Hg(II) adsorption by Bacillus mucilaginosus: mechanism and equilibrium parameters

Abstract

Our previous findings have indicated that Bacillus mucilaginosus might be a promising biosorbent. However, up to now, few studies have been performed to examine the use of B. mucilaginosus as a sorbent, especially as a sorbent for Hg(II). The aim of the current study was to investigate the adsorption of Hg(II) by B. mucilaginosus and the underlying mechanism involved. The results showed that B. mucilaginosus exhibited effective adsorption of Hg(II), and the experimental data were well fitted by the Langmuir model with equilibrium constant of 3.32 9 10 4 M -1 and maximum adsorption capacity of 393 mg(Hg)/l(bacterial culture). The average saturated adsorption amount of Hg(II) by each cell was 9.83 9 10 9 atoms, with time to reach adsorption equilibrium less than 10 min. The adsorption efficiency was mainly dependent on pH. Surface adsorption of capsules was identified to be the major mechanism for the biosorption of Hg(II) by B. mucilaginosus, which might be associated with the cell products on the surface of capsules of B. mucilaginosus. Differences observed in adsorption behaviors at different concentrations of Hg(II) were well explained using the Visual minTEQ software. Our findings might shed some lights on the application of B. mucilaginosus as an adsorbent for Hg(II) and other heavy metals.

The Up-regulation of Carbonic Anhydrase Genes ofBacillus mucilaginosusunder Soluble Ca2+Deficiency and the Heterologously Expressed Enzyme Promotes Calcite Dissolution

“…In our research group, we often use Bacillus mucilaginosus to study the interactions between microbes and minerals (Mo and Lian 2011;Xiao et al 2012a). Zhang et al (2011) showed B. mucilaginosus can capture atmospheric CO 2 by carbonic anhydrase.…”

Iron and lead ion adsorption by microbial flocculants in synthetic wastewater and their related carbonate formation

“…removal from the solutions) and adsorption capacity (Q, the amount of adsorbed Fe 3+ and Pb 2+ in mg by 1 L MBF) were calculated using the following formula Mo and Lian, 2011;Yao and Lian, 2009):…”

“…The nucleation of iron and lead carbonates may have initiated on the MBF and cell surfaces, a phenomena commonly observed on bacterial surfaces (Konhauser, 1997;Konhauser et al, 1993Konhauser et al, , 2002Konhauser and Urrutia, 1999). Considering that the pH value of the viscous floc materials (bacterailmineral complex) has some buffering capacity (Mo and Lian, 2011), and the carbonic anhydrase secreted by B. mucilaginosus can catalyze the following Reaction (7), which promotes carbonate formation.…”

Tolerance of Chemoorganotrophic Bioleaching Microorganisms to Heavy Metal and Alkaline Stresses

“…In the EPS layer, the optimal conditions for pH and solute concentration are maintained. Moreover, the EPS is involved in the capture of metal ions from the solution, preventing their entrance into the bacterial cell [ 23 ].…”