Cobalt ferrite catalyst in the degradation of caffeine by hydrogen peroxide under induction heating

Caffeine is an emerging contaminant that is difficult to remove with conventional remediation methods. Wet peroxide oxidation with heterogeneous cobalt ferrite catalyst was tested an efficient and environmentally friendly technology for caffeine removal. Due to its ferromagnetic properties, cobalt ferrite is especially suitable to induction heating (IH) by alternating magnetic field. Cobalt ferrite was synthesized by “green” auto-combustion method using Ginkgo Biloba extract as a fuel. Spinel structure of the obtained material was confirmed by XRD. The degradation of caffeine in aqueous solutions was studied using cobalt ferrite suspension in a batch reactor under neutral conditions (pH = 7). The synthesized cobalt ferrite effectively accelerates the oxidative degradation of caffeine (Caf). Three independent process variables were tested: initial caffeine concentration (1–5 mg/L), hydrogen peroxide concentration (10–50 mM), and induction heating (IH). The reaction kinetics was monitored by measuring the concentrations of Caf and H2O2 by spectrophotometry. Kinetics of the Caf degradation was described by the first-order model and the corresponding reaction rate constants were measured. The efficiency of the Caf degradation was evaluated using percentage removal. The Caf degradation efficiency strongly depends on the initial concentration of H2O2 and catalyst dose. For the initial Caf concentration of 1.0 mg/L, the catalyst dose of 3.0 g/L and H2O2 concentration of 30 mM result in caffeine degradation efficiency of 92.45%. The results of the study show that CoFe2O4 synthesized using Ginkgo Biloba extract is a promising heterogeneous catalyst for wastewater remediation.