Suhaimi, Noorul Aisyah Md (2015) Photocatalytic Degradation Of Phenol And Fast Green Fcf Using Lithium Doped Zno Under Fluorescent Light Irradiation. Masters thesis, Universiti Sains Malaysia.
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Abstract
Zink oksida (ZnO), memainkan peranan utama dalam jenis rawatan ini kerana ciri-ciri yang istimewa yang dipunyainya seperti kos yang rendah, sesuai untuk alam sekitar dan sangat stabil. ZnO fotopemangkinan telah diubahsuai dengan mendopkan bersama Lithium (Li) menggunakan kaedah pemendakan kimia. Fotopemangkinan ini telah berjaya disintesis dan telah dianalisa dengan menggunakan kaedah pencirian Pembelauan sinar-X (XRD), Microskop Imbasan Elektron (SEM), Mikroskop Penghantaran Elektron (TEM), Spektroskop menyerap pantulan (UV-vis DRS) dan analisis luas permukaan. Li merupakan dopan logam yang sangat baik kerana mampu memerangkap pasangan elektron dan lubang yang terhasil. Aktiviti pemfotomangkinan untuk ZnO yang tulen dan ketiga-tiga Li/ZnO dengan jumlah Li yang berlainan (5 wt%, 7 wt% dan 10 wt%) telah diuji untuk degradasi kedua-dua fenol dan Fast Green FCF di bawah penyinaran cahaya pendafluor. Keputusan menunjukkan aktiviti pemfotomangkinan untuk ketiga-tiga Li/ZnO lebih tinggi berbanding ZnO tulen yang disintesis dan TiO2 komersial untuk penurunan fenol dan Fast Green FCF, terutamanya 7 wt% Li/ZnO yang menunjukkan prestasi pemfotomangkinan yang unggul berbanding yang lain. Seterusnya, kesan daripada pembolehubah proses seperti kepekatan awal bahan pencemar, bebanan fotomangkin dan pH larutan terhadap penurunan kedua-dua bahan pencemar juga telah dikaji. Kajian menunjukkan kondisi terbaik untuk kepekatan awal fenol dan Fast Green adalah pada 5 mg/L. Di samping itu, bebanan fotomangkin yang terbaik untuk penurunan fenol dan Fast Green FCF didapati pada 2g/L. Tambahan lagi, fotodegradasi fenol dan Fast Green FCF yang baik telah diperhatikan masing-masing pada pH 5.8 dan 4.4. Penggunaan semula yang tinggi dan keupayaan pemisahan yang tinggi untuk 7 wt% Li/ZnO mencadangkan potensi penggunaannya untuk aplikasi praktikal dalam rawatan air kumbahan. Spesis aktif yang terlibat dalam penurunan fenol dan Fast Green FCF telah dikaji dengan menambahkan bahan kimia tertentu dalam tindakbalas larutan. Kemudian, radikal hidroksil dan anion superoksida masing-masing dikenalpasti sebagai spesis aktif untuk penurunan fenol dan Fast Green FCF. Selain itu, beberapa produk semasa penurunan fenol telah dikesan menggunakan kromatografi cecair prestasi tinggi (HPLC), dan laluan tentatif degradasinya telah dicadangkan. Analisis Kinetik penurunan fenol dan Fast Green FCF dengan menggunakan 7 wt% Li/ZnO telah mematuhi kinetik tertib-pertama diwakili oleh model Langmuir-Hinshelwood. ________________________________________________________________________________________________________________________ Zinc oxide (ZnO), plays a main role in this treatment due to its special characteristic such as, non-toxic, low cost, environmental friendly and stable. However, modification has to be done to improve its limitation. ZnO photocatalyst was modified by doping with lithium (Li) using chemical precipitation method. It has been successfully synthesized and synthesized photocatalyst was characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-VIS DRS), and surface analyzer. Li was found o be a promising metal dopant due to ability for trapping the photogenerated electron hole pairs from recombine. The photocatalytic activities of pure ZnO and three Li/ZnO with different Li loading (5 wt%, 7 wt% and 10 wt%) were being evaluated for the degradation of phenol and Fast Green FCF under fluorescent light irradiation. Results showed that the photocatalytic activities of all three Li/ZnO were higher than synthesized pure ZnO and commercial TiO2 for both phenol and Fast Green FCF degradation, especially 7 wt% Li/ZnO which gives superior photocatalytic performance compare to others. Next, effects of operating parameters such as initial pollutant concentration, photocatalyst loading and solution pH towards the photocatalytic degradation of both pollutants were investigated. Results showed that the best conditions of initial phenol and Fast Green FCF concentrations were found to be 5 mg/L. Besides, the optimal photocatalyst loading was found at 2 g/L for both phenol and Fast Green FCF degradation. In addition, favorable photodegradation of phenol and Fast Green FCF were observed at pH 5.8 and 4.4, respectively. The high reusability and high sedimentation test of 7 wt% Li/ZnO were achieved suggested its potential usage for practical applications in wastewater treatment. The actives species involved in phenol and Fast Green FCF degradation were also investigated by adding certain chemical into the solution reaction. Then, hydroxyl radical and superoxide anion radical are detected as active species for phenol and Fast Green FCF degradation, respectively. In addition, several intermediates product during phenol degradation were detected using high performance liquid chromatography (HPLC), and its tentative pathway degradation has been proposed. The kinetics analysis of the degradation of phenol and Fast Green FCF was over 7 wt% Li/ZnO fitted well by the first-order kinetics represent by the Langmuir-Hinshelwood model.
| Item Type: | Thesis (Masters) |
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| Additional Information: | Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=3074 |
| Subjects: | T Technology T Technology > TP Chemical Technology > TP155-156 Chemical engineering |
| Divisions: | Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Kimia (School of Chemical Engineering) > Thesis |
| Depositing User: | Mr Mohd Jasnizam Mohd Salleh |
| Date Deposited: | 29 Aug 2018 07:50 |
| Last Modified: | 29 Aug 2018 07:50 |
| URI: | http://eprints.usm.my/id/eprint/41580 |
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