The mercury removal capacity of biochar can be improved by plasma modification and the functional group is an important factor affecting the mercury removal. This paper examines factors such as discharge voltages, gas flow rates, chlorine concentrations and discharge times that may affect functional groups on the surface of biochar. The mercury removal performance of the tobacco stem biochar prepared under different Cl2 plasma modification conditions was investigated using a fixed bed reactor. The number of C–Cl bonds and carboxyl increased after modification and decreased in mercury removal. Longer discharge times can destroy the biochar surface and possibly cause a decrease in the number of active sites. Increasing the discharge voltage promotes the formation of C–Cl bonds and carboxyl groups. Excessive gas flow rates cause active chlorine to be carried out of the reactor quickly which reduces the formation of C–Cl. The amount of C–Cl bonds increases with increased chlorine concentration. In the modified biochar, C–Cl and carboxyl take part in the adsorption of mercury to form HgCl2 and HgO, while the unmodified biochar is mainly physically adsorbed Hg0. C–Cl is the main functional group participated in mercury removal and the carboxyl is a secondary functional group. The proportion of HgCl2 is at least 68.2% in the used modified biochar. Under optimum conditions, the initial mercury removal efficiency of modified tobacco biochar was 99.1%, and the efficiency was still 79.1% after 100 min.

中文翻译：

---

等离子体诱导活性官能团添加到生物炭以去除元素汞

等离子体改性可以提高生物炭的除汞能力，而官能团是影响除汞的重要因素。本文研究了可能影响生物炭表面官能团的因素，如放电电压、气体流速、氯浓度和放电时间。采用固定床反应器研究了在不同Cl2等离子体改性条件下制备的烟梗生物炭的除汞性能。改性后C-Cl键和羧基的数量增加，除汞减少。较长的放电时间会破坏生物炭表面，并可能导致活性位点数量减少。增加放电电压会促进 C-Cl 键和羧基的形成。过高的气体流速会导致活性氯快速从反应器中排出，从而减少 C-Cl 的形成。C-Cl 键的数量随着氯浓度的增加而增加。在改性生物炭中，C-Cl和羧基参与吸附汞形成HgCl2和HgO，而未改性生物炭主要是物理吸附Hg0。C-Cl是参与除汞的主要官能团，羧基是次要官能团。使用的改性生物炭中HgCl2的比例至少为68.2%。在优化条件下，改性烟草生物炭的初始脱汞效率为99.1%，100 min后脱汞效率仍为79.1%。在改性生物炭中，C-Cl和羧基参与吸附汞形成HgCl2和HgO，而未改性生物炭主要是物理吸附Hg0。C-Cl是参与除汞的主要官能团，羧基是次要官能团。使用的改性生物炭中HgCl2的比例至少为68.2%。在优化条件下，改性烟草生物炭的初始脱汞效率为99.1%，100 min后脱汞效率仍为79.1%。在改性生物炭中，C-Cl和羧基参与吸附汞形成HgCl2和HgO，而未改性生物炭主要是物理吸附Hg0。C-Cl是参与除汞的主要官能团，羧基是次要官能团。使用的改性生物炭中HgCl2的比例至少为68.2%。在优化条件下，改性烟草生物炭的初始脱汞效率为99.1%，100 min后脱汞效率仍为79.1%。2% 在使用的​​改性生物炭中。在优化条件下，改性烟草生物炭的初始脱汞效率为99.1%，100 min后脱汞效率仍为79.1%。2% 在使用的​​改性生物炭中。在优化条件下，改性烟草生物炭的初始脱汞效率为99.1%，100 min后脱汞效率仍为79.1%。