Biosorption of Cu, Zn and Pb by thermophilic bacteria - effect of biomass concentration on biosorption capacity

Abstract

The aim of this work was to study the biosorption capacity of metals copper, lead and zinc by Geobacillus thermodenitrificans and Geobacillus thermocatenulatus. Solution of each metal was mixed with dry biomass and incubated at room temperature. The supernatant was taken and used for complexometric titration. The sorption capacity for Cu2+ was highest when using 0.5 g·l−1 Geobacillus thermodenitrificans (57 ± 4 mg·g−1). The sorption capacity rapidly decreases with increased concentrations. Similarly for Zn2+ ions, the highest sorption capacity was for biomass concentration 0.5 g·l−1 (18 ± 3 mg·g−1) and slowly decreases. For Pb2+ ions, the decrease is almost linear to the biomass concentration 2 g·l−1, i.e. from 117 ± 13 mg·g−1 to 53 ± 3 mg·g−1.The sorption capacity of Cu2+ ions was highest at the lowest biomass concentration of Geobacillus thermocatenulatus (65 ± 3 mg·g−1), then it sharply decreased and at concentration of biomass of 1 g·l−1 did not changed. In the case of Zn2+ ions, we could seen a moderate drop with the increasing concentration with the range of 24 ± 3 to 12.3 ± 0.4 mg·g−1. For Pb2+ ions was the decrease slow, from 119 ± 8 mg·g−1 to 54 ± 4 mg·g−1.Affinity of metals to bacteria was determined in the order Pb2+ > Cu2+ > Zn2+. The results show, that Geobacillus thermocatenulatus has better sorption capabilities than Geobacillus thermodenitrificans.

Study on the Assessment of Adsorption Potential of Dry Biomass of Canna indica with Reference to Heavy Metal Ions from Aqueous Solutions

“…Thus, the time of contact required to reach saturation varied with the biomass quantity. The figure shows that within a short time a large fraction of the total amount of heavy metal ion was removed but the uptake capacity of heavy metal ion per unit amount of sorbent (mg/g) decreases with increase in biomass concentration [9,10]. It is observed that there is a sharp increase in percentage removal of heavy metals with adsorbent quantity for studied heavy metal ions upto 1-2 gm of adsorbent quantity but after that there is gradual percentage removal with increasing quantity, it is due to the greater availability of the exchangeable sites or surface area [11] and as the sites are occupied the adsorption slowly decreases.…”

Isotherm Study in Arsenic Tolerant Bacteria Isolated from Arsenic Affected Area in West-Bengal, India

“…Zhu, 2010 reported that the competitive sorption of Cr and Cu by goethite-Bacillus thuringiensis, where Cr had the stronger affinity on the sorbents (Goethite-Bacillus thuringiensis than Cu). Babak et al, 2012 showed the affinity order of the metals to the bacteria and they also reported that Geobacillus thermocatenulatus had the highest metal sorption capacities than Geobacillus thermodenitrificans.…”

“…According to Tarangini, 2009, Pathak and Dikshit, 2011, Babak et al, 2012, the effect of various temperature on the bacterial heavy metal adsorption study was shown. The optimum biomass concentration i.e 700µl.…”

“…strain CCBAU 51490 and Bacillus subtilis subsp. subtilis where the depression zone of the curve is indicated the highest uptake of As in the optimum growth condition of these two bacteria.This condition satisfies both pseudo-first order and pseudo-second order rate kinetics graphs, which are made on the basis of the pseudo-first order and pseudo-second order differential equation dq t /d t =k 1 (q e -q t ) and dq t /d t =k 2 (q e -q t ) 2 of Yang and Duri, 2005, where q e (mg g-1) is the solid phase concentration at equilibrium, q t (mg g-1) is the average solid phase concentration at time t (min), and k 1 (min-1) and k 2 (g mg-1 min-1) are the pseudo-first-order and pseudo-second order rate constants, respectively and from these equations, ln(q eq t )=ln(q e )-k 1 t and t/q t =1/k 2 q e 2 +t/q e equations are derived, when t=0 and q t =0 in the initial condition. Thus the absorption process of C-7 bacteria and A-2 i.e Bacillus sp.…”

“…According to Tarangini, 2009, Zhu, 2010and Babak et al, 2012, the effect of the bacterial biomass concentration on the biosorption study was done. Biomass was centrifuged at 9,000 rpm for 10 minutes and different weights of the biomass ranging from 300 µl.to 900 µl.…”