<p>This study investigates the adsorption of diclofenac potassium and ivermectin on physically activated biochar functionalized with phosphoric acid produced from grape residues. The study presents an innovative approach that uses a sustainable and functionalized adsorbent and an advanced modeling approach to understand the removal mechanism of these emerging pollutants. The results indicate that adsorption occurs via the formation of multiple layers. The number of layers formed for ivermectin varies between 6 and 4 layers (298–328&#xa0;K), with ivermectin being sensitive to temperature variations. At the same time, for diclofenac potassium, adsorption occurs mainly in two layers, with no significant changes in molecular organization with increasing temperature. The analysis of the adsorption energy revealed that the energy of the first layer varies from 23.03 to 27.80&#xa0;kJ&#xa0;mol⁻¹ for ivermectin and from 18.90 to 21.50&#xa0;kJ&#xa0;mol⁻¹ for diclofenac, confirming that the removal mechanism occurs predominantly by physical forces. The proposed mechanism indicates small differences between the removal mechanisms of the drugs. Ivermectin is adsorbed via electrostatic, dipole–dipole, hydrogen bonding, and π-π interactions. At the same time, diclofenac potassium is removed via electrostatic, π-π EDA interactions, n-π interactions, hydrogen bonding, and conventional π-π interactions. The physically activated biochar functionalized exhibited maximum adsorption capacities of 49.2&#xa0;mg&#xa0;g⁻¹ and 46.6&#xa0;mg&#xa0;g⁻¹ for diclofenac (DCF) and ivermectin (IVM), respectively. At an initial concentration of 50&#xa0;mg L⁻¹, removal efficiencies of approximately 70% for DCF and 55% for IVM were achieved. The findings provide an in-depth understanding of the adsorption process on functionalized biochar, highlighting its potential for efficient drug removal from wastewater and contributing to the development of sustainable and optimized adsorbent materials.</p> Graphical Abstract <p></p>