State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, China E-mail:
College of Energy and Environment, Shenyang Aerospace University, Shenyang 110136, China.
Water Sci Technol. 2022 Nov;86(9):2336-2347. doi: 10.2166/wst.2022.337.
The inherent periodic structure of montmorillonite limits the adsorption capacity of its endogenous active units such as Si-O tetrahedron and Al-O octahedron for pollutants. The high-intensity ultrasound method was used to release these active units and the layer-by-layer assembly was adopted to prepare carbon@chitosan@montmorillointe microsphere adsorbent (C@CS@Mt) to give full play to the adsorption capacity of montmorillonite. The montmorillonite nanosheet exhibited good hole-making ability, resulting in high surface area, pore volume and pore diameter of microspheres. Benefitting from the release of active sites in Si-O tetrahedron and Al-O octahedron of montmorillonite nanosheets, the adsorption capacity of C@CS@Mt was significantly improved. The maximum adsorption capacities of Pb and methylene blue (MB) reached 884.19 mg·g and 326.21 mg·g, respectively. The simultaneous adsorption experiments indicated that the occupation of active sites by Pb caused the observed decrease of MB adsorption capacity. The theoretical calculations indicated that Pb was preferentially adsorbed by active adsorption units due to strong electron donating ability in comparison to MB. As an active unit, Si-O tetrahedron exhibited stronger adsorption capacity for cationic dyes than Al-O octahedron due to both the large electronegativity and lower adsorption binding energy.
蒙脱土的固有周期性结构限制了其内生活性单元（如 Si-O 四面体和 Al-O 八面体）对污染物的吸附能力。高强度超声法被用于释放这些活性单元，并采用层层组装的方法制备了碳@壳聚糖@蒙脱土微球吸附剂（C@CS@Mt），以充分发挥蒙脱土的吸附能力。蒙脱土纳米片具有良好的造孔能力，使得微球具有高的比表面积、孔体积和孔径。受益于蒙脱土纳米片的 Si-O 四面体和 Al-O 八面体中活性位点的释放，C@CS@Mt 的吸附容量显著提高。Pb 和亚甲基蓝（MB）的最大吸附容量分别达到 884.19 mg·g 和 326.21 mg·g。同时吸附实验表明，Pb 占据活性位点导致观察到的 MB 吸附容量下降。理论计算表明，与 MB 相比，由于较强的电子供体能力，Pb 优先被活性吸附单元吸附。作为一个活性单元，Si-O 四面体由于较大的电负性和较低的吸附结合能，对阳离子染料表现出比 Al-O 八面体更强的吸附能力。
