Photodegradation of catechol in water over magnetically separable Fe3O4/TiO2 composite photocatalysts

Catechol is a serious polluter for effluents released from different industrial sectors. This compound is toxic and persistent under environmental conditions. The purpose of the current research was to evaluate the photocatalytic degradation of catechol by using the illuminated Fe3O4/TiO2 nanoparticles at some catalyst dosages, pHs, catechol concentrations, purging gases, H2O2 contents, organic materials. The results of the FT-IR and XRD analyses indicated the combination of the Fe3O4 and TiO(2)nanoparticles.The one-factor-at-a-time (OFAT) method was used to study the kinetics and the impacts of some key variables. In order to investigate the photocatalytic decomposition of catechol, a solution containing catechol and the Fe3O4-TiO2 nanocomposite was made and allowed to reach the equilibration within 30 min. Magnet was permanently done for 3 min to separate the nanocomposite from the mixture solution. Catechol contents were detected by HPLC through a calibration curve which was indicated according to the Beer-Lambert law. Under the optimum conditions pH 3, [catechol](0) 50 mg/L, nanocatalyst dose 0.5 g/L, H2O2 content 5 mM, all of the pollutant was decomposed over 60 min. k(obs) increased between 0.0029 and 0.0004 min(-1) with enhancing catechol content (10 to 200 mg/L). Photocatalytic studies showed o-Benzoquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and organic acids to be the main degradation products of catechol in aqueous solution. The electrical-energy consumption for the photocatalytic removal of catechol using the UV/Fe3O4/TiO2 method was lower than those of the UV/Fe3O4, UV/TiO2 and UV processes. Also, the efficiency increased with the addition of H2O2 in comparison with ambient conditions. Moreover, organic compounds presented an inhibition effect on the removal efficiency.