Construction of glycine modified NZVI@gelatin aerogel for high efficient activation of dissolved oxygen towards catalytic degradation of tetracycline

The congregate and passivation of Nanoscale zero-valent iron (NZVI) can be significant challenges in wastewater remediation. In this study, a glycine-modified gelatin carbon aerogel-loaded NZVI catalyst (NZVI@G-GEL) was synthesized in an atmospheric setting, eliminating the requirement for nitrogen shielding. This approach significantly ameliorated the deficiencies of NZVI and aerogel. The comparison of SEM, BET, and Fe leaching demonstrated that NZVI@G-GEL not only augmented the active sites and enhanced the catalytic activity but also mitigated the risk of secondary pollution. Under the optimal conditions (0.12 g/L, pH = 6.5, 30 mg/L TC, 298 K), the degradation efficiency of tetracycline (TC) by NZVI@G-GEL reached 96.99 % in 60 min. This represents a 29.68 % improvement compared to the degradation efficiency of unmodified NZVI. Electron paramagnetic resonance (EPR) analysis shows that dissolved oxygen (DO) can be activated to generate free radicals ([rad]OH, [rad]O₂⁻) and non-radicals (¹O₂) in synergistic degradation of catalytic TC with each other in the absence of any oxidant addition. Additionally, fifteen intermediate products were identified through the use of liquid chromatography-mass spectrometry (LC-MS), leading to the suggestion of three potential degradation mechanisms for TC. This research offers a novel strategy for the breakdown of organic contaminants in water using advanced oxidation techniques, eliminating the need for additional oxidants and energy.