A kinetic model for electrocoagulation and its application for the electrochemical removal of phosphate ions from brewery wastewater

[Display omitted] •A kinetic model for electrocoagulation with aluminum electrodes was suggested;•It involves electrolysis, dissociation, hydrolysis, ionic, adsorption and flotation reactions;•It obeys the laws of mass conservation, Ohm's and Faraday's laws;•It describes properly the removal of pollutant parameters from brewery effluent;•Phosphate ions, residual soluble aluminum, turbidity, hexoses and COD were examined. A kinetic model based on electrochemical principles, elementary reactions and phase equilibrium was constructed to describe electrocoagulation. The approach was successfully illustrated for the removal of phosphate ions and other pollutant parameters from a brewery effluent. The kinetic results were obtained from a factorial design of experiments at optimal conditions for removal of phosphate and COD. Al3+ from the electrolysis of zero-valent aluminum reacted with phosphate at a rate constant of ~8.16 × 107 L mol−1 s−1 to form aluminum phosphate. Hexose sugars adsorbed on aluminum phosphate at a rate constant of ~5.34 × 102 L mol−1 s−1 were removed by flotation at the same rate of COD. The concentration of soluble aluminum was dependent on multiple reactions involving aluminum species and on the equilibrium between soluble and solid aluminum species. Turbidity was associated with the formation of aluminum phosphate and its removal by flotation at a rate constant of ~1.49 × 10−3 s−1.