Adsorption - Desorption Behaviour Of Nickel (II) On Natural Clays Alone and In a Blend.

In understanding the adsorption tendency of nickel (II) on natural clays, the present study aimed at investigating the optimum conditions like pH, contact time, adsorbent dosage and initial concentration for adsorption of nickel (II) as these operating conditions greatly influence the adsorption process. Batch experimental study was performed to understand the adsorption-desorption tendency with the synthetic solution of nickel (II) on the commercially available clays namely bentonite and kaolinite alone and an admix of these clays at various proportions of 80% bentonite (B) + 20% kaolinite (K), 60% B + 40% K, 40% B + 60% K, 20% B + 80% K and 100%. The results revealed that the percentage adsorption of nickel (II) was significant at pH 8 on bentonite clay, where as for kaolinite clay it was pH 6. On both the clays under the optimum conditions the percent of adsorption of nickel (II) was found to have decreased with increase in initial concentration from 5 mg/L to 100 mg/L. The Freundlich and Langmuir isotherms were plotted which has given a best linear fit for the batch experimental data. Further investigation was carried out to identify the percentage desorption of nickel (II) using several extractants on the exhausted adsorbents stored and dried after the batch experimental studies.