Health & Environmental Research Online (HERO)


Print Feedback Export to File
5931465 
Journal Article 
Regenerable alpha-MnO2 nanotubes for elemental mercury removal from natural gas 
Chalkidis, A; Jampaiah, D; Hartley, PG; Sabri, YM; Bhargava, SK 
2019 
Yes 
Fuel Processing Technology
ISSN: 0378-3820 
193 
317-327 
WOS:000473842100032 
The elemental mercury (Hg) vapor removal ability of a-MnO2 nanotubes (NTs), nanorods (NRs) and nanowires (NWs) was evaluated in simulated natural gas mixtures. It was shown that NTs exhibited superior efficiency (-100%) at the temperature range of interest (25-100 C). The Hg breakthrough (corresponding to 99.5% Hg removal efficiency) at ambient conditions and Hg g, = 870 ugm-3, occurred after 48 h, reflecting a Hg uptake of > 10 mg.g-1 (1 wt%). Most importantly, the developed nanosorbent was repeatedly, sufficiently regenerated at the relatively low temperature of 250 C in a series of seven successive sorption-desorption tests, maintaining its capacity to remove all incoming Her, in each cycle. Interestingly, kinetic studies showed that at least 85% of total adhered Hg could be recovered within the first hour of a 3-h regeneration process. Moreover, the presence of CO2 and H2S did not affect its activity. The thermogravimetric analysis indicated significantly higher dehydration for NTs due to the loss of bound water inside its tunnels, likely indicating the presence of abundant surface adsorbed oxygen species which are believed to facilitate Hg adsorption. This was also confirmed by Xray spectroscopy, possibly explaining the enhanced activity of NTs. 
Alpha-phase manganese dioxide; Morphology; Nanotubes; Elemental mercury removal; Regenerable sorbent; Natural gas processing