Institutional Repository of Institute of Process Engineering, CAS (IPE-IR)
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Science Fund for Creative Research Groups of the National Natural Science Foun-dation of China
Two-dimensional Na-Bentonite@MXene composite membrane with switchable wettability for selective oil/water separation
MXene-based two-dimensional (2D) material membranes have attracted an increasing number of attentions in the field of separation and purification. However, the easily oil-pollution of MXene membrane still limit its further application for oil/water separation. In this work, Na-Bentonite was embedded into MXene nanosheets and then a series of Na-Bentonite@MXene (NBM) composite membranes were prepared by one-step hydro -thermal pretreatment and vacuum self-assembly on polyvinylidene fluoride membrane surface. The modified composite membranes exhibited excellent separation performances with a rejection ratio above 96 % and a flux recovery rate (FRR) higher than 86 % after 8 cycling tests for oil/water emulsion. In addition, the sandwich structure consisting of MXene nanosheets and Na-Bentonite could not only play a positive role in the stability of composite membrane, but also formed a special micro-nano structure on membrane surface, resulting in a switchable wettability of composite membrane. When the membrane surface was pretreated with water or oil, it presented hydrophilic/hydrophobic or hydrophobic/oleophilic surfaces, respectively, which realized the effec-tive separation for different components in oil/water emulsion. This work provides a new method for the design and construction of MXene-based 2D membrane with continuous anti-fouling capacity, which shows a great application potential in the treatment of oily wastewater
Ultra-high NH3 absorption by triazole cation-functionalized ionic liquids through multiple hydrogen bonding
Ionic liquids (ILs) are considered as prospective absorbents for NH3 separation and purification owing to extremely low vapor pressure, great affinity and structural tunability. Up to date, versatile ILs for NH3 absorption have been developed, but NH3 mass capacity of all the reported ILs or IL-based absorbents are still not comparable to that of traditional water absorbent. How to simultaneously improve NH3 mass capacity, selectivity and keep stable reversibility using IL absorbents is still a great challenge. In this work, the triazole cationfunctionalized ionic liquids (TCFILs) by introducing multiple protic H sites into N-heterocyclic cations were firstly designed and synthesized for enhancing NH3 absorption. These TCFILs showed superhigh NH3 mass capacity up to 0.365 g NH3/g IL at 30 degrees C and 1 bar, which is the maximum among the reported absorbents, and is even comparable to that of traditional water absorbent used in industrial. Moreover, the TCFILs also exhibited excellent selectivity of NH3/CO2 up to 182 and recycling stability. Such great comprehensive performances of NH3 absorption and separation were proved to originate from multiple hydrogen bonding between NH3 and protic hydrogens of the TCFIL cations. Therefore, this work will provide useful guidance to design competitive functionalized ILs for efficient and reversible absorption of NH3
Incorporating 2D gamma-Al2O3 nanosheets into the flexible PEO-based solid electrolyte for lithium metal batteries
Solid polymer electrolytes using polyethylene oxide (PEO) are promising for boosting the safety of lithium metal batteries (LMBs), but suffer from low ionic conductivity due to high crystallinity and poor segment motion of PEO. Adding plasticizers like succinonitrile (SN) is one of the solutions to improve the ionic conductivity of PEO, but it sacrifices the cycle performances of LMBs. In addition, the ability to conduct lithium ions of PEO-SN matrixes is yet to be improved. Herein, two-dimensional gamma-Al2O3 nanosheets are first introduced into the PEO-SN matrix to facilitate the long-range migration of lithium ions and improve the electrochemical properties of PEO-SN matrix, realizing the new design of traditional materials. The mechanism between gamma-Al2O3 nanosheets and the polymer matrix is discussed. The addition of gamma-Al2O3 nanosheets improves the ionic conductivities and cycle performances of PEO-LiTFSI-SN (PLS) electrolytes. In specific, the ionic conductivity at 25 degrees C of the PEO-LiTFSI-SN-Al2O3 nanosheet (PLS-A) electrolyte is up to 2.02 x 10-4 S cm-1. Meanwhile, the electrochemical properties of Li/PLS-A/LiFePO4 are tested, with a low overpotential change of 0.06 V, coulombic efficiency above 99.6%, and capacity retention of 95% at 0.5C and 60 degrees C after 50 cycles. The solid electrolyte system provides a feasible strategy for the application of 2D nanofillers in PEO polymer electrolytes