Chars from Waste Tire Rubber by Catalytic Pyrolysis and the Statistical Analysis of the Adsorption of Fe in Potable Water

摘要

Chars were produced by thermal and catalytic pyrolysis of waste tire rubber and used to remove Fe ions from potable water. In the catalytic process a small amount of super-acid catalyst was mixed with tire rubber to obtain better chars for adsorption of heavy metals. Average yields of chars obtained in the thermal and catalytic processes (with 10 wt% of catalyst) were: 46.6 and 33-9 wt%, respectively. The effects of reaction time, pyrolysis temperature and percentage of catalyst on the textural characteristics, elemental composition and adsorption capacity of the resultant chars were investigated. It was demonstrated that operative variables used did not have a significant improvement on the total surface area. Carbon materials from catalytic process showed a high adsorption capacity for Fe ions in potable water; until 41.9 mg of iron were removed per g of char while a thermal char showed an adsorption capacity of 25.2 mg/g. The amount of metal ions adsorbed by chars is not proportional to the total surface area when they were compared with a commercial carbon, revealing that others factors are involved in the adsorption capacity of chars. In order to relate the Fe3* removal and the independent factors, a statistical procedure that consisted in the application of a standard 3~3 factorial design of experiments and response surface methodology were carried out.