Zain, Salmiah Md
(2012)
Photocatalytic Performance Of A Slurry And Immobilized TiO2 Degussa P-25 For The Degradation Of Aqueous Organic Pollutants Under 45W Compact Fluorescent Lamp.
Masters thesis, Universiti Sains Malaysia.
Abstract
A simple and effective dip coating method was used for immobilizing P-25
powder onto glass plates using epoxidized natural rubber (ENR)/ poly (vinyl)
chloride (PVC) blend as adhesives. The reusable P-25/ENR/PVC catalyst plate could
avoid tedious filtration step in aqueous slurry system. Based on the photocatalytic
removal rate of RR4 and the adhesion of the P-25 formulation, the optimum ratio of
ENR to PVC for the immobilization was determined as 1:2. The immobilized P-
25/ENR/PVC catalyst plate was characterized using SEM, TGA and BET analyses.
Due to the low durability of the organic polymer, ENR and PVC applied in this
system were prone to be degraded and resulted in the detection of chemical oxygen
demand (COD) values in the treated ultrapure water. By washing procedure through
irradiation process could stabilize the polymer blend and increase the BET surface
area of the immobilized catalyst. The initial pH of RR4 solution, amount of catalyst
loading, aeration rate, and the initial concentration of RR4 dyes were found to
influence the pseudo-first order rate constant of the photocatalytic activities of RR4.
The presence of aeration as oxygen source promoted the photocatalytic removal. The
optimum catalyst loading was determined at 1.500 ± 0.005 mg cm-2 and the
photocatalytic degradation of RR4 was highest at acidic condition. The increase of
the initial concentration of the RR4 dyes decreased the degradation rate. The role of
adsorption and the chemical structure of the organic pollutants affected the
photocatalytic degradation rate. The degradation rate for RR4 and phenol were much slower using immobilized system. However for the degradation of MB,
immobilized system was found to be much faster than the suspended system. The
immobilized P-25/ENR/PVC/5h catalyst plate can be reused for many repeated cycle
of applications. The mineralization of organic pollutants was also evaluated by
measuring COD, the changes of pH of the solution, and the evolution of nitrate,
sulphate and chloride anions of the pollutants. It was observed that the decolorization
process of the RR4 and MB dyes were always faster than their mineralization
process, however the decomposition of phenol was almost identical with their
mineralization process.
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