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|標題:||TiO2/Ti thin-film electrode manufacturing equipment and combined external circuit photoelectrical catalytic process for reducing silver ions||作者:||Kao, C.L.
|關鍵字:||External circuit;Photoelectrocatalytic;TiO2/Ti;Photoanodes;Silver;recovery;photocatalytic reduction;aqueous-phase;waste-water;oxalic-acid;recovery;degradation;technology;deposition;oxidation;reactor||Project:||Separation and Purification Technology||期刊/報告no：:||Separation and Purification Technology, Volume 63, Issue 3, Page(s) 546-551.||摘要:||
In this study, a nano-class TiO2/Ti thin-film electrode was made using the atmospheric pressure chemical vapor deposition (APCVD). The electrode was combined with an external circuit and anode bias to study the efficiencies of silver ions reduction and acetic acid decomposition. Results of SEM images and XRD patterns of the TiO2/Ti thin-film electrode surface show that the thin-film electrode made using the APCVD method can be as size as 30 nm with the TiO2 photoelectric catalyst in anatase crystal form. More obvious agglomeration of TiO2 particles was observed for shorter APCVD sprayed times. Results of the light response study show that the electrode has a rapid response time to 365 nm UV light to produce electricity with 7 mu A/cm(2) density. Additionally, results of the photocatalytic studies using the electrode combined with an external circuit in the photoelectrical catalytic studies to reduce silver ions reveal that with a reaction time of 180 min, the photocatalytic process will reduce 70% of silver ions in high-concentrated solution (1000 mg/l as Ag) and 93% silver ions in low-concentrated solution (108 mg/l as Ag). When the irradiation time is extended to 240 min, the silver reduction efficiency is as high as 99.8%. Higher solution pH is favorable to the photoelectrical reduction of silver while the anode bias does not benefit the silver reduction efficiency but favors the decomposition of acetic acid. However, the process decomposes less than 10% of acetic acid. The external circuit will transmit the photo-generated electrons to the cathode surface thus reducing the combination of electron and holes at the anode surface. As the reduction of precious metals is concerned, the external circuit is capable of avoiding the metal deposition at the catalyst surface to cause catalyst poison or light shielding that are know to reduce the photo utilization efficiency. (c) 2008 Elsevier B.V. All rights reserved.
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