Magnetic nanoparticles towards efficient adsorption of gram positive and gram negative bacteria: An investigation of adsorption parameters and interaction mechanism

Magnetic Fe3O4 nanoparticles (NPs) are synthesized by two different techniques, top-down (mechanical ball milling) and bottom-up approaches (chemical reduction method). The synthesized NPs were used as efficient adsorbents towards adsorption of gram positive bacterium Staphylococcus aureus and gram negative bacterium Escherichia coli. Fe3O4 NPs synthesized by top-down approach is denoted as Fe(3)O(4)A and that by bottom up method is denoted as Fe3O4B. The surface charge dependent adsorption capacity was observed for the NPs towards both the bacteria. The interactions between the NPs and bacteria was assessed by zeta potential, FTIR and SEM analysis. Adsorption study was evaluated considering parameters like bacteria concentration and pH of the reaction mixture. Adsorption kinetics was evaluated at pH 5 and considering four different temperatures 20, 25, 30 and 35 degrees C. Analysis of the adsorption experiments revealed pseudo-second order (linear) as the best fit kinetic model. Furthermore, the adsorption isotherm study was performed at pH 5 and 25 degrees C and different thermodynamic parameters were calculated. (C) 2016 Elsevier B.V. All rights reserved.