Removal of selected pharmaceuticals from aqueous matrices with activated carbon under batch conditions

Abstract

Adsorption of diclofenac (DCL), naproxen (NPR) and carbamazepine (CRB) from aqueous matrices onto a commercial granulated activated carbon (GAC) has been studied. Data obtained for DCL and NPR were evaluated by applying different adsorption isotherm models. The best fitting was reached using Langmuir equation. The experimental maximal adsorption capacity values were 50 and 80 mg g−1 for DCL and NPR, respectively, which increased to 320 and 280 mg g−1 when pulverized activated carbon was used. Activation energy calculated at different temperatures was between 5 and 9 kJ mol−1 for each compound in the three-component systems. By evaluating adsorption kinetics data with various models, the best fitting was obtained by applying the pseudo first order model. The calculated rate constant was about 0.076 min−1 for each compound in the single solutions. However, the obtained values for the three-component solutions were 0.16, 0.13 and 0.11 min−1 for CRB, NPR and DCL, respectively. According to the model calculations, intra-particle diffusion has a role in the adsorption and it is the sole rate-determining step for CRB and NPR. Applying a semi-open system, removal efficiency was nearly 100% from model sewage water (MSW) and secondary sewage water (SSW) during several cycles using the same GAC. This semi-open system permitted study of i) adsorption of low water-solubility compounds (e.g. CRB), ii) adsorption of NRP, CRB and DCL at a concentration level similar to that in real aqueous matrices and iii) comparison of drug removal from MSW/SSW, iv) modeling for sewage water treatment plants.