Research On The Preparation Of Sulfur-free Exfoliated Graphite And Adsorption Capacity For Oil

In this research,sulfur-free exfoliated graphite with a quite high expansion volume was prepared by chemical method.Orthogonal design method was adopted to screen the optimal condition.Meanwhile,samples prepared were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectrometer(EDS),fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis-differential thermal analysis(TG-DTA)and mercury intrusion porosimetry(MIP).The adsorption capacity of oils and hydrocarbons on expanded graphite had been conducted.Natural flake graphite was used as raw material,potassium permanganate as oxidizing agent and perchloric acid as intercalation agent in preparation process.Dipotassium phosphate was acted as the secondary intercalating agent,which resulted in the graphite layers intercalated sufficiently.The experimental results show that the optimum conditions are as follows: C: KMnO4: HClO4(g: g: mL)=1: 0.4: 7,the reaction temperature and time are 40 ℃ and 70 min respectively.After intercalated by K2HPO4,the graphite intercalation compound(GIC1)has a great high expansion volume of 420 m L/g.The natural flake graphite and oxidizing agent were same with the materials mentioned above,while the intercalation agent was replaced by perchloric acid and phosphoric in preparation process.An orthogonal test method was adopted for optimizing preparing parameters.The experimental results show that the optimum conditions are as follows: C: KMnO4: HClO4: H3PO4(g: g: m L: mL)=1: 0.08: 3: 3,the reaction temperature and time are 40 ℃ and 70 minutes respectively.Under this condition,graphite intercalation compound(GIC2)has a relatively high expansion volume of 410 m L/g.Exfoliated graphite(EG1)is capable to sorb large amounts of oils and hydrocarbons,as much as at least 75 g/g within few minutes,which is twice of sulfuric exfoliated graphite’s(EGs).The adsorption capacity of EG1 for oils on the surface of seawater is larger than that on the surface of deionized water and less than that of pure oils.The Langmuir model is benefit for the description of the isotherm adsorption process and low temperature is advantageous to the reaction.Recycled by vacuum,the EG1 containing oil maintained the adsorption capacity,which could clean up oils more than once.Exfoliated graphite which is deprived of adsorption capacity after regeneration several times can be used as sealing materials if added in lubricating grease.When applied in projects,magnetic exfoliated graphite should be prepared or exfoliated graphite can be sewed in non-woven fabrics,which make it easier to recycle.