Sorption characteristics and mechanisms of Pb(II) from aqueous solution by using bioflocculant MBFR10543

This paper focuses on the effectiveness of removing Pb(II) from aqueous solution using bioflocculant MBFR10543 and a series of experimental parameters including MBFR10543 dose, calcium ions concentration, solution pH, and temperature on Pb(II) uptake was evaluated. Meanwhile, the flocculation mechanism of MBFR10543 was discussed. Results have demonstrated that the removal efficiency of Pb(II) reached 94.7 % (with the sorption capacity of 81.2 mg · g(-1)) by adding MBFR10543 in two stages, separately, 3 × 10(-2) % (w/w) in the 1.0 min's rapid mixing (180 rpm) and 4 × 10(-2) % (w/w) after 2.0 min's slow mixing (80 rpm) with pH value fixed at 6. Pb(II) flocculation process could be described by the Langmuir isotherms model and pseudo-second-order kinetic model. The negative Gibbs free energy change indicated the spontaneous nature of the flocculation. Fourier transform infrared spectra analysis indicated that functional groups, such as -OH, C=O, and C-N, were existed in MBFR10543 molecular chains, which had strong capacity for removing Pb(II). Furthermore, both charge neutralization and bridging being the main mechanisms involved in Pb(II) removal by MBFR10543.