The Antibacterial Activity of Activated Carbon, Silver, Silver Impregnated Activated Carbon and Silica Sand Nanoparticles against Pathogenic E. coli BL21

One of the most widely used nanoparticles for water purification is activated carbon due to its large surface area and high adsorption capacity (Ortiz-Ibarra, et al., 2007). Activated carbon has proven to remove bacteria like Pseudomonas aeruginosa and Escherichia coli from fresh and potable water systems (Percival and Walker, 1999; Quinlivan, et al., 2005). Despite electrostatic repulsion between negatively charged microorganisms and carbon surfaces, microorganisms attach to activated carbon particles through strong Lifshitz van derWaals forces (Jucker, et al., 1996). Potable water systems are considered low in ionic strength so electrostatic interactions can offer the possibly of enhancing the efficacy of activated carbon to remove microorganisms from water by positive charge modification of the carbon surfaces. Once there is a charge reversal, the electrostatic attraction between negatively charged microbial cell surfaces and positively modified carbon particles ISSN: 2319-7706 Volume 2 Number 4 (2013) pp. 20-30 http://www.ijcmas.com