Beach-cast Sargassum cymosum macroalgae: biochar production and apply to adsorption of Acetaminophen in batch and fixed-bed adsorption processes.

In order to add value to the beach-cast Sargassum cymosum algae, its biomass was converted by pyrolysis process at 800°C into biochar, characterized and applied in the adsorption of Acetaminophen in batch and fixed-bed processes. Characterization by pH, Point of Zero Charge (pHPZC), Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric (TG), Scanning Electron Microscopy (SEM) and Surface area (BET) showed that the biochar presents properties favourable for the Acetaminophen adsorption. High surface area was obtained of 368.1 m². g-1, presenting the formation of pores, observed by SEM. The biochar showed basic characteristics (pH = 8.84 and pHPZC = 9.9), inferring an adsorption involving several different mechanisms such as dispersive interactions by π electrons, electrostatic attractions, and hydrophobic interactions. The adsorption mechanism is limited by chemisorption and governed by the formation of monolayer on the biochar surface, the Pseudo-second order kinetic and Langmuir-Freundlich isotherm model described the best behaviour of batch adsorption, with equilibrium and maximum adsorption capacity qe = 6.93 ± 0.07 mg. g-1 and qms = 12.34 ± 0.45 mg. g-1, respectively. Fixed-bed adsorption were performed varying adsorbent mass (0.3 and 0.6 g) and flow rate (2.5 and 5.0 mL. min-1), the best qy = 42.33 mg. g-1 found to adsorbent mass of 0.6 g and flow rate of 2.5 mL. min-1. Yan model described the best behaviour of the breakthrough curves data. Thus, the results provide insights into the development of adsorbents from beach-cast of Sargassum cymosum to adsorption of Acetaminophen, enhancing the use of environmental waste to obtain it.