Sorption of europium by malt spent rootlets, a low cost biosorbent. Effect of pH, kinetics and equilibrium studies

The uptake of lanthanide elements by naturally abundant materials, is a matter of great economic and environmental interest. This study is an exploration of the potential utilization of malt spent rootlets (MSR), which are by-products of malting process, for a cost effective pre-concentration of Eu(III). The effect of solution pH, contact time and initial concentration under constant ionic strength and temperature were studied. Kinetic data were applied to pseudo-first, second order and Elovich equations, as well as intra-particle diffusion model. Pseudo-second order and Elovich equation seem to fit our data equally well, whereas diffusion contributes to the whole process. Equilibrium data were evaluated using Langmuir, Freundlich and Dubinin-Radushkevich equations. According to Langmuir model, which fits the data better, europium maximum capacities for MSR and active carbon were found 156 and 86 mg/g respectively, indicating that MSR is a promising biosorbent. (author)