Adhesion of gram-negative bacteria onto α-Al2O3 nanoparticles: A study of surface behaviour and interaction mechanism

Abstract

α-Al2O3 nanoparticles (NPs) with average particle size ⁓8.6 nm were synthesised adopting top-down (mechanical ball milling) approach. The synthesised NPs were characterised by XRD, FESEM, HRTEM and zeta potential analysis and were used as a highly efficient adsorbent towards the adsorption of pathogenic gram-negative bacterium Escherichia coli. In the present study we mainly focus on the variation of surface morphology, size and the surface charge of the α-Al2O3 NPs synthesised at different time interval of ball milling. The adsorption capacity of the α-Al2O3 NPs towards E. coli is depended on size of the NPs and it increases with decrease in the size of NPs. The interaction mechanism between the α-Al2O3 NPs and bacteria cells was investigated in terms of surface charge and functional groups present on both adsorbent and adsorbate. The kinetics of adsorption was studied at four different temperatures including 20, 25, 30 and 35 °C and pseudo-first order kinetic model was found to be the best fit model. Adsorption isotherm study and thermodynamic parameters were evaluated to understand the nature of the interaction between the adsorbate and adsorbent. This work could provide new insights into the removal of the pathogenic bacteria using α-Al2O3 NPs and facilitate their practical application in environmental remediation issues.