Escherichia coli adhesion to the silica gel surface in the presence of non-ionic surfactants was investigated. E. coli adhesion to silica gel begins with long-range, non-specific van der Waals interactions, followed by short-range, specific Lewis acid-base interactions. When surfactants were introduced to the system before E. coli, the amounts of attached E. coli to silica gel surfaces corresponded to interactions between E. coli and silica gel, which were determined by surface properties of both E. coli and silica gel, as well as the intervening medium. When surfactants were introduced after E. coli colonization, the amounts of attached E. coli desorbed from silica gel surfaces corresponded to interactions between lipopolysaccharides and silica gel, which were determined by surface properties of both lipopolysaccharides and silica gel, as well as the intervening medium.