The Synthesis of PbS NPs and Biosorption of Pb(II) by Shinella Zoogloeoides PQ7 in Aqueous Conditions

Abstract

Increasing heavy metal pollution in water continues to endanger human health. The genus Shinella has potential for heavy metal bioremediation but has rarely been studied. In this study, we report that Shinella zoogloeoides PQ7 turns black in the presence of lead ions. Transmission electron microscopy (TEM), Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) indicated that PbS nanoparticles (NPs) were synthesized by PQ7. Moreover, PQ7 was used as a biosorbent to remove Pb(II) from aqueous solutions. Biosorption performance was evaluated in terms of contact time, pH, biomass dosage and initial Pb(II) concentration. The equilibrium and kinetic data were consistent with the Freundlich isotherm model (R2 = 0.986) and pseudo-second-order model (R2 = 0.977), respectively. The maximum (qmax) Pb(II) adsorption reached 222.22 mg/g, which was higher than that of other bacteria reported in previous literature. SEM–EDS, XRD and Fourier transform infrared (FTIR) analyses also confirmed the adsorption of Pb(II) by the PQ7 cells. In conclusion, PQ7 is a promising strain in removing and recovering Pb(II) from wastewater.

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications

“…[160] promote the biosynthesis of iron sulfide (FeS), greigite (Fe 3 S 4 ), and pyrite (FeS 2 ) NPs. On the other hand, the extracellular biogenesis of PbS nanocrystals has been implemented using Rhodobacter sphaeroides [79] and Shinella zoogloeoides [150]. These studies demonstrated the involvement of cysteine desulfhydrase in H 2 S production and the subsequent NP formation.…”

“…Commonly, green-synthesized NPs are formed at ambient to mild temperatures and atmospheric pressures. Importantly, the parameters particularly relevant to consider are the pH, organism, salt sources, biomass concentration, time, and additional reagents [41,100,137,150].…”

“…The pH-dependent NP synthesis capability is attributed to the decreased SRB sulfide/sulfate production in alkaline media. The biosorption of metal ions by a given organism is also related to the pH as the cell membrane conformation might be altered, thus, increasing or decreasing its biosorption rate and capacity [150]. Lower pH could protonate the cell surface while alkaline pH might cause the precipitation of metal ions by combining with hydroxyl (−OH) groups [150].…”

“…The biosorption of metal ions by a given organism is also related to the pH as the cell membrane conformation might be altered, thus, increasing or decreasing its biosorption rate and capacity [150]. Lower pH could protonate the cell surface while alkaline pH might cause the precipitation of metal ions by combining with hydroxyl (−OH) groups [150]. Therefore, pH adjustment can favor or impede the NP biosynthesis since it impacts both the bio-entity and reaction solution [150].…”

“…Lower pH could protonate the cell surface while alkaline pH might cause the precipitation of metal ions by combining with hydroxyl (−OH) groups [150]. Therefore, pH adjustment can favor or impede the NP biosynthesis since it impacts both the bio-entity and reaction solution [150].…”