Continuous electrooxidation of Methylene Blue in filter press electrochemical flowcell: CFD simulation and RTD validation

[Display omitted] •Pre-pilot electrochemical flowcell for treatment of Methylene Blue (MB) wastewater.•CFD simulation of MB electrooxidation reaction inside flowcell.•Assumption of mass transport controlled reaction in CFD simulations for simplicity.•Validation of CFD simulations with RTD and experimental MB electrooxidation.•Determinant complex degradation mechanism during anodic electrooxidation of MB. Methylene blue (MB) removal by means of a filter press electrochemical flowcell operating in recycle mode, equipped with graphite electrodes was surveyed. Hydrodynamics and mass transport inside flowcell were evaluated by Computational Fluid Dynamics (CFD) simulations and validated by experimental Residence Time Distribution (RTD) technique. Good agreement was observed between experimental data and simulated MB decay. Increasing flowrate from 0.31 to 0.51 L min−1 increased MB decay by 9% validating assumption of mass transfer controlled reaction at the anode. Increasing wastewater pH level from 3 to 9, significantly decreased MB decolorization by 20 %, which is attributed to complex reaction mechanism. Increasing applied electrical voltage from 3 to 7 V led to marginal change in MB concentration decay. By increasing initial MB concentration from 2 to 10 ppm, 5% decrease in MB decolorization was observed. Electrooxidation of 0.5 L synthetic wastewater under optimum operation conditions during 5 h (flowrate of 0.53 L min−1, pH = 3, 5 V applied voltage) led to MB concentration decay of 0.041, 0.059, and 0.08 for initial MB concentration of 2, 5, and 10 ppm, respectively. Results of current study in pre-pilot scale provide valuable information for large scale studies in the field of wastewater treatment.