Creation of oxygen-containing functional groups on the biochar surface can highly improve its hydrophilicity and amend its behaviour in aquatic systems. Hydrogen peroxide, ozone, potassium permanganate and nitrogen acid were most usually used reagents for the surface oxidation. On the contrary, biochar activation by strong acids can be a costly process at the industrial scale and can raise environmental problems due to the disposal of activated carbon. Hence, there is a need to search for cheaper and cleaner products for the modification of biochar. For this reason, weak acids, such as solution of rhamnolipids or rainfall water solution, can be used. In this study, it was found that lower size biochar particles had higher wettability compared to larger size particles, since it was categorized as slightly hydrophobic (2.67 s). Steam of average concentration of rhamnolipid solution (20 mg/l) had the highest effect on the enhancement of biochar surface area (15.2 m²/g) and satisfactory impact on the reduction of initial hydrophobicity (4210 s). Biochar modified with increased concentration of nitric acid solution (from 65 to 20%) wettability was in accordance with the increase of surface area (from 4210 to 3907 s and from 1.27 to 4.36 m²/g).

在生物炭表面创建含氧官能团可以大大提高其亲水性并改善其在水生系统中的行为。过氧化氢、臭氧、高锰酸钾和氮酸是最常用的表面氧化试剂。相反，强酸对生物炭的活化在工业规模上可能是一个昂贵的过程，并且由于活性炭的处置会引起环境问题。因此，需要寻找更便宜、更清洁的产品来改性生物炭。为此，可以使用弱酸，例如鼠李糖脂溶液或降雨水溶液。在这项研究中，发现与较大尺寸的颗粒相比，较小尺寸的生物炭颗粒具有更高的润湿性，因为它被归类为轻微疏水性（2.67 秒）。² /g）和对初始疏水性降低的满意影响（4210 s）。用增加浓度的硝酸溶液（从 65 到 20%）润湿性改性的生物炭与表面积的增加（从 4210 到 3907 s 和从 1.27 到 4.36 m ² /g）一致。