School of Environmental Studies, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
School of Environmental Studies, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
Sci Total Environ. 2020 Jun 1;719:137435. doi: 10.1016/j.scitotenv.2020.137435. Epub 2020 Feb 19.
Improved surface characteristics and incorporated Fe, S, and Cl species are reported in Fe-modified biochar, which makes it a prospective material for Hg(II) removal. In this study, aqueous Hg(II) was removed from solution by unmodified, FeCl-modified, and FeSO-modified biochars pyrolyzed at 300, 600, or 900 °C. Higher pyrolytic temperature resulted in higher removal efficiency, with the biochars pyrolyzed at 900 °C removing >96% of Hg(II). Fe-modification enhanced Hg(II) removal for biochars pyrolyzed at 600 °C (from 88% to >95%) or 900 °C (from 96% to 99%). Based on synchronous extended X-ray absorption fine structure (EXAFS) analysis, Hg coordinated to S in modified and unmodified biochars pyrolyzed at 900 °C, where thiol was reported, and in FeSO-modified biochars pyrolyzed at 600 or 900 °C, where sulfide was recognized; in other biochars, Hg bound to O or Cl. Additionally, confocal micro-X-ray fluorescence imaging (CMXRFI) demonstrated Hg was distributed in agreement with S in biochars where HgS was formed; otherwise, Hg distribution was influenced by Hg species in solution and the pore characteristics of the biochar. This investigation provides information on the effectiveness and mechanisms of Hg removal that is critical for evaluating biochar applications and optimizing modification methods in groundwater remediation.
改良后的表面特性以及 Fe、S 和 Cl 物种的掺入使得 Fe 改性生物炭成为去除 Hg(II)的有前景的材料。在这项研究中，通过未改性、FeCl 改性和 FeSO 改性的生物炭在 300、600 或 900°C 下热解，从溶液中去除了水合 Hg(II)。较高的热解温度导致更高的去除效率，在 900°C 下热解的生物炭去除了超过 96%的 Hg(II)。Fe 改性增强了在 600°C（从 88%到>95%）或 900°C（从 96%到 99%）下热解的生物炭的 Hg(II)去除效率。基于同步扩展 X 射线吸收精细结构（EXAFS）分析，在 900°C 下热解的改性和未改性生物炭中，Hg 与 S 配位，其中报道了硫醇，在 600 或 900°C 下热解的 FeSO 改性生物炭中，识别出了硫化物；在其他生物炭中，Hg 与 O 或 Cl 结合。此外，共聚焦微 X 射线荧光成像（CMXRFI）表明，Hg 的分布与形成 HgS 的生物炭中的 S 一致；否则，Hg 的分布受到溶液中 Hg 物种和生物炭孔特征的影响。这项研究提供了有关 Hg 去除效果和机制的信息，这对于评估生物炭在地下水修复中的应用和优化改性方法至关重要。
