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The precise quantification of Pb exposure from tap water can help water utilities and public health organizations assess and mitigate elevated Pb concentrations. Several sampling protocols have been developed for this purpose; however, each existing protocol has limitations associated with sampling time, sample sizes, and ease of application. This study confirmed the ability of point-of-use faucet filters to accumulate Pb and then developed an extraction method that can enable quantification of Pb exposure from tap water. Nearly all Pb from both real and synthetic tap water was accumulated on POU filters, and four different methods for extracting the accumulated Pb were evaluated. Approximately 100% Pb recovery was achieved with a single pass flow-through method using a nitric acid solution. This Pb exposure quantification method could potentially be applied to real drinking water systems to provide an effective indication of Pb exposure from tap water. 

Based on tunable properties, engineered nanoparticles (NPs) hold significant promise for water treatment technologies. Motivated by concerns regarding toxicity and non-biodegradability of some nanoparticles, we explored engineered magnetite (Fe 3 O 4 ) nanoparticles with a biocompatible coating. These were prepared with a coating of rhamnolipid, a biosurfactant primarily obtained from Pseudomonas aeruginosa . By optimizing synthesis and phase transfer conditions, particles were observed to be monodispersed and stable in water under environmentally relevant pH and ionic strength values. These materials were evaluated for U( vi ) removal from water at varying dissolved inorganic carbon and pH conditions. The rhamnolipid-coated iron oxide nanoparticles (IONPs) showed high sorption capacities at pH 6 and pH 8 in both carbonate-free systems and systems in equilibrium with atmospheric CO 2 . Equilibrium sorption behavior was interpreted using surface complexation modeling (SCM). Two models (diffuse double layer and non-electrostatic) were evaluated for their ability to account for U( vi ) binding to the carboxyl groups of the rhamnolipid coating as a function of the pH, total U( vi ) loading, and dissolved inorganic carbon concentration. The diffuse double layer model provided the best simulation of the adsorption data and was sensitive to U( vi ) loadings as it accounted for the change in the surface charge associated with U( vi ) adsorption.