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