Temperature-responsive lauric acid-coated ferrate-SiO2 composite for sustained release and norfloxacin degradation

Chemical oxidation, a cornerstone for groundwater and soil remediation, continues to face two major challenges: the prolonged delivery time required for oxidant diffusion and competitive consumption of oxidants by coexisting reductants. Potassium ferrate (K 2 FeO 4 ) is a highly efficient and eco-friendly water treatment agent owing to its strong oxidizing properties. However, its practical application is hindered by self-decay and substrate interference. Therefore, this study presented a novel slow-release ferrate material (K 2 FeO 4 @SiO 2 ) that integrated the high oxidizing capabilities of ferrates with the structural stability and functional advantages of nanosized SiO 2 . Given the low heating (30–100 °C) process is currently used for the thermal activation of oxidant in in-situ groundwater and soil remediation, a temperature-responsive system (K 2 FeO 4 @SiO 2 -LA) was further developed using lauric acid as a phase-change material to achieve controlled release of ferrate active components. Characterization confirmed the effective encapsulation of K 2 FeO 4 in the temperature-controlled material. The effectiveness of this material for removing norfloxacin (NOR) from water and its underlying degradation mechanism were comprehensively investigated. The material exhibited a removal efficiency of 9.4 % at 30 °C, which increased to 76.4 % at 50 °C. It exhibited excellent degradation performance and precise temperature responsiveness across a broad pH range and maintained high efficiency. High-valent iron (Fe(VI), Fe(V), Fe(IV)) served as the active oxidizing agent in the K 2 FeO 4 @SiO 2 -LA system. The sustained-release mechanism of the SiO 2 core-shell structure effectively suppressed K 2 FeO 4 self-decay, enhancing the production of high-valent iron and the NOR removal efficiency. Moreover, temperature-controlled materials were applied for efficient antibiotic removal from practical waters, offering a novel strategy for managing antibiotic pollution.