Graphene - based membranes for carbon dioxide separation

Graphene-Based Composite for Carbon Capture

The current energy system is based largely on fossil fuels that emit carbon dioxide (CO2) and contribute to global climate change. Global energy demand is expected to increase, with growth approximately doubled by the year 2050 and tripled by the end of the century. Therefore, research and development on emissions management and carbon cycle solutions that meet energy sustainability is critical to reduce the effects of global warming. The key point of this literature review is the selection of suitable materials for carbon capture. The selection is based on the consideration that the CO2 reduction properties are influenced by the type of material/composite that is being used, the preparation, and the possible characterization method. This Review covers graphene-based materials and their composites as appropriate materials for reducing CO2 and their performance assessment through experiments and theoretical analysis. It is very important to improve the efficiency performance of materials and its scalability. Recently, graphene has become a widely used material for environmental applications, one of which shows good performance in reducing CO2 concentration. To separate CO2, graphene has been developed and is now being showcased and reviewed in this study. Given the measuring technique used, this Review is intended to be a valuable resource for individuals researching CO2 separation employing graphene material in combination with other materials.

A direct one-step synthesis of a smart graphene/silica nanocomposite and its application for improving the acid resistance and corrosion resistance properties of waterborne epoxy coatings

Graphene has attracted tremendous attention as a potential building block of modern high performance coating systems. Herein, we demonstrate a green method for making reduced oxide graphene (rGO) using the natural product rutin as the reducing agent. The rGO, with residual rutin on the surface to provide surface affinity, is used in the one-step fabrication of a nanocomposite of rGO and silica nanoparticles (SN) with a corrosion inhibitor, benzotriazole (BTA), loaded in situ. The ternary nanocomposite, BTA@SN-rGO, can be easily dispersed in water. It not only has a high inhibitor loading capacity (85.1 μg mg-1) but also can release the inhibitor in a controlled manner triggered by pH. Combining both the extraordinarily good barrier properties and smart nanocontainer features, BTA@SN-rGO was further incorporated into an epoxy latex to assemble an intelligent anticorrosion coating. The effective duration of the coating protection for steel was remarkably prolonged in different media, especially in acidic media. In addition to the barrier capability, smart self-healing of artificial damage to the modified coating films is also shown. Electrochemical impedance spectroscopy (EIS) was applied to monitor the failure process of different kinds of coatings. All the results confirm the synergy of the passive and active functions of the BTA@SN-rGO coating.

Functionalized GO Membranes for Efficient Separation of Acid Gases from Natural Gas: A Computational Mechanistic Understanding

Membrane separation technology is applied in natural gas processing, while a high-performance membrane is highly in demand. This paper considers the bright future of functionalized graphene oxide (GO) membranes in acid gas removal from natural gas. By molecular simulations, the adsorption and diffusion behaviors of several unary gases (N₂, CH₄, CO₂, H₂S, and SO₂) are explored in the 1,4-phenylenediamine-2-sulfonate (PDASA)-doped GO channels. Molecular insights show that the multilayer adsorption of acid gases evaluates well by the Redlich-Peterson model. A tiny amount of PDASA promotes the solubility coefficient of CO₂ and H₂S, respectively, up to 4.5 and 5.3 mmol·g^-1·kPa^-1, nearly 2.5 times higher than those of a pure GO membrane, which is due to the improved binding affinity, great isosteric heat, and hydrogen bonds, while N₂ and CH₄ only show single-layer adsorption with solubility coefficients lower than 0.002 mmol·g^-1·kPa^-1, and their weak adsorption is insusceptible to PDASA. Although acid gas diffusivity in GO channels is inhibited below 20 × 10^-6 cm²·s^-1 by PDASA, the solubility coefficient of acid gases is certainly high enough to ensure their separation efficiency. As a result, the permeabilities (P) of acid gases and their selectivities (α) over CH₄ are simultaneously improved (P_CO2 = 7265.5 Barrer, α_CO2/CH4 = 95.7; P_(H2S+CO2) = 42075.1 Barrer, α_H2S/CH4 = 243.8), which outperforms most of the ever-reported membranes. This theoretical study gives a mechanistic understanding of acid gas separation and provides a unique design strategy to develop high-performance GO membranes toward efficient natural gas processing.

Valorization of Different Fractions from Butiá Pomace by Pyrolysis: H2 Generation and Use of the Biochars for CO2 Capture

This work valorizes butiá pomace (Butia capitata) using pyrolysis to prepare CO2 adsorbents. Different fractions of the pomace, like fibers, endocarps, almonds, and deoiled almonds, were characterized and later pyrolyzed at 700 °C. Gas, bio-oil, and biochar fractions were collected and characterized. The results revealed that biochar, bio-oil, and gas yields depended on the type of pomace fraction (fibers, endocarps, almonds, and deoiled almonds). The higher biochar yield was obtained by endocarps (31.9%wt.). Furthermore, the gas fraction generated at 700 °C presented an H2 content higher than 80%vol regardless of the butiá fraction used as raw material. The biochars presented specific surface areas reaching 220.4 m2 g-1. Additionally, the endocarp-derived biochar presented a CO2 adsorption capacity of 66.43 mg g-1 at 25 °C and 1 bar, showing that this material could be an effective adsorbent to capture this greenhouse gas. Moreover, this capacity was maintained for 5 cycles. Biochars produced from butiá precursors without activation resulted in a higher surface area and better performance than some activated carbons reported in the literature. The results highlighted that pyrolysis could provide a green solution for butiá agro-industrial wastes, generating H2 and an adsorbent for CO2.

Classification of Nanomaterials and the Effect of Graphene Oxide (GO) and Recently Developed Nanoparticles on the Ultrafiltration Membrane and Their Applications: A Review

The emergence of mixed matrix membranes (MMMs) or nanocomposite membranes embedded with inorganic nanoparticles (NPs) has opened up a possibility for developing different polymeric membranes with improved physicochemical properties, mechanical properties and performance for resolving environmental and energy-effective water purification. This paper presents an overview of the effects of different hydrophilic nanomaterials, including mineral nanomaterials (e.g., silicon dioxide (SiO₂) and zeolite), metals oxide (e.g., copper oxide (CuO), zirconium dioxide (ZrO₂), zinc oxide (ZnO), antimony tin oxide (ATO), iron (III) oxide (Fe2O3) and tungsten oxide (WO_X)), two-dimensional transition (e.g., MXene), metal-organic framework (MOFs), covalent organic frameworks (COFs) and carbon-based nanomaterials (such as carbon nanotubes and graphene oxide (GO)). The influence of these nanoparticles on the surface and structural changes in the membrane is thoroughly discussed, in addition to the performance efficiency and antifouling resistance of the developed membranes. Recently, GO has shown a considerable capacity in wastewater treatment. This is due to its nanometer-sized holes, ultrathin layer and light and sturdy nature. Therefore, we discuss the effect of the addition of hydrophilic GO in neat form or hyper with other nanoparticles on the properties of different polymeric membranes. A hybrid composite of various NPs has a distinctive style and high-quality products can be designed to allow membrane technology to grow and develop. Hybrid composite NPs could be used on a large scale in the future due to their superior mechanical qualities. A summary and future prospects are offered based on the current discoveries in the field of mixed matrix membranes. This review presents the current progress of mixed matrix membranes, the challenges that affect membrane performance and recent applications for wastewater treatment systems.