A Comparative Investigation on Removal and Recovery of Cadmium from Aqueous Solution Using Novel Adsorbents Prepared from Water Hyacinth

This article sheds light on the preparation of novel activated carbon adsorbents from dried water hyacinth (stems, leaves) and their use as efficient adsorbents for removal of cadmium (II) ions from aqueous solutions. The experimental results revealed that, pH values of solution, contact time, adsorbent dosage, ionic strength, and initial concentration considerably affected the adsorption amount of Cd (II). Based upon the experimental results, maximum adsorption was obtained at pH 5, The amount of Cd2+ adsorbed at equilibrium (qe) increases from 9.2 to 40.8 mg/g, from 9.11 to 26.9 mg/g, from 9.8 to 65.5 mg/g and from 9.7 to 58.9 mg/g upon increasing Cd (II) concentration within the range studied ( 5 - 300 mg/l) for stems (DS), leaves (DL), activated carbon stems (MACS), and activated carbon leaves (MACL), respectively. The kinetic studies were performed based on different kinetic models. The data indicated that the adsorption kinetics of cadmium on all adsorbents followed the pseudo-second order model at different cadmium concentrations. The experimental data fitted with Langmuir isotherm model. Thermodynamic studies revealed that the adsorption process was an endothermic process in nature. The desorption of about 69 % of the adsorbed cadmium from carbon was achieved using 0.6 M HCl.