Integrating structural and thermodynamic mechanisms for sorption of PCBs by montmorillonite.
Integrating structural and thermodynamic mechanisms for sorption of PCBs by montmorillonite.
复制标题
蒙脱石吸附多氯联苯的结构和热力学机制相结合。
DOI：
10.1021/es505205p
复制
发表时间：
2015-03-03
影响因子：
11.4
通讯作者：
Zhou D
中科院分区：
文献类型：
--
作者：
Liu C;Gu C;Yu K;Li H;Teppen BJ;Johnston CT;Boyd SA;Zhou D
已观察到粘土矿物对平面非离子有机化合物的强吸附作用，用于重要类别的有机污染物，包括多环芳烃（PAH）、多氯联苯（PCB）和二恶英，并且假设这种亲和力与蒙脱石粘土的层间疏水性有关。实验结果表明，在Na-，K-，Cs-蒙脱石上，共面3，3 ′，5-三氯联苯（PCB 36）的吸附系数（Kw）明显高于同离子型蒙脱石;共平面PCB 36的Na-、K-和Cs-蒙脱石的log Kw分别为3.69、3.72和4.53，而非平面2，2 ′，6-三氯联苯（PCB 19）的log Kw分别为1.21、1.46和0.87。利用X射线衍射确定的粘土层间距（d-间距）进行MD模拟。层间阳离子、水和PCB的轨迹、密度分布和径向分布函数共同表明，层间区域的疏水性由可交换阳离子的水合状态和相关的d-间距决定。采用自适应偏置力（ABF）方法计算了共面和非共面PCB分子的吸附自由能，并采用扩展的层间水两相模型（由粘土水合物和“本体水”组成）计算了共面和非共面PCB分子的吸附自由能，计算结果与由测得的log Kw计算的Gibbs自由能一致，表明共面PCB分子的吸附增强归因于形状选择性和疏水相互作用。
Strong sorption of planar nonionic organic chemicals by clay minerals has been observed for important classes of organic contaminants including polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and dioxins, and such affinity was hypothesized to relate to the interlayer hydrophobicity of smectite clays. In batch sorption experiments of two trichlorobiphenyls on homoionic Na-, K-, Cs-montmorillonites, considerably greater sorption coefficient (Kw) was observed for coplanar 3,3′,5-trichlorobiphenyl (PCB 36); log Kw for Na-, K-, and Cs-montmorillonite were 3.69, 3.72, and 4.53 for coplanar PCB 36 vs 1.21, 1.46, and 0.87 for the nonplanar 2,2′,6-trichlorobiphenyl (PCB 19). MD simulations were conducted utilizing X-ray diffraction determined clay interlayer distances (d-spacing). The trajectory, density distribution, and radial distribution function of interlayer cation, water, and PCBs collectively indicated that the hydrophobic nature of the interlayer regions was determined by the hydration status of exchangeable cations and the associated d-spacing. The sorption free energies calculated for both coplanar and nonplanar PCB molecules by adaptive biasing force (ABF) method with an extended interlayer–micropore two-phase model consisting of cleaved clay hydrates and “bulk water” are consistent with the Gibbs free energies derived from the measured log Kw, manifesting enhanced sorption of coplanar PCBs was attributed to shape selectivity and hydrophobic interactions.
登录
查看更多内容
影响因子：
2.2
作者：
JAYNES, WF;BOYD, SA
通讯作者：
BOYD, SA
影响因子：
11.4
作者：
Beless, Bradley;Rifai, Hanadi S.;Rodrigues, Debora F.
通讯作者：
Rodrigues, Debora F.
影响因子：
11.4
作者：
Johnston, CT;Sheng, G;De Oliveira, MF
通讯作者：
De Oliveira, MF
影响因子：
11.4
作者：
Li, H;Teppen, BJ;Boyd, SA
通讯作者：
Boyd, SA
影响因子：
9.8
作者：
Breivik, K;Sweetman, A;Jones, KC
通讯作者：
Jones, KC