Dear Oliver, I think it is not so trivial as you wrote - different steps of reactions which you wrote are prefered at different pH. Please for example see this web link and graph on the bottom of the web page: http://ion.chem.usu.edu/~sbialkow/Classes/3650/Carbonate/Carbonic%20Acid.html best wishes, Lidija
On Friday, 8 February 2013 11:52:15 UTC, Oliver Tickell wrote: > > Unfortunately my confusion is only deepening ... > There is more CO2 in the np system - but I thought it was meant to be > H2CO3, not CO2. > There is HCO3- on the nickel - but no bicarbonate in the system. > If the solution is acidic (ie, there is lots of H+ in the solution), where > is the acidity coming from if not from dissociation of carbonic acid: > H2CO3 + H2O <=> H+, HCO3- <=> 2H+, CO3= ? > But you say only carbonic acid present. > > Oliver. > > On 07/02/2013 23:51, gaurav bhaduri wrote: > > Dear all > > Thank you for your interest in our work and your comments. To clarify some > of the misunderstanding in the process conditions that I'd like to clarify. > When we bubble CO2 in water with and without the nanoparticles, we observed > that there is more CO2 in the nanoparticle system than in pure water. We > also observed that there was HCO3- ions on the surface of the Ni > nanoparticles surface, we thus explained that this enhancement could be due > to adsorption of the HCO3- (from the acid) onto the Ni surface. We in no > place claim the formation of CO3-- ions, to be clear on this point the > system we are addressing in this article is at a acidic pH (<5). Thus there > is only carbonic acid species present no bicarbonate or carbonate system as > they exist at higher pH values. > > Now coming to the point of mineralization. We are currently working on > this (as explained by Dr Siller, previously) and would like to use > silicates as our metal source (Ca2+ or Mg2+). > > Regarding the confusion of sea or oceanic system. We do not tend to imply > the use of Ni nanoparticles in the ocean or any thing around it. The > relation with sea urchin (or the marine environment) is just that, the use > of Ni to study the hydration reaction we triggered by the studies done on > the sea urchin by Dr Siller and my other colleagues. > > Our major application is to use this system as a satellite unit (plant) to > an operational point source emitter (for example a power plant). The > carbonate mineral thus produced would be used as landfill or in any other > useful application. As mentioned above, we are working on the use of > silicate sources (terrestrial) for the source of the alkali earth metals > (Ca2+ or Mg2+), thus ruling out acidification of the ocean or any relation > to the ocean. > > Hope I was able to explain the application of our technology. If you still > have any doubts, please feel free to ask. We will try our level best to > clarify any confusion. > > Thanks to all > > Kind regards > Gaurav > > On Thursday, 7 February 2013 18:49:41 UTC, Greg Rau wrote: >> >> Thanks for responding. I really don't follow this. If I have a beaker >> of water fully equilibrated with air (CO2) and add your Ni particles, you >> are saying that more HCO3- and ultimately CO3s will spontaneously be >> produced. This won't happen unless thermodynamically favored, and if that >> water if fully equilibrated with air CO2 there is no thermodynamic >> condition that will force a change in the C chemistry. If your Ni >> particles are somehow consuming H+ or producing OH- then you've got a >> driving force, but you still need a source cations to make CaCO3s (am >> very interested to learn how you cheaply extract cations from silicates.) >> Otherwise, adding a catalyst to a system at thermodynamic equilibrium does >> nothing. On the other hand, adding something to seawater that overcomes >> the natural, chemical inhibition of abiotic CaCO3s precipitation could >> really cause some serious precipitation and CO2 injection into the >> atmosphere. No? >> -Greg >> >> From: "[email protected]" <[email protected]> >> Reply-To: "[email protected]" <[email protected]> >> Date: Thursday, February 7, 2013 8:32 AM >> To: geoengineering <[email protected]> >> Subject: [geo] Re: Nickel nanoparticles catalyse reversible hydration of >> carbon dioxide for mineralization carbon capture and storage - Catalysis >> Science & Technology (RSC Publishing) >> >> >> With presence of Ni we have increases at the same time trapping of CO2 >> and increased the rates of conversion to carbonic acid on room temperature >> and on the atmospheric pressure. >> We still working to find the best mineralisation pathway - we will use >> silicates (magnesium calcium silicates) as a source of Ca2+ or Mg2+. >> >> While nickel nanoparticles are toxic as already mentioned in the paper we >> do not propose to spread this around in the enviroment but to have local >> disposal next to power plant or industrial plant. >> We made brief cost - 8$ per ton of CO2 if we can recover Ni 99% yield >> based on current price of nickel. >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/geoengineering?hl=en. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > To post to this group, send email to [email protected]<javascript:> > . > Visit this group at http://groups.google.com/group/geoengineering?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
