The scientific document, accepted for publication in the Journal of Hazardous Materials Advances, was co-authored by Xiaodong Yang, Jin Zhao, Enshuo Zhang, Bowen Jiang, Shengjun Zhao, Tianyang Luo, Pengkai Sun, Shanlin Yang, Ye Han, Lili Wang, Fanming Zeng, Cheng Ding, and Bin Gao. The extensive use of antibiotics in modern medicine has triggered serious environmental and public health concerns due to the persistent accumulation of active chemical formulations in global aquatic ecosystems. Among these hazardous chemical materials, the quinolone antibiotic norfloxacin is particularly problematic because of its structural stability and its frequent detection in municipal wastewater and global surface waters. To address this structural persistence, the researchers focused on modifying graphitic carbon nitride, a highly stable and promising photocatalyst that historically suffers from poor solar-light utilization and rapid charge carrier recombination. By utilizing sustainable rice husk biochar as an affordable carbon source, the team successfully developed a simplified synthesis protocol to scale up the industrial potential of solar-driven water remediation.

The experimental strategy successfully bypassed traditional multi-step preparation procedures by executing an in-situ coupling approach during thermal treatment. The research team combined pre-treated rice husk elements with a urea precursor and heated the mixture to five hundred and fifty degrees Celsius for two hours to induce carbon doping directly into the crystalline lattice structure. Structural characterization verified that this process successfully substituted bridged nitrogen atoms with carbon atoms, which altered the internal electronic framework without degrading the base molecular configuration. The resulting composites developed a layered, hierarchical nanosheet morphology decorated with porous active sites, which significantly shortens contaminant diffusion paths and optimizes electron mobility under light exposure.

Performance evaluations demonstrated that the catalytic efficiency of the composite material is highly dependent on achieving the correct internal blending ratio. The optimized configuration, labeled as BCN5, achieved an eighty-eight percent norfloxacin removal efficiency with a high degradation rate constant over two hours of visible-light irradiation. This degradation performance represents a substantial improvement over pure graphitic carbon nitride, which achieved a removal efficiency of only fifty-eight percent under identical testing parameters. The presence of localized states from the biochar effectively narrowed the composite bandgap energy to two point seventy-two electron volts, allowing the material to capture a broader spectrum of solar energy. However, exceeding this optimal loading threshold by adding too much biochar caused performance declines because an over-occupation of carbon atoms introduces internal structural defects that trap moving electrical charges.

Mechanistic investigations using chemical scavengers revealed that highly reactive superoxide radicals act as the primary chemical force driving the oxidation and destruction of the target antibiotic. Photogenerated holes and hydroxyl radicals also provided minor supplementary contributions to the degradation pathway, progressively splitting the complex norfloxacin molecules into harmless small-molecule substances. Furthermore, durability assessments established that the composite functions as a highly stable treatment agent, maintaining eighty-five percent of its original photocatalytic performance after completing five consecutive reuse cycles. Backed by financial grants from the National Natural Science Foundation of China and provincial science agencies, this research provides an efficient, low-cost approach for deploying agricultural recycling assets to combat industrial antibiotic contamination.

Source: Yang, X., Zhao, J., Zhang, E., Jiang, B., Zhao, S., Luo, T., Sun, P., Yang, S., Han, Y., Wang, L., Zeng, F., Ding, C., & Gao, B. (2026). One-step calcination synthesis of rice husk biochar-doped g−C3​N4​ for efficient photodegradation of norfloxacin. Journal of Hazardous Materials Advances, 101252.