Products from reducing chromium carcinogen trace hydrogen peroxide

Hexavalent chromium, or Cr(VI), is a highly toxic carcinogen created during industrial processes like welding. It can pollute the environment and negatively impact humans and livestock. In contrast, trivalent chromium, or Cr(III), is an essential element in the human body and about 100 times less toxic.

Reducing Cr(VI) to Cr(III) is therefore one way to combat chromium pollution. Many studies have explored the mechanisms behind this reduction process, but few have focused on the end products. To fill this gap, Yang et al. investigated the morphology and application of Cr(III) after microbial reduction of Cr(VI).

“Nanoparticles containing Cr(III) are obtained by bacterial reduction of Cr(VI),” said author Yongqiang Tian. “Their properties are investigated, and the reduction product, Organo-Cr(III), was used to detect trace hydrogen peroxide.”

To break down the Cr(VI), the team used a strain of Lysinibacillus bacteria, which secretes extracellular products (such as proteins) that act as reducing and end-sealing agents. The resulting Cr(III) nanoparticles maintained a high residual mass at high temperatures, indicating their stability.

Because they react with hydrogen peroxide under certain conditions, Cr(III) nanoparticles can indirectly determine concentration of the chemical compound. This has uses in the food industry, where hydrogen peroxide is often added to packaging to kill harmful microorganisms. However, the Food and Drug Administration places a limit on the amount of hydrogen peroxide, as an excess can have harmful health effects.

“The reduction of high toxicity Cr(VI) to low toxicity Cr(III) is of positive significance for environmental protection,” said Tian. “I also hope these results can be better used to detect trace hydrogen peroxide in the food field.”

Source: “Biosynthesis, characterization and determination of trace hydrogen peroxide of Organo-Cr(III) nanoparticles by Lysinibacillus sp. 4H,” by Yichen Yang, Yi Yang, Guangyang Jiang, Li Yang, Jia Chen, Zhe Xu, Bijun Zheng, and Yongqiang Tian, AIP Advances (2023). The article can be accessed at https://doi.org/10.1063/5.0151141 .