cutting desorption energy costs if well-controlled. It is recommended that more detailed research on amino acid degradation and overall process energy costs is conducted. Overall, amino acid solvents are recognised as promising potential solvents for car- bon dioxide capture.
文摘Using experimental data from a number of pulsed disc and doughnut solvent extraction columns, a unified correla- tion for the prediction of dispersed phase holdup that considers the effects of mass transfer is presented. Pulsed disc and doughnut solvent extraction columns （PDDC） have been used for a range of important applications such as ura- nium extraction and nuclear fuel recycling. Although the dispersed phase holdup in a PDDC has been presented by some researchers, there is still the need to develop a robust correlation that can predict the experimental dispersed phase holdup over a range of operating conditions including the effects of mass transfer direction. In this study, dis- persed phase holdup data from different literature sources for a PDDC were used to refit constants for the correlation presented by Kumar and Hartland lind. Eng. Chem. Res.,27 （1988）,131-138] which did not consider the effect of col- umn geometry. In order to incorporate the characteristic length of the PDDC （i.e. the plate spacing）, the unified cor- relation for holdup proposed by Kumar and Hartland based on data from eight different types of columns [Ind. Eng. Chem. Res.,34 （1995） 3925-3940] was refitted to the PDDC data. New constants have been presented for each hold- up correlation for a PDDC based on regression analysis using published holdup data from PDDCs that cover a range of onerating conditions and nhwical nronerties and consider the direction of mass transfer.
基金Supported by the National Natural Science Foundation of China under Grant Nos.1187224,11432009the Australian Research Council through a Discovery Early Career Researcher Award DE150100169
文摘The fully developed mixed convection hybrid nanofluid flow in a vertical microchannel is examined in detail.The simplified hybrid model that omits the nonlinear terms due to the interaction of different nanoparticle volumetric fractions is derived and compared with the existing one.The generalized model describing hybrid nanofluid suspended with multiple kinds of solid particles is suggested.The argument that the corresponding nanofluid solutions obtained by the homogenous model can be recovered from the results of the regular problems through simple arithmetic operations is checked.Solutions in similarity form for this flow problem are formulated by means of a set of similarity variables.The effects of various parameters on important physical quantities are analyzed and discussed.
基金financial support from Peter Cook Centre for CCS Research
文摘The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process model utilised the Electrolyte Non-Random Two Liquid(ENRTL) thermodynamic model and various packing correlations. The results from the ACM equilibrium model shows good agreement with an inbuilt Aspen Plus?model when using the same input conditions. By further introducing a Murphree efficiency which is related to mass transfer and packing hydraulics, the equilibrium model can validate the experimental results from a pilot plant within a deviation of 10%. A more rigorous rate based model included mass and energy flux across the interface and the enhancement effect resulting from chemical reactions. The rate based model was validated using experimental data from pilot plants and was shown to predict the results to within 10%. A parametric sensitivity analysis showed that inlet flue gas flowrate and K2 CO3 concentration in the lean solvent has significant impact on CO_2 recovery. Although both models can provide reasonable predictions based on pilot plant results, the rate based model is more advanced as it can explain mass and heat transfer, transport phenomena and chemical reactions occurring inside the absorber without introducing an empirical Murphree efficiency.
基金supported in part by the Australian Research Council through a Discovery Early Career Researcher Award to Qiang SUN
文摘We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boundary condition, for instance, the zero electrostatic potential in the middle of the channel. Using the similarity transformation, we employ the homotopy analysis method （HAM） to get the analytical solution of the model. In our approach, the unknown pressure constant and the integral constant related to the electric potential are solved spontaneously by using the proper boundary conditions on the channel walls, which makes our model consistent with the commonly accepted models in the field of fluid mechanics. It is expected that our model can offer a general and proper way to study the flow phenomena in microchannels.
基金The authors would like to thank the German research association"Arbeitsgemeinschaft industrieller Forschungsvereinigungen"for funding this work(IGF 18461N and IGF 19528N).
文摘Knowledge of the rheological behavior of saturated particulate networks is crucial for every process in which a particulate network is built-up,dewatered,or transported,as in a decanter centrifuge.However,difficulties arise as to how to characterize the material properties.Thus far,no standardized method or measurement device has prevailed.In this work,the requirements for a useful device are discussed,followed by the design of a modified shear cell for a Schulze ring shear tester RST-01.pc and its measurement procedure.Shear experiments under normal load with different sediments consisting of inorganic and organic particles whose material properties strongly affect the rheological behavior were performed.The results demonstrate the potential of the modified shear cell.Furthermore,current challenges in characterization are discussed.The characterization possibilities of the developed shear cell are a further step toward understanding the theological behavior of liquid-saturated particulate networks.
文摘Currently, a large proportion of global fossil fuel emissions originate from large point sources such as power generation or industrial processes. This trend is expected to continue until the year 2030 and beyond. Carbon capture and storage （CCS）, a straightforward and effective carbon reduction approach, will play a significant role in reducing emissions from these sources into the future if atmospheric carbon dioxide （CO2） emissions are to be stabilized and global warming limited below a threshold of 2 ℃. This review provides an update on the status of large scale integrated CCS technologies using solvent absorption for CO2 capture and provides an insight into the development of new solvents, including advanced amine solvents, amino acid salts, carbonate systems, aqueous ammonia, immiscible liquids and ionic liquids. These proposed new solvents aim to reduce the overall cost CO2 capture by improving the CO2 absorption rate, CO2 capture capacity, thereby reducing equipment size and decreasing the energy required for solvent regeneration.
基金The authors acknowledge the infrastructure support from the Particulate Fluids Processing Centre(PFPC),the Peter Cook Centre(FCC)for Carbon Capture and Storage(CCS).
文摘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.
文摘Solvent extraction is now finding applications in a broader range of fields than the past. Many of these applications require process equipment with shorter contact times, and in some cases to the point where the traditional equilibrium stage approach is not a good model for predicting performance. In addition, feed streams are becoming lower in concentration of the solute. This means greater feed to solvent flow ratios are being used and so loss of organics as entrainment in the feed is more of a concern both economically and environmentally. These trends mean that a greater emphasis is being placed on the kinetics of extraction and stripping in models to predict performance and on formation and coalescence of drops to control entrainment. This paper reviews recent advances in the tools for investigating kinetics and coalescence in solvent extraction processes and some of the insights that are being uncovered in these fundamental processes in solvent extraction technology.
