Potential of the hydrothermal carbonization process for the degradation of organic pollutants

• The degradation potential of the HTC process is investigated for 12 organic pollutants.
• The degree of conversion and formation of metabolites was analyzed by GC–MS.
• The model biomass sucrose has no negative influence on the degree of degradation.
• Increased conversion of three compounds was observed in presence of biomass.
• Limitations in degradation of chlorinated aromatics remain.

The degree of degradation of 12 organic compounds from various classes, comprising of pharmaceuticals, pesticides, and industrial chemicals, was analyzed after hydrothermal treatment at 200 °C for 4 or 16 h, or 255 °C for 16 h. The reactions were conducted in water, aqueous H2SO4, or sucrose solution in aqueous H2SO4 as a representative matrix of hydrothermal carbonization (HTC) of wet biomasses. The impact of the sucrose-matrix, which formed during the HTC reaction as a solid hydrochar material and a complex pattern of dissolved organic matter in the aqueous phase, was found to be insignificant for the degree of conversion of most compounds. On the contrary, the degree of degradation of 2,6-dinitrotoluene, 2-chloronaphthalene and 3-chlorobiphenyl was enhanced when biomass was present. At high temperatures most of the pollutants were converted except for ibuprofen and chlorinated aromatics. Hydrothermal treatment of β-hexachlorocyclohexane and 4,4′-dichlorodiphenyltrichloroethane led to the formation of stable chlorinated aromatic intermediates.