Preparation and characterization of carbon nanomaterials prepared by thermal treatment of biomass DNA

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The hydrothermal synthesis of DNA carbon nanomaterials (carbon dots) using a conventional hydrothermal reactor and the microwave reactor under the same conditions were conducted to compare the fluorescent properties of products. It was found that while the emission wavelengths were similar for both types of reaction products, the carbon dots prepared in the microwave reactor had 1.5-2-fold higher fluorescence compared to those obtained in the conventional HT heating reaction.Next, biochars and hydrocars were prepared from DNA or DNA-derived materials by the pyrolytic treatment at 300-500 degrees and hydrolytic treatment at 200 degrees. The obtained chars were studied for their adsorption capacities towards typical environmental pollutants (heavy metal ions and pharmaceuticals) by standard batch adsorption experiments. DNA-derived biochars and hydrochars showed low adsorption capacities (ca. 1 mg/g and below) towards all studied adsorbents compared to the original DNA and DNA containing materials and standard adsorbents such as activated carbon. The decrease in the adsorption capacity during thermal treatment of DNA materials was ascribed to the decomposition of nitrogen-containing and other functional groups that served as active centers for binding with the adsorbing molecules. The application of DNA-derived chars as adsorbents was thus shown to be limited. Furthermore, it was concluded that the presence of the phosphate moieties in the DNA prevented the formation of the graphitic carbon structures suggested in the beginning of the study.