Silicate minerals and rocks react with water and carbon dioxide and turn into other minerals and rocks (often clays). This is known as silicate weathering and occurs most rapidly under warm and humid conditions. If the primary minerals contain calcium this will be liberated during the weathering process and eventually be taken up in limestone (CaCO3) when it becomes bonded with carbonate ions. This is a complex process, but the net reaction model for silicate weathering is known as the Urey reaction and can be expressed as:

CaSiO3 + CO2 forms CaCO3 and SiO2.

In this reaction CaSiO3 (wollastonite) represent the generally more complex silicate minerals.

Dissolving CO2 in water produces the weak acid H2CO3. The acid will weather calcium silicate rocks and produce a solution of CaCO3. The problem is then to evaporate the solution in order to produce solid CaCO3 - chalk/limestone.

Perhaps the attached file might be of help in answering the question.

Jorge, The discrepancy between the known about 400 ppm CO2 and your calculated 45 ppm has two explanations:

I predict that someone who know how to calculate a gas concentration find the numbers fit.

It was article about that at science or nature last month

Jorge, Regarding the "compacted mountain (almost a cube) with a squared base with one kilometer each side and 830 meters high every year" there wasn't any increase then CO2 is fixed in the rocks in Iceland. Kenneth had a similar comment in the thread: www.researchgate.net/post/How_does_CarbFix_turns_a_power_plants_CO2_emissions_into_Basalts

I think you didn't consider that you are taking the Ca2+ from another mineral which loses weight and volume.

The final step and the safest of CO2 geological trapping is called mineral trapping. in this final stage, CO2 reacts with the minerals to produce carbonates and be permanently part of the rock. We can recognize the rock by its white color (Carbonates). Some researchers are working on the industrial applications

Interesting question

Interesting discussion.

Thank you Kenneth M Towe. for the useful information.

Jorge,

As I have pointed out before a basic error in your calculation is that you base the calculation on that "One ton of CO2 occupies 556.2m³ of volume." Which is derived based at 1 atm and 25 °C. In reality the pressure of the atmosphere at 10 km height is about 0.25 atm. which result in that the volume of the gas is four-fold higher. It is a basic result of the ideal gas law: V=nRT/P.

Jorge,

I agree with you that in the correct calculation of the concentration increase of CO2 expected by adding 230 Gton carbon to the atmosphere pressure is not important and the ideal gas law cannot be used. The dilemmas of your calculations are both that the temperature and pressure of the atmosphere varies drastically with height if you consider the atmosphere to go up to 10 km, but also about 25 % of the mass of the atmosphere is present above 10 km. While you agree with me on this you still use in your calculations the ideal gas law to get the 24 L/mol that your calculation is based on assuming 1 atm and 25 °C which is both values higher than any meaningful estimate of the average values in the atmosphere. I cannot see that the CO2 should have any other temperature and pressure than the entire atmosphere of the Earth which it is diluted into.

I am sorry that I have to admit that I cannot follow you on the Ostwald law (https://en.wikipedia.org/wiki/Law_of_dilution). To me it only applies to solutes in liquid.

Anyway my point is that if you calculate the concentration without using the ideal gas law and making any assumptions about the volume occupied by the atmosphere, it's temperature nor it's pressure you will - with a very simple calculation - end up at something in the order of 109 ppmv CO2 added which roughly brings us from 285 ppmv to 394 ppmv, not far from the 400 ppmv considering that this can be calculated in just two lines.

Kenneth, It is hard to believe but I agree with you. 230 GtC is just above 100 ppmv in the atmosphere and turning such an amount into carbonate rock is not possible with the technologies and energy sources available today.

Jorge, I also agree with your statement " THERE IS NO INFLUENCE OF PRESSURE NOR OF THE TEMPERATURE IN A MEAN DILUTION CALCULATION. " I try to point out that your calculation is disagrees with your statement as it is based on 1 atm./25 °C which doesn't represent the earths atmosphere well.

Jorge,

Obviously fossil fuel burns at several hundreds degrees before the flue gas goes into the atmosphere and soon equilateral to the ambient temperature. The volume of a gas depend on it's actual temperature and pressure, not that it was. In the atmosphere the pressure is 1 atm at ground level and decreases to 0.5 atm. about 5-8 km up depending on the latitude and reaches 0 atm about 10x higher.

There is no layering of the troposphere. For a simple calculation one should just assume CO2 has the same mixing ratio at least in the troposphere and it doesn't deviate much in the next layers. It is exactly the basis of the calculation of concentration of a gas in the atmosphere with the unit "ppmv" that it is constant with height even the partial pressure and molecular volume is different at any height that a chemist would use but which you claim is wrong. To me it seems you didn't look how others have calculated this but just made your own method based on that CO2 is 24 L/mol which assumes 1 atm and 25 °C.

At 0.25 atm a mole of CO2 takes up slightly more than 100 L if the temperature is still 25 °C; V=nRT/P.

The concentration of CO2 given as volume mixing ratio (unit ppmv) is the same in the atmosphere at ground level and 10 km higher.

(Figur from https://co2islife.wordpress.com/2018/03/11/global-warming-science-fair-project-co2-and-global-warming/)

In your wrongly calculated CO2 increase of 43 ppmv you are missing about 70 ppmv, not 170 ppmv, to get to the current 400 ppmv.

I believe the CO2 volume mixing ratio (unit ppmv) is the same through the troposphere and likely up to 60-80 km. You can find the same in many sources and it also agrees with the behaviour of ideal gases. I have never looked for a figure of this before your question came up because it is so obvious. I selected that one because graphs in scientific works do not include the lower atmosphere or shows deviations from average rather than the actual concentrations as there never was scientific doubt the concentration is constant there and around 400 ppmv. E.g. figure 1 in

Article Validation of the global distribution of CO 2 volume mixing ...

You remain right and wrong: Volume mixing ratio which has the unit ppmv "does not depend on P, T. It only depends on gas volume in 106 volume of air". You are still wrong in in your alternative method of calculation using 1 atm, 25 °C and a height of 10 km for the atmosphere. Obviously the atmosphere pressure is lower except just at ground level. The temperature is lower with an average about 15 °C at ground level and falling with altitude and the atmosphere extending meaningful until about 100 km.

Instead of discusing your calculation that can never succeed because you will never find a representative T and P for your calculation, how about that you explain what you find is wrong in the normal method of calculating volume mixing ratios of gases in the atmosphere: XCO2 = VCO2/VAir = (nCO2RT/P)/(nAirRT/P)= nCO2/nAir

Dear colleagues,

Thanks for the question! I think the conversion of CO2 into powder is the first step which is practical now. The second step is the conversion of power into great stones.

With my best wishes!

Dr. Adel OUESLATI

This debate provides inspiration for a future student assignment on the sense and nonsense of geo-engineering in order to capture CO2 from the atmosphere. Thanks for all contributions.

Jorge,

It seems you don't understand XCO2 is constant with height. You keep on having 1 atm as the pressure in your calcualtion but that doesn't represent the atmosphere. Therefor you make a calculation mistake and that is the basis of your deviation from that you read the XCO2 is. You didn't discover a flaw in the climate scientist data, just in your chemical calculation skills.

Kenneth

One of the rationales of the group assignment is actually to write a preparatory note for policy makers in which the results are summarized. Off topic: Next to rock weathering, a parallel topic might be the assumed CO2 draw down from ocean fertilizing through iron and other nutrients.

Jorge, It is so easy to prove you are wrong. Just lose the fake news idea that the you can calculate the fossil carbon burning only contributed 43.5 ppmv to the atmosphere concentration. If you write it again I will point out your failure again.

Using your several times wrong method of calculating but replacing with the pressure at 10 km of 0.25 atm gives 4x higher volume of CO2 and thus you would end up with an increase of 177 ppmv CO2. Obviously that is higher than the maximum you claim your method can give. Adding this to 285 ppmv gives 459 ppmv. The actual current concentration is about 410 ppmv. https://www.co2.earth/daily-co2.

If you were a scientist you would investigate the actual method used by others and explain how your method is better - obvious you have not even considered this.

Off-topic: Kenneth.I will not take a position on this off-topic here. It's up to the students to do the analysis without prior opinion by the instructor - off-topic closed..

I have already commented on this text.

Article Thermal Enhancement on Planetary Bodies and the Relevance of...

Jorge,

Then I said that I gave several references that support this. The publisher behind the journal (sciencePG) is repeatedly mentioned in literature about predatory publishers. Consult Beall's list of predatory publishers if you have any doubt.

Anyone with a understanding of spectroscopy can see that the author of the paper doesn't understand infrared absorption which an actual reviewer would have used as argument for rejecting the paper.

Jorge, I disagree on your notion about predatory publishers. This have to be addressed frequently, just like other rotten science. If we were to ignore these publishers they would be much more successful in tricking researchers to send manuscripts and pay their fees.