Immobilisation Of Tio2 Powder Onto Glass Plates Via Dip-Coating Technique Using Enr-50/Pvc Polymer Blend As Adhesives And Its Photocatalytic Application
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Date
2010-04
Authors
Ngoh, Ying Shin
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
The objective of this work is to produce a reusable immobilised TiO2 on glass plate utilizing polymer blend as adhesives for the photocatalytic degradation of methylene blue (MB) in aqueous solution. TiO2 powder (99% anatase) was directly immobilised onto glass plates using epoxidised natural rubber (ENR-50)/ poly (vinyl) chloride (PVC) polymer blend as adhesives via simple dip-coating technique. The photocatalytic characterization of the immobilised TiO2 powder was assessed using MB in aqueous solution as the model pollutant under the irradiation of 45W fluorescent lamp. The optimum ratio of ENR-50 to PVC for the immobilisation of TiO2 was determined as 1:3. The photocatalytic efficiency of the immobilised TiO2/ENR/PVC was better than the TiO2 in slurry mode. The optimum catalyst loading was determined as 1.0 mg/cm2 and the photocatalytic degradation rate of MB was highest at pH 12. The presence of aeration as oxygen source promoted the photocatalytic removal of MB. The photocatalytic degradation of MB was mainly governed by the UV residuals emanated from the 45 W fluorescent lamp. Reusability and reproducibility of the immobilised TiO2/ENR/PVC improved proportionally with the intensity of UV irradiances from the light sources. The average pseudo first order rate constant of MB degradation for 10 cycles of 90 min repeated applications of the immobilised TiO2 using light sources with UV irradiances of 1.67, 4.35 and 6.30 Wm-2 were 0.0174 ± 0.00072, 0.0381 ± 0.0039 and 0.0577 ± 0.0027 min-1, respectively. Subsequent analysis using SEM-EDX, TGA and FTIR revealed that the reliability of the immobilised TiO2/ENR/PVC was however plagued by the
degradation of polymer blend used as adhesives upon recycled applications which resulted in the production of chemical oxygen demand (COD). The degradation of ENR-50 was faster than the elimination of PVC in the coating formulation. 50 % mineralization of 20 mg L-1 MB was achieved after 4 hours of photocatalytic treatment using the ‘cleaned’ immobilised TiO2. The degree of mineralization corresponded positively with the percentage of MB colour removal. The presence of inorganic compounds such as SO42-, NO3-, Cl- and the changes of pH in the treated solution represented the mineralized products of the model pollutants. The immobilised TiO2/ENR/PVC on polymer supports such as PVC, acrylic and PET exhibited photo-activity in the degradation of MB albeit at lower degradation rate. Overall, the immobilization of TiO2 powder via this technique is simple, effective, economical and reproducible.
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Keywords
Immobilised TiO2 on glass plate , utilizing polymer blend as adhesives