Entrapment of brown seaweeds (Turbinaria conoides and Sargassum wightii) in polysulfone matrices for the removal of praseodymium ions from aqueous solutions

The aim of the present investigation was to study the potential of two brown seaweeds ( Sargassum wightii and Turbinaria conoides ) to remove praseodymium ions from solutions. Due to swelling problems, the seaweed biomasses were also immobilized using polysulfone matrices which amplified hydraulic conductivity more than 7.1 times. At optimum pH of 5, maximum Pr(III) uptakes of 131.4, 146.4, 111.2 and 119.5 mg/g were observed for free- S. wightii , free- T. conoides , polysulfone immobilized S. wightii (PISW) and polysulfone immobilized T. conoides (PITC), respectively. Experimental biosorption isotherms were successfully described using the Langmuir, Freundlich and Sips model. Owing to intraparticle diffusion, rate of Pr(III) sorption by immobilized biosorbents was slow and equilibrium attainment took 240 min compared to only 90 min by free biomasses. However, regeneration of seaweed biomasses for repeated sorption application was only possible with immobilization biosorbents. With 0.1 mol/L HCl as elutant, both PITC and PISW exhibited invariable Pr(III) uptake capacity and very high mechanical stability over 10 sorption-desorption cycles.