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

•A novel photoelectrochemical reactor for hydrogen production and simultaneous oxidation pollutants was design.•The Oxidation of organic pollutants presents in oilfield produced is limited by the mass transfer.•Maximum hydrogen production rate was obtained using slow flow rate.

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 μmol/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 μmol/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 μmol/h at the most appropriate operating conditions (0.76 L/min, 32.44 mA).

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