Novel application of isolated Micrococcus luteus and Bacillus pumilus for Li⁺ ion biosorption: a comparative study

In this study, Li⁺ biosorption profiles of Micrococcus luteus and Bacillus pumilus bacterial strains were investigated. Comparative surface characterization of the biomasses revealed that B. pumilus had a significantly greater surface negativity than the other, which had a direct positive effect on the ability to attract the Li⁺ ions. Biosorption experiments showed that B. pumilus cell had more efficient performance at all pH and initial Li⁺ concentration values in the ranges of 3.0-10.0 and 2.5-20.0 mg/L, respectively. The maximum adsorption capacities obtained at initial Li⁺ concentration of 20.0 mg/L and pH 9.0 were 1.160 mg Li⁺/g (167.1 µmol/g) and 2.280 mg Li⁺/g (328.5 µmol/g) for M. luteus and B. pumilus, respectively. For all the cases studied, the biosorption equilibrium was reached very quickly, suggesting that physical interaction dominated this process. Experimental data were found to be compatible with both Langmuir and Freundlich models under the studied experimental conditions. This study highlights the idea that B. pumilus bacterial strain will be a new and preferred biosorbent for Li⁺ ions by providing a low cost, rapid and quite efficient process.