Kinetic and parametric studies of refinery effluent treatment in electrochemical reactor

摘要

Treatment of refinery effluent using an electrocoagulation reactor assisted with a natural coagulant, from Acacia tortilis, was investigated under controlled operating conditions. The influence of process variables - namely, type of electrode (copper (Cu), steel and aluminium (Al)), effluent pH (3.5-11.5), influent chemical oxygen (O-2) demand (COD) of the effluent (605-2420 mg/l), coagulant dosage (1.0-6.0 g/l), voltage (15-45 V) and current (1.5-2.5 A) - on the COD removal efficiency was investigated. Among the different electrodes tested, the aluminium electrode performed well and could remove 74.2% at an equilibrium time of 90 min. Formation of the aluminium hydroxide (Al(OH)3) complex was identified as the working mechanism. The optimal conditions for better COD removal efficiency were identified as pH 5.5, coagulant dose of 4.0 g/l, voltage of 45 V and current of 2.5 A. The empirical relationship between the coagulant dose and the COD removal percentage was found to be exponential in nature. A pseudo-second-order kinetic model was found to represent the experimental data very well (coefficient of determination > 0.900) and the kinetic constant (k(2)) was estimated as 0.20 x 10(-3) (g/mg)/min at an initial effluent COD of 2420 mg/l.