Biochar, mainly including pyrochar produced via pyrolysis of biomass at moderate temperatures of 350–700 °C and hydrochar formed by hydrothermal carbonization in a range of 150–350 °C, has received increasing attention because of its significant environmental impacts. It is known that pyrochar can generate reactive oxygen species even in the dark owing to the presence of persistent free radicals, but hydrochar is far less studied. In this study, we systematically investigate the photochemistry of hydrochar and check its effects on the sulfadimidine degradation. Different from pyrochar derived from the same biomass, hydrochar could generate much more H₂O₂ and •OH under daylight irradiation, which could enhance the sulfadimidine degradation rate six times more than that found in the dark. Raman spectroscopy, Fourier transform infrared spectroscopy, electron paramagnetic resonance, and X-ray photoelectron spectroscopy were employed to elucidate this interesting phenomenon. Characterization results revealed that the higher reactive oxygen species generation ability of hydrochar under solar light irradiation was attributed to its abundant photoactive surface oxygenated functional groups. This study clarifies the differences of pyrochar and hydrochar on organic pollutant degradation, and also sheds light on environmental effects of hydrochar.

中文翻译：

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碳氢化合物的光化学：活性氧的产生和磺胺二甲胺的降解

生物炭，主要包括通过在350–700°C的中等温度下对生物质进行热解而产生的焦炭，以及在150–350°C的范围内由热液碳化形成的水炭，由于其对环境的重大影响，因此受到越来越多的关注。众所周知，即使存在黑暗，焦碳也可以产生活性氧，这是由于持久性自由基的存在，但是对水焦的研究却很少。在这项研究中，我们系统地研究了水焦油的光化学性质，并检查了其对磺胺嘧啶降解的影响。与来自相同生物质的焦炭不同，水焦炭可以产生更多的H ₂ O _2。•OH在日光照射下，其磺胺嘧啶的降解速率比在黑暗中提高了六倍。拉曼光谱，傅立叶变换红外光谱，电子顺磁共振和X射线光电子能谱被用来阐明这种有趣的现象。表征结果表明，在太阳光照射下，水炭具有较高的活性氧生成能力，这归因于其丰富的光活性表面含氧官能团。这项研究阐明了焦炭和水炭在有机污染物降解方面的差异，并阐明了水炭对环境的影响。