Functionalization of Extracellular Polymers of Pseudomonas aeruginosa N6P6 for Synthesis of CdS Nanoparticles and Cadmium Bioadsorption

Abstract

Functionalization of the extracellular polymers (EPS) of a marine bacterium Pseudomonas aeruginosa N6P6 was carried out for cadmium (Cd) bioadsorption from an aqueous solution which led to the synthesis of cadmium sulfide (CdS) nanoparticles (NPs). Characterization of pristine, functionalized and Cd-treated functionalized EPS was accomplished by ATR-FTIR spectroscopy which illustrated Cd binding with the sulfhydryl (–SH) group. The XRD pattern confirmed the presence of CdS NPs on the functionalized EPS with diffraction peaks at 2θ = 27.45° and 32.66° indexed to (111) and (220) planes of cubic phase CdS. Maximum Cd adsorption was observed by the functionalized EPS which removed 88.86 ± 0.65% of Cd at pH 6.6 in 48 h. However, pristine EPS and bacterial cell biomass removed 83.61 ± 0.50% and 29.75 ± 0.73% of Cd respectively from aqueous solution. The experimental data of Cd adsorption thermodynamics by functionalized EPS fitted in Langmuir isotherm model. CdS NPs synthesis by functionalized EPS was evident by UV–Vis spectrum with a characteristic peak at 462 nm and Transmission electron microscopy with an average diameter of 8–10 nm. This work delivers an environment-friendly approach for efficient Cd removal from aqueous solution in the form of CdS NPs synthesis.