The interfacial regeneration enabling silver phosphate/alginate hydrogel efficient removal of tetracycline under visible light irradiation

The pervasive presence of tetracycline (TC) in aquatic ecosystems poses a significant risk to human health. Solar-driven photocatalytic degradation of TC using Ag 3 PO 4 is an efficient solution; however, it suffers from photo-corrosion and Ag⁺ leakage. To address these challenges, we developed a novel encapsulation technique using alginate hydrogels polymer (AHGs) to protect Ag 3 PO 4 to prepare Ag 3 PO 4 -AHGs. The strategy effectively enables Ag₃PO₄-AHGs to decrease Ag⁺ leaching by ∼ 378 folds compared to pristine Ag 3 PO 4 . Thus, Ag 3 PO 4 -AHGs retain ca. 80 % of photocatalytic activity after four cycles. Furthermore, the first-order kinetic constant reaches 0.04 min⁻¹ under visible light irradiation, representing a 4.3-fold enhancement compared to AHGs. This exceptional performance is attributed to the efficient production of singlet oxygen (¹O₂) of Ag 3 PO 4 -AHGs. The high-performance liquid chromatography-mass spectrum, electron paramagnetic resonance and density functional theory elucidate the interactions between TC and ¹O₂, enabling efficient TC degradation. The durability of Ag 3 PO 4 -AHGs is primarily attributed to a unique microstructure formed during cycling, facilitated by a stable surface-reconstructed interphase that hinders Ag⁺ leakage. This approach effectively addresses concerns regarding the stability and environmental safety of Ag 3 PO 4 -based photocatalysts, offering a promising solution for sustainable water treatment.