Fan Gongduan, Hong Liang, Zheng Xiaomei, Zhou Jinjin, Zhan Jiajun, Chen Zhong, Liu Siyuan
College of Civil Engineering, Fuzhou University 350116 Fujian China
Department of Chemical & Environmental Engineering, University of Arizona 1133 E James E Rogers Way, Harshbarger 108 Tucson AZ 85721-0011 USA.
RSC Adv. 2018 Oct 15;8(61):35314-35326. doi: 10.1039/c8ra05608k. eCollection 2018 Oct 10.
Metal-organic frameworks (MOFs), as a new type of nanomaterial, have been rapidly developed and widely applied in the environmental area. However, the algae removal efficiency of MOFs, the effect of metal ions and organic ligands contained in MOFs and the stability of MOFs in water need further study. Based on the characteristics of algae, five types of MOFs, which were Cu-MOF-74, Zn-MOF-74, ZIF-8, Ag/AgCl@ZIF-8 and MIL-125(Ti) were synthesized and characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS). The effect of MOFs on the growth of was comparatively studied, and the inhibition mechanism of MOFs on algae as well as the stability of MOFs was explored. Results showed that all of the as-synthetic MOFs had superior stability in water, and the order of stability of MOFs followed the order MIL-125(Ti) > Cu-MOF-74 > Ag/AgCl@ZIF-8 > ZIF-8 > Zn-MOF-74. The types of metal ions and organic ligands doped in MOFs have grade affected the inhibitory efficiency on the algae: containing Cu and Ag ions, MOFs had more significant inhibitory capacity to algae than those containing Zn ions; meanwhile, compared with MOFs which are assembled with 2,5-dihydroxyterephthalic acid (DHTA) organic ligands, MOFs containing 2-methylimidazole (GC) organic contributed to the removal of algae significantly. The order of inhibitory effects of algae by five MOFs follows the order Cu-MOF-74 > Ag/AgCl@ZIF-8 > ZIF-8 > Zn-MOF-74 > MIL-125(Ti). The physiological characteristics of algal cells were changed after being treated with different concentrations of Cu-MOF-74. Once the concentration of Cu-MOF-74 reached 1 mg L, the algal cells began to be inhibited, the relative inhibition rate of algal cells at 120 h was over 400%, and the inhibition process fitted pseudo-second-order kinetic model well. The Cu released by Cu-MOF-74 that the concentration higher than 1 mg L would lead to the destruction of algae cell morphology and the loss of cell integrity, causing cell contents to be partially released into the water, promoting the accumulation and precipitation of algal cells which were destabilizing already to achieve the purpose of inhibition of algae. In summary, MOFs can be used to inhibit the growth of cyanobacteria and have a promising application prospect.
金属有机框架材料（MOFs）作为一种新型纳米材料，已得到快速发展并在环境领域广泛应用。然而，MOFs对藻类的去除效率、MOFs所含金属离子和有机配体的影响以及MOFs在水中的稳定性仍需进一步研究。基于藻类的特性，合成了Cu-MOF-74、Zn-MOF-74、ZIF-8、Ag/AgCl@ZIF-8和MIL-125(Ti)五种类型的MOFs，并通过X射线衍射仪（XRD）、场发射扫描电子显微镜（FESEM）和X射线光电子能谱（XPS）对其进行了表征。比较研究了MOFs对藻类生长的影响，探讨了MOFs对藻类的抑制机制以及MOFs的稳定性。结果表明，所有合成的MOFs在水中均具有优异的稳定性，MOFs的稳定性顺序为MIL-125(Ti)＞Cu-MOF-74＞Ag/AgCl@ZIF-8＞ZIF-8＞Zn-MOF-74。MOFs中掺杂的金属离子和有机配体类型对藻类的抑制效率有分级影响：含有Cu和Ag离子的MOFs对藻类的抑制能力比含有Zn离子的MOFs更强；同时，与由2,5-二羟基对苯二甲酸（DHTA）有机配体组装而成的MOFs相比，含有2-甲基咪唑（GC）有机配体的MOFs对藻类的去除效果显著。五种MOFs对藻类的抑制效果顺序为Cu-MOF-74＞Ag/AgCl@ZIF-8＞ZIF-8＞Zn-MOF-74＞MIL-125(Ti)。用不同浓度的Cu-MOF-74处理后，藻类细胞的生理特性发生了变化。当Cu-MOF-74浓度达到1mg/L时，藻类细胞开始受到抑制，120h时藻类细胞的相对抑制率超过400%，抑制过程很好地符合准二级动力学模型。Cu-MOF-74释放出的浓度高于1mg/L的Cu会导致藻类细胞形态破坏和细胞完整性丧失，使细胞内容物部分释放到水中，促进本已不稳定的藻类细胞的聚集和沉淀，从而达到抑制藻类的目的。综上所述，MOFs可用于抑制蓝藻生长，具有广阔的应用前景。
