Removal of Paracetamol from Aqueous Solutions Using an Eggshell Derived Adsorbent

Pharmaceutical residues are increasingly detected in aquatic environments, and conventional wastewater treatment does not always remove them effectively. This study evaluated an adsorbent prepared from discarded eggshells for the removal of paracetamol from aqueous solutions. Eggshells were washed, dried, ground, and thermally treated at 500 °C for 2 h. Batch experiments examined the effects of adsorbent dose (0.1–0.4 g), contact time (0–20 min), initial paracetamol concentration (10–60 mg L−1), and temperature (20–65 °C). Residual paracetamol was quantified by UV–visible spectrophotometry at 241 nm. The highest removal in the dose experiment was 85.9% at 0.2 g, whereas the greatest mass-normalized uptake reported in that series was 8.406 mg g−1 at 0.1 g. Removal reached 93.1% after 20 min and remained above 91% across the tested concentration range, with a maximum of 92.8% at 50 mg L−1. The temperature response was non-monotonic; removal ranged from 71.7% at 45 °C to 89.54% at 55 °C. The rapid initial uptake and the limited effect of additional contact time suggest that equilibrium was approached quickly under the applied conditions. Nevertheless, the non-monotonic temperature trend and inconsistencies between some reported uptake values and the stated batch volume require confirmation through replicated experiments and a complete mass-balance audit. Because eggshell is predominantly calcium carbonate, the product is described here as an eggshell-derived adsorbent rather than activated carbon unless carbon content, activation chemistry, and surface-area measurements are independently demonstrated. Overall, the material showed promising paracetamol removal, but physicochemical characterization, replication, pH-dependent testing, and validated equilibrium and kinetic modelling are needed before process-scale application.