Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry, Central China Normal University , Wuhan 430079, People's Republic of China.
Environ Sci Technol. 2017 Oct 3;51(19):11278-11287. doi: 10.1021/acs.est.7b02740. Epub 2017 Sep 21.
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 HO 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.
生物炭主要包括在 350-700°C 的中等温度下通过生物质热解产生的热解炭，以及在 150-350°C 的范围内通过水热碳化形成的水炭，由于其对环境的重大影响而受到越来越多的关注。已知热解炭即使在黑暗中也由于存在持久自由基而产生活性氧物种，但对水炭的研究要少得多。在这项研究中，我们系统地研究了水炭的光化学性质，并检查了它对磺胺二甲嘧啶降解的影响。与源自相同生物质的热解炭不同，水炭在日光照射下可以产生更多的 HO 和 •OH，这可以将磺胺二甲嘧啶的降解速率提高六倍以上，而在黑暗中则没有发现这种现象。拉曼光谱、傅里叶变换红外光谱、电子顺磁共振和 X 射线光电子能谱被用来阐明这一有趣的现象。表征结果表明，水炭在太阳光照射下具有更高的活性氧物种生成能力，这归因于其丰富的光活性表面含氧官能团。本研究阐明了热解炭和水炭在有机污染物降解方面的差异，也为水炭的环境效应提供了启示。
