| In recent years, eutrophication has become a serious threat to various water sources of our country and most of the water has different degrees of phosphorus contamination. Phosphorus is the key nutrition control factor of eutrophication of lakes and other water bodies and how to deal with the phosphorus wastewater is the environmental problems that to be solved. In the meantime, our country has the hardest hit of fluoride pollution and dental fluorosis and other diseases that caused by excessive fluoride have a serious influence on the health of the people. In this paper, the removal of phosphate ions and fluoride ions from water has been studied.Adsorption is one of the most effective methods for contaminant removal from polluted water. But the selectivities of many traditional adsorbents aren’t good and their adsorption capacities are always low. In the context of this, it is definitely critical to develop efficient, green adsorbents for sewage treatment.Metal-organic frameworks(MOFs) are new members of porous nanomaterials with hybrid organic-inorganic supramolecular materials. They have incomparable, great applied potential in the adsorption field in comparison with traditional porous materials because of the unique properties such as high porosity, large surface areas, special metal centers (saturated and unsaturated metal sites) and rich geometry. Herein, the MOFs materials have been successfully used in the field of phosphate removal and fluoride removal. The main contents of the research are as follows:(1) ZIF-8was used as adsorbent to remove phosphate from water. Various experimental parameters such as initial concentration, adsorption time, adsorption temperature, the solution pH value, different kinds of adsorbents on the adsorption properties were studied. And the adsorption isotherm of the adsorption process was also researched. It turned out that when initial phosphateconcentration was15mg/L(as P, the same below), adsorption time was20h, adsorption temperature was25℃, solution pH value was7, the amount of ZIF-8was50mg/L, the equilibrium adsorption capacity of phosphate was86.6mg/g for ZIF-8and the theoretical maximum adsorption capacity of phosphate was88.5mg/g for ZIF-8.(2) NH2-MIL-101(A1) was used as adsorbent to remove fluoride from water. The influence factors such as initial concentration, adsorption time, adsorption temperature, the solution pH value, different kinds of adsorbents on the adsorption behaviors were studied. And the adsorption isotherm of the adsorption process was also researched. The results show that when initial fluoride concentration was7mg/L, adsorption time was120min, adsorption temperature was25℃, solution pH value was7, the amount was0.1g/L, the equilibrium adsorption capacity of fluoride was34.8mg/g for NH2-MIL-101(Al) and the theoretical maximum adsorption capacity of fluoride was34.6mg/g for NH2-MIL-101(Al).(3) This paper also used ZIF-8to remove phosphate in actual wastewater. For the pond water that the initial phosphate concentration was3.54mg/L, the remaining phosphate concentration was0.28mg/L (the removal rate was92%) when the amount of ZIF-8was60mg/L and the reaction time was4h. This result reached water quality of class IV(phosphate concentration is less than0.3mg/L) that《Surface Water Quality Standards))(GB3838-2002) required. For the industrial wastewater that the initial phosphate concentration was1.11mg/L, the remaining phosphate concentration was0.09mg/L(the removal rate was92%) when the amount of ZIF-8was50mg/L and the reaction time was5h. This result remotely reached water quality of first level standard’s A standard(phosphate concentration is less than0.5mg/L) that (Urban Sewage Treatment Plant Pollutants Emission Standards》(GB18918-2002) required. |
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