Abstract
Biosorption studies in batch mode were carried out to investigate the adsorption of Ni(II) ions from aqueous solution on A. barbadensis Miller leaves (ABL) residue powder. The effects of Ni(II) ion concentration, pH, biosorbent dose and temperature on removal process were investigated. The maximum biosorption of 60.2% for an initial Ni(II) ion concentration of 100 ppm was achieved. The five equilibrium adsorption isotherms, namely Freundlich, Langmuir, Temkin, Dubinin–Radushkevich (D–R) and BET, were analysed to fit the equilibrium data. Freundlich isotherm was found to best fit (R2 = 0.9975) in this study. Among pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich and Bangham kinetics models, pseudo-second-order model was found to be the best fitted model (R2 = 0.9853) in this adsorption process. Separation factor (RL) value of less than 1.0 indicates that biosorption of Ni(II) on ABL is favourable. Thermodynamics parameters such as Gibbs free energy (∆G°), enthalpy (∆H°) and entropy change (∆S°) of the biosorption process were also estimated, and it was found that biosorption of Ni(II) ion on ABL was spontaneous, feasible and exothermic in nature. The sticking probability (S* ≪ 1) indicates that the biosorption process was physical in nature. The scanning electron microscopy (SEM) analysis was also carried out to study the morphology of the biosorbent used. The results showed that ABL residue has the potential to be used as a low-cost biosorbent for the removal of Ni(II) from wastewater.
Highlights
Heavy metals are the major environmental problem with a global concern
The objectives of this research are to investigate the removal of Ni(II) from simulated aqueous solution by using A. barbadensis Miller leaves (ABL) residue powder as biosorbent
The adsorbent was characterized by measuring the zeta potential using a cylindrical cell of Surpass Electrokinetic Analyser (Anton Paar) at room temperature and different pH values
Summary
Non-biodegradable and known to have detrimental effects on the health of living systems, the need for removing it from the wastewater. Nickel is one of the non-biodegradable toxic heavy metals present in wastewater. Biosorption process is considered as a desirable method because of its convenience, easy handling, lower operating costs and high efficiency in removing heavy metals from dilute solutions even at low concentrations. Heavy metals can be removed by agro-industrial waste products due to their low cost and bulk availability. Potential biosorbents such as non-living biomass of plant wood, roots, leaves, bark (Vinod et al 2010) and grape stalk waste
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