Hydrothermal valorization of waste Enteromorpha Prolifera: Assist in the degradation of tetracycline and multifunctional product synthesis

Enteromorpha Prolifera (EP), a non-native macroalgae, has significantly damaged coastal agricultural ecosystems through its rapid expansion. Thus, developing an eco-friendly and cost-effective waste conversion strategy is urgently required. To address this issue, this study presents a hydrothermal-assisted multifunctional product preparation (HMP) strategy, aimed at enhancing the value-added processing of EP. EP biochar (EBC) was initially employed to coordinate the degradation of tetracycline (TC) by BiOCl. The introduction of EBC effectively modified the energy bands and electrical properties of BiOCl. The results demonstrated that BiOCl@EBC significantly enhanced the degradation efficiency of TC (from 57.34 % to 99.46 % within 60 min). The liquid by-product was valorized to synthesize blue carbon dots (CDs) through a facile process, enabling the fabrication of fluorescent anti-counterfeiting patterns; these CDs demonstrate excitation-wavelength-tunable emission. This study presents a sustainable approach to valorize waste EP into EBC and CDs, while developing an eco-friendly modification strategy for BiOCl photocatalysts. The HMP strategy enables valorization of waste into high-value functional products while establishing a sustainable conversion framework for algal.