<p>Chitin/chitosan bio-adsorbent materials were successfully extracted from shrimp shell waste using an eco-friendly method based on a natural deep eutectic solvent (NaDES) composed of ammonium acetate and lactic acid, assisted by ultrasonic waves. Chitin/chitosan were characterized by degree of deacetylation (DD%), particle size distribution (laser diffraction), functional groups (FT-IR), crystallinity (XRD), morphology and chemical composition (TEM-EDX), surface area (BET), and surface charge (pHpzc). The chitosan obtained showed a high deacetylation degree (81%) and semi-crystalline structure. TEM-EDX analysis revealed a nanofibers morphology with diameters between 9 and 100&#xa0;nm and confirmed the chemical composition of the chitosan. BET surface area was 2.715 m²/g and the total pore volume was 0.0129 cm³/g. The adsorption performance of the chitosan was evaluated for the removal of the antibiotic amoxicillin (AMOX) from aqueous solutions. Chitosan showed excellent adsorption capacity, with a maximum removal efficiency of 91% at pH 7.5. Kinetic, isotherm, and thermodynamic studies of AMOX adsorption onto chitosan were also conducted. The results indicated that the pseudo-second-order kinetic model best described the adsorption process, with a high coefficient of determination (R² = 0.999). The Langmuir isotherm model provided the best fit to the experimental data, suggesting that AMOX adsorption onto chitosan is monolayer. The maximum adsorption capacity, based on the Langmuir model, was 40&#xa0;mg/g. Furthermore, thermodynamic analysis revealed that the adsorption of AMOX was an endothermic and spontaneous process. These findings confirm that chitosan extracted from shrimp shell waste could serve as a promising material for AMOX removal, offering a cost-effective alternative to more expensive adsorbents.</p> Graphical Abstract <p></p>