A nonradical oxidation process initiated by Ti-peroxo complex showed high specificity toward the degradation of tetracycline antibiotics

Nonradical oxidation has received wide attention in advanced oxidation processes for environmental remediation. Understanding the relationship between material characteristics and their ability to initiate nonradical oxidation processes is the key to better material design and performance. Herein, a novel titanium-based metal-organic framework MIL-125-Ti/H 2 O 2 system was established to show a highly selective degradation efficacy toward tetracycline antibiotics . MIL-125-Ti with the abundance of TiO 6 octahedra units was found to effectively activate H 2 O 2 under dark conditions by forming an oxidative Ti-peroxo complex. The presence of the Ti-peroxo complex, confirmed by UV-visible spectrophotometer, fourier transform infrared spectroscopy , and X-ray photoelectron spectroscopy characterizations, showed superior degradation (>95% removal rate) of oxytetracycline hydrochloride (OTC), doxycycline hydrochloride, chlortetracycline hydrochloride, and tetracycline . Density functional theory calculations were performed to assist the elucidation on the mechanism of H 2 O 2 activation and antibiotics degradation. The MIL-125-Ti/H 2 O 2 system was highly resistant to halogens and background organics, and could well maintain its original catalytic activity in actual water matrices. It retained the ability to degrade 75% of OTC within ten test cycles. This study provides new insight into the nonradical oxidation process initiated by the unique Ti-peroxo complex of Ti-based MOF. Ti-peroxo complex initiated a nonradical oxidation process for the degradation of tetracycline antibiotics in a titanium-based MOF/H 2 O 2 system.