EFFECT OF CALCINATION TEMPERATURE ON ZnO/TIO2 COMPOSITE IN PHOTOCATALYTIC TREATMENT OF PHENOL UNDER VISIBLE LIGHT

Abstract

Composite catalyst ZnO/TiO 2 of molar ratio 0.75% was synthesized via sol gel method. The effect of preparation method on the crystal morphology was investigated. The catalyst particles were calcinated at 500 o C,550 o C and 600 °C for 3 hours. The XRD results revealed that calcination temperature controls the crystalline phase in terms of homogeneity and surface area of catalyst produced. The particle size was found to increase with calcination temperature suggesting the effect of different calcination temperatures on catalytic activity for complete degradation of phenol. The result found that ZnO/TiO 2 catalyst calcinated at 600 o C resulted in 70% phenol degradation within five hours of irradiation time under visible light. The kinetic behavior of phenol degradation was found to fit with pseudo first order Langmuir-Hinshelwood kinetic model. Keywords: sol gel, ZnO/TiO 2 catalyst, photocatalytic degradation, visible light, kinetic Abstrak Pemangkin komposit ZnO/TiO 2 dengan 0.75% nisbah molar telah di sintesis melalui kaedah sol gel. Kesan kaedah penyediaan pada morfologi kristal itu telah di selidiki. Zarah-zarah pemangkin telah dikalsinkan pada suhu 500 o C, 550 o C dan 600 o C selama 3 jam. Keputusan XRD menunjukkan suhu pengkalsinan mengawal fasa kristal dari segi kesamaan dan kawasan permukaan pemangkin dihasilkan. Saiz zarah didapati meningkat sejajar dengan peningkatan suhu pengkalsinan mencadangkan kesan suhu pengkalsinan yang berbeza pada aktiviti pemangkin untuk penyingkiran penuh fenol. Keputusan mendapati pemangkin ZnO/TiO 2 yang dikalsinkan pada 600 o C boleh menyebabkan 70% fenol terdegradasi bagi tempoh lima jam masa penyinaran di bawah cahaya nampak. Kelakuan kinetik degradasi fenol didapati sesuai dengan pseudo peringkat pertama model kinetik Langmuir -Hinshelwood.