Environmental Science Research Institute, Huazhong University of Science and Technology, Luoyu Road 1037#, Wuhan, 430074, People's Republic of China.
Institute of Energy and Environment, Inner Mongolia University of Science and Technology, Arding Street 7#, Baotou, 014010, China.
Environ Sci Pollut Res Int. 2019 Sep;26(26):27482-27493. doi: 10.1007/s11356-019-05881-w. Epub 2019 Jul 22.
Sunflower stalk-derived biochars (BC) were prepared at various temperatures (i.e., 500, 650, and 1000 °C) and demonstrated as a highly efficient catalyst in persulfate (PS) activation for the oxidation of p-nitrophenol (PNP) at 60 °C. The apparent PNP oxidation rate constant in the BC500 (0.1543 L mol S), BC650 (0.6062 L mol S), or BC1000 (2.1379 L mol S) containing PS system was about 2, 8 and 28 times higher than that in PS/PNP (0.0751 L mol S) system, respectively. The effect of reaction temperature on PNP oxidation was also investigated. Furthermore, the radical quenching tests and electron paramagnetic resonance spectroscopy (EPR) were employed to investigate the sulfate and hydroxyl radicals for PNP oxidation. The Raman results suggested that the defective sites on biochars possess vital role for oxidation of PNP in PS system. The possible activation pathway of PS/BC was proposed that the defective sites on BC were involved for weakening the O-O bond in PS and subsequently cleaving O-O bond by heat to generate sulfate radical. The oxidation of PNP at low concentration (below 100 μg L) was completely removed in urban wastewater by PS/BC system within 30 min. This work would provide new insights into PS activation by BC catalyst and afford a promising method for organic pollutant removal in high-temperature wastewater.
向日葵秸秆衍生生物炭（BC）在不同温度（即 500、650 和 1000°C）下制备，并在 60°C 下作为过硫酸盐（PS）活化的高效催化剂，用于氧化对硝基苯酚（PNP）。在含有 PS 的 BC500（0.1543 L mol S）、BC650（0.6062 L mol S）或 BC1000（2.1379 L mol S）体系中，PNP 的表观氧化速率常数约为 PS/PNP（0.0751 L mol S）体系的 2、8 和 28 倍。还研究了反应温度对 PNP 氧化的影响。此外，进行了自由基猝灭试验和电子顺磁共振波谱（EPR）以研究硫酸根和羟基自由基用于 PNP 氧化。拉曼结果表明，生物炭上的缺陷位对 PS 体系中 PNP 的氧化具有重要作用。提出了 PS/BC 的可能活化途径，即 BC 上的缺陷位参与削弱 PS 中的 O-O 键，随后通过热量将 O-O 键断裂，生成硫酸根自由基。在 30 分钟内，PS/BC 体系可完全去除城市废水中低浓度（低于 100μg L）的 PNP。这项工作将为 BC 催化剂活化 PS 提供新的见解，并为高温废水中有机污染物去除提供一种有前途的方法。
