Abstract：
Phenols are the widely detected contaminants in the aquatic environment. Pyrogenic carbon (PyC) can mediate phenols degradation, but the specific properties of PyC or phenols influencing this reaction remain unknown. The present study investigated the kinetic process and mechanism of removal of various phenols by different PyC in aqueous phase system. To avoid the impact of the accumulated degradation byproducts on the overall reaction, we conducted a short-term experiment, quantified adsorption and degradation, and obtained reaction rate constants using a two-compartment first-order kinetics model. The adsorption rate constants (ka) of phenols by PyC were 10-220 times higher than degradation rate constants (kd), and they were positively correlated. Interestingly, no correlation was found between kd and common PyC properties, including functional groups, electron transfer capacities, and surface properties. Phenols were primarily attacked by •OH in the adsorbed phase. But neither the instantly trapped •OH, nor the accumulated •OH could explain phenol degradation. Chemical redox titration revealed that the electron transfer parameters, such as the electron donating rate constant (kED) of PyC, correlated well with kd (r>0.87, P < 0.05) of phenols. Analysis of 13 phenols showed that Egap and ELUMO negatively correlated with their kd, confirming the importance of the electronic properties of phenols to their degradation kinetics. This study highlights the importance of PyC electron transfer kinetics parameters for phenols degradation and manipulation of PyC electron transfer rate may accelerate organic pollutant removal, which contributes to a deeper understanding of the environmental behavior and application of PyC systems.
摘要：
酚类是水生环境中广泛检测到的污染物。热解碳（PyC）可以介导酚的降解，但是影响该反应的PyC或酚类的具体性质仍然未知。本研究研究了水相体系中不同PyC去除各种酚类的动力学过程和机理。为了避免累积的降解副产物对整个反应的影响，我们做了一个短期实验,定量吸附和降解，并使用两室一阶动力学模型获得反应速率常数。PyC对苯酚的吸附速率常数(ka)是降解速率常数(kd)的10-220倍,它们呈正相关。有趣的是,Kd和常见的PyC性质之间没有发现相关性，包括官能团，电子转移能力，和表面属性。苯酚主要在吸附相中受到·OH的攻击。但无论是瞬间被困的•OH，积累的·OH也不能解释苯酚的降解。化学氧化还原滴定法揭示了电子转移参数,例如PyC的给电子速率常数(kED)，酚类物质kd与相关程度较好(r>0.87,P<0.05)。对13种酚的分析表明，Egap和ELUMO与它们的kd呈负相关，确认酚类的电子性质对其降解动力学的重要性。本研究强调了PyC电子转移动力学参数对酚类降解的重要性，操纵PyC电子转移速率可能加速有机污染物的去除。这有助于更深入地了解PyC系统的环境行为和应用。
