Treatment of hydroquinone by photochemical oxidation and electrocoagulation combined process

Today, considerable attention has been focused on the improved elimination of non-biodegradable pollutants through hybrid (combined) processes. In this study, a combination of electrocoagulation (EC) and photochemical oxidation (PCO) was proposed for the removal of hydroquinone (HQ) from aqueous solution. The experiments were carried out to investigate the effects of current density, HQ concentration, UV light power and different combination of both processes (EC and PCO recirculation loop process, only EC, only PCO with or without air supply) on the removal efficiencies of HQ and p-Benzoquinone (BQ). Furthermore, the adsorption capacity of aluminum hydroxide electrocoagulant flocs was calculated and the oxidation extent of HQ to BQ was investigated. According to the results, HQ removal efficiency increased nearly 40% owing to air supply in the reaction medium, while high removal extent of BQ by electrocoagulant flocs increased the performance of the EC–PCO process which allowed the removal extent of HQ to be as high as 91.5% at the following operating conditions; current density: 5 A/m2, UV light power: 24 W (37 W per dm3 of the solution), operating time: 60 min.