| Expanded graphite (EG) is a renewable environment rehabilitation material. The graphite intercalation compound with some atomes and radicles is prepared through electrochemical oxidation methods or chemical oxidation methods using natural graphite falakes as raw materials. EG is obtained through the instant expand of the graphite intercalation compound. EG have many special characteristics, such as porous structure, low density and high chemical stability.In this paper, graphite intercalation compound is prepared with H2SO4 as inserting reagent and KMnO4 as oxidizing agent. EG is obtained through the instant expansion of the graphite intercalation compound under 900℃. The composition, structure and properties of the graphite intercalation compound are characterized and analyzed with XRD, EDS. Specific surface area, pore diameter and pore volume of EG are also detected. Adsorption capacities of EG for Polyvinyl Alcohol (PVA) and competitive adsorption for Sodium anthraquinone-1-sulfonate (SAS) and xylenol orange (XO) are investigated.PVA is obtained by alcoholysis of polyvinyl acetate, and its performance is between rubber and plastic. PVA has been widely used in the textile industry because it's good adhesion, film toughness and wear resistance, but it also has the non-environment friendly problems. PVA waste water has the characteristics of high organic pollutant concentration and difficult to be biodegradable (B/C is less than 0.1). After discharging into the water body, PVA will accumulate in water body, so that it makes the water surface foam and viscosity increase, and also affect the activities of aerobic microorganisms. So it can result in serious environmental problems. In the present study, EG is used as an adsorbent, and its adsorption capacity for PVA with different polymerization degrees (DP) of 500, 700, 1750, is studied. We investigate the adsorption kinetic and thermodynamic characteristics of EG for PVAs in aqueous solution.Kinetic studies show that the kinetic data can be delineated by pseudo second-order kinetic model, and internal diffusion may dominate the overall adsorption kinetics. The thermodynamic studies show that the adsorption of PVA on EG is spontaneous and the adsorption isotherm on EG is type I. Adsorption capacities are not only dependent on initial concentration of PVA, adsorption time and ionic strength, but also relate with the polymerization degree of PVA. The adsorption characteristics can be described with Langmuir isotherms equation, and the adsorbed PVA molecules lie flat on the surface of EG.In the research, two compounds of Sodium anthraquinone-1-sulfonate (SAS) and xylenol orange (XO) with obvious difference in molecular weights were selected as organic adsorbates. The adsorption and competitive adsorption characteristics on EG were studies. The results are: EG has adsorption capacity for both SAS and XO. In the adsorption of single component system, the isotherm of SAS on EG is type I; while, isotherm of XO is type II. In the competitive adsorption of dual component system, the existence of the other component SAS or XO would greatly decrease the adsorbance of EG for XO or SAS, which might be caused by the competitive adsorption of SAS and XO for the same adsorbing site on EG. But the existence of competitive adsorbates doesn't affect the adsorption isotherm, it is the same as the one-component system. Adsorption of SAS or XO on EG is spontaneous, and the increase of ionic strength, temperature and expansion volume of adsorbates would cause the increase of SAS or XO adsorbance, but expansion volume does not affect adsorption isotherm type. No matter the adsorption of single component system of SAS or XO, or the competitive adsorption of dual component system of SAS and XO, the adsorption kinetics models can all be well described with pseudo second-order kinetic model. Adsorption rate increases with the increase in temperature. Physical adsorption is the main action between EG with SAS or EG with XO.
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