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Prof. Dr. Salah Eldin EIMofty Prof. of Mining & Environmental Engineering, Faculty of Engineering, Cairo University, Egypt October/2011 4 th Kuwait Waste Management Conference 2011 USE OF ELECTROPHORESIS TECHNIQUE TO STUDY REMOVAL OF TOXIC METAL IONS FROM WASTE WATER BY ADSORPTION ON MINERAL SURFACE
Double-layer showing the surface of clays particles (left side), and the distribution of the adsorbed cations and anions within the double layer (right side) .
On the other hand, the second-order equation was used to predict the behavior over the whole range of adsorption. The second-order rate equation is described by:
(4)
Where K2 is the rate constant of pseudo-second-order sorption (g/mg min). Integrating eqn (4) at the boundary conditions t =0 and qt =0 to t = t and q e = qt eq. (4) becomes:
(5)
The constants q e and k 2 can be determined using Excel Solver. The values of constants q e and k 2 for second-order sorption.
Kinetic Models Constants For Heavy Metals Adsorption On Clay
Heavy metals Model constants Model type Ni Co Cd Pb 0.006 18.196 0.006 18.196 0.01 18.196 0.02 18.196 q e k 1 First order 0.008 200 0.008 200 0.0124 200 0.0228 200 q e k 2 Second order
Electrophoresis measurements (Zeta potential) of these studies indicated the adsorption of the hydrolysable metal toxic ions on the Clay surfaces.
The sorption study indicated that the heavy and toxic metals Pb (II), Ni (II), Co (VI) and Cd (II) could be adsorbed and thus removed significantly by Clay from aqueous solutions.
The batch adsorption tests showed that the removal of metal ion by Clay is a fast process which can reach the equilibrium after 30 seconds.
The adsorption increases with increasing the initial ions concentration and pH. Kinetic modeling showed that the first-order model was appropriate for the description of this type of adsorption.
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