Photocatalytic Oxidation of Ethanol Catalyzed by Zeolite and Tio2

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EFFECTS OF pH ON ETHANOL PHOTOCATALYTIC OXIDATION

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Jurnal Teknologi, 43(C) Dis. 2005: 27–38
© Universiti Teknologi Malaysia

EFFECTS OF PH ON ETHANOL PHOTOCATALYTIC
OXIDATION USING TIO2 AND ZEOLITE 13X AS CATALYST
NORZITA NGADI1* & SITI KHATIJAH JAMALUDIN2
Abstract. Photocatalytic oxidation is a very beneficial technique used in the treatment of various organic pollutants. In this research, two of the most prominent catalysts, TiO2 and zeolite 13X were tested for their ability in optimising the photocatalytic oxidation of ethanol in aqueous solution in terms of ethanol adsorption and production of acetaldehyde as an intermediate for the reaction. Besides that, the effects of pH on the photocatalytic oxidation of ethanol in an aqueous solution by using TiO2 and zeolite 13X as catalysts were also determined. The experiments were conducted under UV irradiation with the presence of dissolved oxygen. Samples were taken every 40 minutes for 200 minutes of irradiation at different pH values (pH 3, pH 5, pH 7 and pH 9) and then analysed by HPLC. The findings of the experiments indicated that TiO2 was a better catalyst compared to zeolite 13X in terms of ethanol adsorption (i.e. adsorbs more ethanol) and the production of acetaldehyde as an intermediate product (i.e. produces less acetaldehyde). The results also indicated that the optimum level for photocatalytic oxidation of ethanol was in acidic condition. It was also found that the duration of irradiation plays a big role and shows tremendous effect to the photocatalytic oxidation of ethanol. Keywords: Photocatalytic oxidation, TiO2, zeolite 13X, ethanol adsorption, acetaldehyde production, pH values

Abstrak. Proses pengoksidaan fotomangkin adalah suatu teknik yang amat berguna dalam rawatan bahan pencemar organik. Dalam kajian ini, keberkesanan dua jenis mangkin iaitu, TiO2 dan zeolite 13X dalam mengoptimumkan proses pengoksidaan fotomangkin bagi etanol dalam fasa akueus diuji dari segi keberkesanan penjerapan etanol dan kuantiti asetaldehid yang dihasilkan sebagai produk perantaraan bagi tindakbalas fotomangkin ini. Selain itu, kesan pH ke atas proses pengoksidaan fotomangkin ini juga ditentukan. Eksperimen telah dijalankan di bawah sinar UV dengan kehadiran oksigen terlarut. Persampelan dibuat setiap 40 minit untuk selama 200 minit di bawah pendedahan sinar UV pada berbagai pH berbeza (pH 3, pH 5, pH 7 dan pH 9). Sampel-sampel tersebut dianalisis menggunakan teknik HPLC. Hasil daripada uji kaji menunjukkan bahawa TiO2 mempunyai keberkesanan yang lebih tinggi berbanding zeolite 13X dari segi penyerapan etanol (iaitu menyerap lebih banyak etanol) dan dari segi penghasilan asetaldehid (iaitu menghasilkan kuantiti asetaldehid yang lebih rendah). Hasil kajian juga menunjukkan bahawa proses pengoksidaan fotomangkin bagi etanol mencapai tahap optimum dalam keadaan berasid. Begitu juga, hasil kajian mendapati jangkamasa pendedahan sistem fotomangkin kepada sinar UV memainkan peranan yang penting dan memberi kesan yang hebat terhadap proses pengoksidaan fotomangkin bagi etanol. Kata kunci: Pengoksidaan fotomangkin, TiO2, zeolite 13X, penyerapan etanol, penghasilan asetaldehid, nilai pH

1&2

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JTDIS43C[03].pmd

Department of Chemical Engineering, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM, Skudai, Johor Bahru, Malaysia. Corresponding author: E-mail: norzita @fkkksa.utm.my

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02/15/2007, 16:10

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NORZITA NGADI & SITI KHATIJAH JAMALUDIN

1.0 INTRODUCTION
In the production of chemical products, often, organic compounds would be involved commercially. Along the process, mainly in chemicals and petrochemicals industries, the waste water discharged could be contaminated with toxic organic residuals, which may be hazardous to the environment and could disturb the water quality once the effluent flows into the river and other waterways [1].

Environmental pollution, especially water pollution is one of...
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