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Examining the efficiency of muffle furnance-induced alkaline hydrolysis in determining the titanium content of environmental samples containing engineered titanium dioxide particles
Citation:
Silva, G., M. Nadagouda, J. Webster, S. Govindaswamy, K. Hristovski, R. Ford, C. Patterson, AND C. Impellitteri. Examining the efficiency of muffle furnance-induced alkaline hydrolysis in determining the titanium content of environmental samples containing engineered titanium dioxide particles. Environmental Science: Processes & Impacts. RSC Publishing, Cambridge, Uk, 15(3):645-652, (2013).
Impact/Purpose:
This work provides researchers with a less costly safer method for quantifying titanium in samples containing titanium nanoparticles.
Description:
A novel muffle furnace (MF)-based potassium hydroxide (KOH) fusion digestion technique was developed and its comparative digestion and dissolution efficacy for different titanium dioxide nanoparticles (TiO2-NPs)/environmental matrices was evaluated. Digestion of different environmental samples containing sediments, clay minerals and humic acid with and without TiO2-NPs was first performed utilizing the MF-based KOH fusion technique and its dissolution efficacy was compared to a Bunsen burner (BB)-based KOH fusion method. The three types of TiO2-NPs were then digested with aforementioned KOH fusion techniques and microwave (MW)-based nitric (HNO3)/hydrofluoric (HF) mixed acid digestion methods. Statistical analysis of results revealed that the dissolution of TiO2-NP spiked environmental matrices in the MF-based KOH fusion was comparable to the BB-based KOH fusion. The measured Ti recoveries compared to calculated values were 96%, 85% and 87% for anatase, brookite and rutile TiO2-NPs, respectively, by the MF-based fusion technique. These recoveries were consistent and less variable than the BB-based fusion technique recoveries of 104%, 97% and 72% and MV-based HNO3/HF mixed acids digestion recoveries of 80%, 81% and 14%, respectively, for anatase, brookite and rutile TiO2-NPs. The MF-based fusion technique is consistently superior in digestion efficiency across all three TiO2-NPs and complete dissolution of the refractory metal titanium (Ti) can be achieved in a simpler experimental set-up. The MF-based fusion technique required 20 minutes for digestion of 25 samples (based on in-house Lindberg MF capacity) compared to 8 hours for the same number of samples using the BB-based fusion technique. Thus, the MF-based fusion technique can be used to dissolve a large number of samples in a shorter time (e.g., 500 samples/8 hours) while conserving energy and eliminating health and safety risks from methods involving HF.
