Electrochemical oxidation treatment of offshore produced water using modified Ti/Sb-SnO2 anode by graphene oxide

To improve Persian gulf severely damaged marine environment and prevent long term exposure risks of toxic chemicals being discharge into the sea, total COD removal of produced water (PW) at a South Pars gas field is proposed by electrochemical oxidation process (EO), using Ti/Sb-SnO2 anode modified with graphene oxide (GO) prepared in a simple and cost effective technique. Comprehensive electrochemical tests, morphological and structural examinations indicated that addition of GO, improved considerably electrocatalytic activity for the fabricated anode, confirmed formation of uniform SnO2 nanoparticles ranging 15−26 nm and presence of reduced GO. Maximum COD removal and energy efficiency for the pre-discharged offshore oxidation process unit was optimized using Box-Behnken methodology in the EO design experiments. For 2 h electrolysis of PW with prepared anodes, software optimized conditions of CD = 10 mA/cm2, pH = 4.00, electrode distances of 10 mm, and predicted 59.96 % COD removal and energy efficiency of 42.83 g/Kwh which were compatible with experimental data of 58.60 % and 42.63 g/Kwh, respectively. COD removal rate equation was a pseudo-first order with a constant rate of 0.006 min−1. Considering offshore platform operational limitations and associated process economics, the optimized EO unit process cost for total COD removal of PW, was estimated at U$5.74/m3.