Removal of Catechol from Aqueous Solutions Using Catalytic Ozonation by Magnetic Nanoparticles of Iron Oxide Doped with Silica and Titanium Dioxide: A Kinetic Study

Background and Catechol is a ring form organic compound with high toxicity that is used in petrochemical, pharmaceutical and manufacturing of pesticide. It has adverse effects on human and environmental health if discharged into the environment. The purpose of this study was removal of catechol using catalytic ozonation using core-shell magnetic nanoparticles of iron oxide doped with silica and titanium dioxide from aqueous solution.
We conducted a basic-applied study in which magnetic nanoparticle Fe3O4@SiO2@TiO2 was synthesized using sol-gel method. To determine the characteristics of nanoparticle, XRD, SEM and EDX tests were used. Then effect of different parameters on removal efficiency were investigated. These included solution pH (2-10), reaction time (0-60 min), dose of catalyst (0.2-3 gr/L), initial concentration of catechol (50-1000 mg/L), recycled test (7 times), and determining the mineralization and scavenger effect. The residual concentration of catechol was measured using high-performance liquid chromatography at 275 nm.
The optimal pH for the catalytic ozonation process was 8. The maximum efficiency of the process in optimal conditions (catechol concentration 1000 mg/l, pH=8, catalyst dosage 3 gr/L and dose of ozone 0.38 gr/hr) was 100% after 60 minutes of contact time. Kinetics of degradation of catechol followed first degree model. After reaction time the amount of mineralization was 91.5%. Reusability of catalyst was done 7 times and its efficiency decreased by about 4%. Scavenger (1 gr/l tert-butanol) decreased removal of catechol by 4.16%.
The catalytic ozonation process using Fe3O4@SiO2@TiO2 nanoparticles in an alkaline pH was found to be capable of eliminating high concentrations of catechol effectively.