Effective adsorption of nickel (II) with Ulva lactuca dried biomass: isotherms, kinetics and mechanisms.

This study aimed to evaluate the Ni ions adsorption capability of Ulva lactuca. The isotherms, kinetics and mechanisms for the adsorption of Ni from aqueous solution by Ulva lactuca were also investigated. Influencing factors including initial pH, initial Ni concentration, biomass, contact time were examined. The results indicate that the maximum Ni adsorption capacity of 38.28 mg/g was obtained at pH 5, initial Ni concentration 250 mg/L, biomass dosage 0.5 g/L and contact time 30 min. The adsorption can be well fitted with Langmuir isotherm, and the kinetics were well described by the pseudo-second-order model. The parameters of thermodynamics verified that Ni adsorption on Ulva lactuca was a spontaneous and endothermic process. Analyses of FT-IR, SEM-EDS and XPS indicate that carboxyl and hydroxyl groups on the surface of biomass are involved in Ni adsorption. The dried biomass of Ulva lactuca can be a cost-effective and eco-friendly adsorbent for the removal of Ni from wastewater.