Titanium dioxide (TiO2, anatase) is used to remove contaminants such as arsenic from drinking water supplies. The TiO2 solid phase becomes enriched with arsenic as it removes arsenic from the water. Often, the source of arsenic is geogenic in nature, but it still causes problems for humans and the environments that are exposed to it. Adverse health effects due to arsenic consumption in humans can include kidney disease, cardiovascular problems, and several types of cancer. This research aims to identify and quantify arsenic speciation mobility from TiO2 particles from field samples used to remove arsenic from drinking water. The field samples were obtained from the Bagaces area of Guanacaste, Costa Rica, where geogenic arsenic concentrations in aqueduct waters has been found at levels ranging from 31-80 ppb, and there is an estimated exposure of up to 12,000 people. During the dry season, high winds in this region also produce a risk of dust inhalation from these arsenic-enriched TiO2 sediments and soils, where the filter product was distributed in the environment. Results presented here include solid phase characterization and wet chemical analysis of arsenic-enriched TiO2 water filter waste products using several methods to determine speciation of arsenic, quantification, and evaluation of its mobility and bioavailability. In addition, water retention curves from affected soils will be presented. Initial results from X-ray absorption near edge structure (XANES) spectroscopy indicate arsenic is present in the pentavalent (5+) oxidations state, which is the less mobile phase. Samples with the highest arsenic concentrations contained up to 600 ppm arsenic in the filter waste. There was a high correlation between arsenic and titanium (&gt;0.96). In addition,TiO2-enriched worm castings contained up to 530 ppm arsenic, indicating a possible biotic pathway for arsenic into soil organisms.

Speciation, quantification, and release of arsenic bound to titanium dioxide (TiO2, anatase) drinking water filter waste: Case study from the field to molecular scale

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.