Posted by A new superadsorbent was synthesized via a crosslinking reaction using the reaction of β-cyclodextrin and coffee grounds with citric acid and this material was employed to remove two organic cationic molecules, methylene blue and crystal violet from aqueous solution. The interactions between adsorbent-adsorbate in aqueous media were also investigated.
The total carboxyl content in the β-CD/coffee grounds polymer was estimated to be 4.22 mmol g−1, which can provide numerous negative charges to interact with cationic pollutants. In addition, the active β-CD content was estimated to be 0.234 mmol g−1, which is suggested to be suitable for encapsulating hydrophobic compounds.
The new adsorbent presented impressive adsorption capacity values, higher than 1500 mg g−1. This high adsorption capacity results from three main mechanisms: electrostatic attraction, hydrogen bonds, and hydrophobic interactions between the hydrophobic parts of dyes and the inner hydrophobic cavity of cyclodextrin. Thermodynamic parameters revealed an endothermic and spontaneous process with increased randomness in the liquid-solid interface. Overall, the adsorbent exhibited an excellent performance for dye removal and potential use in wastewater treatment plants.
The coffee ground applied in this work was not characterized. It is not clear wether fresh, roasted or spent coffee ground was used; if Coffee arabica or other cultivar was studied.
Fakhreddine Ben Amara, Franciele da Silva Bruckmann, Suliman Yousef Alomar, Marcos Leandro Silva Oliveira, Luis Felipe Oliveira Silva, Guilherme Luiz Dotto, Samir Bejar, Sonia Jemli (2025) A novel superadsorbent β-cyclodextrin crosslinked coffee grounds biopolymer to remove organic molecules from water matrices. Journal of Molecular Structure 1334, 141800.
https://doi.org/10.1016/j.molstruc.2025.141800.