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Title:	Titanium dioxide and its cellulose based nanocomposites for organic dye decomposition via photocatalytic activity
Authors:	Evyan Yang Chia Yan (P63243)
Supervisor:	Sarani Zakaria, Prof. Dr.
Keywords:	Cellulose Organic dye Photocatalytic Titanium dioxide
Issue Date:	7-Dec-2017
Description:	Rutile phase titanium oxides (TiO2) nanocrystals were synthesized using single step hydrothermal method. The presence of hydrochloride (HCl) as a by-product during the hydrothermal synthesis played an important role in the growth of morphology and phase structure. The samples were calcined at 400oC, 500oC and 600oC to improve their crystallinity. The morphology and particle size of the nanocrystals were characterized using scanning electron microscopy (SEM), transmission electron scanning (TEM) and X-ray diffractometer (XRD). Band gap energy (Eg) of the nanocrystals were estimated from the Ultra violet - visible light (UV-vis) absorption spectra using Kubelka-Munk function, the values of Eg were ranging from 2.75 - 3.2eV. The values of Eg decreased with increasing of calcination temperature and particle size. TiO2 nanowires (TNW), which the dimensionality modified from zerodimension to one-dimension, were synthesized using TiO2 powder (same gred with P-25) in strong alkaline (10 M of NaOH) via hydrothermal method. The length of the nanowires achieved was in the range of 1-6 mm. The Eg of TNW that calcined at 500oC was nearly same with the Eg of the bulk anatase - TiO2 at 3.2eV. The Eg of TNW calcined at 400oC and 600oC were 3.25eV and 2.95eV respectively. This results also reflected in photocatalytic activity which TNW calcined at 500oC performed the highest rate constant at 0.0182min-1 in the decomposition of methylene blue. This can be explained by the change in dimensionality and structure after calcination. TiO2 powder was mixed with cellulose to fabricate TiO2 powder embedded on regenerated cellulose membranes. The results indicated that cotton linter has been converted from cellulose I to cellulose II after the pre-cooled dissolution-regeneration process. Meanwhile, TiO2 nanoparticles embedded on the membrane maintained its original crystal structures. The physical, chemical and mechanical properties of the composite membranes were characterized. The TiO2 composite membranes possessed high water absorption properties with total pore volume ranged from 0.45±0.01 to 0.53±0.02 cm3/g. The elongation at break of the prepared membranes increased 29% averagely from dry state to wet state. The tensile strength of the membranes remained at a minimum value of 0.50±0.03 MPa in wet state thus enabled the films to withstand in wet for long period of time under weak UV irradiation. The regenerated cellulose membranes with TiO2 performed well in photocatalytic activity while exhibiting distinct absorption abilities. The formation of beads contained TNW (TWB) enabled to overcome the problem of powder leaching. The result showed that less than 2% of TNW leached from the beads but more than 14% of TiO2 powder lost after five cycles of photocatalytic experiments. The surface tension and the physically crosslink of the regenerated cellulose beads were strong enough to hold the long TNW tightly. The beads performed better photocatalytic activity with spherical shape, leading to larger specific area. Both TiO2 embedded membranes and beads provided potential application in energy-saving decomposition system in which the dye compound can be easily removed via two simultaneous pathways: adsorption and photocatalytic decomposition.,Certification of Master's/Doctoral Thesis" is not available
Pages:	142
Call Number:	QD181.T6Y336 2017 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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