Study On Adsorption Of Pb(Ⅱ),Cd(Ⅱ),Hg(Ⅱ) By Synthetic Tobermorite

Tobermorite is a mineral material with good ion exchange properties.based on the research work of our group, its adsorption properties was studied.The factors of adsorption were studied such as pH values ,the reaction time, initial concentration, the temperature. The adsorption equation was curvefitting,by the Langmuir and Freundlich adsorption isotherm and the rmodynamics adsorption was analyzed.By the orthorhombic experiment of the adsorption, wen can get the optimize condition of the adsorption: (1) For Pb²⁺, the reaction temperature is 40℃, the reaction time is 20 min, the initial concentration of 20 mg ? L-1 , pH value of 6.0 ;(2) For Cd²⁺, the reaction temperature is 40℃, the reaction time is 20 min, the initial concentration of 20 mg ? L-1, pH value of 6.0; (3) For Hg²⁺, the reaction temperature is 35℃, the reaction time is 40 min, the initial concentration of 20 mg ? L-1, pH value of 6.2 .In different temperatures, Langmuir-adsorption isotherm this three ions are better fitted through the tobermorite adsorption Pb²⁺, Cd²⁺, Hg²⁺ thermodynamic parameters of the three-fitting can be drawn.Theâ–³G are negative, with increasing temperatureâ–³H increased, so the adsorption process is a spontaneous reaction to the heat.The second order kinetics, the diffusion equation, the Elovich equation can be a better fit on the tobermorite adsorption Pb²⁺,Cd²⁺ process. The first order kinetics, the second order kinetics, the diffusion equation, Elovich equation can be a better description to the adsorption of Cd²⁺.