Biosorption of nickel by Halobacillus sp. KN57 isolated from the Miankaleh Wetland, Iran

Heavy metals are generally discharged from untreated wastewater in the aquatic ecosystem. This study was aimed to investigating the effective parameters in the sorption of nickel metal by a native halophile bacterium isolated from sediments of the Miankaleh Wetland in the north of Iran. Halobacillus sp. KN57 as the most resistant Gram-positive strain was selected and identified by phenotypic and phylogenetic properties (16S rRNA). The optimum contact time, pH, temperature, salinity, and initial biosorbent concentration of nickel for this strain were 100 min, 7, 30°C, 10%, 1 g.L-1, and 150 mg.L-1, respectively. The nickel biosorption was 111.11 mg/g by the selected strain under the laboratory conditions, followed Langmuir isotherm with a correlation coefficient of more than 0.98 and the maximum single layer sorption. In addition, the kinetics of nickel biosorption of this strain correspond to a pseudo second order kinetic model with a correlation coefficient of more than 0.99. Scanning electron microscopy was applied to confirm the biosorption of Ni2+ by Halobacillus sp. KN57. Finally, the FT-IR spectrum identified that the amide, carbonyl, and amine functional groups were participated in binding to nickel ions. The results showed that the native bacterial strain (Halobacillus sp. KN57) isolated from Miankaleh Wetland, is potentially a promising biosorbent for sorption of nickel metal.