The properties of supercritical CO₂ (SCCO₂) and supercritical water (SCW) turn them into fluids with a great ability to remove organic adsorbates retained on solids. These properties were used herein to regenerate an activated carbon fiber (ACF) saturated with a pollutant usually contained in wastewater and drinking water, phenol. Severe regeneration conditions, up to 225 bar and 400 °C, had to be employed in SCCO₂ regeneration to break the strong interaction established between phenol and the ACF. Under suitable conditions (regeneration temperature, time, and pressure, and flow of SCCO₂) the adsorption capacity of the exhausted ACF was completely recovered, and even slightly increased. Most of the retained phenol was removed by thermal desorption, but the extra percentage removed by extraction allowed SCCO₂ regeneration to be significantly more efficient than the classical thermal regeneration methods. SCCO₂ regeneration and SCW regeneration were also compared for the first time. The use of SCW slightly improved regeneration, although SCW pressure was thrice SCCO₂ pressure. The pathways that controlled SCW regeneration were also investigated.

Steam gasifies dodecane faster than supercritical water, but supercritical water is able to produce greater amounts of H₂.

High pressure supercritical water efficiently destroys and upgrades phenol by converting the pollutant into H₂ and CH₄.