Estudo da deposição de TiO2 sobre crisotila brasileira
AUTOR(ES)
Carolina Vautier Teixeira Giongo
DATA DE PUBLICAÇÃO
1995
RESUMO
The deposition of dispersed particles of TiO2 on brazilian chrysotile fibers was studied as a fuction of the amount of particles and fibers present in the system, time of contact between the materials, temperature and ionic strenght. The amount of TiO2 deposited on chrysotile is independent of the chrysotile amount, and a quantitative relationship is observed in the range from 0 to 2.5 g of oxide per g of fibers. The addition of an inert electrolyte increased the amount of TiO2 deposited on the chrysotile, showing the eletrostatic nature of the interaction between these materiaIs. However, the detachment of only 14% of the oxide from samples of TiO2/chrysotile sonicated in the presence of sodium dodecylbenzene sulphonate (DBS), suggests that the interaction between TiO2 and chrysotile is not purely eletrostatic. The deposition process is fast and quite reproducible, showing no dependence on oxide origin nor on oxide surface pretreatment. After 20 min of contact between the particles and the fibers, a steady-state is reached. The temperature does not affect significatively the amount of TiO2 deposited on chrysotile. The deposition isotherms obtained are similar to the high affinity Langmuir isotherms, and were linearized according to they classical model, in order to obtain thermodynamic parameters. The optical gap of TiO2 is unaffected by the deposition. Titanium dioxide supported on chrysotile showed catalytic activity in photodegradation reactions of DBS, induced by sunlight. The efficiency of the supported catalyst is promising in applications as, for instance, the purification of efluents contaminated by surfactants.
ASSUNTO(S)
crisotila - brasil reações quimicas
