Acetaminophen removal by calcium alginate/activated hydrochar composite beads: Batch and fixed-bed studies

The occurrence of acetaminophen in surface water has been reported worldwide, indicating the need of alternative wastewater treatments. Activated hydrochar (AHC) is efficient for pharmaceuticals removal. Powdered AHC presents challenges that hamper its expansion. However, these issues can be overcome by adding polymers, such as alginate, in composite beads. Therefore, the present study aimed to develop and characterize alginate/brewer's spent grain AHC beads, applying them to acetaminophen adsorption in batch and fixed-bed experiments. The adsorbent presented a high surface area (533.42 m² g^-1) and Fourier-transform infrared spectroscopy (FTIR) showed that alginate assigned new functional groups to the composite. Batch studies revealed an endothermic behavior and maximum adsorption capacity of 165.94 mg g^-1, with an equilibrium time of 240 min. The fixed-bed maximum adsorption capacity was 127.01 mg g^-1, with a mass transfer zone of 5.89 cm. The importance of alginate for the adsorbent development has been successfully proven.