Efficient removal of doxycycline using Schwertmannite as a heterogeneous Fenton-like catalyst over a wide pH range

Residual doxycycline (DOX) in the aquatic environment has received a considerable amount of critical attention due to its toxicity and widespread distribution in the environment. This study explored a simplified and rapid method to remove DOX over a wide pH range (pH = 2-10). Schwertmannite (SCH) was synthesized using biological methods to remove DOX in combination with H2O2. The results showed that 98.52% of DOX and 57.35% of total organic carbon (TOC) was removed over 30 min at 50 degrees C without any external energy input, where the addition of SCH and H2O2 was 1.6 g/L and 71 mg/L, respectively. Meanwhile, the DOX removal efficiency was 98.18% at 50 degrees C over 30 min and 97.70% of DOX could even be removed at 10 degrees C when the reaction time was prolonged to 120 min. Hydroxyl radicals (.OH) were the main oxidative species. Moreover, the removal efficiencies of DOX after 3 h in the SCH/H2O2 system were 26.97%, 31.54%, 39.23%, 47.07%, 68.43%, 88.92%, and 97.64% in actual aquaculture wastewater when the COD concentrations was 7000, 5000, 3000, 1000, 500, 200, and 100 mg/L, respectively. The results of this study provided a simple and rapid method for removing DOX from DOX-containing wastewater.