Rice husk biochar catalyst breaks down antibiotic pollutants in minutes
Rice husk biochar loaded with cobalt oxide destroyed the antibiotic levofloxacin in four minutes, a Chinese Academy of Sciences team reported in Biochar.
Photo by Pixabay on Pexels
A rice husk biochar catalyst broke down a common antibiotic in water in four minutes, researchers at the Institute of Urban Environment, Chinese Academy of Sciences, reported in the journal “Biochar.” Announced on 16 June 2026, the work describes a catalyst made by loading cobalt oxide (Co₃O₄) onto biochar derived from rice husks, an agricultural waste, that achieved complete removal of levofloxacin at neutral pH. The corresponding author is Dr Jiafang Xie.
The result targets a growing problem: antibiotics that pass through people and livestock and end up in rivers and treated wastewater, where they can drive antimicrobial resistance. The team’s approach turns a low-value crop residue into a catalyst that destroys those drugs rather than simply filtering them out.
How the rice husk biochar catalyst works
The catalyst activates peroxymonosulfate (PMS), a chemical that, once triggered, produces reactive species that oxidise organic pollutants. The best-performing material, named RHBA800@25Co₃O₄, pairs the porous structure of rice-husk biochar with well-dispersed cobalt-oxide nanostructures. Under reaction conditions, the team reported, lattice oxygen drives formation of a surface species, Co₃O₄−α–OH, that binds PMS more strongly and speeds the electron transfer needed for fast oxidation. With that catalyst, levofloxacin was fully removed within four minutes at neutral pH.
The catalyst was not limited to one drug or to clean laboratory water. The team reported that it also degraded ciprofloxacin, tetracycline and sulfadiazine, and that it worked in real lake water, tap water and secondary effluent from a sewage-treatment plant. After treatment, the solution lost its antibacterial effect on Escherichia coli, indicating the antibiotic activity was removed rather than just diluted. In a fixed-bed reactor, the system ran continuously and stably for 72 hours.
| Measure | Result |
|---|---|
| Best-performing catalyst | RHBA800@25Co₃O₄ (rice-husk biochar + cobalt oxide) |
| Levofloxacin removal | 100% within 4 minutes, at neutral pH |
| Other antibiotics degraded | Ciprofloxacin, tetracycline, sulfadiazine |
| Water types tested | Lake water, tap water, secondary sewage effluent |
| Continuous operation | Fixed-bed reactor stable for 72 hours |
| After treatment | Solution lost antibacterial effect on E. coli |
Source: Institute of Urban Environment, Chinese Academy of Sciences; “Biochar” 8, 113 (2026), via EurekAlert (16 June 2026).
Why a waste-derived catalyst matters
The design fits a circular-economy approach in which one process’s waste becomes another’s input. Rice husk is one of the world’s most abundant crop residues, often burned or dumped. Converting it to biochar and adding a small amount of cobalt oxide yields a catalyst for water treatment, an example of the eco-efficiency that pairs innovation with lower resource use. Two features matter for any real deployment: the catalyst worked at neutral pH, avoiding the acid dosing some treatments need, and it held up across genuine water samples rather than only distilled water. The authors present laboratory and bench-scale reactor results; scale-up, catalyst lifetime, cobalt retention and cost are the questions a pilot would need to answer next.
Background
Biochar is a porous, carbon-rich solid made by heating biomass with little or no oxygen, a process known as pyrolysis. First valued as a soil amendment and a way to store carbon, it has more recently been studied as a low-cost support for catalysts in water treatment. A growing line of research uses biochar to activate persulfate compounds such as peroxymonosulfate, generating reactive species that break apart stubborn organic pollutants, including pharmaceuticals that conventional treatment plants do not fully remove. Antibiotic contamination of surface water and treated effluent has drawn particular concern because trace drug residues can promote resistant bacteria. The new “Biochar” study adds a rice-husk catalyst to that field, pairing a fast removal time for levofloxacin with tests in real water and a 72-hour reactor run, while leaving field-scale performance for future work.
Sources: Biochar (Springer); EurekAlert! (Institute of Urban Environment, CAS); Bioengineer
Featured image: photo by Pixabay on Pexels (free Pexels license).
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I specialize in sustainability education, curriculum co-creation, and early-stage project strategy. At WINSS, I craft articles on sustainability, transformative AI, and related topics. When I’m not writing, you’ll find me chasing the perfect sushi roll, exploring cities around the globe, or unwinding with my dog Puffy — the world’s most loyal sidekick.
