Biosorptionof heavy metals from aqueous solutions by the brown marine algae of the Oman Sea

In this work, the biosorption properties of Cd (II), Ni (II) and Pb (II) on both intact and pre-treated brown marine algae; Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated by formaldehyde, glutaraldehyde, polyethylene imine, calcium chloride and hydrochloric acid have been studied. Experimental results were obtained from batch equilibrium tests. The optimum sorption conditions were investigated and results showed that the highest biosorption capacities (19.42 mg/g, 10.06 mg/g and 51.83 mg/g for Cd(II), Ni(II) and Pb(II), respectively) were obtained at an optimum pH of 5.5, 6.0 and 5.5 for Cd(II), Ni(II) and Pb(II), respectively. Initial metal concentration was 0.5 mmol/L while contact time was about 120 min. The one-way ANOVA and one sample t-test were performed on experimental data to evaluate the statistical significance of biosorption capacities after five sorption and desorption cycles. To describe the biosorption isotherms, the Langmuir, Freundlich, Toth, Khan and Radke-Prausnitz isotherm models were applied. The results fit well to the Radke-Prausnitz, the Toth and the Khan isotherms for Cd(II), Ni(II) and Pb(II), respectively. The kinetic data were fitted by the models including pseudo-first and pseudo-second order. From the results obtained, the pseudo-second-order kinetic model described well the biosorption of cadmium, nickel and lead ions, in that the R2 obtained was above 0.99 for all the mentioned metals.

Keywords:

Biosorption , Brown Algae , Heavy Metals , Isotherm , Kinetics