Shanghai Academy of Environmental Sciences, 200233, Shanghai, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Environ Sci Pollut Res Int. 2022 Aug;29(36):54988-55002. doi: 10.1007/s11356-022-19351-3. Epub 2022 Mar 21.
Nitrobenzene is a widespread contaminant in water. Biochar (BC) is a promising material for removing organic pollutants, but the adsorption capacity of pristine BC is low. Chemical modification is often used to improve the adsorption performance, but information on the sorption of nitrobenzene by modified BC is rare. In this study, BCs pyrolyzed at 300, 500, and 700 °C were modified by hydrochloric acid (HCl), sulfuric acid (HSO), sodium hydroxide (NaOH), hydrogen peroxide (HO), and nitric acid (HNO), respectively. The properties, nitrobenzene sorption behaviors, and sorption mechanisms of different BCs were analyzed. The results showed that chemical modification decreased the sorption of nitrobenzene on BCs pyrolyzed at 300 °C, possibly due to the loss of the partition phase and the increase in polarity after modification. Regarding BCs pyrolyzed at 500 and 700 °C, the NaOH and HCl modifications significantly increased the sorption capacity by 19% and 60%, 18%, and 41%, respectively, possibly due to the increase in surface area, available pores, and aromaticity, while HNO modification decreased the sorption capacity by 41% and 31%. Two reasons were probably responsible for the decrease: one was the decrease in surface area after HNO modification due to the destruction of pore walls and the continuity of holes; the other was the strong repulsion between the nitro groups formed on the surface of BC and the nitro groups of nitrobenzene that drove nitrobenzene molecules away from the surface. A principal component-based comprehensive evaluation of the BC properties, which were significantly correlated with the sorption isotherm parameters, was used to evaluate the nitrobenzene sorption performance of the modified BC. Overall, BC pyrolyzed at 700 °C modified with NaOH or HCl were proposed as effective sorption materials for the removal of nitrobenzene in environment, which also provided a chemical modified method of biochar derived from agricultural waste.
硝基苯是一种广泛存在于水中的污染物。生物炭（BC）是一种很有前途的去除有机污染物的材料，但原始 BC 的吸附能力较低。化学修饰通常用于提高吸附性能，但关于修饰 BC 对硝基苯的吸附的信息很少。在这项研究中，分别用盐酸（HCl）、硫酸（HSO）、氢氧化钠（NaOH）、过氧化氢（HO）和硝酸（HNO）对在 300、500 和 700°C 下热解的 BC 进行了修饰。分析了不同 BC 的性质、硝基苯吸附行为和吸附机理。结果表明，化学修饰降低了 300°C 热解的 BC 对硝基苯的吸附，这可能是由于修饰后分配相的损失和极性的增加。对于在 500 和 700°C 下热解的 BC，NaOH 和 HCl 修饰分别显著提高了 19%和 60%、18%和 41%的吸附能力，这可能是由于表面积、可用孔和芳构性的增加，而 HNO 修饰降低了 41%和 31%的吸附能力。下降的原因可能有两个：一是 HNO 修饰后由于孔壁的破坏和孔的连续性丧失导致表面积减小；另一个是由于 BC 表面形成的硝基基团与硝基苯的硝基基团之间的强烈排斥作用，导致硝基苯分子从表面被驱离。基于主成分的综合评价法评估了 BC 的性质，这些性质与吸附等温线参数显著相关，用于评价修饰 BC 对硝基苯的吸附性能。总体而言，建议将 700°C 热解的 BC 与 NaOH 或 HCl 进行修饰，作为去除环境中硝基苯的有效吸附材料，这也为农业废弃物衍生生物炭的化学修饰提供了一种方法。
