Interpretation of initial adhesion of Pseudomonas Putida on hematite and quartz using surface thermodynamics, DLVO, and XDLVO theories

The initial adhesion behavior of the Pseudomonas (P.) putida bacterium on hematite and quartz was interpreted by the surface thermodynamics, Derjaguin–Landau–Verwey–Overbeek, and extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theories. Physical-chemical analyses revealed that both the bacterium and the minerals are hydrophilic (γ- >28.8 mJ/m2), with hematite being the least hydrophilic (35.06 mJ/m2), followed by P. putida as moderately hydrophilic (54.42 mJ/m2), and then quartz as the most hydrophilic (54.90 mJ/m2). The zeta potential of the hematite-P. putida interaction was more electropositive than that of the quartz interaction, thus there were higher interactions between hematite and P. putida at all pH values. The thermodynamics results indicated a repulsion interaction between the bacterium and the minerals. However, the XDLVO theory effectively predicted the attachment behavior of P. putida on minerals. According to the findings, at a very short distance, interactions between the bacterium and the minerals surfaces were dominated by Lewis acid-base interactions, which constituted most of the total interaction energy. A higher positive value for the total interaction energy for quartz results in a repulsion interaction with the bacterium. Therefore, a more attractive interaction occurs between hematite and P. putida as its interaction energy is less positive. The comparison made between the theoretical results found that the XDLVO theory provides more effective and accurate outcomes for the adhesion behavior prediction between the bacterium and the minerals.