Adsorption and thermal degradation of Atenolol using carbon materials: Towards an advanced and sustainable drinking water treatment

With the aim to present an alternative material that can be used in adsorption/degradation processes to remove pharmaceutical pollutants present in water, a biocarbon was designed from Melia Azedarach stones. Material has a high surface area (1230 m2 g−1) with mainly oxygenated groups; these properties give it exceptional characteristics for removing Atenolol. To show the versatility of the material, the adsorption of Atenolol in different water matrices was tested: Ultrapure water (0 mg L−1 CaCO3), solution model (200 mg L−1 CaCO3), and tap water from Lisbon city (80 mg L−1 CaCO3). The pseudo-second-order model can well describe the adsorption kinetics; kinetic constants obtained were: 75.70, 46.18, and 42.58 g mmol h−1, respectively. The adsorption isotherms are correctly described by the Langmuir model, obtaining maximum adsorption capacities of 1.83, 2.00, and 1.81 mmol g−1, respectively. Physisorption phenomena carry out the adsorption mechanism (E < 1 kJ mol−1) between the atenolol molecule, positively charged, and the material's surface, negatively charged, forming a monolayer onto the material's surface. Once the material was saturated, its regeneration was studied by employing thermal treatment at 450 °C. Results show a decrease in the surface area after treatment, resulting in a loss of adsorption capacity (30 %). This procedure makes it possible to achieve repeat cycles of adsorption-degradation until the adsorbent is completely exhausted. The results obtained show this new material as a promising adsorbent for wastewater treatment contaminated with pharmaceutical pollutants since it has higher adsorption capacities than those reported in the literature in different water matrices.