Preparation, characterization and photocatalytic applications of immobilized polyaniline coated titania composite for the removal of dye and diuron from aqueous solution

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Date
2014-08
Authors
Abdul Razak, Mohd Fairul Sharin
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Abstract
P-25TiO2/PANI/ENR/PVC composite photocatalyst has been successfully fabricated and immobilized onto glass plates via a dip coating method. Dip coating dispersion was prepared by simple mixing of soluble polyaniline (PANI) with P-25TiO2 powder in the dichloromethane-toluene solvent containing epoxidized natural rubber (ENR) and polyvinlycholoride (PVC) which function as binding agents. Inclusion of soluble PANI into P-25 dispersion had strengthened the adhesion of the fabricated photocatalyst plate. The present of PANI in the P-25 dispersion had also reduced the PL intensity indicating the lower effect of electron-hole recombination. Additionally, the photoresponse of P-25TiO2/PANI/ENR/PVC was extended into the visible light region which simultaneously improved the photoactivity of the composite respectively. The band gap energy of the optimum composite P- 25TiO2/PANI/ENR/PVC (1:0.0035) was 2.86 eV where PANI formed a core shell coating of about 0.9 nm with a strong PANI-TiO2 interaction. Based on reactive red 4 (RR4) dye and diuron as model pollutants, the photocatalytic activity of the optimum P-25TiO2/PANI/ENR/PVC (1:0.0035) composite was 2.8 and 2 fold faster than the immobilized P-25TiO2/ENR/PVC system. As observed, the mineralization rates of both pollutants were improved and the degradation mechanism pathways were proposed respectively. Interestingly, pre-irradiation of the immobilized P- 25TiO2/PANI/ENR/PVC (1:0.0035) composite for 7 h improved the photocatalytic xxiii activity of the system whereby degradation rate of RR4 was nearly as same as the TiO2 suspended system. In fact the photodegradation of diuron was more effective than suspended photocatalytic system under similar conditions. Moreover, P- 25TiO2/PANI/ENR/PVC(1:0.0035)-7h was visible light sensitive where 85 % of 30 mg L-1 RR4 dye was decolorized after 60 minutes of irradiation. Both the immobilized P-25TiO2/PANI/ENR/PVC(1:0.0035)-7h and P-25TiO2/ENR/PVC-7h photocatalyst systems were highly reusable and sustainable with pseudo first order rate constant values of 0.103 ± 0.002 min-1 and 0.066 ± 0.001 min-1 respectively.
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Immobilized polyaniline coated titania composite, Aqueous solution
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