Dynamic removal of Pb(II) by live Dunaliella salina: A competitive uptake and isotherm model study

Abstract

Abstract The main aim of this study is modeling of a continuous biosorption system for the removal of lead (II) ions in the aqueous conditions using live Dunaliella salina microalgae. The live microalgae can grow in saline water and opens new opportunities in varying the biosorbent properties. The effects of five parameters including pH, optical density of algae as a factor indicating the adsorbent dosage, injection time, contact time and initial concentration of lead ion were optimized by means of Response Surface Methodology (RSM) based on the Central Composite Design (CCD). Dunaliella salina algae showed maximum Pb (II) biosorption with 96% efficiency. For the selective lead (II) uptake in the presence of cadmium and nickel ions binary and ternary systems of ions were chosen. The mutual effect of each heavy metal ion in all systems on total uptake percentage was also examined. The ion selectivity was investigated in the presence of diverse heavy metal ions and lead (II) uptake percentage was determined to be 70%. Both Langmuir and Freundlich isotherm models were suitable for describing multicomponent binary and ternary systems depending on competitive ions. Main functional groups and surface properties of the Dunaliella salina was identified by Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive spectrometry. Hence, effective heavy metal ion uptake, simple design and cost-effective cultivation confirmed live Dunaliella salina as suitable microalgae for purifying contaminated water in an economic and safe manner.