Effects of inorganic additive of two-dimensional hexagonal boron nitride on the gas separation/permeation for PVDF-derived membranes

1D and 2D Boron Nitride Nano Structures: A Critical Analysis for Emerging Applications in the Field of Nanocomposites

Boron nitride (BN) with its 1D and 2D nano derivatives have gained immense popularity in both the field of research and applications. These nano derivatives have proved to be one of the most promising fillers which can be incorporated in polymers to form nanocomposites with excellent properties. These materials have been around for 25 years whereas significant research has been done in this field for only the past decade. There are many interesting properties which are imparted to the nanocomposites wherein thermal stability, large energy band gap, resistance to oxidation, excellent thermal conductivity, chemical inertness, and exceptional mechanical properties are just a few worthy of mention. Hexagonal boron nitride (h-BN) was selected as the parent material by most researchers reviewed in this paper through which 2D derivative Boron nitride nanosheets (BNNS) and 1D derivative Boron nitride nanotubes (BNNTs) are synthesized. This review will focus on the in-depth properties of h-BN and further will concisely focus on BNNS and BNNTs for their various properties. A detailed discussion of the addition of BNNS and BNNTs into polymers to form nanocomposites, their synthesis, properties, and applications is followed by a summary determining the most suitable synthesizing processes and the materials, keeping in mind the current challenges.

CO2 adsorption enhancement over Al/C-doped h-BN: A DFT study

Reducing energy barriers of CO₂ being chemisorbed on hexagonal boron nitride (h-BN) is a kernel step to efficiently and massively capture CO₂. In this study, aluminum/carbon (Al/C) atoms are used as dopants to alter surface potential fields of h-BN, which aims at lowering energy barriers of adsorption processes. Through theoretical calculations, direct-adsorption structures/properties of CO₂, joint-adsorption structures/properties of CO₂/H₂O, transition state (TS) energy barriers, effects of temperatures on adsorption energies/TS energy barriers and changes of reaction rate constants over different adsorbents are investigated in detail in order to reveal how doping of Al/C atoms promotes CO₂ adsorption strength over doped h-BN. According to DFT calculation results, the average adsorption energy of CO₂ being directly adsorbed on Al/C-doped h-BN arrives at -59.43 kJ/mol, which is about 5 times as big as that over pure h-BN. As to the average adsorption energy of CO₂/H₂O and relevant TS energy barrier, they are modified to -118.89 kJ/mol and 40.23 kJ/mol over Al/C-doped h-BN in contrast with -33.91 kJ/mol and 1695.11 kJ/mol over pure h-BN, respectively. What is more, based on thermodynamic analyses and reaction dynamics, the average desorption temperatures of CO₂(/H₂O) are promoted over doped h-BN and the temperature power exponent is negatively correlated with the activation energy in the Arrhenius equation form. The complete understanding of this study would supply crucial information for applying Al/C-doped h-BN to effectively capturing CO₂ in real industries.

Polyethersulfone based MMMs with 2D materials and ionic liquid for CO2, N2 and CH4 separation

Increasing concerns on global warming and climate change have led to numerous attempts on developing new membrane materials to reduce excessive CO₂ emission into the atmosphere. In the present work, we focused on the separation of CO₂ from gas mixtures through two-dimensional (2D) materials based mixed matrix membranes (MMMs). The ionic liquid (IL) 1-Ethyl-3methylimidazolium bis (trifluoromethylsulfonyl) imide together with different weight fractions (0.5-1.5 wt %) 2D materials, such as molybdenum disulfide (MoS₂) and hexagonal boron nitride (h-BN), were homogenously blended to prepare polyether sulfone (PES) MMMs. The main aim was to investigate the effect of the addition of 2D materials on the gas separation/permeation properties of the PES membranes. Pure gas permeation for N₂, CO₂, and CH₄ and binary gas mixtures separation for CO₂/N₂ and CO₂/CH₄ were investigated through pure PES and modified PES membranes. The prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and water contact angle tests. The gas permeabilities were found to be improved by average 15-20 times higher compared to pure PES. The [Formula: see text] and [Formula: see text] were improved up to 124% and 18% using PES/h-BN (1 wt %)/IL and PES/MoS₂ (1.5 wt %)/IL combination, respectively. In overall, 2D materials and IL together as a filler into PES matrix revealed a significant improvement in the gas separation/permeation properties of PES and can be considered as a competent membrane for CO₂/CH₄ and CO₂/N₂ separation.