Adsorption of Amoxicillin Drug from its Aqueous Solution on the Surface of Activated Carbon Prepared from Date Pits: A Kinetic and Thermodynamic Study

This study addressed the use of activated carbon prepared from date pits as an adsorbent to remove the antibiotic amoxicillin from aqueous solutions, with the aim of evaluating its efficiency in treating water pollution with antibiotics. The results showed that the pH value had a significant impact on the adsorption efficiency, with the highest removal achieved at a pH value of 6.6.
The results also showed that increasing the weight of the adsorbent within the range of (0.15–0.20) grams improved the adsorption efficiency due to the increase in the number of active sites, while the contact time indicated that the adsorption process reaches a quasi-equilibrium state within two hours. The concentration of the remaining amoxicillin was measured using UV spectroscopy at a wavelength of 230 nanometers for an initial concentration of 20 mg/L.
The kinetics study indicated that the adsorption process follows a pseudo-second-order model, suggesting that the adsorption rate depends on the interaction between the adsorbent and the adsorbate. The equilibrium study also showed that the adsorption data fit well with the Langmuir model, indicating the formation of a monolayer on the surface of the activated carbon.
Thermodynamic calculations showed that the values of Gibbs free energy (ΔG°) were negative, confirming that the adsorption process is spontaneous, while the thermal values indicated that the process is exothermic. The activation of the coal using potassium hydroxide (KOH) also contributed to increasing porosity and improving surface properties, which positively reflected on the adsorption efficiency.