Tailoring tea residue-derived nitrogen-doped activated carbon for CO₂ adsorption: influence of activation temperature...

Embracing CO₂ mitigation strategies, such as state-of-the-art CO₂ capture technologies, is essential for effectively reducing atmospheric carbon levels and advancing global efforts toward a more sustainable future. In this context, adsorption sequestering techniques utilising carbon materials have emerged as promising candidates for CO₂ capture. These materials have been extensively researched with a range of tuning methods to optimise their physicochemical features. In this study, an alteration of the N-doped activated carbon was successfully performed, utilizing tea residue as the carbon precursor and ammonia as the nitrogen source, facilitated through an impregnation procedure. With the objective of discovering the effect of diverse activation parameters on prepared adsorbent physicochemical properties, several selections of activating agents (AA) were investigated: KOH, H₃PO₄, ZnCl_2, and NaOH, together with broad thermal activation temperature from 873 to 1173 K. The best-performed adsorbents from the respective AC group were subjected to several characterisation analyses and found to the enhanced structural features, heteroatom doped-rich surface (i.e. N and O); together with AA-induced metal/mineral functionalization, the NaOH-used AC (NAC-N-1173) was the optimum-performed adsorbent with a promising 4.12 mmol/g CO₂ uptake capacity, higher than other prepared adsorbent including N-doped tea residue-derived char and commercialized AC with 175 and 325% higher, respectively.