This research explores how capping agents affect the adherence of silver nanoparticles (AgNPs) to porous ceramic water filters. AgNPs are added as an in situ disinfectant in ceramic pot filters used for household drinking water treatment in developing countries and could possibly be introduced into ceramic membranes in the developed world.  The presentation will connect results from modeling theoretical DLVO interaction energies with experimental data collected from isotherm tests. Two types of filters were used in this work: aluminum oxide (Al2O3) ceramic disks (pores = 0.1 �m diameter, Whatman Anodiscs) and clay disks (pores < 20 �m diameter, produced in-house from Illite clay and sawdust).  The Al2O3 disks are intended to represent membranes used for municipal water treatment in developed countries, and the clay disks are intended to represent the pot filters used in developing countries.  They also represent substantially different surface charges (e.g., at neutral pH, Al2O3 filters ~ +15 mV vs clay filters ~ -40 mV). The different AgNPs studied include particles capped with: citrate, polyvinylpyrrolidone (PVP), and branched polyethylenimine (BPEI).  Citrate and PVP were selected due to their differences in functional groups/stabilization and widespread use.  Also, the surface charge at natural water conditions (pH 7-9) for all of these particles vary.  PVP and citrate are negative (and differ in magnitude by up to 4.5 times), whereas BPEI has a positive charge. The welfare of societies depends upon safe water.  A better understanding of the fundamental attachment mechanisms of differently capped AgNps represents progress towards predicting the lifespan of AgNp amendments, thus ensuring sustainability of safe water treatment processes.

DLVO theory and capping agents: Attaching silver nanoparticles to ceramic water filters

247th National Meeting (2014)

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