Degradation of α-terpineol in aqueous solution by UV/H2O2: kinetics, transformation products and pathways

Abstract

The monoterpene alcohol α-terpineol is extensively used as the foaming agent in mineral processing and can be released to environment along with the wastewater. This study evaluated the feasibility of eliminating α-terpineol in water by ultraviolet irradiation (UV) in combination with hydrogen peroxide (H2O2). Within an H2O2 dose of 10 mg/L and an UV fluence of 64.8 J/cm2, more than 95% of the α-terpineol can be removed. The reactions fitted well to pseudo-first-order kinetics, and the apparent rate constant was 0.0678 min−1. The effects of matrix species including various anions and humic acid (HA), were evaluated. The degradation rate decreased significantly with the addition of bicarbonate and HA. Further verification was carried out with three types of real water samples. In the ground water and the surface water, the degradation rate decreased likely due to the presence of natural organic matter. Finally, possible degradation pathways were proposed based on the identification of transformation products, and the occurrence of two main transformation products were monitored. This study demonstrated that the UV/H2O2 is an effective technology for the degradation of α-terpineol in water.

Bicarbonates and carbonates as antioxidants in vegetable oils at frying temperatures

“…It was reported that the carbonate ion (CO 3 2− ) could scavenge hydroxyl radical (OH • ) by the electron transfer reaction of carbonate ion to hydroxyl radical (OH • + CO 3 2− → OH − + CO 3 • − ) in an aqueous solution (Hoigné & Bader, 1976). The bicarbonate ion also acted in the same way to scavenge free radicals slowing the rate of ozone decomposition (Chen et al., 1987) and preventing the degradation of α‐terpineol under UV/H 2 O 2 treatment (Yao et al., 2019). However, since their effectiveness in stripped SBO was not as great as in unstripped SBO, other factors such as the interactions with tocopherols may also be involved in the antioxidant activity.…”