Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry, Beijing Normal University , Beijing 100875, China.
Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
J Am Chem Soc. 2016 Mar 2;138(8):2858-66. doi: 10.1021/jacs.6b00110. Epub 2016 Feb 15.
The MoS4(2-) ion was intercalated into magnesium-aluminum layered double hydroxide (MgAl-NO3-LDH) to produce a single phase material of Mg0.66Al0.34(OH)2(MoS4)0.17·nH2O (MgAl-MoS4-LDH), which demonstrates highly selective binding and extremely efficient removal of heavy metal ions such as Cu(2+), Pb(2+), Ag(+), and Hg(2+). The MoS4-LDH displays a selectivity order of Co(2+), Ni(2+), Zn(2+) < Cd(2+) ≪ Pb(2+) < Cu(2+) < Hg(2+) < Ag(+) for the metal ions. The enormous capacities for Hg(2+) (∼500 mg/g) and Ag(+) (450 mg/g) and very high distribution coefficients (Kd) of ∼10(7) mL/g place the MoS4-LDH at the top of materials known for such removal. Sorption isotherm for Ag(+) agrees with the Langmuir model suggesting a monolayer adsorption. It can rapidly lower the concentrations of Cu(2+), Pb(2+), Hg(2+), and Ag(+) from ppm levels to trace levels of ≤1 ppb. For the highly toxic Hg(2+) (at ∼30 ppm concentration), the adsorption is exceptionally rapid and highly selective, showing a 97.3% removal within 5 min, 99.7% removal within 30 min, and ∼100% removal within 1 h. The sorption kinetics for Cu(2+), Ag(+), Pb(2+), and Hg(2+) follows a pseudo-second-order model suggesting a chemisorption with the adsorption mechanism via M-S bonding. X-ray diffraction patterns of the samples after adsorption demonstrate the coordination and intercalation structures depending on the metal ions and their concentration. After the capture of heavy metals, the crystallites of the MoS4-LDH material retain the original hexagonal prismatic shape and are stable at pH ≈ 2-10. The MoS4-LDH material is thus promising for the remediation of heavy metal polluted water.
MoS4(2-) 离子被嵌入到镁铝层状双氢氧化物 (MgAl-NO3-LDH) 中，生成单相材料 Mg0.66Al0.34(OH)2(MoS4)0.17·nH2O (MgAl-MoS4-LDH)，该材料对 Cu(2+)、Pb(2+)、Ag(+) 和 Hg(2+) 等重金属离子具有高度选择性的结合和极其有效的去除能力。MoS4-LDH 对金属离子的选择性顺序为 Co(2+)、Ni(2+)、Zn(2+) < Cd(2+) ≪ Pb(2+) < Cu(2+) < Hg(2+) < Ag(+)。MoS4-LDH 对 Hg(2+)（∼500 mg/g）和 Ag(+)（450 mg/g）的巨大容量和非常高的分配系数（Kd）∼10(7) mL/g，使 MoS4-LDH 成为已知用于此类去除的材料的佼佼者。Ag(+) 的吸附等温线符合 Langmuir 模型，表明单层吸附。它可以迅速将 Cu(2+)、Pb(2+)、Hg(2+) 和 Ag(+) 的浓度从 ppm 水平降低到痕量水平（≤1 ppb）。对于高毒性的 Hg(2+)（在 ∼30 ppm 浓度下），吸附非常迅速且具有高度选择性，在 5 分钟内去除 97.3%，在 30 分钟内去除 99.7%，在 1 小时内去除约 100%。Cu(2+)、Ag(+)、Pb(2+) 和 Hg(2+) 的吸附动力学符合准二级模型，表明通过 M-S 键合发生化学吸附。吸附后样品的 X 射线衍射图谱表明，根据金属离子及其浓度，存在配位和插层结构。重金属被捕获后，MoS4-LDH 材料的微晶保留原始的六方棱柱形状，在 pH≈2-10 时稳定。因此，MoS4-LDH 材料有望用于重金属污染水的修复。
