Selective Separation of Toluene/n‐Heptane by Supported Ionic Liquid Membranes with [Bmim][BF₄]

Abstract

Room‐temperature ionic liquids serve as alternative solvents for volatile organic compounds in liquid‐liquid extraction and liquid membrane separation. 1‐Butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF4]) was applied for extraction and supported ionic liquid membranes (SILMs) to separate toluene and n‐heptane. A high separation factor of toluene was achieved due to the strong interaction between ionic liquid cations and toluene. The mass transfer performance of the SILM process was enhanced by higher operating temperature. With the increase of initial toluene concentration in the feed phase, the mass transfer flux and removal efficiency of the SILM process were improved, while the separation factor decreased. The mass transfer flux was growing with the increase of flow rate at both sides. The SILM process was stable over a long time period due to the high viscosity and low volatility of [Bmim][BF4].

Molecular Design of Precise Network Polymerized Ionic Liquid Membranes for Toluene/Heptane Separations

“…The permselectivity goes through a maximum in the 50% ImC 11 TFSI system, which is dominated by diffusion coefficient differences (Table ), emphasizing the importance of understanding the effect of molecular details in separation membranes due to this unexpected maximum. The observed permselectivities are an order of magnitude larger than previous reports using ionic liquids for toluene–heptane separation. ,,,, However, the permselectivities found in the present work are overestimates, because real binary mixtures will competitively adsorb in the membrane. However, an important aspect of our work is that there is a maximum in the selectivity as a function of network density, which may outperform a linear PIL or a fully cross-linked network in a binary mixture test.…”

“…The observed permselectivities are an order of magnitude larger than previous reports using ionic liquids for toluene−heptane separation. 14,15,26,36,38 However, the permselectivities found in the present work are overestimates, because real binary mixtures will competitively adsorb in the membrane. However, an important aspect of our work is that there is a maximum in the selectivity as a function of network density, which may outperform a linear PIL or a fully cross-linked network in a binary mixture test.…”

“…Recent works have investigated membranes where ILs are incorporated into porous supports, termed supported ionic liquid membranes (SILMs). − ,− SILMs provide considerable advantage over traditional supported liquid membranes (SLMs) due to the increased viscosity and nonvolatility of ILs over organic solvents. For the separation of aromatics from aliphatic compounds, specifically benzene, toluene, and p -xylene from heptane, Matsumoto et al found that the permeation rates of aromatics increased with increasing imidazolium alkyl substituent chain length, while the selectivity decreased .…”

A Bibliometric Analysis of Research on Supported Ionic Liquid Membranes during the 1995–2015 Period: Study of the Main Applications and Trending Topics

“…As observed in Table 6 , which summarizes the cases of SILMs applied to hydrocarbon separations, the investigated paraffins include aliphatic and cyclic hydrocarbons, while all the members of the BTEX family (Benzene, Toluene, Ethylbenzene and Xilenes) are included among the investigated aromatic compounds. Since the initial studies that demonstrated that these aromatic hydrocarbons were successfully transported through SILMs based on ILs such as [BMIM][PF 6 ], [HMIM][PF 6 ], [OMIM][PF 6 ] or [Et2MeMoEtN][NTf 2 ] [ 112 ], new research efforts were focused on the improvement of the selectivity of the SILMs and their stability [ 113 , 114 , 115 , 116 , 117 ]. Moreover, SILMs have demonstrated their validity for the removal of aromatics compounds from aqueous phases.…”

Toluene vapor removal using an inorganic/organic double-network ion gel membrane

“…[54][55][56] It is also reported that when small amount of water was co-existed in an IL, the water molecule could be mainly distributed in a polar domain in the IL. [56] Because the imidazolium ring in the [C 4 mim][Tf 2 N] interacts with toluene though the C-H···π type of hydrogen bonding, [57,58] In the previous work, we also indicated that the light gas permeabilities of the DN ion gel membrane was dependent on the composition of inorganic and organic networks. [47] The CO 2 and N 2 permeabilities were increased with the increase of the inorganic network composition in the DN ion gel membrane with a constant IL content.…”