Study On The Adsorbing Characteristics Of Expanded Graphite For Oil And Phenyl Organic Molecules

Expanded graphite (EG) is a well known material usually produced from various intercalation compounds submitted to a thermal expansion. Expanded graphite has many special characteristics, such as porous structure, low density and so on.In the experiment, EG is prepared with H2SO4 as intercalation reagent and KMnO4 as oxidant, respectively. The X-ray diffraction analysis and energy dispersive spectroscopy (EDS) of crude graphite and graphite intercalation compounds (GICs) approves the existence of intercalation. Specific surface area, pore diameter and pore volume of EG are also detected.Organic compound is one kind of contaminants in wastewater. The adsorption thermodynamic characteristics of organic compounds on EG are discussed. These reference compounds are Phenol, Benzoic acid, Benzenesulfonic acid, P-Methylbenzene sulfonic acid. Influences of organic compound concentration, pH, temperature, ionic strength on adsorption capacities are studied in the sorption thermodynamics. Langmuir constants are calculated.There is an evident difference between the adsorption capacities for phenyl organic molecules and oils. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of phenyl organic molecules and oil on EG are firstly detected. And then stepwise adsorption for oils is carried out with EG which has been saturated firstly by phenyl organic molecules, the difference between adsorbance of oil on EG is checked with deviation analysis. Scanning electronic microscopy (SEM) analysis is used to show structure difference of EG adsorbed different adsorbates.In the present work, we investigate the adsorption capacities of EG for oils and EG' regenerative method. The influence of oils viscosity and expanded volume of EG on adsorption capacity is investigated. Two regeneration methods of vacuum filtration and combustion for EG saturated by oil are discussed. Experimental results represente a linear relationship between adsorption capacity of oil and expanded volume of EG, between oil viscosity coefficients and adsorption capacity, also. Oil removing efficiencies of vacuum filtration and combustion method are 68.6% and 98%, respectively. Regenerative efficiencies and the four-time cumulative regenerative efficiencies of vacuum filtration and combustion method are about 57.1% and 58.5%,47.3% and 50.5%, respectively. Adorption capacity of oil on EG is mainly influenced by structure of the worm-like particles. The method of vacuum filtration could be used in the recovery of oil and regeneration of EG.