Hydrocotyle vulgaris derived novel biochar beads for phosphorus removal: static and dynamic adsorption assessment

As a promising adsorbent, the recovery and reuse of biochar was limited due to its light texture and poor precipitation characteristics. Herein, recyclable biochar beads (MBCB) were successfully prepared by compositing Hydrocotyle vulgaris derived biochar (HBC) and sodium alginate (SA) for phosphorus (P) adsorption from wastewater. The as-prepared MBCB showed high adsorption capacity for P, reaching 255.88 mg/g. Based on the analysis of equilibrium, kinetic and thermodynamics models, it can be concluded that the adsorption behavior of P by MBCB was spontaneous and exothermic, which was dominated by monolayer and non-uniform surface adsorption, and contains multiple physical and chemical mechanisms. Both Thomas and Yoon-Nelson models are well fitted to describe the dynamic adsorption behavior of MBCB in the column adsorption tests. After five adsorption-desorption cycles, the removal efficiencies of P by MBCB still remained 87.06% and 84.06%, respectively. Overall, this study provides a recyclable and promising adsorbent for removing P from wastewater.