Aqueous two-phase system (ATPS) is considered a new method to remove heat stable salts (HSS) from flue gas desulfurizer 1,4-bis-(2-hydroxyethyl)-piperazine (BHEP). In this work, the liquid-liquid phase equilibrium data of BHEP-Na₂SO₄ ATPS in 303.15 – 323.15 K were measured and correlated by NRTL equation with the redefined adjustable characteristic constant at different concentrations. It is revealed that the redefined NRTL equation correlate to the phase equilibrium data of the ternary two-phase system well within the experimental temperature range. The root-mean-square deviations (RMSD) and the average absolute deviations (AAD) of the calculated value and experimental value are less than 1.9% and 1.5% respectively. The binary interaction parameters of NRTL equation have minor changes, ranging from -68 – 75. Thereby, the parameters of redefined NRTL equation are consistent with the actual calculation and engineering application requirements.

In the production of high-purity industrial phosphoric acid by wet process, the symbiotic elements are often treated as solid or liquid waste. This causes a waste of natural resources. In this work, a new wet-process phosphoric acid (WAP) purification route was proposed. In particular, the regeneration process of extractant was optimized, and the recovery process of aluminum was studied in detail (including stripping and crystallization). The effects of operational parameters and composition on the stripping behavior were investigated by single factor experiment and relevant analysis. Dissolution equilibrium date indicated the mother liquor could be circulated when the crystallization temperature was 298.15 K. Aiming to yield the purified extractant, the theoretical stages of stripping were simulated by plotting McCabe-Thiele diagram. Two-stage countercurrent extraction was carried out through a series of cascade experiments, indicating that over 95% Al³⁺ was stripped into aqueous phase. Furthermore, Al³⁺ in WPA was successfully changed into ammonium aluminum sulfate by this process, and it had higher purity than industrial grade. The results provide a basis for the high-quality utilization of associated resources in WPA.

The extraction behavior of 14 trivalent lanthanoids (Lns) with bis(2-ethylhexyl)phosphoric acid (HR) into a typical hydrophobic ionic liquid (IL), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, was investigated. The extraction is so slow that a shaking time of more than 36 hours is needed to reach extraction equilibrium. Compared to the extraction system using toluene as an extraction solvent, the IL extraction system has higher extraction ability for all Lns and higher selectivity for some couples of Lns (e.g., Ce/La and Tb/Gd). The dependences of the distribution ratio on the aqueous pH and the HR concentration suggest that the main extracted species are neutral LnR₃(HR)₃ for light and middle Lns and Tb, but anionic LnR₄(HR)₂^– and LnR₅(HR)^2– for heavy Lns (except for Tb). The addition of 1-octanol as a phase stabilizer decreases the extractability of Lns, which can be explained in terms of interaction between 1-octanol and HR dimer.

Recently, the extraction of Au(III) using the series of aliphatic ketones in hydrochloric acid media has been investigated in detail. The present study describes the extraction behaviors of Au(III) using a series of aromatic ketones, which has never been reported. Aromatic ketones with shorter alkyl side chains showed higher extractability. The rapid extraction and the extraction capacity using aromatic ketones were comparable to the industrial extractant dibutyl carbitol (DBC). Aromatic ketones, except acetophenone, are less soluble in water than DBC. The flash points of aromatic ketones are satisfactorily high for industrial operation, but their specific gravities comparable to that of water are unwelcome. Butyrophenone selectively extracted Au(III) from many other metals, except for high extraction of Fe(III) and Ga(III) at high concentrations. Au(III) extracted using butyrophenone recovered quantitatively as metallic gold by reduction using oxalic acid.

To separate both copper and 2,2',2'',2'''-(ethane-1,2-diyldinitrilo)tetraacetic acid (EDTA) from the waste electroless copper plating solution by solvent extraction, the liquid–liquid equilibria of the copper-EDTA complex and unbound EDTA ion were experimentally measured. An organic solution of tri-n-octylmethylammonium chloride (TOMACl) was used as solvent. The kerosene solution of TOMACl could extract both copper-EDTA complexes and EDTA ions from the model wastewater. The fractional removal and distribution ratios of both the copper-EDTA complex and EDTA ions decreased as the pH increased. The valence number of the major copper-EDTA complex or EDTA ion in the aqueous phase increased with pH, and the number of TOMA⁺ cations required to chelate the complexes and ions increased. These complexes and ions had lower reactivity with TOMACl owing to steric hindrance. These effects caused lower removal of both copper and EDTA in a higher pH range, which is a typical condition of waste electroless copper solution.

Recycling platinum group metals from secondary resources such as spent automotive exhaust catalysts is promising for the circular economy. However, the selective separation of Pt over massive amounts of impurity metals such as Mg and Al is particularly challenging. In this study, non-aqueous direct leaching of platinum from a spent automotive catalyst (SAC) using hydrophobic ionic liquids, namely, trihexyl(tetradecyl)phosphonium chloride (P₆₆₆₁₄Cl) and trioctyl(dodecyl)phosphonium chloride (P₈₈₈₁₂Cl) with the aid of pre-loading hydrochloric acid/hydrogen peroxide was proposed. The more hydrophobic P₈₈₈₁₂Cl exhibited more efficient and selective leaching of Pt over Mg and Al. The recovery of Pt from the metal-loaded P₈₈₈₁₂Cl, and the reusability of the IL for SAC leaching were also demonstrated.

The novel extraction method called "emulsion-flow" is characterized by using a layer of accumulated droplets in the column to supply both phases in the form of droplets. To clarify the flow behavior of both phases in the layer, extraction of iodine from organic to aqueous phase was carried out to enhance visibility of organic phase with the help of iodine. In addition, the mass-transfer in the organic phase was examined by extracting iodine from organic phase to aqueous Na₂S₂O₃ solution. The results indicated that two phases in the droplet layer were in the state of O/W/O emulsion where most of the water flows down in the form of film around the droplets. Also, progress of coalescence of organic-phase droplets during extraction of iodine from organic phase was observed. The height of droplet layer increased with the square of organic phase flow velocity. The trend was the same as that observed for extraction of iodine from the aqueous phase. The mass-transfer capacity coefficient of the organic phase increased linearly with the organic-phase flow velocity, with a small dependence on the aqueous-phase flow velocity. The trend of the distribution of iodine concentration in the column was predicted by solving the convection-diffusion equation with an appropriate setting of the Peclet number.

We report here the sequential refreshment of a water-immiscible ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P14TFSI) enhanced the production amount of paclitaxel and the related taxanes with in situ extraction from an aqueous medium in a plant cell culture. The production amount of the taxanes with refreshment of 2.5 vol% P14TFSI twice every 2 days was three times greater than that without the refreshment and 600 times greater than that of control culture without P14TFSI. The enhanced production amounts of taxanes in the culture with P14TFSI might be due to the deceased feedback inhibition of paclitaxel and abiotic stress responding against elevation of intracellular production of reactive oxygen species (ROS) derived from P14TFSI's abiotic stress.

Tryptophan, which is an essential amino acid, is used as a nutrient enhancer, a preservative, and a feed additive. Development of a cost-effective and straightforward separation technique is still required to extract and purify tryptophan in the bioproduction processes. We conducted permeation of tryptophan through poly(vinyl chloride)-based membrane containing Aliquat 336 as a carrier. Tryptophan successfully permeated through the membranes against its concentration gradient when the feed and receiving solutions were prepared by 0.1 mol/dm³ sodium hydroxide solution and hydrochloric acid, respectively. The up-hill transport of tryptophan was achieved and more than 85% of tryptophan in the feed solution was recovered.