Preparation of TiO2-activated kaolinite composite for photocatalytic degradation of rhodamine B dye

Abstract

ABSTRACT. Rhodamine B (RhB) is one of the prominent dyes discovered to be carcinogenic and mutagenic substance present in the ecosystem. Alteration of the characteristics of TiO₂ through modification with clay influences the behavior of some organic molecules at its surface, and thus its photocatalytic properties. This study investigates the photocatalytic degradation of RhB using TiO₂-activated kaolinite composite (TiO₂-AKC). TiO₂-AKC was prepared in absolute ethanol and characterized using SEM, EDX, TEM, BET and FTIR. The photodegradation of RhB using TiO₂-AKC at room temperature under visible-light was studied at various time intervals and the concentration of RhB was monitored using Ultraviolet-Visible spectrophotometer. Characterisation of TiO₂-AKC revealed an adequate distribution of TiO₂ over the AKC surface, with an enhanced surface area (TiO₂-AKC 808 m²g^-1, TiO₂ 50.0 m²g^-1, AKC 20.6 m²g^-1) necessary for effective degradation. The degradation was efficient in TiO₂-AKC than in sole TiO₂ resulting in 99.51% and 88.35%, respectively. The experimental data was analysed using zeroth and first order kinetics, parabolic diffusion, and modified Freundlich model. The degradation kinetics conforms to first order kinetics in TiO₂-AKC and sole TiO₂. The mechanism of the degradation using TiO₂-AKC fit into modified Freundlich model and parabolic diffusion model while sole TiO₂ was best described by parabolic diffusion model.

KEY WORDS: Kaolin, Kinetics, Organic dyes, Photodegradation, Pollutants, Titanium(IV) oxide

Bull. Chem. Soc. Ethiop. 2022, 36(1), 13-24.                                                                   

DOI:   https://dx.doi.org/10.4314/bcse.v36i1.2