In situ visualization of transformation of organic matter in water at high pressures and temperatures

Water of high pressure and temperature is attracting attention for its unique properties and here an in situ observational technique has been developed to study organic matter transformations in H-P and -T (high-pressure and -temperature) water. Three samples of different kind involving aromatic organic compound, polymer, and natural biomass behave greatly different. Anthracene dissolves in water at the temperature of 325 °C and corresponding pressure of 315.9 MPa and remains stable till the highest temperature of 420 °C of this work. Polystyrene and rice straw hydrolyze in the form of heterogeneous phases in H-P and -T water. Polystyrene melts to form non-soluble liquid spherule before hydrolysis, whereas rice straw hydrolyzes directly from non-soluble solid. The light organic molecules produced from hydrolysis dissolve in water at high temperatures and separate out during cooling. The study is helpful to understand reaction mechanism and process of hydrolysis of biomass and polymer in H-P and -T water.