Characterization of Polymer Inclusion Membranes (PIMs) Containing Phosphonium Ionic Liquids as Zn(II) Carriers

Abstract

Phosphonium ionic liquids (IL), i.e., trihexyl­(tetradecyl)­phosphonium chloride (Cyphos IL 101), trihexyl­(tetradecyl)­phosphonium bis­(2,4,4-trimethylpentyl)­phosphinate (Cyphos IL 104), and tributyl­(tetradecyl)­phosphonium chloride (Cyphos IL 167), were used as ion carriers in CTA or PVC-based polymer inclusion membranes (PIM). Up to now, the morphology and structure of PIMs with phosphonium ILs have not been characterized in detail. Thus, the following techniques were proposed in this papercontact angle measurements, FT-IR, XRD, DSC, AFM, and SEMto analyze the influence of PIM morphology on the efficiency of Zn­(II) transport. CTA-based membranes appeared to be more hydrophilic, with a more expanded and rough surface that allowed better accessibility of the metal ions to the membrane. PVC-based PIMs were more hydrophobic and completely amorphous, and their surface showed less diversity, resulting in worse accessibility. Also, PIM stability after five cycles of transport processes was examined.

Selective removal of silver(i) using polymer inclusion membranes containing calixpyrroles

“…PVC-based PIMs were more hydrophobic and completely amorphous, and their surface showed less diversity, resulting in worser accessibility. 35…”

Effect of cross-linking on the performance of polymer inclusion membranes (PIMs) for the extraction, transport and separation of Zn(II)

“…Emerging as a potential alternative to traditional solvent extraction, separation based on polymer inclusion membranes (PIMs), consisting of a base-polymer, carrier (extractant) and plasticizer or modifier in some cases, has been attracting increased attention in recent years [1]. The main reason behind this trend is based on the better stability of PIMs than supported liquid membranes (SLMs) which are the most frequently used liquid membranes at present [1][2][3][4][5][6][7][8][9][10]. Despite the better stability of PIMs [1,11], their robustness is still considered insufficient for applications on an industrial scale.…”

“…The limited stability of PIMs is mainly caused by the loss of membrane liquid phase, composed of the PIM carrier and plasticizer or modifier (if used), to the aqueous phase(s) (i.e., feed and receiving solutions) in contact with the membrane [12][13][14]. The factors, responsible to a great extent for the leaching of the membrane liquid phase, include (1) problems associated with the miscibility of the membrane components [15], (2) solubility of the membrane liquid phase in the aqueous phase(s) [16,17], and (3) the composition of the aqueous phase(s) in contact with the membrane [10,13]. Different approaches have been proposed with the aim to eliminate or minimise the effect of these three factors.…”

Crosslinking improved ion transport in polymer inclusion membrane‐electrodialysis process and the underlying mechanism

“…Whereas, the topography of both PVDF‐HFP based PIMs was more developed and lots of bulges were observed on the membrane surface, resulting in a far greater surface roughness in comparation with CTA based membranes. It have been demonstrated that an enhancement in surface roughness of membrane supplies a larger effective area on membrane surface, which is favorable to metal ions transport 26 . The transport efficiency for non‐cross‐linked PVDF‐HFP based membrane was much better than non‐cross‐linked CTA based membrane (Figure 2), according with the dramatical high surface roughness of the former membrane (129 nm) compared with that of the latter one (4.3 nm).…”