Degradation of phenol using a combination of ultrasonic and UV irradiations at pilot scale operation

In the present work, combination of ultraviolet (UV) irradiations (using 8 W UV tube) with ultrasonic (US) irradiations (rated power 1 kW and frequency of 25 kHz) has been investigated for the degradation of phenol at pilot scale of operation. Different modes of operation viz. UV alone, US alone, UV/US, UV/TiO2 (photocatalysis), UV/H2O2, UV/NaCl, UV/US/TiO2 (sonophotocatalysis) and H2O2 assisted sonophotocatalysis have been investigated with an objective of maximizing the extent of phenol degradation. Effect of presence of hydrogen peroxide and sodium chloride at a concentration of 10 g/l and TiO2 over a range of 0.5–2.5 g/l has been investigated. It has been observed that 2.0 g/l of TiO2 is the optimum concentration, beyond which a decrease in the extent of degradation is observed. Maximum extent of degradation of phenol was 37.75% for H2O2 assisted photosonocatalysis at pH of 2. The present work is first of its kind to report the use of combined ultrasonic and UV irradiations at pilot scale operation and obtained results should induce some degree of certainty in proposed industrial applications of sonochemical reactors for wastewater treatment.