Remediating oxytetracycline-contaminated aquaculture water using nano calcium peroxide (nCaO2) produced from flue gas desulfurization (FGD) gypsum

Abstract

Antibiotic-contaminated water, particularly oxytetracycline (OTC), which is widely used in aquaculture, can threaten human health through the ingestion of edible aquatic organisms. The objective of this study was to develop novel and cost-effective calcium peroxide nanoparticles (nCaO 2 ), synthesized using flue gas desulfurization (FGD) gypsum for improving water quality and OTC removal. The nCaO 2 -FGD was synthesized using a 1:7 (FGD:H 2 O 2 ) mixture. The results showed that nCaO 2 -FGD had spherical particles with diameters of 20–60 nm. The dissolved oxygen production in water by nCaO 2 -FGD significantly increased, with an oxygen release rate of 0.0079 min −1 . The nCaO 2 -FGD achieved OTC removal of 83.92% within 48 h. Radical trapping experiments revealed that hydroxyl radical, superoxide ion, and singlet oxygen play important roles in OTC degradation. The mineralization of the OTC investigated by total organic carbon (TOC) was 71 ± 4%. The nCaO 2 -FGD dosage, initial OTC concentration, carbonate ion, and humic acid (HA) significantly affected OTC removal, while the initial pH and chloride ion did not at the 95% confidence level. Using response surface methodology, we found that the optimum conditions for treating 10 mg/L of OTC were 53.25 mg/L HA, 558.72 mg/L CO 3 2 − and 2,320.75 mg/L CaO 2 -FGD. The nCaO 2 -FGD encapsulated in alginate aided in maintaining the pH of water (pH 6.5–7). The nCaO 2 -FGD was then used to treat real aquaculture water. After 48 h, 10 mg/L of OTC was degraded by 75.83 ± 2.1%. The zooplankton communities in the aquaculture water did not significantly differ before and after treatment. Therefore, our results indicate that nCaO 2 -FGD is safe for implementation • FGD gypsum, a solid waste byproduct of coal-based power generation, was economically utilized. • As a novel dual-function material, nCaO 2 -FGD acts as an oxygen-release and effective oxidizing material. • O 2 was released mainly from nCaO 2 -FGD dissolution. • Active radicals generated in the nCaO 2 -FGD/water system play important roles in degrading OTC.