Photocatalytic Oxidation Of Chitosan And Its Derivatives And Phenol By Immobilized Tio2 Bilayer Assemblage Systems Under Visible Light
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Date
2011
Authors
al-Taie, Ali Hadi Jawad
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Simple bilayer systems consisting of TiO2 as a top layer and chitosan (CS), cross-linked chitosan-glutaraldehyde (CS-GLA) and chitosan-epichlorohydrin (CS-ECH) as sub-layers were successfully fabricated and immobilized onto a glass plate. The deposition and adhesive properties of TiO2 were improved by adding organic binders like epoxidized natural rubber (ENR50) and phenol-formaldehyde resin (PF) in the coating formulation. Exposing these bilayer systems in aerated aqueous solution to 45-W fluorescent lamp caused significant changes in content of both ENR50 and PF of TiO2 top layer, in addition to the remarkable physico-chemical changes of CS, CS-GLA and CS-ECH sub-layers. However, it was found that the ENR50 and PF had actually acted as pore-forming agents via their photodegradation process to create macro pores on the TiO2 surface as shown by SEM analysis, while TGA, EDX and COD analyses indicated quantitatively that there is no significant change in ENR50 and PF content that can be observed after 5 cycles of repeated usage. This porous structure of immobilized TiO2 layer allows better diffusion of pollutants, increases the light penetration and improves the optical property as indicated by photoluminescence spectroscopy (PLS) analysis.
CS, CS-GLA and CS-ECH sub-layers were mildly oxidized within 5 cycles (Each cycle was equivalent to two hours of irradiation) of repeated usage. Characterization studies via elemental analysis, Fourier-transform infrared spectroscopy (FTIR),13C solid state nuclear magnetic resonance (13C-NMR), UV- Visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PLS) analyses and swelling measurement generally indicated the formation of carbonyl group and partial elimination of some amino groups without altering much of the whole polymeric structure of CS and its cross-linked derivatives.
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Keywords
Photocatalytic oxidation of chitosan , immobilized TiO2 bilayer assemblage systems