Boron removal by iron-aluminum combined anodes from fracturing flowback fluid: Advantages and mechanisms

During the process of oilfield wastewater reuse, residual Boron in fracturing flowback fluid will lead to premature crosslinking with gelling agents, resulting in excessive viscosity at the front end of the fracturing fluid configuration. This phenomenon has heavily influenced the reuse of wastewater. Electrocoagulation (EC), as an effective approach to decreasing Boron concentration, has been widely studied, while further research of Boron removal from complicated wastewater is required to optimize. EC parameters were investigated to explore the optimal Boron removal effect of Fe, Al and Fe-Al three combined anodes. Under 46.3–57.2 mA/cm2, 90 min and pH of 9, Fe-Al anodes exhibit the best effect of Boron removal (84% ± 1.5%). Furthermore, high adaptive capacity of low current density and suitable pH confirm the best choice of Fe-Al combined anodes. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrate the complexation between Boron and metallic oxide. Finally, the common removal of various pollutants including Ca, Cl, K and Na further conduces to the reuse of oil wastewater.