Biosynthesis of silver nanoparticles by cell-free extracts from some bacteria species for dye removal from wastewater

ObjectivesTo investigate the biosynthesis of silver nanoparticles (AgNPs) using extracts of some bacterial isolates Bacillus pumilus, Bacillus paralicheniformis and Sphingomonas paucimobilis. The formation of AgNPs was detected by the change in color into yellow and confirmed by the UV-Vis spectroscopy. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR).ResultsThe obtained AgNPs were spherical to oval in shape with particle size ranged from 4 to 20nm and surface area 118m(2)/g. The AgNPs have been used as nanocatalyst for the removal of malachite green dye (MG) from aqueous solution. The dye was chosen as a model dye released in wastewater. The AgNPs showed excellent nanocatalyst for the removal of MG. The dye removal process was observed by the continuous decrease in dye absorbance at 617nm until it vanished over 160min. The removal kinetics followed closely the pseudo-first-order kinetic model.ConclusionThe B. paralicheniformis strain KJ-16 was the most effective isolated bacteria to give extract for biosynthesis of AgNPs and dye removal. This method may be considered easy and eco-friendly, and could be applicable for large-scale decontamination of wastewater from harmful dyes.