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 frombiomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over conventional VOCs, such as lowtoxicity, biodegradability and renewability. This reviewaims 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. Futurework is required to develop and test newbio-derived solvents and understand the kinetic performance as well as solvent extraction pilot plant studies.

In the extraction method for preparing KH₂PO₄, one of the key processes is the selective extraction of HCl over H₃PO₄. In our work, extraction kinetic studies have been carried out in a microfluidic device with a coaxial microchannel, using the extractant of 33.3% (by volume) trioctylamine (TOA) dissolved in n-octanol,with different aqueous phases: the HCl solution, the H₃PO₄ solution, and H₃PO₄ and KCl solutions of different concentrations. The changes of the extraction efficiency of HCl and H₃PO₄ and the selectivity for HCl along with the residence timewere investigated.Wefound that fast extraction kinetics could be realized in microfluidic devices, and that HCl could be extracted faster than H₃PO₄ due to smallermass transfer resistance and much stronger reaction between HCl and TOA. For the extraction of H₃PO₄ and KCl solutions, the selectivity for HCl first increased and then decreased when TOAwas in excess of H₃PO₄ in the initial feeds, and in contrast, always increasedwhen H₃PO₄was in excess of TOA in the initial feeds. The diverse changes of selectivity for HCl alongwith the residence timeindicate that a dynamic control of selectivity in microfluidic devices may be important and accessible for improving the KH₂PO₄ conversion efficiency in extraction method.

Using experimental data froma number of pulsed disc and doughnut solvent extraction columns, a unified correlation for the prediction of dispersed phase holdup that considers the effects ofmass transfer is presented. Pulseddisc and doughnut solvent extraction columns (PDDC) have been used for a range of important applications such as uranium 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 ofmass transfer direction. In this study, dispersed phase holdup data fromdifferent literature sources for a PDDC were used to refit constants for the correlation presented by Kumar and Hartland [Ind. Eng. Chem. Res.,27 (1988),131-138] which did not consider the effect of column geometry. In order to incorporate the characteristic length of the PDDC (i.e. the plate spacing), the unified correlation 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 holdup correlation for a PDDC based on regression analysis using published holdup data fromPDDCs that cover a range of operating conditions and physical properties and consider the direction of mass transfer.

A new extractant, [N,N-di(2-ethylhexyl)amino]methylphenylphosphinic acid (DEAPP), was synthesized to develop the mutual separation techniques of In(III), Ga(III) and Zn(II). The extraction selectivity for In(III), Ga(III) and Zn(II) with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1 mol·L^-1 aqueous ammonium nitrate solution with DEAPP was in the following order: In(III) > Ga(III) > Zn(II). These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of In(III), Ga(III) and Zn(II). The extraction equilibria of In(III), Ga(III) and Zn(II) with DEAPP (=HR) were expressed by the following reactions: In³⁺+2(HR)₂ ⇋InR₃(HR)+3H⁺, Ga³⁺+1.5(HR)₂+NO₃^- ⇋GaR₂(HR)(NO₃)+2H⁺, and Zn²⁺+2(HR)₂ ⇋ ZnR₂(HR)₂ + 2H⁺. The extraction equilibrium constants of In(III), Ga(III) and Zn(II) with DEAPP were determined to be Kex,M=1.7 × 10⁴ [dm³·mol^-1], 4.17 [(dm³·mol^-1)^0.5], and 1.55 x 10^-2 [-], respectively.

A number of synergistic solvent extraction (SSX) systems have been developed to recover nickel, cobalt, zinc and copper from sulphuric and chloride leach solutions by the solvent extraction team of CSIRO, Australia. These include (1) Versatic 10/CLX50 system for the separation of Ni from Ca in sulphate solutions, (2) Versatic 10/4PC systemfor the separation of Ni and Co fromMn/Mg/Ca in sulphate solutions, (3) Cyanex 471X/HRJ-4277 system for the separation of Zn from Cd in sulphate solutions, (4) Versatic 10/LIX63 systemfor the separation of Co from Mn/Mg/Ca in sulphate solutions, (5) Versatic 10/LIX63/TBP systemfor separation of Ni and Co fromMn/Mg/Ca in sulphate solutions, (6) Versatic 10/LIX63 systemfor the separation of cobalt fromnickel in sulphate solutions by difference in kinetics, (7) Cyanex 272/LIX84 system for the separation of Cu/Fe/Zn from Ni/Co in sulphate solutions, (8) Versatic 10/LIX63/TBP system to recover Cu/Ni from strong chloride solutions, and (9) Versatic 10/LIX63 system to separate Cu from Fe in strong chloride solutions.
The synergistic effect on metal separation and efficiency is presented and possible industrial applications are demonstrated. The chemical stability of selected SSX systems is also reported.

This article describes the development of a coalescence model using various CFDwork packages, and is validated using as toluene watermodel system. Numerical studies were performed to describe droplet interactions in liquid-liquid test systems. Currentmodels use adjustable parameters to describe these phenomena. The research in the past decades led to different correlations to model coalescence and breakage depending on the chemical system and the apparatus geometry. Especially the complexity of droplet coalescence requires a detailed investigation of local phenomena during the droplet interaction. Computational fluid dynamics (CFD) studies of single droplet interactions were performed and validated with experimental results to improve the understanding of the local hydrodynamics and film drainage during coalescence. The CFD simulations were performed for the interaction of two differently sized droplets at industrial relevant impact velocities. The experimental verification and validation of the numerical results were done with standardized high-speed imaging studies by using a special test cell with a pendant and a free rising droplet. An experimental based algorithm was implemented in the open source code OpenFOAM to account for the contact time and the dimple formation. The standard European Federation of Chemical Engineering (EFCE) test systemtoluene/waterwas used for the numerical studies and the experimental investigations aswell. The results of the CFD simulations are in good accordancewith the observed coalescence behavior in the experimental studies. In addition, a detailed description of local phenomena, like film rupture, velocity gradients, pressures and micro-droplet entrainment could be obtained.

The extraction of ethanol with the solvents of aldehydes mixed with m-xylene was studied for the bioethanol concentration process. Furfural and benzaldehydewere selected as extraction solvents,withwhich the solubility of water is small, expecting large distribution coefficient of ethanol. The liquid-liquid two-phase region was the largest with m-xylene solvent, followed by benzaldehyde and furfural. The region of two liquid-liquid phase becamelarger with themixed solvent ofm-xylene and furfural than that with furfural solvent. The NRTLmodelwas applied to the ethanol-water-furfural-m-xylene system, and the model could well express the liquid-liquid equilibrium of the system. For any solvent used in this study, the separation selectivity of ethanol relative to water decreased as the distribution coefficient of ethanol increased. The separation selectivity with m-xylene was the largest among the employed solvents, but the distribution coefficientwas the smallest. The solvent mixture of furfural andm-xylene showed relatively high distribution coefficient of ethanol and separation selectivity, even in the higher mass fraction of m-xylene in the solvent phase.
The ethanol extraction with a countercurrent multistage extractor by a continuous operation was simulated to evaluate the extraction performance. The ethanol content could be concentrated in the extract phase with relatively small number of extraction stages but low yield of ethanol was obtained.

This paper shows that one-dimensional (1-D) [and three-dimensional (3-D) computational fluid dynamics (CFD)] simulations can replace the state-of-the-art usage of pseudo-homogeneous dispersion or back mixing models. This is based on standardized lab-scale cell experiments for the determination of droplet rise, breakage, coalescence and mass transfer parameters in addition to a limited number of additional mini-plant experiments with original fluids. Alternatively, the hydrodynamic parameters can also be derived usingmore sophisticated 3-D CFD simulations. Computational 1-D modeling served as a basis to replace pilot-plant experiments in any column geometry. The combination of 3-D CFD simulations with droplet population balance models (DPBM) increased the accuracy of the hydrodynamic simulations and gave information about the local droplet size. The high computational costs can be reduced by open source CFD codes when using a flexible mesh generation. First combined simulations using a three way coupled CFD/DPBM/mass-transfer solver pave the way for a safer design of industrial-sized columns, where no correlations are available.

Drop breakage and coalescence influence the particle formation in liquid-liquid dispersions. In order to reduce the influencing factors of the whole dispersion process, single drops where coalescence processes can be neglected were analyzed in this work. Drops passing the turbulent vicinity of a single stirrer blade were investigated by high-speed imaging. In order to gain a statistically relevant amount of drops passing the area of interest and corresponding breakage events, at least 1600 dropletswere considered for each parameter set of thiswork. A specially developed fully automatic image analysis based onMatlab®was used for the evaluation of the resulting high amount of image data. This allowed the elimination of the time-consuming manual analysis and furthermore, allowed the objective evaluation of the drops' behavior. Different deformation parameters were considered in order to describe the drop deformation dynamics properly. Regarding the ratio of both main particle axes (θ_axes), which was therefore approximated through an ellipse, allowed the determination of very small deviations from the spherical shape. The perimeter of the particle (θ_peri) was used for the description of highly deformed shapes. In this work the results of a higher viscosity paraffin oil (η_d = 127 mPa·s) and a low viscosity solvent (petroleum, η_d = 1.7 mPa·s) are presented with and without the addition of SDS to the continuous water phase. All results showthat the experimentally determined oscillation but also deformation times underlie a wide spreading. Drop deformations significantly increased not only with increasing droplet viscosity, but also with decreasing interfacial tension. Highly deformed particles of one droplet species were more likely to break than more or less spherical particles. As droplet fragmentation results from a variety of differentmacro-scale deformed particles, it is not assumed that a critical deformation value must be reached for the fragmentation process to occur. Especially for highly deformed particles thin particle filaments are assumed to induce the breakage process and, therefore, be responsible for the separation of drops.

Among the current technologies for post-combustion CO₂ capture, amine-based chemical absorption appears to be the most technologically mature and commercially viable method. This review highlights the opportunities and challenges in post-combustion CO₂ capture using amine-based chemical absorption technologies. In addition, this review provides current types and emerging trends for chemical solvents. The issues and performance of amine solvents are reviewed and addressed in terms of thermodynamics, kinetics,mass transfer, regeneration and solvent management. This review also looks at emerging and future trends in post-combustion CO₂ capture using chemical solvents in the near to mid-term.

A photorheologically reversible micelle composed of polymerizable cationic surfactant n-cetyl dimethylallyl ammonium chloride (CDAAC) and trans-4-phenylazo benzoic acid (trans-ACA) was prepared. The effects of molar ratio of CDAAC/trans-ACA, time of UV and visible light irradiation and temperature on the rheological properties of micellar system were investigated. The results show that before UV irradiation the system with an optimum CDAAC/trans-ACA molar ratio of 1.4 forms viscoelastic micelles at 45 ℃. After 365 nm UV irradiation, the viscosities of micelle systems with different concentrations at fixed molar ratio of 1.4 are decreased by 85%-95%. The CDAAC/trans-ACA (14mmol·L^-1/10mmol·L^-1) micelle system exhibits shear thinning property and its viscosity is decreased obviously with the increases of UV irradiation time less than 1 h. The rheological process during UV irradiation for CDAAC/trans-ACA (14mmol·L^-1/10mmol·L^-1) micelle proves that viscosity, elastic modulus G' and viscous modulus G″ will reduce quickly with the UV light. Furthermore, the micelle system after 1 h UVirradiation is able to revert to its initial high viscositywith 460 nmvisible light irradiation for 4 h, and the micelle can be cycled between low and high viscosity states by repetitive UV and visible light irradiations. The UV-Vis spectra of CDAAC/trans-ACA micelle indicate that its photosensitive rheological properties are related closely to photoisomerization of trans-ACA to cis-ACA.

In this work, the effects of injecting an evaporating liquid jet into solid-gas floware experimentally investigated. A new model (SHED model) and a supplementary model (spray model) have also been proposed to investigate some flow-field characteristics in three-phase fluidized bed with the mean relative error 4.3% between model and measured results. Some experiments were conducted to study the influences of flow-field parameters such as liquid volumetric flow rate, injection velocity, jet angle and gas superficial velocity as well as solid mass flux on the jet penetration depth (JPD). In addition, independent variables were experimentally employed to propose two empirical correlations for JPD by usingmultiple regression method and spray cone angle (SCA) by using dimensional analysis technique. The mean relative errors between the JPD and SCA correlations versus experimental datawere 7.5% and 3.9%, respectively. In addition, in order to identify the variable effect, a parametric studywas carried out. Applying the proposedmodel can avoid direct use of expensive devices to measure JPD and to predict droplet size.

The extraction fraction E and overall volumetric mass transfer coefficient kLa of TBP extracting butyric acid process in confined impinging jet reactors (CIJR)with two jetswere investigated. The main variables testedwere the concentration of tri-butyl-phosphate (TBP) and butyric acid, the impinging velocity V, the impinging velocity ratio of two phases V_org/V_aq, the nozzle inner diameter di and the distance L between the jet axes and the top wall of the impinging chamber. The results showed that E and kLa increase with an increase of the impinging velocity V, the concentration of TBP C_org, and the impinging velocity ratio V_org/V_aq.However, E and kLa decreasewith an increase of the inner diameter d_i from 1 to 2 mm, the concentration of butyric acid C_aq from 0.5% (v/v) to 2% (v/v). The factor L ranging from 3 to 11 mm has a negligible effect on E and k_La. A correlation on these variables and kLa was proposed based on the experimental data. These results indicated good mass transfer performance of CIJR in the extraction operation.

This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe. The particles are spherical and are large with respect to the diameter of the pipe (8%, 10%, 16% and 25%). Experiments were done to test the important parameters in solid transport (pressure, velocity, etc.). As a result, the relationship between the pressure gradient forces and the mixture velocity was sub-stantially different from the pure liquid flow. However, in a single-phase flow a monotonous behavior of the pres-sure drop curve is observed, and the curve of the solid particle flow attains its minimum at the critical velocity. The regimes are characterized with differential pressure measurements and visualizations.

In this work, an equilibrium-dispersion model was successfully established to describe the breakthrough performance of Ca(II) imprinted chitosan (Ca(II)-CS) microspheres packed column for metal adsorption, and the assumptions of Langmuir isotherms and axial dispersion controlled mass transfer process were confirmed. The axial dispersion coefficient in Ca(II)-CS microspheres packed column was found to be almost proportional to the linear velocity and fit for prediction through single breakthrough test. Sensitivity analysis for breakthrough curve indicated the axial dispersion coefficient as well as Langmuir coefficient was sensitive variable for deep removal requirement. The retrieval of the adsorption isotherms of Ca(II)-CS microspheres from breakthrough curve was fulfilled by modelling calibration. A strategy based on the correlation between adsorption isotherms and breakthrough performance was further proposed to simplify the column adsorption design using absorbents with small/uniformsize and fast adsorption kinetics like Ca(II)-CSmicrospheres to cut down the gap between lab and industry.