Nanobiochar has received much attention recently among engineered biochar types owing to its useful chemical and physical properties. Research efforts have attempted to discover novel methods for nanobiochar preparation and applications. In this review, we summarize the literature on various aspects of nanobiochar preparation, production and use. Often, the bulk parent biochar is obtained from biomass pyrolysis, and mechanically ground using different milling processes to fabricate nanobiochar. Apart from mechanical means, direct fabrication of nanobiochar through flash heating resulting in graphitic nanosheets has been reported. Process conditions applied to the parent biochar directly influence the properties of the resulting nanobiochar. For instance, over 70% of 33 nanobiochar samples derived from biomass pyrolyzed above 450 °C demonstrated 32 times greater BET specific surface areas than nanobiochar produced at <450 °C. Nanobiochar has diverse applications, such as in wastewater treatment, health care applications, use as an electrode material, and in supercapacitors and sensors, owing to its wide range of physical and chemical properties. However, the toxicity of nanobiochar to human and ecosystem health has not received sufficient research attention. More research should be performed to elucidate the drawbacks, such as the high agglomeration potential and low yield, of nanobiochar for practical uses. Furthermore, reported data are insufficient to obtain a clear idea of the nature and behavior of nanobiochar, despite the growing interest in the research topic. Hence, future research should be driven towards exploring techniques to improve the yield of nanobiochar, reduce agglomeration, upscale it for electrode supercapacitor production and understand toxicological aspects.

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纳米生物炭：生产，特性和多功能应用

纳米生物炭由于其有用的化学和物理性质，最近在工程生物炭类型中受到了很多关注。研究努力试图发现用于纳米生物炭制备和应用的新方法。在这篇综述中，我们总结了有关纳米生物炭制备，生产和使用各个方面的文献。通常，从生物质热解中获得大量的母体生物炭，并使用不同的研磨工艺进行机械研磨以制造纳米生物炭。除了机械手段，已经报道了通过快速加热直接制造纳米生物炭产生石墨纳米片的方法。应用于母体生物炭的工艺条件直接影响所得纳米生物炭的性能。例如，在高于450°C的温度下进行热解的33个生物质纳米生物炭样品中，超过70％的BET比表面积是<450°C时产生的纳米生物炭的32倍。由于其广泛的物理和化学特性，纳米生物炭具有多种应用，例如在废水处理，医疗保健应用，用作电极材料以及在超级电容器和传感器中。然而，纳米生物炭对人类和生态系统健康的毒性尚未引起足够的研究关注。应该进行更多的研究来阐明纳米生物炭在实际应用中的缺点，例如高集聚潜力和低产量。此外，尽管对研究主题的兴趣日益浓厚，但所报道的数据仍不足以清楚地了解纳米生物炭的性质和行为。因此，