Preparation And Properties Of Adsorption Photocatalytic Composites Based On Carbon Materials

After entering21th century, environmental issues became one of the important factors endangering human life and health with the continuous development of China’s industrialization. Water and air are closely related to human’s survival, so how to govern water and air pollution is one of the important researchs for the majority of research workers. As a novel and green method, photocatalysis gets more and more people’s attention and promotion. Titanium dioxide as an excellent photocatalyst is most widely studied; small particle size titania with high surface area and more active sites does better in the target pollutant removal under photoinduced condition; but which also presents the long light-induced degradation time, separation and recovery difficulties, secondary particle pollution. Combination of photocatalyst and adsorbent support can effectively solve the above problems. As a traditional adsorbent, carbon material with low price, strong adsorption properties, wide market applications is worth studying. On the basis of previous studies, we select mesoporous carbon nanaospheres with moderate size, regular morphology and large specific surface area as a target carrier, using microwave radiation to form titania shell on the surface of which, and then study the structure and adsorption-photocatalytic properties. Here, our paper carried out a three-part work which includes:(1) The Preparation of MCN@TiO2composite materials for the removal of phenol and other pollutants in the waterUsing the strong oxidizing ability of concentrated nitric acid to generate oxygen-containing groups on the surface of MCN. The fuctionalized MCN(F-MCN) and TiCl4were dispersed well in the desired amount of tert-butanol. Under a given time and temperature, microwave irradition was proceeding to form MCN@TiO2core-shell materials. FESEM, TEM and XRD were performed to characterize chemical groups, mass ratios, morphologies and internal composition. Then we test the adsorption and photocatalytic ability of the synthesized materials under254nm UV lights. The results indicated that MCN@TiO2calcined at700℃with the mass fraction of TiO260%showed the optimal removal effect. For the removing of other pollutants such as dyes and heavy metal ion, MCN@TiO2showed different adsorption and phtocatalytic results.(2) The preparation of yolk-shell MCN/TiO2and hollow TiO2composites for selective adsorption of phenols and dyesOn the basis of the synthesized MCN@TiO2in the first part, we continued the secondary calcination of which in the air atomosphere. Under different given calcination temperature and time, the internal MCN retained different ratios, forming yolk-shell like MCN/TiO2composites. Under365nm UV light, the adsorption and photocatalytic capacity were tested for different substrates. The results showed that after calcination in air, the composites showed selective adsorption of phenols and dyes. By further extension of the calcination time, the internal carbonaceous compositions were completely removed, forming hollow TiO2with different shell thickness. Since black carbon shield msot of the lights, the photocatalytic ability of MCN@TiO2was rather weak. So there is no doubt that the yolk-shell MCN/TiO2with less carbon and hollow TiO2with little carbon showed better capacity of photocatalytic degradation. The testing results showed that under moderate thickness of the shell, hollow TiO2owned the best photocatalytic activity. Also FESEM, TEM, XRD, BET etc, were used to chracterize the structure of these materials.(3) The preparation of MCN with highly selective ability and the research on itHydrophobicity is an important factor to affect the selective adsorption of organics in the water about selective materials. The preparation of materials with highly selective adsorption of organics is significant. Carbonaceous material is widely used hydrophobic one, commercial activated carbon shows excellently selective adsorption of organics. We used inorganic salts and some organic solvents as precursors, with high temperature reacting in the autoclave to prepare MCN. Our materials own mesoporous channels and large pore volume, which show better selective adsorption of toluene than activated carbon.