Copper biosorption by Bacillus pumilus OQ931870 and Bacillus subtilis OQ931871 isolated from Wadi Nakheil, Red Sea, Egypt

Abstract

Background: Despite being necessary, copper is a toxic heavy metal that, at high concentrations, harms the life system. The parameters that affect the bioreduction and biosorption of copper are highly copper-resistant bacteria. Results: In this work, the ability of the bacterial biomass, isolated from black shale, Wadi Nakheil, Red Sea, Egypt, for Cu2+ attachment, was investigated. Two Cu2+ resistance Bacillus species were isolated; Bacillus pumilus OQ931870 and Bacillus subtilis OQ931871. The most tolerant bacterial isolate to Cu2+ was B. pumilus. Different factors on Cu2+ biosorption were analyzed to estimate the maximum conditions for Cu biosorption. The qmax for Cu2+ by B. pumilus and B. subtilis determined from the Langmuir adsorption isotherm was 11.876 and 19.88 mg. g−1, respectively. According to r2, the biosorption equilibrium isotherms close-fitting with Langmuir and Freundlich model isotherm. Temkin isotherm fitted better to the equilibrium data of B. pumilus and B. subtilis adsorption. Additionally, the Dubinin-Radushkevich (D-R) isotherm suggested that adsorption mechanism of Cu2+ is predominately physisorption. Conclusion: Therefore, the present work indicated that the biomass of two bacterial strains is an effective adsorbent for Cu2+ removal from aqueous solutions.