A novel approach for determining total titanium from titanium dioxide nanoparticles suspended in water and biosolids by digestion with ammonium persulfate.
Titanium dioxide (i.e. TiO(2)) in nano-form is a constituent of many nanomaterials that are used in sunscreens, cosmetics, industrial products and in biomedical applications. Quantification of TiO(2) nanoparticles in various matrixes is a topic of great interest for researchers studying the potential health and environmental impacts of nanoparticles. However, analysis of TiO(2) as Ti(4+) is difficult because current digestion techniques require use of strong acids that may be a health and safety risk in the laboratory. To overcome this problem, we developed a new method to digest TiO(2) nanoparticles using ammonium persulfate as a fusing reagent. The digestion technique requires short times to completion and optimally requires only 1 g of fusing reagent. The fusion method showed >95% recovery of Ti(4+) from 6 μg mL(-1) aqueous suspensions prepared from 10 μg mL(-1) suspension of different forms of TiO(2,) including anatase, rutile and mixed nanosized crystals, and amorphous particles. These recoveries were greater than open hot-plate digestion with a tri-acid solution and comparable to microwave digestion with a tri-acid solution. Cations and anions commonly found in natural waters showed no significant interferences when added to samples in amounts of 10 ng to 110 mg, which is a much broader range of these ions than expected in environmental samples. Using ICP-MS for analysis, the method detection limit (MDL) was determined to be 0.06 ng mL(-1), and the limit of quantification (LOQ) was 0.20 ng mL(-1). Analysis of samples of untreated and treated wastewater and biosolids collected from wastewater treatment plants yielded concentrations of TiO(2) of 1.8 and 1.6 ng mL(-1) for the wastewater samples, respectively, and 317.4 ng mg(-1) dry weights for the biosolids. The reactions between persulfate ions and TiO(2) were evaluated using stoichiometric methods and FTIR and XRD analysis. A formula for the fusing reaction is proposed that involves the formation of sulfate radicals.
Water Quality Centre, Trent University, Peterborough, Ontario, K9J 7B8, Canada. kambizkhosrav@trentu.ca
Kambiz
K
Khosravi
M Ehsanul
ME
Hoque
Brian
B
Dimock
Holger
H
Hintelmann
Chris D
CD
Metcalfe
D000645:Ammonium Sulfate / Q000737:chemistry*; D013058:Mass Spectrometry; D053768:Metal Nanoparticles / Q000737:chemistry*; D013473:Sunscreening Agents / Q000737:chemistry; D014025:Titanium / Q000032:analysis* / Q000737:chemistry; D014865:Waste Disposal, Fluid; D014867:Water / Q000737:chemistry*
D013473:Sunscreening Agents; D014867:Water; C009495:titanium dioxide; C031276:ammonium peroxydisulfate; D014025:Titanium; D000645:Ammonium Sulfate