Zhou Wei, Rajic Ljiljana, Meng Xiaoxiao, Nazari Roya, Zhao Yuwei, Wang Yan, Gao Jihui, Qin Yukun, Alshawabkeh Akram N
School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts 02115, United States.
Chem Eng J. 2019 May 15;364:428-439. doi: 10.1016/j.cej.2019.01.175. Epub 2019 Jan 30.
Electrochemical synthesis of HO offers a great potential for water treatment. However, a significant challenge is the development of efficient cathode materials for the process. Herein, we implement a practical electrochemical cathode modification to support efficient HO electrogeneration via the reduction of dissolved anodic O. Graphite felt (GF) is anodically modified by electrode polarity reversal technique in an acid-free, low-conductivity electrolyte. The modified GF exhibits a significantly higher activity towards O reduction. Up to 183.3% higher HO yield is obtained by the anodized GF due to the increased concentrations of oxygen-containing groups and the hydrophilicity of the surface, which facilitates electron and mass transfer between GF and the electrolyte. Another significant finding is the ability to produce HO at a high yield under neutral pH and low current intensity by the modified GF (35% of the charge need to produce the same amount by unmodified GF). Long-term stability testing of the modified GF showed a decay in the electrode's activity for HO production after 30 consecutive applications. However, the electrode regained its optimal activity for HO production after a secondary modification by electrode polarity reversal. Finally, electrochemically modified GF is more effective for removal of reactive blue 19 (RB19, 20 mg/L) and ibuprofen (IBP, 10 mg/L) by the electro-Fenton process. The modified GF removed 62.7% of RB19 compared to only 28.1% by the unmodified GF in batch reactors after 50 min. Similarly, 75.3% IBP is removed by the modified GF compared to 57.6% by the unmodified GF in a flow-through reactor after 100 min.
电化学合成羟基自由基（HO）在水处理方面具有巨大潜力。然而，该过程面临的一个重大挑战是开发高效的阴极材料。在此，我们实施了一种实用的电化学阴极改性方法，通过还原溶解的阳极氧来支持高效的HO电生成。石墨毡（GF）在无酸、低电导率的电解质中通过电极极性反转技术进行阳极改性。改性后的GF对氧还原表现出显著更高的活性。由于含氧基团浓度增加以及表面亲水性增强，阳极氧化的GF使HO产率提高了高达183.3%，这有利于GF与电解质之间的电子和质量传递。另一个重要发现是，改性后的GF能够在中性pH和低电流强度下高产率地产生HO（产生相同量的HO所需电荷是未改性GF的35%）。对改性GF的长期稳定性测试表明，在连续应用30次后，电极产生HO的活性有所下降。然而，通过电极极性反转进行二次改性后，电极恢复了其产生HO的最佳活性。最后，电化学改性的GF在电芬顿过程中对去除活性蓝19（RB19，20 mg/L）和布洛芬（IBP，10 mg/L）更有效。在间歇反应器中，50分钟后改性GF去除了62.7%的RB19，而未改性GF仅去除了28.1%。同样，在流通式反应器中，100分钟后改性GF去除了75.3%的IBP，而未改性GF去除了57.6%。
