Photodegradation of 4-tert-butylphenol in aqueous solution by UV-C, UV/H₂O₂ and UV/S₂O₈²⁻ system

ABSTRACT

The photolytic degradation of 4-tert-butylphenol (4-t-BP) in aqueous solution was investigated using three kinds of systems: UV-C directly photodegradation system, UV/H₂O₂ and UV/S₂O₈²⁻ system. Under experimental conditions, the degradation rate of 4-t-BP was in the order: UV/S₂O₈²⁻ > UV/H₂O₂ > UV-C. The reaction kinetics of UV/S₂O₈²⁻ system were thoroughly investigated. The increase of S₂O₈²⁻ concentration enhanced the 4-t-BP degradation rate, which was inhibited when the concentration of S₂O₈²⁻ exceeded 4.0 mM. The highest efficacy in 4-t-BP degradation was obtained at pH 6.5. The oxidation rate of 4-t-BP could be accelerated by increasing the reaction temperature and irradiation intensity. The highest rate constant (k_obs = 8.4 × 10⁻² min⁻¹) was acquired when the reaction temperature was 45°C. The irradiation intensity was measured by irradiation distance, and the optimum irradiation distance was 10 cm. Moreover, the preliminary mechanism of 4-t-BP degradation was studied. The bond scission of the 4-t-BP molecule occurred by the oxidation of SO₄^•−, which dimerized and formed two main primary products. Under the conditions of room temperature (25°C±1°C) and low concentration of K₂S₂O₈ (0.5 mM), 35.4% of total organic carbon (TOC) was removed after 8.5-h irradiation. The results showed that UV/S₂O₈²⁻ system was effective for the degradation of 4-t-BP.

KEYWORDS:

• 4-tert-butylphenol
• photodegradation
• sulfate radical
• UV/S₂O₈²⁻

Funding

This research was financially supported by National Natural Science Foundation of China (NSFC 21077027), China Scholarship Council and Shanghai Tongji Gao Tingyao Environmental Science & Technology Development Foundation (STGEF).