Efficiency of extremophilic microbial mats for removing Pb(II), Cu(II), and Ni(II) ions from aqueous solutions

Two different extremophilic films were used as natural biosorbents to remove Cu(II), Ni(II), and Pb(II) from aqueous solutions. Surface area, scanning electron microscopy imaging, and Fourier transformation infrared spectroscopy were used to characterize the surfaces of the biosorbents. The results indicated high affinity of the biosorbents to remove Pb(II), Cu(II), and Ni(II), with adsorption rates ranging from 73.6 to 100% for both biosorbents. The biosorbents succeed in removing the metal ions from aqueous mixtures in the following order: Pb(II) > Cu(II) > Ni(II). The maximum removal rates of metal ions were achieved at pH 6, contact time of 150 min, biosorbent dose of 2.5 g/L, and metal ion concentration of 50 mg/L. The isothermal studies showed that both Langmuir and Freundlich models well expressed the adsorption process. Kinetically, the pseudo-second-order reaction better expressed the type of reaction than the pseudo-first-order reaction.