Saharudin, Khairul Arifah (2015) Development Of Nonmetal-Doped Tio2 Nanotube Photocatalyst For Decolorization Of Methyl Orange. PhD thesis, Universiti Sains Malaysia.
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Abstract
Tiubnano (TN) TiO2 telah menarik perhatian dalam bidang fotopemangkinan. Walaupun TiO2 adalah fotopemangkin yang digunakan secara meluas, kebolehannya untuk menyerap cahaya nampak adalah lemah dan rekombinasi pembawa cas menjadi satu cabaran yang besar. Oleh itu, matlamat kajianini adalah untuk membentukTN TiO2 terdop karbon (C)dan fosforus (P) untuk penyahwarnaanmetil oren (MO). Penghasilan TN C-TiO2 melalui penganodan telah berjaya dihasilkan di dalam elektrolit organik yang berfluorin. Gliserol dan glikol etilena (EG) pH neutral telah diguna sebagai elektrolit organik.Morfologi dan struktur bagi TN beroksida yang terbentuk telah dikaji.Melalui penganodan, faktor-faktor utama yang mempengaruhi struktur TN adalah jenis-jenis elektrolit, komposisi elektrolit, voltan penganodan dan masa penganodan.TN C-TiO2 telah berjaya dihasilkan dengan pantas dalam EG yang mengandungi 0.89 wt% air (H2O) dan 0.66 wt% ammonium fluorida (NH4F). Kadar pembentukan dalam elektrolit tersebut adalah 308 nm / min. C yang terdop di dalam TN TiO2mewujudkan satuaras tenaga baru di atas jalur valens (VB), yang terhasil daripadakarbon celahan C 2p serta satu lagi di bawah jalur konduksi (CB) yang berkaitan dengan anti ikatan, C - O yang berasal daripada pembentukan kekosongan oksigen. TN C-TiO2 disepuh lindap pada 500 ° C dengan purata saiz liang 95 nm, ketebalan dinding 18 nm dan panjang 18.5 m dengan nisbah aspek tinggi (141.2) dan luas permukaan (1025.6 m2g-1) menunjukkan kadar penyahwarnaanMO sebanyak39%dengan kadar tetap k = 5.9 x 10-3 min-1 berbanding 11% kadar penyahwarnaan oleh partikel nano TiO2 bersaiz 25 nm. Dalam usaha untuk meningkatkan aktiviti fotopemangkinan TN C-TiO2, P didop ke dalam TN C-TiO2 melalui penganodan Ti dalam EG mengandungi 1 M asid fosforik (H3PO4) dan kaedah rendamandi dalam H3PO4. Kajian menunjukkan bahawa TN C-TiO2direndam dalam 0.02 M H3PO4selama 90 minit pada 40 ° C dan disepuh lindap pada suhu 500 °C menunjukkan 45% penyahwarnaan dengan kadar tetap k = 8.1 x 10-3 min-1. P yang didop ke dalam TN C-TiO2 didapati mempunyai keadaan pengoksidaan pentavalen yang bakal menggantikan kekisi Ti4+ dan membentuk ikatan Ti-O-P lalu meningkatkan responsif TiO2terhadap cahaya nampak. ________________________________________________________________________________________________________________________ Well aligned TiO2nanotubes (NT) arrays have attracted substantial attention in the area of photocatalysis (PC). Although TiO2 is a widely used catalyst support, its poor visible light absorption and high recombination of charge carriers remains a major challenge for its application. Hence, this work aims to develop carbon (C) incorporated TiO2 NT and carbon phosphorus (CP)incorporated TiO2 NT for photocatalytic decolorization of methyl orange (MO) dye. The formation of C-TiO2 NT by anodization was successful in fluorinated organic electrolyte. Glycerol and ethylene glycol (EG) were the organic electrolyte with their neutral pH. The properties including morphology and structural of the nanotubular oxide formed were investigated. During anodization, the main factors effecting nanotubular structures are types of electrolyte, its composition, anodization voltage applied to anode and anodization time.C-TiO2 NT arrays were rapidly grown in EG containing 0.89 wt% of water (H2O) and 0.66 wt% of ammonium fluoride (NH4F). The optimized rate of formation was 308 nm/min. The incorporation of C into TiO2 NT induced the formation of a new state above valence band (VB), which is attributed to the C 2p state of the interstitial carbon, as well as new state below the conduction band (CB), corresponding to antibonding C–O state produced due to the formation of oxygen vacancies.C-TiO2 NT arrays annealed at 500 °C with average pore size of 95 nm, wall thickness of 18 nm and length of 18.5 m, with high aspect ratio (141.2) and surface area (1025.6 m2g-1) exhibited decolorization of about 39% under visible light illumination with rate constant of k = 5.9 x 10-3 min-1as compared to TiO2 nanoparticle of 25 nm which possessed 11% decolorization. In order to improve further the photocatalytic activity of C-TiO2 NT, incorporation of P into C-TiO2 NT was done via anodization of Ti in EG containing 1 M phosphoric acid (H3PO4) and wet impregnation in H3PO4. It was found that C-TiO2 NT impregnated in 0.02 M H3PO4 for 90 min at 40 °C and annealed at 500 °C exhibited 45% decolorization with rate constant of k = 8.1 x 10-3 min-1. It was found that the doped phosphorus existed in a pentavalent oxidation state, replacing part of Ti4+ in the anatase lattice in the form of Ti-O-P bonds, thus extended the spectral response of TiO2 NT to the visible region.
| Item Type: | Thesis (PhD) |
|---|---|
| Additional Information: | Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=3203 |
| Subjects: | T Technology T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials |
| Divisions: | Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Bahan & Sumber Mineral (School of Material & Mineral Resource Engineering) > Thesis |
| Depositing User: | Mr Mohd Jasnizam Mohd Salleh |
| Date Deposited: | 06 Sep 2018 08:01 |
| Last Modified: | 06 Sep 2018 08:01 |
| URI: | http://eprints.usm.my/id/eprint/41770 |
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