Carbon adsorbent as a functional material for solving the environmental problem of greenhouse gases

Abstract

Carbon materials have been obtained from spent coffee grounds using chemical activation, capable of becoming highly effective adsorbents for the greenhouse gas methane. The influence of the conditions of the synthesis process (the mass ratio of the activating agent to the precursor) on the development of the porous structure of adsorbents was studied using the methods of Romanov spectroscopy, X-ray phase analysis, and Fourier transform infrared spectroscopy. Samples with different pore hierarchies and different specific surface areas were obtained, including microporous adsorbents (SBET: 1131–2251 m2/g; VMIK/VPORE: 100%) and micromesoporous adsorbents (SBET: 2951–3304 m2/g; VMIK/VPORE: 43– 64%; VMEZ/VPORE: 36-57%). The resulting carbon materials have a narrow pore size distribution up to 5 nm. A study was made of the adsorption of the greenhouse gas methane in carbon adsorbents obtained by chemical activation at various ratios of potassium hydroxide to the precursor. It was found that the highest adsorption of methane, equal to 18.6 mmol/g at 100 bar and a temperature of 298 K, is achieved on a sample with high BET specific surface area and DFT specific pore volume (SBET: 3304 m2/g; VPORE: 1,49 cm3/g).