Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China.
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China.
Sci Total Environ. 2022 Jan 20;805:150413. doi: 10.1016/j.scitotenv.2021.150413. Epub 2021 Sep 20.
Modified biomass-based adsorption technique has attracted much attention in heavy metal ions removal, but selective adsorption behavior and mechanism of heavy metal ions adsorption onto biosorbent still need to be further clarified. Herein, a carboxylated biogas residue (BR-COOH) was prepared to remove the Cu and Zn from single/binary heavy metal ions solution and explore selective adsorption mechanism. The results exhibited that the adsorption capacities of BR-COOH for Cu was higher than that for Zn obviously, whether in the single or binary heavy metal ions solution. Meanwhile, the introduced carboxy groups were identified as the main sites for metal ions adsorption. Density functional theory (DFT) calculation results exhibited that the adsorption energy of Cu (-0.51 eV) onto BR-COOH was lower than that of Zn (-0.47 eV), indicating that the Cu adsorbed on BR-COOH was more stable than Zn. Moreover, the metal ions adsorption capacity of BR-COOH was positively correlated with their electronegativity, which was due to that the metal ions with stronger electronegativity was more easily interacted with the negatively charged oxygen in carboxyl groups. The same results were also verified in the control experiment conducted with two other biosorbents. Therefore, the work provided a new and in-depth insight into selective adsorption of metal ions onto carboxylated biosorbent.
改性生物质吸附技术在重金属离子去除方面引起了广泛关注，但生物吸附剂对重金属离子的选择性吸附行为和机制仍需进一步阐明。本研究制备了一种羧化沼气残留物（BR-COOH），用于去除单一/二元重金属离子溶液中的 Cu 和 Zn，并探讨其选择性吸附机制。结果表明，BR-COOH 对 Cu 的吸附容量明显高于 Zn，无论是在单一重金属离子溶液还是二元重金属离子溶液中。同时，引入的羧基被确定为金属离子吸附的主要位点。密度泛函理论（DFT）计算结果表明，Cu（-0.51 eV）在 BR-COOH 上的吸附能低于 Zn（-0.47 eV），表明 Cu 在 BR-COOH 上的吸附比 Zn 更稳定。此外，BR-COOH 的金属离子吸附容量与金属离子的电负性呈正相关，这是因为电负性更强的金属离子更容易与羧基中的带负电荷的氧相互作用。在使用另外两种生物吸附剂进行的对照实验中也得到了相同的结果。因此，该工作为深入了解羧化生物吸附剂对金属离子的选择性吸附提供了新的见解。
