Graphene Oxide Nanosheets Based Novel Facilitated Transport Membranes for Efficient CO2 Capture

Ultrathin Reduced Graphene Oxide/Organosilica Hybrid Membrane for Gas Separation

Here, reduced graphene oxide (r-GO) nanosheets were embedded in an organosilica network to assemble an ultrathin hybrid membrane on the tubular ceramic substrate. With the organosilica nanocompartments inside the r-GO stacks and the intensified polymerization, r-GO sheets endow the as-prepared hybrid membranes with high H₂ and CO₂ separation performance. The resulting selectivities of H₂/CH₄ and CO₂/CH₄ are found to be 223 and 55, respectively, together with gas permeance of approximately 2.5 × 10^-7 mol·m^-2·s^-1·Pa^-1 for H₂ and 6.1 × 10^-8 mol·m^-2·s^-1·Pa^-1 for CO₂ at room temperature and 0.2 MPa. To separate larger molecules from H₂, the H₂/C₃H₈ and H₂/i-C₄H₁₀ selectivities are as high as 1775 and 2548, respectively. Moreover, at 150 °C and 0.2 MPa, the hybrid membrane retains high separation performances with ideal selectivities higher than 200 and 30 for H₂/CH₄ and CO₂/CH₄, respectively, which are attractive for gas separation and purification of practical applications.

CO2 capture using membrane contactors: a systematic literature review

With fossil fuel being the major source of energy, CO2 emission levels need to be reduced to a minimal amount namely from anthropogenic sources. Energy consumption is expected to rise by 48% in the next 30 years, and global warming is becoming an alarming issue which needs to be addressed on a thorough technical basis. Nonetheless, exploring CO2 capture using membrane contactor technology has shown great potential to be applied and utilised by industry to deal with post- and pre-combustion of CO2. A systematic review of the literature has been conducted to analyse and assess CO2 removal using membrane contactors for capturing techniques in industrial processes. The review began with a total of 2650 papers, which were obtained from three major databases, and then were excluded down to a final number of 525 papers following a defined set of criteria. The results showed that the use of hollow fibre membranes have demonstrated popularity, as well as the use of amine solvents for CO2 removal. This current systematic review in CO2 removal and capture is an important milestone in the synthesis of up to date research with the potential to serve as a benchmark databank for further research in similar areas of work. This study provides the first systematic enquiry in the evidence to research further sustainable methods to capture and separate CO2.

Rational Design of Halloysite Surface Chemistry for High Performance Nanotube-Thin Film Nanocomposite Gas Separation Membranes

The interfacial region has a critical role in determining the gas separation properties of nanofiller-containing membranes. However, the effects of surface chemistry of nanofillers on gas separation performance of thin film nanocomposite (TFN) membranes, prepared by the interfacial polymerization method, have been rarely studied in depth. In this work, pristine and three differently surface-modified halloysite nanotubes (HNTs), by non- (SHNT), moderately (ASHNT), or highly CO₂-philic (SFHNT) agents, are embedded in the polyamide top layer of thin film nanocomposite (TFN) membranes for CO₂/N₂ and CO₂/CH₄ separations. Trimethoxyoctyl silane, 3-(2-aminoethylaminopropyl)trimethoxysilane, and poly(styrenesulfonic acid) are used as modifying agents to quantitatively investigate the effects of interfacial interactions between the polyamide and HNTs on the gas permeation of TFNs. This allows us to provide an interfacial design strategy to fabricate high-performance gas separation membranes. Pure gas permeations conducted on the TFNs at the feed gas pressure of 10 bar showed that CO₂ permeance and CO₂/N₂ and CO₂/CH₄ selectivities were increased by 145%, 130%, and 108%, respectively, after addition of 0.05 w/v% of sulfonated HNTs. The experimental gas permeations through all TFNs/HNTs, except TFNs/SFHNTs, agree well with predictions of a recently developed model, which suggests the importance of considering the neglected role of CO₂ interactions with the HNT/polyamide interface in the model. These results unambiguously proved that designing the interfacial layer thickness in the nanotube-containing membranes is an effective approach to tuning the gas separation properties. The results show that the dispersion of HNTs in the polyamide top layer and the experimental CO₂/gas selectivity was increased with increasing interfacial thickness, a_int, upon surface modification. Moreover, it is quantitatively demonstrated that the thickness of the interfacial layer between the filler and polymer matrix is a function of gas pressure applied on the membrane.

Synthesis of novel Co(ii) complexed bipyrimidine polyimide and preparation of thin film composite membranes

A systematic study was carried out on the effect of the polyimide complexed with Co²⁺ as the selective layer of thin film composite membranes on gas separation.

Porous Graphene Oxide/Porous Organic Polymer Hybrid Nanosheets Functionalized Mixed Matrix Membrane for Efficient CO2 Capture

The computational simulation of porous graphene oxide (PGO) indicated that it has great potential for the preparation of gas separation membranes. However, scaling up the manufacture of multilayer, defect-free porous graphene oxide membrane with consistently sized nanopores is extremely challenging. Here, we prepared layer-by-layer CO₂-philic Pebax^@1657 membranes that were functionalized by o-hydroxyazo-hierarchical porous organic polymers (o-POPs) and PGO. The d-spacing of pristine PGO could be finely regulated through CO₂-philic o-POPs to facilitate the permeability of CO₂. In addition, the o-POPs exhibit "N₂-phobic, CO₂-philic" properties with the phenolic hydroxyl and the azo group. The best of the POP-PGO membrane exhibits that the CO₂ permeability and ideal selectivity of CO₂/N₂ are 232.7 Barrer and 80.7, respectively, and it has surpassed the Robeson's upper bound (2008).

The Preparation and Properties of Nanocomposite from Bio-Based Polyurethane and Graphene Oxide for Gas Separation

Petroleum depletion and climate change have inspired research on bio-based polymers and CO₂ capture. Tung-oil-based polyols were applied to partially replace polyether-type polyols from petroleum for sustainable polyurethane. Tung-oil-based polyurethane (TBPU), was prepared via a two-step polycondensation, that is, bulk prepolymerization and chain extension reaction. The graphene oxide (GO) was prepared via Hummer’s method. Then, TBPU was composited with the GO at different ratios to form a TBPU/GO hybrid film. The GO/TBPU films were characterized by fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM), followed by the measurement of mechanical properties and gas permeability. The results showed that the addition of tung-oil-based polyols enhanced the glass transition temperature and thermal stability of TBPU. The mechanical properties of the hybrid film were significantly improved, and the tensile strength and elongation at break were twice as high as those of the bulk TBPU film. When the GO content was higher than 2.0%, a brittle fracture appeared in the cross section of hybrid film. The increase of GO content in hybrid films improved the selectivity of CO₂/N₂ separation. When the GO content was higher than 0.35%, the resulting GO agglomeration constrained the gas separation and permeation properties.