| At present, the environmental pollution problem about metalloids and antibiotics in groundwater becomes more and more serious. In the face of such environmental deterioration, the pollutant removal is imminent. Conventional removal ways for these metalloids and antibiotics in water include:biological methods, chemical oxidation and adsorption. Among these methods, adsorption method has great advantages including relatively low cost, simple operation, no producing secondary pollution and easy regeneration, therefore it is widely used. However, adsorbent performance is one of the important indexes to judge the adsorption effect. As a new type of adsorbent, graphene oxide has unique pore structure, large specific surface area, rich oxygen containing functional group and can interact with a variety of pollutants. Moreover, graphene oxide has excellent adsorption performance for inorganic and organic pollutants in the water.According to the chemical and physical properties of graphene oxide (GO), it can be effectively controlled by chemical modified methods, such as solid phase activation and magnetic modification. A series of new type of modified graphene oxide adsorbent were successfully synthetized in the study. The relationship between physicochemical properties and adsorption characteristics of pollutants onto modified GO has been systematicly investigated with qualitative and quantitative analysis with high power transmission electron characterization methods. The adsorption mechanism of the adsorbent for single pollutant or various pollutants coexisting was analyzed from microcosmic point.The research contents and important conclusions of this work are summarized as follows:(1) A kind of magnetic oxide graphene (MGO) with high iron content was prepared with a simple step, and was used to study the adsorption mechanism for metalloid arsenic.The reslts showed that MGO had a fold of graphite layer structure, iron particles evenly distributed on the surface of graphene oxide, and the iron on the surface of MGO with the form of a-Fe2O3and Fe3O4had a content of51%, through microscopy scanning (HRTEM), X-ray diffraction analysis (XRD), Raman spectroscopy (Raman), thermal analysis (TGA and DTA), X-ray photoelectron spectroscopy (XPS), magnetic analysis, and X-ray absorption near edge structure (XANES). In addition, after adsorption, it can be seen the distribution of As (V) closely linked with the distribution of iron from the macroscopic with μ-XAFS map. These data indicated that iron played an important role during the whole adsorption process. (2) Experiment studyed the adsorption performance of As(Ⅲ) and As(Ⅴ).with magnetic graphene oxide.Results showed that the adsorption capacities of MGO for As(Ⅲ) and As(Ⅴ) reached54.18mg/g and26.76mg/g (pH (As (Ⅲ))=8, pH (As (Ⅴ))=5), respectively. The adsorption process accorded with Freundlich adsorption isotherm models and secondary kinetics; The pH, ionic strength and coexisting ions all had a effect on the adsorption performance of MGO. In addition, it found that MGO had the desorption ability so that it had the potential of being reused.(3) The activated oxide grapheme (KOH-GO) was prepared with the activating agent KOH. The adsorption performance for tetracycline with KOH-GO was researched with the activation of graphene oxide (KOH-GO) and no activated graphene oxide GO. The adsorption isothermal model, the adsorption dynamics, the influence of pH, ionic strength, coexistence of anionic and cationic on adsorption performance were studied too.According to the analysis of the solid-liquid ratio, kinetics and isotherm fitting, it can be concluded that the adsorption performance of KOH-GO for tetracycline was higher than that of GO. The adsorption isotherm met the Langmuir model. The adsorption capacity of GO and KOH-GO for tetracycline arrived at a maximum of269.36mg/g and525.64mg/g, respectively. The adsorption process conformed to the second dynamic model, and the pH and ionic strength had a certain influence on the adsorption of tetracycline. The anionic and cationic had an inhibitory effect on the adsorption of KOH-GO when there were anionic and cationic in the water. Moreover, the anionic and cationic could produce a competition between compound pollutants and occupied adsorption holes so as to reduce the adsorption performance of KOH-GO. |
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