| Metal materials associated with human closely, and widely used in all walks of the life. With the metal materials process and corrosion caused a lot of heavy metal wastewater. Due to the heavy metal ion can not be biodegradable, it will pass through the food chain gradually bio-accumulation into the plants, animals, and ultimately harm the health of human beings. So how to effectively remove heavy metal ions has become an important subject for human beings. Compared to other heavy metals removal method, adsorption is one of the most promising treatment method because it is simple, cost-effective, and extensively used. In this study, we prepared several kinds of composites as heavy metal ion adsorbent based on graphene. And the adsorption behavior of the composite materials for heavy metal ions in aqueous solution were investigated systematically. The main researchs are listed as follows:(1) Prepared polyethyleneimine-graphene oxide (PEI-GO) composite, and adsorption performance of the composite for Cr(Ⅵ) was investigated systematically. Effects of the ratio of PEI and GO in composites, pH and contact time, initial concentration of Cr(Ⅵ) and the temperature of solution were examined in batch experiments. The morphology of GO and PEI-GO was characterized by scanning electron microscopy(SEM), fourier-transform infrared(FT-IR) spectroscopy, and X-ray photoelectronic spectroscopy(XPS) methods, and adsorption mechanism of the composites for Cr(Ⅵ) was also studied. The experimental results showed that the PEI-GO composites exhibited an encouraging uptake capacity of 539.53 mg·g-1. It was also found that the composites shows excellent regeneration property, adsorption capacity of the composite could still maintain above 81% of its initial capability after 5 cycles of adsorption-desorption. The results suggest that the prepared composites were a promising adsorbent for removing Cr(Ⅵ) ions from aqueous solution with high efficiency.(2) Graphene oxide nanosheets were cross-linked with poly(allylamine) (PAA) to prepared a novel PAA-GO composite, which was used for removing Cu(Ⅱ) ions from aqueous solutions. The physico-chemical properties of PAA-GO composites were characterized by various characterization methods. The effect of different proportion of PAA and GO in PAA-GO on the adsorption performance of PAA-GO for Cu(Ⅱ) was also investigated. The adsorption isotherm, kinetics, and thermodynamics have also been studied. The results demonstrated that the adsorption capacities of PAA-GO for Cu(II) was more than three times of the pristine GO; The Langmuir adsorption isotherm was applicable fit adsorption process; Adsorption kinetic process could be described by the pseudo-second-order model, thermodynamic parameters of ΔGo, AHo and ΔS0 suggested that adsorptions were endothermic and spontaneous processes. Adsorption-desorption results showed that the reusability of PAA-GO composite was encouraging. After 5 cycles of adsorption-desorption, adsorption capacity still maintain above 87.6% of its initial capability. This shows that PAA-GO composites show highly stability.(3) The nanocomposite of triethylenetetramine-reduction magnetic graphene oxide (TET-MRGO) composites were prepared and characterized by scanning electron microscopy(SEM), fourier-transform infrared(FT-IR) spectroscopy, X-ray photoelectron spectroscopy(XPS), X-ray diffraction(XRD) and magnetization curve. The composites were used for adsorption of Cu(II) from aqueous solution. The effects of the parameters such as pH value, contact time, and initial concentration of Cu(II) on adsorbing ability of TET-MRGO for Cu(II) were examined. The adsorption isotherm, kinetics, and thermodynamics have also been studied. The saturation magnetization of the TET-MRGO is 42.13 emu.g-1, indicating that the TET-MRGO can be fast separation from liquid suspension by an external magnetic field. The Langmuir isotherm model matched the experimental data very well. Adsorption kinetic process could be described by the pseudo-second-order model. Cu(II) adsorption capacity of the prepared TET-MRGO still remained up 75% of its initial capability after 5 times usage, indicating a promising property of the prepared TET-MRGO. |
