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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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Coconut (Cocos nucifera) shell was chemically treated with sulfuric acid (H2SO4) to produce acid-factionalized biosorbent for methylene blue (MB) dye removal from aqueous environment. Various analytical techniques were utilized to investigate the surface area, surface morphology, crystallinity, elemental composition, and functional group of the sulfuric acid-treated coconut shell (SATCS). The adsorption parameters such as adsorbent dosage (0.02-0.20 g), solution pH (3-10), contact time (0-360 min), and initial MB dye concentration (25-200 mg/L) were studied. The adsorption results were illustrated by pseudo-second order kinetic and Freundlich isotherm models. It was found that SATCS has a maximum adsorption capacity (q max) of 50.6 mg/g at 303 K. The adsorption mechanism of MB dye on the SATCS surface can be assigned to the various types of interactions such as electrostatic attractions, H-bonding interaction, and π-π interaction. This work shows SATCS as promising acid-factionalized biosorbent for removal MB dye.

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