Preparation Of Graphite/Silicon Composite Material And Its Adsorption Properties For Toluene In Water

With the rapid development of industry,the water environment is deteriorating.Toluene is an aromatic organic compound.Although it is slightly soluble in water,even a small amount can cause harm to the human body.Therefore,in order to ensure the safety of the water supply,it is very important to remove these organic pollutants from the water,and the adsorption method is currently the more commonly used method for treating wastewater.Reduced graphene oxide has a large specific surface area and a hydrophobic surface,so it has strong adsorption capacity for aromatic organic compounds,but it is difficult to recover after adsorption.Therefore,this paper chooses to mix graphene oxide with silica sol.After the rapid gelation,and then high temperature reduction,an adsorbent material which is easy to recover and has good adsorption performance is obtained.In this project,we use graphite as the raw material to prepare graphene oxide by the modified Hummers method.By changing the amount of sulfuric acid and potassium permanganate in the experiment,the graphene oxide with good oxidation degree and crystal structure is obtained,and then infrared spectrum is used.The obtained product was characterized by analysis,thermogravimetric analysis and scanning electron microscopy.The experimental results show that when the amount of potassium permanganate is 5g and the concentration of concentrated sulfuric acid is 20mL,graphene oxide with better oxidation degree and better crystallinity can be obtained.In the preparation of graphite/silicon composites,the excessive concentration of the graphite oxide suspension will cause excessive blockage of the pores.If the concentration is too low,the specific surface area is low and the effect is not obvious;during the reduction process,the high temperature reaction time and temperature have on the samples.If the reaction time and temperature are not enough,the reduction is not complete,and some oxygen-containing functional groups will not reach a good adsorption effect.When the reaction time and temperature are too high,the carbon structure in the composite will be Decomposed.Therefore,when the concentration of graphene oxide is 1 mg/mL,the addition ratio is 1:1,and calcination at 500℃ for 3 h can obtain a graphite/silicon composite material having a specific surface area of 196.5 m 2/g and an average pore diameter of about 20 nm.Finally,we obtained the graphite/silicon composites for the adsorption of toluene in aqueous solution,and explored the effects of adsorption time,adsorbent dosage and solution pH on the adsorption performance,and analyzed the adsorption behavior from adsorption kinetics and adsorption isotherms.The results showed that when the reaction time was 180 min and the amount of adsorbent was 0.1g,the adsorption reached equilibrium at pH 7,and the adsorption reaction was suitable for quasi-secondary reaction kinetics with a linear correlation coefficient of 0.994.The adsorption process was more suitable for the Langmuir model and R2 is 0.996.