Abstract
Since large amounts of pineapple leaves are abandoned after harvest in agricultural areas, the possibility of developing value-added products from them is of interest. In this work, cellulose fiber was extracted from pineapple leaves and modified with ethylenediaminetetraacetic acid (EDTA) and carboxymethyl (CM) groups to produce Cell-EDTA and Cell-CM, respectively, which were then used as heavy metal ion adsorbents. A solution of either lead ion (Pb(2+)) or cadmium ion (Cd(2+)) was used as wastewater for the purpose of studying adsorption efficiencies. The adsorption efficiencies of Cell-EDTA and Cell-CM were significantly higher than those of the unmodified cellulose in the pH range 1-7. Maximum adsorptions toward Pb(2+) and Cd(2+) were, for Cell-EDTA, 41.2 and 33.2 mg g(-1), respectively, and, for Cell-CM, 63.4 and 23.0 mg g(-1), respectively. The adsorption behaviors of Cell-CM for Pb(2+) and Cd(2+) fitted well with a pseudo-first-order model, but those of Cell-EDTA for Pb(2+) and Cd(2+) fitted well with a pseudo-second-order model. All of the adsorption behaviors could be described using the Langmuir adsorption isotherm. Desorption studies of Pb(2+) and Cd(2+) on both adsorbents using 1 M HCl suggested that regenerability of Cell-EDTA was, for both adsorbates, better than that of Cell-CM. Moreover, adsorption measurements in a mixture of Pb(2+) and Cd(2+) at various ratios showed that for both adsorbents the adsorption of Pb(2+) was higher than that of Cd(2+), while the adsorption selectivity for Pb(2+) of Cell-CM was greater than that of Cell-EDTA. This study showed that the modified cellulosic adsorbents made from pineapple leaves were able to efficiently adsorb metal ions.