CO2 adsorption capacities of amine-functionalized microporous silica nanoparticles

Interplay between alkali-metal cations and silanol sites in nanosized CHA zeolite and implications for CO2 adsorption

Silanols are key players in the application performance of zeolites, yet, their localization and hydrogen bonding strength need more studies. The effects of post-synthetic ion exchange on nanosized chabazite (CHA), focusing on the formation of silanols, were studied. The significant alteration of the silanols of the chabazite nanozeolite upon ion exchange and their effect on the CO₂ adsorption capacity was revealed by solid-state nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) spectroscopy, and periodic density functional theory (DFT) calculations. Both theoretical and experimental results revealed changing the ratio of extra-framework cations in CHA zeolites changes the population of silanols; decreasing the Cs⁺/K⁺ ratio creates more silanols. Upon adsorption of CO₂, the distribution and strength of the silanols also changed with increased hydrogen bonding, thus revealing an interaction of silanols with CO₂ molecules. To the best of our knowledge, this is the first evidence of the interplay between alkali-metal cations and silanols in nanosized CHA.

Advances in the utilisation of carbon-neutral technologies for a sustainable tomorrow: A critical review and the path forward

Global industrialisation and overexploitation of fossil fuels significantly impact greenhouse gas emissions, resulting in global warming and other environmental problems. Hence, investigations on capturing, storing, and utilising atmospheric CO2 create novel technologies. Few microorganisms, microalgae, and macroalgae utilise atmospheric CO2 for their growth and reduce atmospheric CO2 levels. Activated carbon and biochar from biomasses also capture CO2. Nanomaterials such as metallic oxides, metal-organic frameworks, and MXenes illustrate outstanding adsorption characteristics, and convert CO2 to carbon-neutral fuels, creating a balance between CO2 production and elimination, thus zeroing the carbon footprint. The need for a paradigm shift from fossil fuels and promising technologies on renewable energies, carbon capture mechanisms, and carbon sequestration techniques that help reduce CO2 emissions for a better tomorrow are reviewed to achieve the world's sustainable development goals. The challenges and possible solutions with future perspectives are also discussed.

A Systematic Review of Amino Acid-Based Adsorbents for CO2 Capture

The rise of carbon dioxide (CO2) levels in the atmosphere emphasises the need for improving the current carbon capture and storage (CCS) technology. A conventional absorption method that utilises amine-based solvent is known to cause corrosion to process equipment. The solvent is easily degraded and has high energy requirement for regeneration. Amino acids are suitable candidates to replace traditional alkanolamines attributed to their identical amino functional group. In addition, amino acid salt is a green material due to its extremely low toxicity, low volatility, less corrosive, and high efficiency to capture CO2. Previous studies have shown promising results in CO2 capture using amino acids salts solutions and amino acid ionic liquids. Currently, amino acid solvents are also utilised to enhance the adsorption capacity of solid sorbents. This systematic review is the first to summarise the currently available amino acid-based adsorbents for CO2 capture using PRISMA method. Physical and chemical properties of the adsorbents that contribute to effective CO2 capture are thoroughly discussed. A total of four categories of amino acid-based adsorbents are evaluated for their CO2 adsorption capacities. The regeneration studies are briefly discussed and several limitations associated with amino acid-based adsorbents for CO2 capture are presented before the conclusion.