Functionalization of waste-derived activated carbon for the removal of carbamazepine from water

• Autor(a) principal: Pereira, Diogo Esteves
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/27903
• topic: Activated carbon; Industrial wastes; Pyrolysis; Magnetic nanoparticles; Adsorption; Pharmaceuticals; Environment; Wastewater treatment

Adsorption of pharmaceuticals onto activated carbons constitutes one of the most promising technologies for the removal of these persistent contaminants from water. Production of activated carbon from wastes provides an alternative and eco-friendlier option to commercial nonrenewable- based activated carbon and simultaneously contributes to the valorisation of industrial and agricultural biomass residues that enforces the principles of a circular economy. However, the application of powdered activated carbon in continuous treatment systems is hampered by the difficulty in recovering the material from the treated aqueous phase. The loading of magnetic iron oxide nanoparticles onto the surface of the activated carbon can facilitate the recovery of the adsorbent by the application of an external electromagnetic field or a permanent magnet, avoiding expensive and complex processes such as filtration or coagulation. In this work, magnetic activated carbon (MAC) was produced via two synthesis pathways. Waste-based powdered activated carbon (WPAC) produced from primary paper mill sludge (PS) was used as precursor in both routes. The in-situ route involves the coprecipitation of magnetic iron oxides onto the surface of WPAC. The ex-situ route involves the separate production of magnetic iron oxide particles, subsequently added in suspension to WPAC, at controlled pH. The produced materials were physically and chemically characterized (total organic carbon, Fourier transform infrared spectroscopy, specific surface area, pore morphology, point of zero charge, vibrating sample magnetometer, scanning electron microscopy imaging and X-Ray diffraction) and subject of preliminary adsorption tests for the removal of the anti-epileptic carbamazepine (CBZ) from ultrapure water. Best materials were selected (in-situ MAC2-MP1 and ex-situ MACX1-MP1), and kinetic and equilibrium studies were performed in both ultrapure water and real effluent collected from a local wastewater treatment plant. Kinetic studies revealed that equilibrium was achieved at around 30-45 min for both materials in both matrices. Maximum adsorption capacities for CBZ in ultrapure water were 90 ± 4 mg g-1 and 121 ± 5 mg g-1, for MAC4-MP1 and MACX1-MP1, respectively. In real effluent maximum adsorption capacities were lower for both materials, 60 ± 3 mg g-1 and 78 ± 2 mg g-1 for MAC4-MP1 and MACX1-MP1, respectively. Both materials presented lower adsorption capacities than the non-magnetic WPAC. However, magnetization was successfully achieved in both cases and the materials proved to be competitive with a non-magnetic commercial PAC in ultrapure water, which indicates to a potential application in continuous water treatment systems.