Impact of chlorination on silver elution from ceramic water filters

Mechanisms and efficacy of disinfection in ceramic water filters: A critical review

“…Similar results were reported by Lyon-Marion et al (2018), where approximately 0.1 mg/L and 0.25 mg/L of silver was released from disk filters exposed to 1 mM and 10 mM IS of NaNO 3 , respectively (Lyon-Marion et al, 2018). The reason for the difference in observations is uncertain (Lyon-Marion et al, 2018;Mittelman et al, 2015), however is most likely due to MgSO 4 releasing divalent cations into the water, which cannot exchange with the monovalent Ag þ , relative to NaNO 3 releasing monovalent cations into the water, which can engage in ion exchange processes (Crittenden, 2012c). It may also be because the former study injected ions and silver into the feed, whereas the silver was only in the disks in the latter.…”

“…These results align with the findings from Yakub and Soboyejo (2012), who enumerated the attachment force between silver and CWF material to be only 125 ± 32 nN after painting/submerging, which was attributed to van der Waals forces (Yakub & Soboyejo, 2012). As such, the interfacial energy between the materials is low, which is why co-firing has exhibited more consistent release and less vulnerability to the impacts of water chemistry (Ren & Smith, 2013;Lyon-Marion et al, 2018). Because the energy between two interfaces (c; i.e.…”

“…Interestingly Mittelman et al (2015) demonstrated opposing results when disks were painted with a 200 mg/L silver solution and flushed with clear water for 12-15 h, where they released approximately 0.006 mg/L, 0.08 mg/L and 0.8 mg/L with an influent water IS of 1 mM, 10 mM and 50 mM NaNO 3 , respectively (Mittelman et al, 2015). Similar results were reported by Lyon-Marion et al (2018), where approximately 0.1 mg/L and 0.25 mg/L of silver was released from disk filters exposed to 1 mM and 10 mM IS of NaNO 3 , respectively (Lyon-Marion et al, 2018). The reason for the difference in observations is uncertain (Lyon-Marion et al, 2018;Mittelman et al, 2015), however is most likely due to MgSO 4 releasing divalent cations into the water, which cannot exchange with the monovalent Ag þ , relative to NaNO 3 releasing monovalent cations into the water, which can engage in ion exchange processes (Crittenden, 2012c).…”

“…Lyon-Marion et al (2018) found similar results for the co-firing method, where after 20 pore volumes of filtration with water containing an ionic strength (IS) of 10 mM (NaNO 3 ), co-fired filters released an average of 0.5% of the silver applied, compared with 11.8% and 8.7% for filters painted with AgNO 3 and Ag-NPs, respectively (Lyon-Marion et al, 2018). These results, as well as others, illustrate the comparatively low-level and consistent release of silver realized when filters are impregnated with the co-firing method (Ehdaie et al, 2017;Kahler et al, 2016;Lyon-Marion et al, 2018;Nunnelley et al, 2016;Ren & Smith, 2013). Conversely, studies that have investigated painting and dipping methods illustrate much higher releases, particularly at the beginning of filtration.…”

“…Filters painted with Ag-NP had an initial release of approximately 0.5 mg/L, decreasing to 0.1 mg/L after 20 pore volumes, and then linearly decreasing to 0.03 mg/L after 160 pore volumes (Mittelman et al, 2015). Lyon-Marion et al (2018) found almost identical results to those of Mittelman et al (2016) (Lyon-Marion et al, 2018. Furthermore, when scaled to full filters, saw initial releases of 0.7 mg/L, 0.12 mg/L, 0.4 mg/L and 0.325 mg/L for filters painted with citrate-, polyvinylpyrollidine-(PVP), branched polyethylenimine-(BPEI) and Casein-stabilized nanoparticles, respectively, after exposure to a real surface water .…”