Adsorption Behavior of Cd2+ and Zn2+ onto Natural Egyptian Bentonitic Clay

In the present work, an Egyptian bentonitic clay sample has been structurally characterized using different techniques such as XRD, IR, SEM, and EDX analyses then evaluated as a sorbent for heavy metal ions removal. The characterization results showed that the clay sample is in the bentonite form with montmorillonite and kaolinite as mixed-clay minerals. The specific surface area (SSA) and cation exchange capacity (CEC) were determined using methylene blue test and they were found to be 367 m(2)/g and of 85 meq/100 g, respectively. The applicability of this clay sample for Cd (II) and Zn (II) removal from aqueous media was tested using batch procedures. Experimental parameters affecting the removal process were analyzed to get optimum conditions for the process. The experimental kinetic data were fitted very well to pseudo-second order with very high correlation coefficients. The Freundlich model appeared to correlate the adsorption data much better than Langmuir model with maximum adsorption capacities of 8.2 and 9.45 mg/g for Cd2+ and Zn2+, respectively. Successful application of the studied adsorbent for the removal of Cd2+ and Zn2+ ions from natural water samples greatly supports its potential for practical application.