Photodegradation of Famotidine by Integrated Photocatalytic Adsorbent (IPCA) and Kinetic Study

Integrated photocatalytic adsorbents (IPCAs) comprised of nanocrystalline titanium dioxide (TiO₂) and activated carbon (AC) were prepared using an ultrasonic impregnation technique. The IPCAs were characterised by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy and were employed as catalysts for the photodegradation of famotidine-an active pharmaceutical ingredient-in aqueous solutions using illumination from a 125 W medium pressure mercury lamp. The degradation kinetics were found to follow a pseudo-first-order rate law and varying TiO₂ loadings induced different increases in the apparent first-order rate constant of the process. The kinetic behaviour can be described in terms of a modified Langmuir-Hinshelwood (LH) model. The IPCA prepared using a 10% TiO₂ to AC loading exhibited the highest rate constant with a K C and k r of 0.0172 L/mg and 0.237 mg/L/min, respectively. The LH model fits the experimental data and elucidates the effect of the TiO₂ content of the IPCA on the degradation rate. The use of calcination (heat treatment) in IPCA preparation and its effect on photocatalytic and adsorption performance were also investigated. The present work demonstrates that the combination of TiO₂ and AC results in a promising material for application in the degradation of organic pollutants. Graphical Abstract The values of the adsorption equilibrium constants, K C , and the rate constants, k r , for the photodegradation of famotidine were dependent on TiO₂ content of IPCAs. [graphic removed]