Removal and recovery of Ni and Zn from aqueous solution using activated carbon from Hevea brasiliensis: batch and column studies.

In the present study, the adsorption behavior of Ni and Zn from aqueous systems onto activated carbon prepared from Hevea brasiliensis sawdust has been attempted via batch and column mode studies under various operating conditions. The experimental data were fitted to various isotherm models. The maximum adsorption capacity of Ni and Zn were found to be 17.21 and 22.03 mg g(-1), respectively, at 30 degrees C according to Langmuir model. Kinetic studies showed the adsorption process followed pseudo second-order rate model. Breakthrough curves were plotted for the adsorption of metal ions using continuous-flow column operation by varying the bed height, flow rate, initial metal ion concentration and temperature. At the end, an attempt has also been made to model the data generated from column studies using the empirical relationship based on Adam-Boharts model and Thomas model. The model constants were also evaluated. This has helped in ascertaining the practical applicability of the adsorbent. The column regeneration studies were carried out for three adsorption-desorption cycles. The elutant used for the regeneration of the adsorbent was 0.1 M H2SO4. On the basis of the results, ACHB can be economically and effectively used as an adsorbent for the removal of metal ions from wastewaters.