Metal–Organic Frameworks (MOFs) Containing Adsorbents for Carbon Capture

Investigation on cost-effective composites for CO2 adsorption from post-gasification residue and metal organic framework

Cost-effective CO2 adsorbents are gaining increasing attention as viable solutions for mitigating climate change. In this study, composites were synthesized by electrochemically combining the post-gasification residue of Macadamia nut shell with copper benzene-1,3,5-tricarboxylate (CuBTC). Among the different composites synthesized, the ratio of 1:1 between biochar and CuBTC (B 1:1) demonstrated the highest CO2 adsorption capacity. Under controlled laboratory conditions (0°C, 1 bar, without the influence of ambient moisture or CO2 diffusion limitations), B 1:1 achieved a CO2 adsorption capacity of 9.8 mmol/g, while under industrial-like conditions (25°C, 1 bar, taking into account the impact of ambient moisture and CO2 diffusion limitations within a bed of adsorbent), it reached 6.2 mmol/g. These values surpassed those reported for various advanced CO2 adsorbents investigated in previous studies. The superior performance of the B 1:1 composite can be attributed to the optimization of the number of active sites, porosity, and the preservation of the full physical and chemical surface properties of both parent materials. Furthermore, the composite exhibited a notable CO2/N2 selectivity and improved stability under moisture conditions. These favorable characteristics make B 1:1 a promising candidate for industrial applications.

Leveraging experimental and computational tools for advancing carbon capture adsorbents research

CO2 emissions have been steadily increasing and have been a major contributor for climate change compelling nations to take decisive action fast. The average global temperature could reach 1.5 °C by 2035 which could cause a significant impact on the environment, if the emissions are left unchecked. Several strategies have been explored of which carbon capture is considered the most suitable for faster deployment. Among different carbon capture solutions, adsorption is considered both practical and sustainable for scale-up. But the development of adsorbents that can exhibit satisfactory performance is typically done through the experimental approach. This hit and trial method is costly and time consuming and often success is not guaranteed. Machine learning (ML) and other computational tools offer an alternate to this approach and is accessible to everyone. Often, the research towards materials focuses on maximizing its performance under simulated conditions. The aim of this study is to present a holistic view on progress in material research for carbon capture and the various tools available in this regard. Thus, in this review, we first present a context on the workflow for carbon capture material development before providing various machine learning and computational tools available to support researchers at each stage of the process. The most popular application of ML models is for predicting material performance and recommends that ML approaches can be utilized wherever possible so that experimentations can be focused on the later stages of the research and development.

Enhanced removal of acidic dyes (AB1 and MO) from binary systems using anion exchange membrane BII: kinetic, isotherm, and thermodynamic analyses

In the current work, the adsorption of acid black 1 (AB1), a hair dye, and methyl orange (MO) on anion exchange membrane BII (AEM-BII) in a binary system was studied experimentally. The effects study for contact time, adsorbent's and adsorbates' concentration, and temperature of aqueous media on the AB1 and MO removal, AEM-BII recovery, and reusability were also investigated. The highest removal was observed at optimum conditions, 150-min contact time and 5 g L-1 of adsorbent for AB1 (91.2%) and MO (83.4%). Adsorption kinetics was estimated by pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetics. The experimental findings were fitted well by PSO kinetics with an adsorption capacity of 19.45 ± 0.93 and 19.34 ± 0.84 mg g-1 for ABI and MO, respectively. Moreover, the adsorption isotherm study confirmed that AB1 and MO adsorption by AEM-BII from the binary system was followed by Langmuir isotherms. Adsorption thermodynamics revealed that adsorption of both AB1 and MO by AEM-BII was endothermic and spontaneous. Moreover, the desorption phenomenon of ABI and MO from the loaded AEM-BII showed that dye removal from AEM-BII was found to be 74.95%, demonstrating AEM-BII can be considered as good adsorbent for acidic dyes from the binary system.

Experimental investigation of the dehumidification and decarburization performance of metal-organic frameworks in solid adsorption air conditioning

Solid adsorption air conditioning systems use solid adsorption materials to co-adsorb water vapor and carbon dioxide, allowing the humidity and carbon dioxide concentration in the air-conditioned room to be controlled. Exploring the co-adsorption mechanism of H₂O and CO₂ is essential for the screening of adsorbent materials, system design, and system optimization in solid adsorption air conditioning systems. A fixed-bed adsorption-desorption device was built, and the dynamic adsorption properties of three MIL adsorbent materials MIL-101(Cr), MIL-101(Fe), and MIL-100(Fe) for co-adsorption of H₂O and CO₂ were studied. The results showed that all three MIL adsorbent materials are capable of performing co-adsorption of H₂O and CO₂ and meet the requirements of solid adsorption air conditioning systems. MIL-101(Cr) is recommended for solid adsorption air conditioners where dehumidification is the main focus, while MIL-100(Fe) is recommended for solid adsorption air conditioners where carbon removal is the main focus.

Review of the Pressure Swing Adsorption Process for the Production of Biofuels and Medical Oxygen: Separation and Purification Technology

The production of biofuels has had a great impact on climate change and the reduction of the use of fossil fuels. There are different technologies used for the separation and production of biofuels, which allow having compounds such as ethanol, methane, oxygen, and hydrogen, one of these promising technologies is the Pressure Swing Adsorption process (PSA). The objectives of this article focus on the production and purification of compounds that achieve purities of 99.5% bioethanol, 94.85% biohydrogen, 95.00% medical oxygen, and 99.99% biomethane through the PSA process; also, a significant review is contemplated to identify the different natural and synthetic adsorbents that have greater adsorption capacity, the different configurations in which a PSA operates are studied and identified, and the different mathematical models that describe the dynamic behavior of all the variables are established that interact in this PSA process, parametric studies are carried out in order to identify the variables that have the greatest effect on the purity obtained. The results obtained in this review allow facilitating the calculation of parameters, the optimization of the process, the automatic control to manipulate certain variables and to achieve the rejection of disturbances to have a recovery and production of biofuels with a high degree of purity.

Multilayer Graphene Oxide Supported ZIF-8 for Efficient Removal of Copper Ions

To address the performance deterioration of ZIF-8 for the adsorption of copper ions caused by powder volume pressure and particle aggregation, we employed multilayer graphene oxide (MGO) as a support to prepare composite adsorbents (MGO@ZIF-8) by using the in situ growth of ZIF-8 on MGO. Due to a good interfacial compatibility and affinity between ZIF-8 and graphene nanosheets, the MGO@ZIF-8 was successfully prepared. The optimal Cu²⁺ adsorption conditions of MGO@ZIF-8 were obtained through single factor experiments and orthogonal experiments. Surprisingly, the Cu²⁺ adsorption capacity was significantly improved by the integration of MGO and ZIF-8, and the maximum Cu²⁺ adsorption capacity of MGO@ZIF-8 reached 431.63 mg/g under the optimal adsorption conditions. Furthermore, the kinetic fitting and isotherm curve fitting confirmed that the adsorption law of Cu²⁺ by MGO@ZIF-8 was the pseudo-second-order kinetic model and the Langmuir isotherm model, which indicated that the process of Cu²⁺ adsorption was monolayer chemisorption. This work provides a new approach for designing and constructing ZIF-8 composites, and also offers an efficient means for the removal of heavy metals.