| Summary: | A precipitation reaction method was employed to prepare mesopore calcium carbonate (CaCO<sub>3</sub>) using rape flower pollen as the template. CaCO<sub>3</sub> adsorbent was characterized using X-ray diffraction (XRD), scanning electronic microscopy (SEM), and Brunner−Emmet−Teller measurements (BET). The equilibrium adsorption data on amoxicillin were explained using Langmuir, Freundlich, and Temkin adsorption isotherm models. The pseudo-first order, second order, pseudo-second order, and intra-particle diffusion kinetic models were used to explore adsorption kinetics. Equilibrium adsorption of as-prepared CaCO<sub>3</sub> was better depicted using the Langmuir adsorption model with an R<sup>2</sup> of 0.9948. The separation factor (<i>R<sub>L</sub></i>) was found to be in the range of 0 < <i>R<sub>L</sub></i> < 1, indicating the favorable adsorption of amoxicillin. The adsorption capacity of mesopore CaCO<sub>3</sub> reached 13.49 mg·g<sup>−1</sup> in 0.2 g∙L<sup>−1</sup> amoxicillin solution. The values of adsorption thermodynamic parameters (Δ<i>H</i><sup>θ</sup>, Δ<i>S</i><sup>θ</sup>, Δ<i>G</i><sup>θ</sup>) were obtained. In addition, the adsorption process turned out to be endothermic and spontaneous for the CaCO<sub>3</sub> product at 298 K, 308 K, and 318 K.
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