(721g) Hydrothermal Degradation of Hormones and Antibiotics

The concentration of hormone and antibiotic in soil and water has become a big concern in US in the last few year. The half-lives of the hormones and antibiotics in soil can be as long as 10 months depending on the chemical type and soil condition. Therefore, runoff of those is an inevitable scenario. Hormones are biologically active at very low levels and may disrupt the reproductive endocrinology of fish, while antibiotics facilitates the development and proliferation of antibiotic resistance bacteria (ARB). Both hormones and antibiotics are considered as emerging pollutants for the environment, which need to be degraded.

Hydrothermal carbonization (HTC) a thermochemical process, where biomass is treated with high-pressure high-temperature liquid water. It is a promising conversion technology that can degrade emerging pollutants (i.e., hormone, antibiotic, etc.). Subcritical water around 160-280°C shows self-dissociation also the formation of H⁺ and OH^− is influenced by the strong clustering effect. This leads to a high “local concentration” of H⁺ and OH^− ions. As a result, a hydrogen atom of water comes very near to a reactive center of an organic molecules. The targeted hormones and antibiotics contain saturated and unsaturated C-C bond as well ketone, hydroxyl, and amines. Therefore, individual compound participates into different reactions (e.g., hydrolysis, nucleophilic substitution, deprotonation etc.) at different rates in subcritical conditions and degrade differently. However, reaction rate depends on the chemical bonds of the organic molecule.

Therefore, the objective of this study was to investigate the degradation phenomenon of emerging pollutants with HTC temperature. A series of HTC experiments were conducted at different temperature (180-280 °C) and residence time of 60 min by using model compounds like, oxytetracycline, sarafloxacin, β-estradiol, α-zearalanol etc. HPLC and LC-MS were used to analyze the process liquid. The analysis showed that the concentration of pollutants reduced significantly with the HTC temperature.