Study On Adsorption Of The Organic Environmental Pollutants And First Category Metal Pollutants By Functionalized Graphene Material

Graphene, a fascinating two dimensional carbon-based material with atomic thickness, has attracted considerable attention all around the world. Because of its unique nanostructure and a variety of fascinating thermal and mechanical properties. The functionalized graphene can not only retain the original two dimensional planar structure of graphene to provide large surface area, but also can be designed as adsorbent with special properties for target pollutants. In this paper, a series of functionalized graphene-based materials were synthesized and further explored their adsorption behavior for organic pollutants and heavy metals in the environment. The main contents and results were as following:1. Removal of organic dyes from water by NH2-GAmino functionalized graphenes (NH2-G) were synthesized. The morphology, physical structure and chemical properties of the NH2-G were characterized by transmission electron microscopy (TEM), fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and N2 adsorption-desorption isotherms respectively. Batch experiments were conducted on the adsorption of metanil yellow and malachite green by the prepared modified graphenes to investigate the effect of several parameters such as pH, dye concentration and adsorption time. The optimal conditions for the adsorption system were as follows:pH of 7,0.4 g·L-1 adsorbent and contact time of 120 min with the maximum adsorption capacity of 71.62 mg·g-1 for metanil yellow; pH of 8,0.4 g·L-1 adsorbent and contact time of 150 min with the maximum adsorption capacity of 91.48 mg·g-1 for malachite green. The adsorption mechanism was investigated by (on the basis of) adsorption isotherms, adsorption kinetic and adsorption thermodynamics. Metanil yellow adsorption by NH2-G was better fitted by both Langmuir isotherm among five different equilibrium models and pseudo-second-order kinetic model. Furthermore, the thermodynamic experiments results illustrated that the adsorption process of metanil yellow onto NH2-G was endothermic and spontaneous in nature; Malachite green adsorption by NH2-G was better fitted by Freundlich isotherm and pseudo-second-order kinetic model. Furthermore, the thermodynamic experiments results illustrated that the adsorption process of malachite green onto NH2-G was endothermic and spontaneous in nature2. Removal of Methylene blue and Hg2+ from water by Fe3O4-xGOIn this study, xanthation of GO cross linked Fe3O4 nanoparticles (Fe3O4-xGO) was synthesized and characterized by FTIR, XRD, BET, SEM, TEM, Zeta potential and magnetic properties analyses. Batch experiments were conducted on the adsorption of methylene blue and Hg2+ by Fe3O4-xGO to investigate the effect of several parameters such as pH, dye concentration and adsorption time. Optimal conditions for the adsorption system were as follows:pH of 5.5,0.28 g·L-1 adsorbent and contact time of 120 min with the maximum adsorption capacity of 521.54 mg·g-1 for methylene blue; pH of 7,0.16 g·L-1 adsorbent and contact time of 180 min with the maximum adsorption capacity of 118.55 mg·g-1 for Hg2+. The adsorption mechanism was investigated by adsorption isotherms, adsorption kinetic and adsorption thermodynamics. Methylene blue adsorption by Fe3O4-xGO was better fitted by both Langmuir isotherm and pseudo-second-order kinetic model. The thermodynamic experiments results illustrated that the adsorption process of methylene blue onto Fe3O4-xGO was endothermic and spontaneous in nature; Hg2+ adsorption by Fe3O4-xGO was better fitted by Langmuir isotherm and pseudo-second-order kinetic model. The thermodynamic experiments results illustrated that the adsorption process of Hg2+ onto Fe3O4-xGO was endothermic and spontaneous in nature.3. Removal of Hg2+ from water by MRCGIn this study, MRCG was synthesized and characterized by SEM and Zeta potential properties analyses. Batch experiments were conducted on the adsorption of Hg2+ by MRCG to investigate the effect of several parameters such as pH, dye concentration and adsorption time. Optimal conditions for the adsorption system were as follows:pH of 6,0.32 g·L-1 adsorbent and contact time of 60 min with the maximum adsorption capacity of 60.95 mg·g-1 for Hg2+. The adsorption mechanism was investigated by adsorption isotherms, adsorption kinetic and adsorption thermodynamics. Hg2+ adsorption by MRCG was better fitted by both Langmuir isotherm and pseudo-second-order kinetic model. The thermodynamic experiments results illustrated that the adsorption process of Hg2+ onto MRCG was endothermic and spontaneous in nature.