Hexavalant chromium, Cr(VI), is known to pose health threats and is under scrutiny and investigation for regulation. In order to meet regulatory and safe drinking water standards, an emerging option of reducing or removing hexavalent chromium from drinking water or effluent discharge of industrial cooling water is photocatalytic reduction and/or sorption. In this investigation, hexavalent and total chromium levels (inclusive of trivalent chromium) were reduced through photocatalytic processes using nano-titanium dioxide, UV radiation (254 nm medium pressure lamps) and no hole scavenger. A pilot-scale photocatalytic system, the Purifics Photocat, was investigated for use as both a batch and flow through reactor to photoreduce and sorb Cr(VI) using nTiO2 (0.1 and 1 g/L). Initial verification experiments ran 5 mM NaHCO2 buffered distilled water and dechlorinated tap water at spiked concentrations of 500 ug/L in a batch mode recirculating at 20 L/min. A 300 gallon flow-through investigation will be completed using water from an Arizona Salt River Project site known to have detectable and concerning levels of hexavalent chromium as well as with 500ug/L spiked dechlorinated tap water. Sorption of reduced chromium to the nTiO2 photocatalyst was investigated using XPS, and chromium concentrations were measured using ion chromatography [Cr(VI)] and inductively coupled plasma optical emission spectroscopy [total Cr]. Removal was tested on an energy-input basis, involving a varied number of lamps over time in addition to varied doses of nTiO2. For use as a removal method, this system effectively achieved above 90% reduction/removal of Cr(VI) and total chromium species. Increasing energy input resulted in higher removal efficiencies.

Cr(VI) treatment using pilot-scale UV photcatalytic reactor with nTiO<sub>2</sub>

246th National Meeting (2013)

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

Cr(VI) treatment using pilot-scale UV photcatalytic reactor with nTiO2

Cr(VI) treatment using pilot-scale UV photcatalytic reactor with nTiO₂