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

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.