Photoelectrocatalytic hydrogen production from oilfield-produced wastewater in a filter-press reactor using TiO2-based photoanodes

Photoelectrocatalytic hydrogen production and simultaneous oxidation of organic pollutants from oilfield-produced wastewater were evaluated in a continuous filter-press reactor at bench scale using TiO2-based photoanodes under visible-light illumination. TiO2 films were prepared on AISI/SAE 304 stainless steel expanded meshes by sol-gel dip-coating. Nickeled AISI/SAE 304 stainless steel expanded meshes were used as cathode. Initially, the experiments were carried out using synthetic produced wastewater with a salinity equivalent to that of oilfield-produced wastewater and containing phenol at the same concentration as the refractory organic pollutants in this effluent. Cathodic and anodic potential ranges were established by micro-electrolysis studies using voltammetric techniques. Appropriate cathode/anode area ratios for different flow rates were estimated by macro-electrolysis studies using chronoamperometric measurements, in order to establish the cell currents required to obtain the adequate electrode potentials. After 2 h, the highest hydrogen production rate (12.36 mu mol/h) was achieved at a flow rate of 0.76 L/min applying a cell current of 32.44 mA and the lowest hydrogen production rate (5.98 mu mol/h) was achieved at a flow rate of 2.00 L/min applying a cell current of 17.90 mA. Using oilfield-produced wastewater, the hydrogen production rate was 9.11 mu mol/h at the most appropriate operating conditions (0.76 L/min, 32.44 mA). (C) 2016 Elsevier B.V. All rights reserved.