Fig 1.
Radical conversion of (1) terephthalic acid to (2) 2-hydroxyterephthalic acid [16].
Fig 2.
Variation of input energy [kJ] and HTA concentrations [*104 mM] at different power inputs [W] of 200 and 400 W and probe depths [mm] of 5–20 mm.
Fig 3.
Normalized extraction efficiencies (%) for ultrasound-assisted extractions: (A) extraction without pretreatment, (B) extraction with one boiling water pretreatment and (C) extraction with two following boiling water pretreatments.
Fig 4.
Summarised concentrations [mg/mL] of products extracted in two cycles from bamboo bast fibre powder at 200 and 400 W input power, with 15 mm probe depth, 22kHz, obtained by LC-ESI-TOF analyses.
Fig 5.
(A) Relative increase [%] of (+)-pinoresinol measured by LC-ESI-TOF after extraction B (extraction with one boiling water pretreatment) and C (extraction with two following boiling water pretreatments) using an input power of 200 or 400 W with a 15 mm probe depth (B) Dimerization reaction of coniferyl alcohol radicals generated by ultrasound induced radical formation to (+)-pinoresinol; the control consisted on the extraction without ultrasound.