Cellulose-supported TiO2 catalyst degrades antibiotic ofloxacin under direct sunlight

Ofloxacin, a fluoroquinolone antibiotic that resists biodegradation and contributes to antimicrobial resistance in aquatic environments, can be nearly completely broken down by a new sunlight-driven photocatalyst, according to a peer-reviewed accepted study published in Discover Chemical Engineering. The work, shared early with a permanent DOI and subject to final edits, reports that cellulose nanocrystal-supported TiO2 nanocomposites degraded approximately 98.6% of the antibiotic under direct sunlight.

The research team, comprising Abhijit Saha, Murali Mohan Seepana and Swambabu Varanasi, created the sustainable photocatalytic system by anchoring titanium dioxide onto cellulose nanocrystals. This support changed the optical properties of the catalyst in a way that matters for solar applications: the nanocomposite showed a lower band gap of 2.99 electronvolts, compared with 3.29 electronvolts for pristine TiO2, promoting better absorption of sunlight.

Under optimized conditions of 250 milligrams per litre catalyst dosage, pH 7 and 300 minutes of irradiation, the system achieved its peak performance, with the degradation following pseudo-first-order kinetics. The authors note that the findings indicate the potential of these nanocomposites as reusable photocatalysts for sunlight-driven antibiotic degradation in complex wastewater matrices.

A central result of the study concerns which reactive species actually drives the chemistry. Reactive-species scavenging experiments showed that photogenerated holes governed the degradation process, while superoxide radicals provided a secondary oxidative route. This hole-driven mechanism gives the nanocomposite its name in the paper’s title and distinguishes its operating chemistry from catalysts dominated by other radical pathways.

The degradation was not merely a fragmentation of the parent molecule into smaller pollutants. Liquid chromatography tandem mass spectrometry analysis confirmed multiple degradation pathways that finally led to mineralization, with 73.82% removal of total organic carbon. In other words, most of the organic carbon originally present in the antibiotic was converted out of organic form during treatment.

Performance in realistic conditions was also tested. In an ofloxacin-spiked complex wastewater matrix, the catalyst achieved approximately 94% degradation at laboratory scale, a result the authors describe as promising for hospital wastewater applications.

The study reports that cellulose nanocrystal incorporation improves catalyst recovery, and the catalyst retained 81.2% degradation efficiency after five reuse cycles. The authors also highlight the catalyst’s good stability and reusability over multiple cycles.

The study’s scope deserves careful reading. All results come from laboratory-scale experiments with ofloxacin-spiked matrices rather than continuous treatment of real wastewater streams, and the published version remains subject to further edits before the final Version of Record appears. The authors frame the work as indicating potential rather than demonstrating full-scale readiness.

By combining a bio-based support material with a lowered band gap, a hole-dominated mechanism and demonstrated reuse over five cycles, the CNC-TiO2 system offers a documented laboratory benchmark for sunlight-driven degradation of one of the more persistent antibiotic classes found in aquatic environments.

Subject of Research: Sunlight-driven photocatalytic degradation of the antibiotic ofloxacin using cellulose nanocrystal-supported TiO2 nanocomposites

Article Title: Hole-driven solar photocatalysis of ofloxacin using cellulose nanocrystal-supported TiO2 nanocomposites

Article References: Saha, A., Seepana, M. M., & Varanasi, S. (2026). Hole-driven solar photocatalysis of ofloxacin using cellulose nanocrystal-supported TiO2 nanocomposites. Discover Chemical Engineering. https://doi.org/10.1007/s43938-026-00154-8

Image Credits: AI Generated

DOI: 10.1007/s43938-026-00154-8

Keywords: ofloxacin, photocatalysis, TiO2, cellulose nanocrystals, antibiotic degradation, wastewater treatment, solar photocatalysis, photogenerated holes, mineralization, fluoroquinolone antibiotics, catalyst reusability, antimicrobial resistance