Synthesis of rod-like α-FeOOH nanoparticles and its photocatalytic activity in degradation of an azo dye: Empirical kinetic model development

Goethite (alpha-FeOOH) nanostructures were synthesized using a well-known one-step facile hydrothermal method. The X-ray diffraction pattern confirmed the formation of the alpha-FeOOH with orthorhombic structure. The field emission scanning electron microscopy revealed that the synthesized alpha-FeOOH had rod-like morphology. The photocatalytic activity performance of synthesized alpha-FeOOH was evaluated in the degradation of C.I. Acid Orange 7 (AO7), as a model organic pollutant. The degradation of AO7 in mere photolysis without alpha-FeOOH and adsorption with alpha-FeOOH is negligible. The degradation of AO7 with alpha-FeOOH under UVA irradiation was considerable which confirmed the photocatalytic activity of synthesized alpha-FeOOH. The band gap of synthesized nanoparticles was obtained by Tauc-Mott plot and determined around 2.5 ev. The photocatalytic degradation kinetic characteristics were studied by investigation effect of different operational parameters including alpha-FeOOH dosage, pH and initial AO7 concentration as the effective operational parameters. Using the non-linear regression, an empirical kinetic model was developed for predicting the photocatalytic degradation efficiency by taking account into the apparent first order kinetic and operational parameters. The predictive capability of developed model was evaluated by comparing the experimental photocatalytic degradation efficiency and calculated ones by model. It was found that the developed model fit well with experimental data. (C) 2015 Elsevier B.V. All rights reserved.