2,4-dichlorophenoxyacetic acid (2,4-D) is a common herbicide that has been used widely. Due to its excessive usage, the 2,4-D herbicides can cause contamination over agricultural land and water bodies. In the present work, a simple impregnation method was used to modify the commercial titanium dioxide (P25 TiO 2 ) nanoparticles with the copper oxide. The prepared samples were characterized by X-ray Diffraction (XRD), reflectance UV-visible and fluorescence spectroscopies. It was observed that the incorporation of copper oxide did not significantly affect the crystal structure of P25 TiO 2 . On the other hand, the presence of copper oxide was confirmed by reflectance UV-visible and fluorescence spectroscopies. The activity of the prepared sample was evaluated for photocatalytic removal of the 2,4-D. The photocatalytic activity of the TiO 2 increased with the increase of copper oxide loading up to 0.5 mol%. Unfortunately, the higher loading amount of copper oxide resulted in the lower photocatalytic activity. This study suggested that the higher photocatalytic activities obtained on the low loading samples were due to the lower electron-hole recombination.Keywords: P25 TiO 2 , copper oxide, impregnation, photocatalyst, 2,4-D herbicide Abstrak Asid 2,4-diklorofenoksiasetik (2,4-D) adalah herbisid biasa yang telah digunakan secara meluas. Oleh kerana penggunaan yang berlebihan, herbisid 2,4-D boleh menyebabkan pencemaran di kawasan pertanian dan sistem air. Dalam kajian ini, satu kaedah pengisitepuan yang mudah telah digunakan untuk mengubahsuai nanozarah titanium dioksida komersial (P25 TiO 2 ) dengan kuprum oksida. Sampel yang disediakan telah dicirikan dengan XRD, spektroskopi pantulan serakan ultra lembayung-cahaya nampak, dan spektroskopi pendarfluor. Didapati pengubahsuaian P25 TiO 2 dengan kuprum oksida tidak memberi kesan yang signifikan kepada struktur kristal P25 TiO 2 . Sebaliknya, kehadiran kuprum oksida telah disahkan oleh spektroskopi pantulan serakan ultra lembayung-cahaya nampak. Aktiviti sampel telah diuji untuk penyingkiran 2,4-D. Aktiviti fotomangkin TiO 2 meningkat dengan peningkatan jumlah kuprum oksida kepada 0.5 mol%. Malangnya, jumlah kuprum oksida yang lebih tinggi menghasilkan aktiviti fotomangkin yang lebih rendah. Kajian ini mencadangkan bahawa aktiviti fotomangkin yang tinggi diperolehi pada sampel loading rendah adalah disebabkan oleh penggabungan elektron-lubang yang lebih rendah Kata kunci: P25 TiO 2 , kuprum oksida, pengisitepuan, fotomangkin, 2,4-D herbisid

2,4-dichlorophenoxyacetic acid (2,4-D)

In the present study, commercial Hombikat N100 TiO2 that consists of 100% of anatase phase was modified with copper (Cu) as a co-catalyst via two different preparation methods, which were photocatalytic UV reduction and impregnation methods. The Cu loading was fixed to be 0.1 wt%. The X-ray diffraction (XRD) patterns showed that Cu/TiO2 sample prepared via different preparation methods gave different crystallinity and/or crystallite size. The Cu/TiO2 sample prepared by photocatalytic UV reduction method has lower crystallinity and/or crystallite size than the sample prepared by impregnation method. The performance of the TiO2 and Cu/TiO2 samples was evaluated for degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). After 1 hour reaction, the TiO2 showed percentage removal of 31%, while the Cu/TiO2 sample prepared by photocatalytic UV reduction and impregnation methods gave 39 and 28%, respectively. It was proposed that the higher activity on the Cu/TiO2 sample prepared by photocatalytic UV reduction method was caused by the more successful suppression of electron-hole recombination, as supported by the emission spectra.

No abstract

Here phosphorescent trinuclear copper (I) pyrazolate complexes ([Cu3Pz3]), synthesized from 3,5-dimethyl and 4-(3,5-dimethoxybenzyl)-3,5-dimethyl pyrazole ligands for complexes [Cu3Pz3]1 and [Cu3Pz3]2, were successfully impregnated into TiO2 with concentration of 0.1 mol%. These luminescent photocatalyst composites ([Cu3Pz3]1or 2/TiO2) gave 60% and 49% of dichlorophenoxyacetic acid (2,4-D) degradation after 1 h for [Cu3Pz3]1/TiO2 and [Cu3Pz3]2/TiO2, while TiO2 only showed 48%. The higher activity observed on [Cu3Pz3]1/TiO2 than the TiO2 would come from the efficient reduction of electron-hole recombination, while less dispersion of complex [Cu3Pz3]2 with more rigid structure compared to complex [Cu3Pz3]1 gave similar activity of the [Cu3Pz3]2/TiO2 to the TiO2.