Heavy Metals Adsorption from Aqueous Solutions onto Unmodified and Modified Jordanian Kaolinite Clay: Batch and Column Techniques

Awareness of, and concern about, water pollution all over the world has been increasing. In Jordan, water also has been polluted by different kinds of pollutants such as heavy metals, It is widely agreed that a properly developed green, low – cost and more efficient adsorbent is desired approach towards removing pollutants. Jordan has huge reserves of kaolinite. Unfortunately, it has a relative low cation–exchange capacity and a small surface area. However, it can be modified to enhance its adsorption capacity towards heavy metal ions. Humic acid was used to this purpose. Two types of humic acid were used; one was commercial from Fluka Company and the other was natural extracted from King Talal Dam sediments. Comparison of Pb (II), Cd (II) and Zn (II) adsorption from aqueous solutions onto unmodified and modified Jordanian kaolinite clay were studied using batch technique at different temperatures (25, 35 and 45°C) and different pH (4, 5 and 6). The effects of contact time, adsorbent dose, and the initial metal ion concentration were also studied. The uptake at low concentration reaches above 90% for Pb (II). The adsorbed amount trend was as follows: Pb (II) > Cd (II) > Zn (II) for both modified kaolinite clay. The column technique was used effectively for the determination of metal ion loading capacity. The uptake percentage fall in the same order (Pb (II) > Cd (II) > Zn (II)) for both modified kaolinite clay