Razali, Nurul Fitrahanis
(2018)
Synthesis And Characterization Of
Fexoy Doped Tio2 Immobilized On
Activated Carbon For Degradation Of
Single And Binary Mixture Of
Methylene Blue And Methyl Orange
Dyes Under Visible Light.
Masters thesis, Universiti Sains Malaysia.
Abstract
The purpose of this study is to produce the photocatalyst that has good
photocatalytic activity under visible light. In this study the modification of TiO2 was
conducted by immobilization of TiO2 on 10% wt activated carbon (TiO2-10% AC)
and FexOy doping of different Fe weight percentages (0.1, 0.5, and 1% wt) on the
TiO2-10%AC using a sol-gel method. The effects of FexOy doping and
immobilization onto AC towards the removal efficiency of single dye methylene blue
(MB) and methyl orange (MO), and binary dye mixtures of MB and MO were
compared to pure TiO2. The X-ray diffraction (XRD) analysis showed that the
crystallite size of TiO2 decreased from 56.5 to 24.4 nm after immobilization onto
AC, while the surface area increased from 114 to 204 m2 g-1 as the % wt of the
dopant increased. In fact, the band gap of the anatase phase of TiO2 was also reduced
from 3.15 to 2.8 eV as the % wt of FexOy dopant were increased to 1%. The optimum
parameters for the removal of single MB and MO dyes were determined to be 0.10 g
of the catalyst dosage, 75 mg/L of MB, 50 mg/L of MO, at ambient pH with the
contact time of 2 h. Meanwhile, the parameters for the binary dyes mixture were
found to be optimum at a high concentration (mg/L) ratio of MB to MO (40:40) and
at ambient pH with the contact time of 2 h. The 1% FexOy/TiO2-10% AC
photocatalyst showed maximum removal of 93% for the MB dye with initial
concentration of 75 mg/L, while the 0.1% FexOy/TiO2-10% AC showed up to 96% removal for MO with the initial concentration of 50 mg/L after 2 h of irradiation
under normal laboratory light. The 0.5% FexOy/TiO2-10% AC photocatalyst showed
the highest removal of binary dye mixture at the initial concentration ratio of 40:40
(mg/L) after 2 h of irradiation where 88 and 99% of MB and MO were removed,
respectively. This study revealed that the immobilization of TiO2 onto AC improved
the photocatalytic activity of the material. To increase the reusability of the
photocatalyst, different desorbing agents such as H2O, NaNO3, H2SO4, and NaOH,
were used and it was found that NaOH is the best eluent for MB but for MO none of
the desorbing agent shows good desorption activity. The results showed that the
treated photocatalysts can be repeatedly used although the percentage of removal
decreased to 40% at the 10th and 3rd cycles for MB and MO, respectively.
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