Preparation And Application Of Expanded Graphite Loaded With Titania

Expanded graphite (EG) is a kind of recycling entironment material. The graphite intercalation compound named expandable graphite can be prepared through electrochemical methods or chemical methods with natural graphite as raw materials. EG is obtained through the instant expanse of expandable graphite. EG have many special characteristics, such as porous structure, low density and high chemical stability.TiO₂ is a photo-catalyst with good chemical thermal stability, low cost, non-toxic characteristics. In order to recycle this catalyst after reaction, TiO₂ is often loaded with some kinds of carriers. EG loaded with titania is a kind of adsorbent with porous structure, it couples sorption of EG and photo-catalysis of TiO₂. EG loaded with titania will play an important role in dealing with organic pollutants.In this paper, EG loaded with titania was prepared with 50 mesh natural graphite as raw materials, potassium permanganate as oxidant, vitriol and tetranbutyl titanate as intercalation compound. The expanded volume of EG loaded with titania is 320 mL/g. The composition and structure characteristics of the graphite intercalation compound were characterized and analyzed with XRD, EDS. Specific surface area, pore diameter and pore volume of EG loaded with titania were also detected.The esterification of acetic acid with isoamyl alcohol catalyzed by expandable graphite loaded with TiO₂ was studied. We got the suitable conditions of the esterification as follows: molar ratio of isoamyl alcohol to acetic acid equals to 1.5:1.0, mass of catalyst equals to 7.5% of the total reactants amount, reaction time 2.5h and temperature is kept at the boiling point. Under the optimum condition, an esterification rate of 87.9% can be achieved.We investigated the decoloration thermodynamic characteristics of expanded graphite loaded with titania for dyes of Acid brilliant red-3B, Auramine lake yellow-O and Basic fuchsine with different structures. Influence of dye concentration, pH and ion strength on the decoloration rate was investigated. Research has provided that dye concentration has no obvious influence on decoloration time, but it can decrease the total decoloration rate. Ion strength plays an important role in decoloration, higher ion strength or the presence of salts can improve the treatment of dye. pH not only affects dye absorbency, but also affects decoloration of EG loaded with titania for dye. EG loaded with titania possess a higher decoloration rate for dyes than the sorption of EG or photo-degradation of titania. Further more, sorption of EG for dyes is stronger than photo-degradation of titania.The decoloration kinetic characteristics of Basic flavine-O on this adsorbent can be well described by the pseudo second-order kinetic model. Decoloration of Basic flavine-O on EG loaded with titania holds small activation energy, and physical adsorption plays main role in the total decoloration process.