Interaction forces between waterborne bacteria and activated carbon particles

• Published in: Journal of colloid and interface science Vol. 322; no. 1; pp. 351 - 357
• Main Authors: Busscher, Henk J., Dijkstra, Rene J.B., Langworthy, Don E., Collias, Dimitris I., Bjorkquist, David W., Mitchell, Michael D., Van der Mei, Henny C.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.06.2008; Elsevier
• Subjects: Activated carbon; Adsorbents; Adsorption; AFM; Animals; Bacterial adhesion; Bacterial Adhesion - drug effects; Bacterial Adhesion - physiology; Charcoal - pharmacology; Chemistry; Colloidal state and disperse state; Enterobacteriaceae - drug effects; Enterobacteriaceae - metabolism; EPS; Escherichia coli - drug effects; Escherichia coli - metabolism; Escherichiae coli; Exact sciences and technology; General and physical chemistry; Interaction force; Microscopy, Atomic Force; Particle Size; Raoutella terrigena; Surface physical chemistry; Surface Properties; Water filtration; Water Microbiology; Water Purification - methods; Raoutella terrigena; Water filtration; Interaction force; Activated carbon; AFM; EPS; Bacterial adhesion; Escherichiae coli; Water; Atomic force microscopy; Filtration; Force; Adhesion; Particle
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2008.03.018

Activated carbons remove waterborne bacteria from potable water systems through attractive Lifshitz–van der Waals forces despite electrostatic repulsion between negatively charged cells and carbon surfaces. In this paper we quantify the interaction forces between bacteria with negatively and positively charged, mesoporous wood-based carbons, as well as with a microporous coconut carbon. To this end, we glued carbon particles to the cantilever of an atomic force microscope and measured the interaction forces upon approach and retraction of thus made tips. Waterborne Raoultella terrigena and Escherichia coli adhered weakly (1–2 nN) to different activated carbon particles, and the main difference between the activated carbons was the percentage of curves with attractive sites revealed upon traversing of a carbon particle through the bacterial EPS layer. The percentage of curves showing adhesion forces upon retraction varied between 21% and 69%, and was highest for R. terrigena with positively charged carbon (66%) and a coconut carbon (69%). Macroscopic bacterial removal by the mesoporous carbon particles increased with increasing percentages of attractive sites revealed upon traversing a carbon particle through the outer bacterial surface layer. By attaching an activated carbon particle to a cantilever, AFM enables direct measurements of the interaction forces between activated carbon particles and immobilized, waterborne bacteria.