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In the sustainability paradigm, the concept of converting waste into valuable products is one of the problem solvers. The goal of this study was to investigate the adsorption mechanism of carbon-based adsorbent particles from papaya seed waste with various sizes (i.e. 500, 1000, and 2000 microns) that can be used as alternative adsorbents in pollutant removal in aqueous solution. In the experiment, papaya seeds were carbonized at 400°C for 4 hours and ground to produce carbon-based particles, which were then used as adsorbent. The adsorption characteristics of curcumin (as a dye model) by carbon adsorbents were evaluated in a batch reactor. The results showed that adsorption occurred via monolayer (for small adsorbents) and multilayer (for large adsorbents). Concerns on the size of the adsorbent have been found, playing a role in the enhancement of adsorption capacity due to its offering the existence of a larger surface area. In addition, small adsorbents have attractive electrostatic adsorbent-adsorbate interaction, giving benefits in the adsorption process, while large adsorbents have issues in the repulsive electrostatic interaction. In conclusion, effective carbon-based adsorbents can be designed and produced from papaya stem wastes, providing alternative ways to remove pollutants from aqueous solutions, thereby achieving the primary objective of the sustainable development goals (SDGs), Moroccan Journal of Chemistry, Vol. 11, No 2 (2023): In progress