Search

Using N,N-bis(1-methylheptyl)acetamide (N503) synergized with TBP-NaFeCl 4 (T Fe), a ternary composite extraction membrane known as T Fe N-PIM was created. Under optimum membrane phase conditions, the mass transfer properties of T Fe N-PIM-Li(Ⅰ) and its Li/Mg selective separation performance by electric field augmentation were examined, and confirmed the mechanism of T Fe N-PIM-Li(Ⅰ) electric field enhanced mass transfer. The findings demonstrate a homogeneous distribution of [FeCl 4 -] in the T Fe N-PIM membrane phase and a decrease in the water contact angle as the T Fe content increases. In the T Fe N-PIM membrane, the cation binding order of the composite carrier was H+>Li+>Na+>Mg2+, and the mass transfer was carried out at the interface of the two phases of the membrane through the mechanism of "cation exchange-neutralization", in which Li(Ⅰ) was bonded with the carrier in the form of 2N503-LiFeCl 4 -2TBP, and showed a fixed-site "hopping" mass transfer characteristics under the reinforcement of electric field. The mass transfer process of the T Fe N-PIM- Li(Ⅰ) system under electric field enhancement conforms to the first-order kinetic rate equation, and the voltage (5–45 V) is positively correlated with the permeability coefficient P Li(Ⅰ) but decreases the Li/Mg selectivity of T Fe N-PIM. The S Li(Ⅰ)/Mg(Ⅱ) of T Fe N-PIM was 9.18 at 3 V. After three cycles of 72 h cycling at 40 V, the decrease rate of P Li(Ⅰ) was <7.42 %, which showed good stability. [Display omitted] • A ternary composite extraction membrane (T Fe N-PIM) of N503 synergy with TBP-NaFeCl 4 (T Fe) was prepared. • The increase in permeability coefficient stabilization after T Fe /N503 > 2/1 (w/w) in T Fe N-PIM. • Voltage accelerates the "ion hopping" rate of Li(Ⅰ) in T Fe N-PIM. • Voltage positively correlates with permeability coefficient but reduces Li/Mg selectivity of T Fe N-PIM. • The separation factor of T Fe N-PIM for Li/Mg at 3 V was 9.18. [ABSTRACT FROM AUTHOR]

A polymer inclusion membrane (PIM) that contains a polyvinyl chloride (PVC) polymer matrix and 1-octanol (OCT) as specific carrier (PO-PIM) was prepared to investigate the mass transfer behaviour of phenol in aqueous solutions. Results showed that the mass transfer behaviour of the PO-PIM for phenol conformed to the first-order kinetics. In addition, the mass transfer efficiency for phenol reached the maximum when the OCT content was 82.8 wt%. The mass transfer activation energy (E a) was 14.46 kJ mol−1, which indicated that intramembranous diffusion was the main controlling factor in the mass transfer process. The introduction of hydrophobic additives, such as kerosene, liquid paraffin and vegetable oil, into the PO-PIM could remarkably improve its stability. In an aqueous solutions of phenol ranging from 0 mg L−1 to 9000 mg L−1, the initial flux (J 0) of kerosene/PVC/OCT-PIM (KPO-PIM) was positively correlated with the initial concentration of phenol. For a stripping solution with a feed solution pH of 2.0 and a sodium hydroxide concentration of 0.1 mol L−1, the maximum permeability coefficient during stable mass transfer reached 12.55 μm s−1. At a mass transfer area of 3.14 cm2, an enrichment factor (EF) of 3.5 for 200 mg L−1 of phenolic aqueous solution was achieved within 48 h through KPO-PIM. Image 1 • Optimal conditions of mass transfer by PO-PIM were confirmed. • Effects of hydrophobic additives on the stability of PO-PIM were evaluated. • Kerosene content in PO-PIM was optimised. • Mass transfer mechanism of PO-PIM for phenol was proposed. • Enrichment of low-concentration phenol by KPO-PIM was confirmed. This study may provide a clean, economical and convenient method for the prevention of phenol pollution. [ABSTRACT FROM AUTHOR]

The transport behaviour of Cr(VI) from the aqueous phase through a polymer inclusion membrane (PO-PIM) containing 1-octanol (OCT) as carrier and polyvinyl chloride (PVC) as support at a low voltage drive (0–30 V) is investigated. The correlation between the OCT content and the surface or cross-sectional micromorphology of PO-PIM is also analysed. Under optimised mass transfer conditions, the transmission rules and mechanism of Cr(VI) under an electrodriven membrane extraction system are investigated. Results show that the surface and interior of PO-PIM exhibit micro/nanopores with an OCT content exceeding 50% (w/w). The mass transfer behaviour of OCT to Cr(VI) conforms to the proton coupling mechanism. The voltage drive effectively solves the residue problem of Cr(VI) in the membrane phase, and the permeability coefficient ( P ) of PO-PIM to Cr(VI) increases with the voltage. The P of PO-PIM to Cr(VI) reaches 43.38 μm·s −1 at 30 V when the OCT content is 82.8% and the feed and stripping phases are pH 2.0 HCl solution and 0.1 mol·L −1 NaOH solution environments, respectively. After the introduction of hydrophobic kerosene into the membrane phase, the stability of the membrane is significantly enhanced. When the composition ratio of kerosene/OCT/PVC is 0.8:2.2:0.5 and the voltage is 30 V, the initial current density rise is only 0.1 A and the pH increases slightly with the repeated use of PO-PIM to four cycles. [ABSTRACT FROM AUTHOR]

The polymer inclusion membranes (PIMs) containing polyvinyl chloride (PVC) as polymer matrix and N,N-di(1-methylheptyl) acetamide (N503) as a specific carrier were prepared by solvent evaporation. Microstructure and mechanical properties of PIMs were characterized by scanning electron microscope (SEM) and tension tester, respectively. The prepared PIMs were used to investigate the facilitated transport of phenol from model solution. The mass transfer dynamics and the transmission thermodynamics of transport process were investigated. Meanwhile, the effects of carrier content in membrane and solution environment on the transport performance of PIMs and its stability were also researched. The results showed that the content of carrier in membrane had a significant impact on the microstructure and mechanical property of PIMs. The transport of phenol was in line with the first order kinetics equation. The PIM presented an optimal transport performance and a certain degree of stability when the carrier content in membrane was 68.8%, feed solution pH was 2 and sodium hydroxide concentration of strip solution was 0.1 mol/L. The initial flux of the PIM reached maximum 25.0 mg m −2 s −1 when phenol initial concentration was 8000 mg/L in feed solution. The thermodynamic analysis indicated that the transport of phenol through PIMs in the range of 0–45 °C was the diffusion-controlled process. [ABSTRACT FROM AUTHOR]

The effective extraction of liquid rubidium resources such as salt lake brine and seawater and the recovery of rubidium(I) at the end of the extraction process of lithium resources have always been a challenge in the industry. Two series of polymer inclusion membranes(PDA-PIM and PDT-PIM) were prepared to study the separation and enrichment of Rb(I). PDA-PIM and PDT-PIM used polyvinyl chloride (PVC) and dicyclohexano 18 crown 6(DCH18C6) as carriers, and tricaprylmethylammonium chloride (Aliquat 336) and trioctylphosphine oxide (TOPO) as a plasticizer, respectively. The optimal mass ratio (W/W) of PDA-PIM and PDT-PIM were P25D3.5A25 and P25D3.5T1, respectively. The applied electric field is a core condition for the mass transfer and separation of Rb(I). With the increase of voltage, the permeability coefficient P of Rb(I) and the separation factor (S) relative to Na(I) and K(I) increases. At 180 V, the PRb of PDA-PIM and PDT-PIM were 12.08 and 2.39 µm/s, and the SRB/NA were 11.21 and 14.44. After four mass transfer cycles of PDT-PIM, PRb only decreased by 4.6%. In addition, after 81.5 h of mass transfer, the enrichment ratio of Rb(I) was 3.02 times. These results show the excellent stability and mass transfer performance of PDT-PIM. It's of great significance for low concentration Rb(I) extraction. [Display omitted] • Separation of Rb(I), K(I) and Na(I) was realised by PIMs coupled with electric field. • PD-PIMs are composed of DC18C6/PVC and two different plasticisers. • Plasticiser improves the structure of PD-PIM and provides a mass transfer channel. • Voltage is the key factor affecting the permeability and selectivity of Rb(I). • The difference of hydration energy is the internal reason for selective separation. [ABSTRACT FROM AUTHOR]

A polymer inclusion membrane (PDT-PIM) composed of bis(2-ethylhexyl) phosphate (D2EHPA) and tributylphosphate (TBP) compound carrier is developed in this study. The PIM membrane carrier composition, thickness, voltage, two-phase solution environment and other factors for Li+ electro-membrane extraction (EME) behaviour are investigated using applied electric field assessment. Results showed that the PDT-PIM system composed of alkaline feed phase and acidic stripping phases can achieve preferential mass transfer to Li+ in the coexisting solution of Na+ and K+ ions. The D2EHPA functional group is responsible for the main mass transfer of ions. Synergistic extraction effect of TBP appears when D2EHPA/TBP (w /w) ratio is 1/2 and reaches maximum at a ratio close to 1/1. The total optimised carrier accounts for 70.6% of the mass percentage of PIM. The applied electric field can effectively increase the mass transfer rate but will reduce the selectivity of Li+ relative to Na+ and K+. Mass transfer coefficient (P) of 70.6% of PDT-PIM to Li+ can reach 12.9 μm s−‍1 and the initial flux of Li+ is 249 mg m−2 s−1 under a voltage of 20 V. Separation factor of Li+ relative to Na+ and K+ (S Li/Na and S Li/K) are 6.41 and 5.64 on 10 V as well as 2.56 and 2.51 on 20 V, respectively. Enrichment factor of Li+ of up to 9.02 shows acceptable stability after 120 h of continuous mass transfer of 1 L of 20 mg L−1 Li+ solution. [Display omitted] • Electro-membrane extraction system based on PDT-PIM for Li(I) was developed. • The compound extractant in PDT-PIM is composed of D2EHPA and TBP. • TBP cooperates with D2EHPA to participate in the complexation of Li(I). • Applied electric field can significantly increase the mass transfer rate of Li(I). • High voltage reduces the mass transfer selectivity of Li(I) relative to Na(I)/K(I). [ABSTRACT FROM AUTHOR]

Highlights The development of the electroplating and battery industries has increased the environmental problems and the needs for resource recovery of Cd(II). In this study, the Electro-membrane extraction (EME) behaviour of Cd(II) was investigated by using polymer inclusion membrane with bis(2-ethylhexyl) phosphate as carrier and polyvinyl chloride as base polymer(PD-PIM) at 0−80 V. Results showed that the EME of Cd(II) by PD-PIM can be obtained in the feed phase with pH 3–8 and stripping phase of dilute acid. Voltage is the main factor to increase the mass transfer rate of Cd(II). The applied electric field reduced the mass transfer activation energy of Cd(II) by PD-PIM and weakened the mass transfer interference of Cd(II) on the background material of the feed phase. After using kerosene-stabilised PD-PIM for operation at pH5, 60 V for 120 h, Cd(II) in the 1 L solution reduced from 15 mg/L to 0.08 mg/L, and the enrichment factor was 9.79. [ABSTRACT FROM AUTHOR]