One carbon-nanofiber electrode treats antibiotic-laden sewage, makes peroxide and power

Researchers at CSIR-Advanced Materials and Processes Research Institute in Bhopal, India, have built a single electrode that lets a microbial fuel cell do three things at once: break down an antibiotic in sewage, make hydrogen peroxide and deliver a small electrical current. The work, led by Yashmeen Budania and colleagues including Shiv Singh, is published in the Journal of Power Sources. It is a laboratory demonstration using 250 millilitre chambers, not a treatment-plant trial.

Turning wastewater chemistry to advantage

In a microbial fuel cell, bacteria digest organic matter in wastewater and release electrons. These pass through an external circuit to a second electrode, where they normally reduce oxygen to water in a four-electron reaction. If the reaction stops after two electrons, hydrogen peroxide forms instead. Peroxide is a widely used oxidant for disinfection, bleaching and chemical manufacturing, and its industrial production is energy- and chemical-intensive.

The team aimed to use that two-electron route, while the same electrode also hosted the bacteria that clean the water.

A electrode grown in place

The electrode starts with flexible carbon cloth impregnated with iron and nickel salts. The cloth is heated to convert the salts to oxides, then exposed to acetylene gas at 800°C. Carbon nanofibers grow from the cloth, carrying metal oxide particles at their tips. Because the fibres are grown directly on the cloth, no glue or binder is needed. The rough, forest-like surface also gives bacteria a place to form a thick film.

The same electrode was used on both sides of a two-chamber cell. One chamber held sewage from Bhopal spiked with 50 milligrams per litre of chloramphenicol; the other held sodium sulfate solution.

What the cell achieved

• Chloramphenicol fell to essentially undetectable levels by chromatography within 48 hours, against only about 5% loss when the circuit was left open.
• Chemical oxygen demand, a measure of organic pollution, fell by 94%.
• Hydrogen peroxide accumulated to 0.74 millimoles per litre, and most of the electrons passing through the wire went into making it.
• The cell produced about 0.6 volts and a peak power density of 24.7 milliwatts per square metre.

The open-circuit control suggests that adsorption onto the electrode does not explain the removal. Electrodes containing only iron or only nickel performed worse than the mixed one, which carried the most current and showed the lowest charge-transfer resistance. X-ray photoelectron spectra showed iron and nickel shifting in opposite directions, which the authors interpret as electron redistribution between the two metals.

Limits and next steps

The authors are clear about the constraints. Power output is small, as is typical for microbial fuel cells. The antibiotic was transformed rather than fully mineralised: total organic carbon fell by about half, and mass spectrometry identified eight breakdown products, several that had lost their chlorine atoms. Their toxicity is not yet known.

The team says this is, to its knowledge, the first time one binder-free electrode has combined wastewater treatment, antibiotic removal, peroxide production and electricity generation in one cell. Only one antibiotic, one wastewater source and a single 48-hour run were described.

Planned work includes longer operation, tests with other drugs, toxicity assessment of the degradation products and connecting several cells in series to raise power output. For researchers in electrocatalysis and wastewater engineering, the study offers a design for multifunctional bioelectrodes, with scale-up and by-product safety as the main open questions.

Source: One system, three solutions: Tackling antibiotic pollution while generating hydrogen peroxide and electricity (Tech Xplore, 4 November 2026).

Image: AI-generated illustration.