State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200090, China; CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Material, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Material, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2021 Apr 10;764:142846. doi: 10.1016/j.scitotenv.2020.142846. Epub 2020 Oct 8.
This work successfully fabricated a novel magnetic adsorbent, i.e., phosphate modified magnetite@ferrihydrite (Mag@Fh-P), and explored its potential application for Cd(II) removal from water, soil, and sediment. To synthesize the adsorbent, ferrihydrite-coated magnetite (Mag@Fh) was firstly developed with partially acid-dissolved natural magnetite particles, followed by in-situ synthesis of ferrihydrite on magnetite surface via alkali addition. Selection of natural magnetite as iron source for ferrihydrite synthesis and as magnetic core is believed to save the cost of adsorbent. Then, phosphate was loaded on Mag@Fh by impregnation-heating treatment to produce Mag@Fh-P. Batch adsorption experiments revealed that the Cd(II) adsorption on Mag@Fh-P could reach equilibrium within 60 min, and the calculated adsorption capacity using Langmuir model was 64.1 mg/g, which was significantly higher than that on magnetite (0.44 mg/g) and Mag@Fh (23.9 mg/g). The results from X-ray photoelectron spectroscopy analysis and batch adsorption experiments confirmed that both ligand exchange and electrostatic attraction contributed to Cd(II) adsorption. Besides, Mag@Fh-P can also be an efficient amendment for soil and sediment remediation. The spent Mag@Fh-P could be easily recovered via magnetic separation, accompanied by the significant decrease in total Cd(II) concentration in soil/sediment. At an adsorbent dosage of 2 wt%, 0.82 and 0.74 mg/kg of total Cd(II) in soil and sediment was removed, respectively. In all, the synthesized Mag@Fh-P as adsorbent has the merits of cost effectiveness, fast adsorption rate, high adsorption capacity, and easy separation, and thus it has promising application for the removal of heavy metal cations from water, soil, and sediment.
这项工作成功制备了一种新型磁性吸附剂，即磷酸盐修饰的磁铁矿@水铁矿（Mag@Fh-P），并探索了其在去除水中、土壤和沉积物中的 Cd(II)方面的潜在应用。为了合成吸附剂，首先通过部分酸溶解天然磁铁矿颗粒制备了水铁矿包覆的磁铁矿（Mag@Fh），然后通过添加碱原位合成磁铁矿表面上的水铁矿。选择天然磁铁矿作为水铁矿合成的铁源和磁性核，被认为可以降低吸附剂的成本。然后，通过浸渍-加热处理将磷酸盐负载在 Mag@Fh 上，制备出 Mag@Fh-P。批处理吸附实验表明，Mag@Fh-P 对 Cd(II)的吸附可在 60 分钟内达到平衡，使用 Langmuir 模型计算的吸附容量为 64.1mg/g，明显高于磁铁矿（0.44mg/g）和 Mag@Fh（23.9mg/g）。X 射线光电子能谱分析和批处理吸附实验的结果证实，配体交换和静电吸引都有助于 Cd(II)的吸附。此外，Mag@Fh-P 也可以作为土壤和沉积物修复的有效改良剂。用过的 Mag@Fh-P 可以通过磁分离很容易地回收，同时土壤/沉积物中的总 Cd(II)浓度也显著降低。在吸附剂用量为 2wt%时，土壤和沉积物中总 Cd(II)的去除率分别为 0.82 和 0.74mg/kg。总之，所合成的 Mag@Fh-P 作为吸附剂具有成本效益高、吸附速率快、吸附容量高、易于分离等优点，因此有望用于去除水中、土壤和沉积物中的重金属阳离子。
