Li Deyun, Li Yongtao, He Shuran, Hu Tian, Li Hanhao, Wang Jinjin, Zhang Zhen, Zhang Yulong
School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China.
College of Natural Resources and Environment, Joint Institute for Environmental Research & Education, South China Agricultural University, Guangzhou 510642, China.
Toxics. 2024 Jan 15;12(1):72. doi: 10.3390/toxics12010072.
Argillaceous limestone (AL) is comprised of carbonate minerals and clay minerals and is widely distributed throughout the Earth's crust. However, owing to its low surface area and poorly active sites, AL has been largely neglected. Herein, manganic manganous oxide (MnO) was used to modify AL by an in-situ deposition strategy through manganese chloride and alkali stepwise treatment to improve the surface area of AL and enable its utilization as an efficient adsorbent for heavy metals removal. The surface area and cation exchange capacity (CEC) were enhanced from 3.49 to 24.5 m/g and 5.87 to 31.5 cmoL(+)/kg with modification, respectively. The maximum adsorption capacities of lead (Pb), copper (Cu), and nickel (Ni) ions on MnO-modified argillaceous limestone (MnO-AL) in mono-metal systems were 148.73, 41.30, and 60.87 mg/g, respectively. In addition, the adsorption selectivity in multi-metal systems was Pb > Cu > Ni in order. The adsorption process conforms to the pseudo-second-order model. In the multi-metal system, the adsorption reaches equilibrium at about 360 min. The adsorption mechanisms may involve ion exchange, precipitation, electrostatic interaction, and complexation by hydroxyl groups. These results demonstrate that MnO modification realized argillaceous limestone resourcization as an ideal adsorbent. MnO-modified argillaceous limestone was promising for heavy metal-polluted water and soil treatment.
泥质灰岩（AL）由碳酸盐矿物和粘土矿物组成，在地壳中广泛分布。然而，由于其比表面积低且活性位点较少，AL在很大程度上被忽视了。在此，通过氯化锰和碱分步处理，采用原位沉积策略用氧化锰（MnO）对AL进行改性，以提高AL的比表面积，并使其能够作为一种高效吸附剂用于去除重金属。改性后，比表面积和阳离子交换容量（CEC）分别从3.49 m²/g提高到24.5 m²/g，从5.87 cmoL(+)/kg提高到31.5 cmoL(+)/kg。在单金属体系中，MnO改性泥质灰岩（MnO-AL）对铅（Pb）、铜（Cu）和镍（Ni）离子的最大吸附容量分别为148.73、41.30和60.87 mg/g。此外，在多金属体系中的吸附选择性顺序为Pb＞Cu＞Ni。吸附过程符合准二级模型。在多金属体系中，吸附在约360分钟时达到平衡。吸附机制可能包括离子交换、沉淀、静电相互作用和羟基络合。这些结果表明，MnO改性实现了泥质灰岩作为理想吸附剂的资源化利用。MnO改性泥质灰岩在处理重金属污染的水和土壤方面具有广阔前景。
