Electro-activation has been an important surface modification strategy to enhance the signal of analytes on glassy carbon electrodes (GCE). However, its unique effects on certain analytes remain to be further explored. Hence, due to the electro-active hydroxyl groups (–OH), phenolic compounds were selected as the analyte to reveal it to some extent. Except for the improved electrocatalytic activity of electro-activated GCE (e-GCE) which was attributable to the improved charge transfer ability and optimized surface properties ( eg. surface area, surface roughness, and active sites), the oxygen-containing functional groups on the e-GCE surface were also identified as being of significant importance for enhanced response of phenolic compounds. After electro-activation, the newly generated C O constituted 12.81 % of the C1s spectra and 51.75 % of the O1s spectra, effectively facilitating the formation of donor–acceptor complexes between the analytes and the electrodes, thereby enhancing the adsorption of phenolic compounds. Furthermore, it was found that the structure of phenolic compounds had a remarkable impact on the response signal. The increase in the number of –OH groups involved in the electron transfer process, the increase in the number of aromatic rings, and the enhancement of the electronegativity of substituents all contributed positively to the response signal of phenolic compounds. At last, based on the great adsorption of catechol, a sensor for catechol with a sensitivity 12-fold higher than prior has been established. These results provide insights for the subsequent fabrication of green sensors for more electro-active molecules.
Cong He,Xiangjuan Ma,Huajun Feng,Yangcheng Ding,Yijing Xia,Zhiwei Wang
A flow-through peroxymonosulfate (PMS) electro-activation system with a polyacrylonitrile-based carbon fiber (PCF) membrane anode (denoted as E-PCF-PMS system) was developed. The introduction of the PCF membrane anode enabled the flow-through electrocatalytical system to achieve a remarkable tetracycline (TC) removal of 96.0 ± 0.2 % within 15 min, with a degradation rate of 0.273 min −1 . Scavenging investigations revealed that singlet oxygen ( 1 O 2 ) was the dominant reactive oxygen species for TC degradation in the E-PCF-PMS system, and this finding was confirmed by electron paramagnetic resonance tests. Potential degradation pathways of TC were identified according to the detected intermediates and calculations of density functional theory, and a decreasing trend in the toxicity of TC intermediates was discovered. Thanks to the 1 O 2 -dominated pathway, the constructed E-PCF-PMS system could achieve efficient TC degradation under different concentrations of several common anions (Cl − , NO 3 − , HPO 4 2− , and HCO 3 − ) and humic acid (HA). General applicability and reusability tests demonstrated the excellent practicability of the proposed system. The PMS electro-activation system offers a potential technique for high-efficient degradation of contaminants in water and wastewater.
Levofloxacin (LFX), which is difficult to degrade effectively due to its molecular stability, has become an problem that needs to be solved urgently. The advanced oxidation technology of persulfate has received increasing attention from researchers. In this study, a Ce-MOF derivative (Ce-MOF-T) was prepared by hydrothermal synthesis and calcination, which synergistically responded to electroactivation to generate sulfate radicals for the efficient degradation of LFX. It has been proven that electrical activation and the Ce-MOF derivatives work together to generate sulfate radicals and effectively degrade LFX. Ce-MOF-550-modified carbon cloth was used as the cathode and a platinum electrode as the anode, the concentration of LFX was 20 mg·L−1, the loading of Ce-MOF-550 was 15 mg, pH = 5, the concentration of sodium persulfate (PMS) was 0.3 g·L−1, the current density was 100 A·m−2, and the degradation rate was 82.05% after 1 h of reaction and 95% after 3 h of reaction. After five cycle tests, the degradation rate was still higher than 75.00%, indicating that the material had good stability. In addition, the degradation of LFX was consistent with a quasi-primary kinetic reaction with apparent rate constants of 2.26 × 10−2min−1.
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