Advances in Resources and Environmental Science

Coffee grounds, a byproduct of coffee production, have garnered significant attention from researchers due to their abundant availability and diverse composition, prompting exploration into their potential resource utilization. In this study, coffee grounds were utilized as raw materials to synthesize hydrochar, with an analysis conducted on the impact of alkaline treatment on the morphology, surface functional groups, and U(VI) adsorption capabilities of the resulting material. The results revealed that coffee grounds treated with a 3 mol/L KOH solution yielded hydrochar (AHOC) with a more porous surface, increased oxygen-containing functional groups, and exhibited superior U(VI) adsorption performance. The influence of temperature on the U(VI) adsorption performance of the three hydrochar materials was found to be inconsistent. The adsorption amount of U(VI) by HAC increased with increasing temperature, while the adsorption amount of U(VI) by HOC and AHOC at 298 K was higher than that at 288 K and 308 K. Furthermore, the coffee grounds based hydrochar demonstrated rapid U(VI) adsorption kinetics, reaching equilibrium within 60 minutes of reaction. Importantly, the coffee grounds based hydrochar not only exhibited adsorption behavior towards U(VI), but also demonstrated reduction effect.

Coffee grounds; Hydrochar; Alkali treatment; Uranium; Adsorption