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The Research on the Adsorptive Capability and Adsorption Isotherm of Modified Talcum Powder to Methylene Blue

The preparation conditions of modified talcum powder were investigated by discuss the effects of nitric acid mass concentration, nitric acid soak temperature, roasting temperature and roasting time on adsorption properties of methylene blue by talcum powder. Methylene blue dye, as target pollutant, exhibits difficult biochemical degradable characters. The adsorption isotherm of adsorption process was discussed by using the Langmuir isotherm model and Freundlich isotherms model. The results show that the rate of adsorption of methylene blue decreased with the increasing of roasting temperatures and nitric acid soak temperature of modificated talcum powder. The adsorption value of methylene blue of the modified talcum powder increased gradually，then decreased with the increase of roasting time. Compare with the unmodified talcum powder，the adsorption value of methylene blue of the modified talcum powder decreased when roasting temperature and roasting time is too high. With the nitric acid mass concentration increasing, the adsorption of methylene blue on the modified talcum powder increased. It is found that the adsorptive ability of modified talcum powder by HNO3 is higher than original talcum powder. The best talcum powder modified preparation condition is that nitric acid mass concentration 50%, the nitric acid soaks temperature 40°C, calcined temperature 200°C for 120 mins. The removal rate of methylene blue is 84.6% under these preparation conditions. The experimental date fitted very well with the Langmuir isotherms model.