(53aa) An Experimental Analysis of Photocalytic Degradation for Pharmaceutical Personal Care Products Using Rhodamine B As a Surrogate

Experimental studies were conducted on the photocatalytic degradation of Pharmaceutical Personal Care Products (PPCP) in wastewater using Rhodamine B dye as a surrogate. Rhodamine B dye (C₂₈H₃₁CIN₂O₃) was investigated in the presence and absence of UV irradiation. TiO₂ catalyst was used as the photocatalytic material to determine the kinetics of the degradation process by applying the quasi-steady-state-assumption for all intermediate species. A fluorimeter was employed to measure concentration in these studies. The effect of Cu²⁺ metal ions on the photo-degradation of Rhodamine B dye was also investigated by using a detailed Langmuir-Hinshelwood kinetic model. This work is an extension of the model generated in a previous study. A catalyst loading of 1 g/L, 0.05 g/L and 0.02 g/L was employed throughout the experiments. All reactions were performed at room temperature. The Cu²⁺ concentration used was varied at concentrations ranging from 0 - 500 µg/L. Each sample was analyzed in the fluorimeter every hour. A pseudo-first order reaction was generated from the plot of the dye concentration in ppb (µg/L) against the time in minutes. Linear and non-linear regression were performed on the generated data to obtain values for the reaction rate constants and adsorption equilibrium constants. The electron scavenging properties of Cu²⁺ were exploited to isolate the direct hole and electron degradation pathways.It was shown that the dye degrades faster under UV irradiation due to the direct hole attack but mainly via the electron pathway for OH^-production.

Keywords: Photo-catalysis, UV, Adsorption, Contaminants, Langmuir-Hinshelwood kinetic model, TiO₂ catalyst, Cu²⁺metal ions.

Reference

1. T. Aarthi and Giridhar Madras*. ‘Photocatalytic Degradation of Rhodamine Dyes with Nano-TiO2’. Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India. Ind. Eng. Chem. Res. 2007, 46, 7-14 

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