Abstract
An agricultural residue, white yam (Dioscorea rotundata) tuber peel (YTBS), was used for the removal of Cd(II) ion from an aqueous solution using a batch method. The adsorbent was characterized using FTIR, TGA, SEM, EDX, N2 BET, XRD, and XRF. The optimization of sorption variables such as pH, contact time, adsorbent dose, and initial metal ion concentration at 25 °C were also carried out. The results indicated the dependence of sorption on the adsorbate pH and adsorbent dose, while the adsorption system reached equilibrium in 180 min. The sorption kinetics was fitted to three models (pseudo first order, pseudo second order, and Elovich) to validate the kinetics, and the pseudo first order was the best model for the description of Cd(II) uptake. Equilibrium isotherm modelling was also carried out using the Langmuir, Freundlich, and Temkin models, with the Langmuir isotherm giving the best fitting to the experimental results. The maximum loading capacity (qmax) of the adsorbent for Cd(II) obtained from the Langmuir isotherm model was 22.4 mg∙g−1 with an isotherm constant (KL) of 3.46 × 10−3 L·mg−1 and r2 value of 0.99. This result indicates that the YTBS residue was a good adsorbent for the removal of Cd(II) ion from aqueous system.
Highlights
Heavy metal pollution is one of the consequences of the industrial revolution that has had detrimental impacts on human life, as well as the environment, in a large number of regions around the world, especially in developing countries
The kinetics of Cd(II) ion sorption indicated that metal ion loading showed a two stage uptakean initial quick uptake up to 180 min, which was followed by a gradual metal ion removal up till 1440 min
The sorption kinetics was modelled using three equations to determine which gives the best description of Cd(II) uptake
Summary
Heavy metal pollution is one of the consequences of the industrial revolution that has had detrimental impacts on human life, as well as the environment, in a large number of regions around the world, especially in developing countries. The pollution of air, water, and land environments by toxic heavy metal ions such as mercury, cadmium, lead, and chromium, and their accumulation through the food chain has resulted in a number of diseases and disorders [1]. These pollution incidences and their implications for our environment has become a matter of huge global concern, especially in developing countries where advanced technologies, capital investment, and environmental regulatory enforcement are limited [2]. Prolonged exposure to cadmium has been reported to cause several biological problems such as; kidney failure, anaemia, cardiovascular diseases, and growth impairment [11]
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