Ecofriendly adsorbent sugarcane bagasse biochar beads for tetracycline removal: From batch adsorption to packed-bed performance and sustainability index evaluation

The increasing prevalence of industrial wastewater, particularly from pharmaceutical companies, poses significant environmental challenges. This study focuses on the removal of specific pharmaceutical compound tetracycline hydrochloride (THC), using sugarcane biochar beads (BCB). THC, an antibiotic used to treat bacterial infections, is the target for removal in this study, aiming for a sustainable solution. BCB were developed as a recoverable material for the removal of THC from batch to continuous treatment in a fixed-bed system. Under optimum batch conditions, BCB was capable of 85% THC removal, which corresponds to an adsorption capacity of 3.43 mg g⁻¹ . The Freundlich isotherm and fractional power kinetic model were best suited to describe the equilibrium and kinetic data, respectively, and thermodynamic analysis showed that the adsorption was both spontaneous and exothermic. Breakthrough experiments were carried out in the continuous fixed-bed units, and the results were obtained for three variables of interest: flow rate, influent THC concentration and bed height. The batch-to-fixed-bed capacity ratio (1.23–1.55) further validated the relationship between the equilibrium uptake and dynamic column performance. BCB also showed regeneration potential and an Adsorbent Sustainability Index (ADSUS) of 0.85 was excellent sustainability. The integrated evaluation of the waste derived immobilized biochar by batch adsorption, continuous fixed-bed treatment, regeneration, scale-up and sustainability assessment constitutes the main innovation of this work.