In this work, the kinetics of the photocatalytic decolourization of methylene blue (MB) is investigated using different surface morphologies of multilayer TiO 2 coating onto a glass plate under irradiation from a 55-W household florescent lamp. A simple direct dip-coating technique was used, and the coating properties of TiO 2 powder were improved by adding epoxidized natural rubber (ENR) as an organic binder in the coating formulation. The effects of the fundamental parameters that govern the kinetics of the photocatalytic decolourization of MB, such as the mass of TiO 2 coated onto the glass plate, the pH and the TiO 2 surface morphology, were also studied. The kinetics of the MB decolourization in all cases was found to be pseudo-first-order kinetics and was fitted to the Langmuir-Hinshelwood model. The degraded part of the ENR binder led to generating pores within the surface of the TiO 2 /ENR film and converting it into porous form, as confirmed by SEM analysis. Furthermore, TGA, FTIR and leachability analyses were conducted to further confirm the depletion of the ENR from the TiO 2 /ENR film. The kinetics of the MB decolourization and the efficiency of the MB colour removal indicated that the porous TiO 2 /ENR film becomes approximately twice as fast as the non-porous TiO 2 /ENR film.

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Chitosan beads (CHB) were prepared and studied in a batch mode operation for the adsorption of Reactive Red 120 dye from aqueous solution. Characterization on the surface of CHB was achieved by using point of zero charge (pH pzc ) method, Fourier transform infrared spectroscopy, and scanning electron microscopy. Adsorbent dosage (0.02-1.5 g), initial pH solution (4-12), initial dye concentrations (30-400 mg/L), and contact time (2-500 min) were used as the function to optimize the adsorption equilibrium experiments that were carried out during the course of this study. The adsorption equilibrium data show that the adsorption process obeys the Langmuir model with maximum adsorption capacities of 114.9, 123.5 and 129.9 mg/g for 303, 313 and 323 K, respectively. The kinetics of the RR 120 adsorption was wellfitted to the pseudo-second-order kinetics. Thermodynamic parameters such as standard Gibbs free energy (DG°), standard enthalpy (DH°) and standard entropy (DS°) were determined. The positive value of enthalpy indicates that the uptake of RR 120 onto CHB is endothermic in nature. The results obtained supported the use of CHB as an effective as well as favorable adsorbent in treating RR 120 dye.

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