Nickel removal by Nymphaea alba leaves and effect of leaves treatment on the sorption capacity: A kinetic and thermodynamic study

• Published in: Water resources Vol. 42; no. 5; pp. 690 - 698
• Main Authors: Zahedi, Reza, Dabbagh, Reza, Ghafourian, Hossein, Behbahanini, Azita
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.09.2015; Springer Nature B.V
• Subjects: agitation; Aquatic plants; Aquatic Pollution; Aqueous solutions; batch systems; biomass; biosorption; calcium chloride; Earth and Environmental Science; Earth Sciences; energy; enthalpy; entropy; Floating plants; Fourier transform infrared spectroscopy; hydrochloric acid; Hydrogeology; Hydrology/Water Resources; Kinetics; leaves; magnesium chloride; Nickel; Nymphaea alba; Sorption; sorption isotherms; sulfhydryl groups; temperature; Thermodynamics; Waste Water Technology; water lilies; Water Management; Water Pollution Control; Water Quality And Protection: Environmental Aspects; White water; nickel; kinetic; biosorption; modification
• ISSN: 0097-8078; 1608-344X
• DOI: 10.1134/S0097807815050152

In this study, ability of Nymphaea alba (White Water lily) leaves to remove Ni²⁺ from aqueous solution was studied in the batch system. HCl, MgCl₂, and CaCl₂ chemical modification of N. alba leaves showed increasing sorption capacity of Ni²⁺ (24 mg/g; pH 6.5). Removal percentage of Ni²⁺ increased by adding more biomass. Increasing Ni²⁺ concentration up to 210 mg/L and temperature up to 35°C caused higher biosorption capacity. However, higher Ni²⁺ concentrations and rising temperature had vice versa effect. The optimum agitation time was 90 min. The prolongation of the agitation period had no considerable effect on the biosorption capacity. The kinetics study of modified N. alba leaves revealed that Ni²⁺ sorption follows pseudo-second order kinetic model. Estimated parameters, the rate constant of second order biosorption (K ₂) and biosorption capacity (q ₑ), for this model at T = 293 K were 0.225 g/mg min and 17.42 mg/g, respectively. The experimental results were correlated reasonably well with Langmuir model (q ₘₐₓ = 118 mg/g; b = 0.022 L/mg). The changes in Gibb’s free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) of Ni²⁺ sorption by modified N. alba leaves were estimated as–1.726, 0.208, and 0.0018 KJ/mol K, respectively. Thermodynamic parameters revealed spontaneous, endothermic, and irreversible nature for Ni⁺² sorption. XRF and FT–IR analysis results showed that N. alba leaves had different functional carboxyl and sulfhydryl groups responsible for the sorption process.