Photocatalytic removal of phenol using supported nano-TiO2 doped with lanthanum
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Date
2015-05-01
Authors
Muhammed Ahshath A. Jamal Muhammed
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Abstract
Titanium dioxide (TiO2), plays a main role in this treatment due its special
characteristics such as inert, non- toxic and also very stable. However, some
modifications have to be done to improve its limitation. Commercial TiO2, Degussa
P25 photocatalyst was modified by doping with lanthanum using wet impregnation
method and immobilized onto silica gel. It has been successfully synthesized in order
to degrade chosen organic pollutant, phenol, effectively under UV light using a batch
reactor system. The photocatalyst has been characterized using Scanning Electron
Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction
(XRD), Brunauer-Emmett-Teller (BET), UV-Vis spectroscopy and Fourier Transform
Infrared Spectroscopy (FTIR). The modification on TiO2 has enhanced its
photoactivity due to change in the energy band gap, electron-hole recombination,
crystalline size, surface area and also reusability of the photocatalyst. The best dopant
loading of lanthanum is 2.0 mol % (La:Ti) while for silica gel as a support is 3:1 (Ti/Si)
weight ratio for the photocatalyst. The photocatalyst is known as 2.0 La-TiO2/ silica
gel. The result in phenol photocatalytic degradation was up to 98% compare to
commercial TiO2 P25 alone 57.9% within 4 hours using UV A light. The 2.0 La-TiO2/
silica gel also proven to have an excellent reusability after the three time of usage and
sedimentation ability. Various operating parameters such as initial phenol
concentration, initial phenol pH and also photocatalyst loading dosage were examined.
The results showed that the best conditions are as follows: initial concentration of 10
ppm, photocatalyst loading 1.0 g/L, and initial phenol pH 5.3. Kinetic for photocatalytic degradation of phenol also has been studied using Langmuir-
Hinshelwood model. Result showed that the reaction kinetic for this study followed
pseudo-first order kinetic with k (reaction rate constant) and K (equilibrium adsorption
constant) value of 1.149 mg/ L.min and 0.0106 L/ mg respectively.