Huang Renyao, He Li, Zhang Tao, Li Dianqing, Tang Pinggui, Zhao Yingying, Feng Yongjun
State Key Laboratory of Chemical Resource Engineering, Beijing Engineering Center for Hierarchical Catalysts, Beijing University of Chemical Technology, Beijing 100029, China.
Beijing Center for Physical & Chemical Analysis, Beijing 100089, China.
Nanomaterials (Basel). 2018 Apr 24;8(5):271. doi: 10.3390/nano8050271.
Magnesium silicate as a high-performance adsorption material has attracted increasing attention for the removal of organic dye pollution. Here, we prepared a series of magnesium silicate hydrates (MSH) in a hydrothermal route, and carefully investigated the corresponding adsorption behavior towards methylene blue (MB) as well as the effect of surface charge on adsorption capacity. The results show that surface charge plays a key role in the adsorption performance of MSH for MB, a negative surface charge density follows the increase of Si/Mg feeding ratio from 1.00 to 1.75, and furthermore the higher negative charge favors the improvement of the adsorption capacity. Among four investigated samples (MSH = 1.00, 1.25, 1.50, and 1.75), MSH-1.75 has the highest negative surface charge and shows the largest adsorption capacity for MB. For example, the equilibrium adsorption quantity is 307 mg·g for MSH-1.75, which is 35% higher than that of 227 mg·g for MSH-1.00. Besides, for MSH-1.75, the as-prepared sample with negative charge exhibits ca. 36% higher adsorption quantity compared to the sample at the zero point of charge (pH). Furthermore, magnesium silicate hydrate material with Si/Mg feeding ratio = 1.75 demonstrates the promising removal efficiency of beyond 98% for methylene blue in 10 min, and the maximum adsorption capacity of 374 mg·g calculated from the Langmuir isotherm model.
硅酸镁作为一种高性能吸附材料，在去除有机染料污染方面受到了越来越多的关注。在此，我们通过水热法制备了一系列水合硅酸镁（MSH），并仔细研究了其对亚甲基蓝（MB）的相应吸附行为以及表面电荷对吸附容量的影响。结果表明，表面电荷在MSH对MB的吸附性能中起关键作用，随着Si/Mg投料比从1.00增加到1.75，表面负电荷密度随之增加，而且更高的负电荷有利于吸附容量的提高。在所研究的四个样品（MSH = 1.00、1.25、1.50和1.75）中，MSH-1.75具有最高的表面负电荷，对MB的吸附容量也最大。例如，MSH-1.75的平衡吸附量为307 mg·g，比MSH-1.00的227 mg·g高35%。此外，对于MSH-1.75，与零电荷点（pH）的样品相比，带负电荷的制备样品的吸附量高出约36%。此外，Si/Mg投料比为1.75的水合硅酸镁材料在10分钟内对亚甲基蓝的去除效率有望超过98%，根据朗缪尔等温线模型计算的最大吸附容量为374 mg·g。
