ZnO/PEG-Co(II)-PbOナノコンポジット電極の作製と特性評価、フェノールの電極触媒分解の検討

Preparation and characterization of ZnO/PEG-Co(II)-PbO nanocomposite electrode and an investigation of the electrocatalytic degradation of phenol.

• Lai Gui
• Zhen Chen
• Bangyao Chen
• Yuzhu Song
• Qiang Yu
• Wei Zhu
• Qi Hu
• Yuanyuan Liu
• Zhaoyi Zheng
• Lv Ze
• Hongjun You
• Farhana Yeasmin

抄録

陽極電着法を用いてZnO/PEG(ポリエチレングリコール)-Co(II)-PbOナノコンポジット電極を作製し、フェノールの電極触媒分解に用いた。その結果、電極表面には多数のPbOナノスフィア構造が形成され、単一のナノスフィアの平均サイズは約0.4μmであった。XRDおよびEDSの結果、活性層はβ-PbOからなり、少量のコバルトと炭素を含んでいた。電気化学的測定から、電極は低い活性化エネルギー(E = 17.517 kJ∙mol)と電荷移動抵抗(R = 7.564 Ω cm)とより大きな交換電流密度(i°=1.476 × 10 mA cm)を有することが示された。この電極は半減期が短く、反応速度定数が大きく、180分後の分解効率(RE=91.1%)が高いことがわかった。また、反応順序を計算したところ、疑似的な一次反応速度論に沿って分解が行われた。HPLCの結果、分解経路は以下のようになっていることがわかった。次に、ベンゾキノンはマレイン酸とフマル酸に分解される。最後に、これらの酸性化合物はシュウ酸に分解され、最終的に鉱化される。

A ZnO/PEG (polyethylene glycol) -Co(II)-PbO nanocomposite electrode was constructed by using the anodic electrodeposition method and used for the electrocatalytic degradation phenol. The results showed that the electrode surface formed numerous PbO nanosphere structures, and the average size of a single nanosphere is approximately 0.4 μm. XRD and EDS results showed the active layer consisted of β-PbO, and contained small amounts of cobalt and carbon. The electrochemical measurements showed that the electrode possessed a lower activation energy (E = 17.517 kJ∙mol) and charge transfer resistance (R = 7.564 Ω cm) and a larger exchange current density (i°=1.476 × 10 mA cm). The phenol degradation process was controlled by the adsorption process and kinetic parameters were obtained with an initial concentration of 100 mg L. The electrode possessed a shorter half-life, larger reaction rate constant, and degradation efficiency (RE = 91.1 %) after 180 min. Reaction order was also calculated, and the degradation followed the pseudo-first-order reaction kinetics. HPLC results showed that the degradation pathway is as follows: firstly, phenol is gradually decomposed into o-diphenol, p-diphenol and benzoquinone under hydroxyl radicals attack. Then, benzoquinone is broken into maleic acid and fumaric acid. Finally, these acidic compounds are broken into oxalic acid, which is eventually mineralized.

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